Extracción del cristalino para el glaucoma crónico de ángulo cerrado
Resumen
Antecedentes
El glaucoma primario de ángulo cerrado (GPAC) se caracteriza por un aumento de la presión intraocular (PIO) secundario a una obstrucción del flujo acuoso, siendo el bloqueo pupilar relativo el mecanismo subyacente más frecuente. Cada vez hay más evidencia de que la extracción del cristalino podría aliviar el bloqueo pupilar y, por tanto, mejorar el control de la PIO. Por ello, la comparación de la efectividad de la extracción del cristalino con otras modalidades de tratamiento utilizadas habitualmente podría ayudar a informar el proceso de toma de decisiones.
Objetivos
Evaluar la efectividad de la extracción del cristalino en comparación con otras intervenciones en el tratamiento del GPAC crónico en personas sin ataques agudos de ángulo cerrado anteriores.
Métodos de búsqueda
Se hicieron búsquedas en CENTRAL, MEDLINE, Embase, otra base de datos y dos registros de ensayos (diciembre de 2019). También se revisaron las listas de referencias de los estudios incluidos y la base de datos Science Citation Index. No se aplicaron restricciones de fecha ni de idioma.
Criterios de selección
Se incluyeron los ensayos controlados aleatorizados (ECA) que compararan la extracción del cristalino con otras modalidades de tratamiento para el GPAC.
Obtención y análisis de los datos
Se siguió la metodología estándar de Cochrane.
Resultados principales
Se identificaron ocho ECA con 914 ojos. Se obtuvieron los datos de los participantes que cumplían los criterios de inclusión de esta revisión en estos estudios (sólo GPAC, sin ataques agudos de ángulo cerrado previos), lo que dio como resultado que se incluyeran 513 ojos. Los participantes procedían de una gran variedad de países. No fue posible realizar metanálisis debido a los diferentes períodos de seguimiento y a los datos insuficientes.
Un estudio comparó la facoemulsificación con la iridotomía periférica con láser (IPL) como tratamiento estándar. Los participantes del grupo de facoemulsificación tuvieron menos probabilidades de experimentar una progresión de la pérdida del campo visual (odds ratio [OR] 0,35; intervalo de confianza [IC] del 95%: 0,13 a 0,91; 216 ojos; evidencia de certeza moderada), y requirieron menos fármacos reductores de la PIO (diferencia de medias [DM] ‐0,70; IC del 95%: ‐0,89 a ‐0,51; 263 ojos; evidencia de certeza moderada) en comparación con la atención estándar a los 12 meses. Evidencia de certeza moderada también indicó que la facoemulsificación mejoró los hallazgos gonioscópicos a los 12 meses o más (DM ‐84,93; IC del 95%: ‐131,25 a ‐38,61; 106 ojos). Hubo poca o ninguna diferencia en las medidas de calidad de vida relacionadas con la salud (DM 0,04; IC del 95%: ‐0,16 a 0,24; 254 ojos; evidencia de certeza moderada), y en la agudeza visual (AV) (DM 2,03 letra ETDRS; IC del 95%: ‐0,77 a 4,84; 242 ojos) a los 12 meses, y ninguna diferencia observable en la PIO media (DM ‐0,03 mmHg; IC del 95%: ‐2,34 a 2,32; 257 ojos; evidencia de certeza moderada) en comparación con la atención estándar. Se observó una pérdida irreversible de la visión en un participante del grupo de facoemulsificación y en tres participantes de la atención estándar a los 36 meses (evidencia de certeza moderada).
Un estudio (91 ojos) comparó la facoemulsificación con la facoviscogonioplastia (faco‐VGP). Evidencia de certeza baja indicó que se necesitaron menos fármacos reductores de la PIO a los 12 meses con la facoemulsificación (DM ‐0,30; IC del 95%: ‐0,55 a ‐0,05). Evidencia de certeza baja también indicó que la facoemulsificación podría haber mejorado los hallazgos gonioscópicos a los 12 meses o más en comparación con la faco‐VGP (DM del grado angular ‐0,60; IC del 95%: ‐0,91 a ‐0,29; DM de TISA500 ‐0,03; IC del 95%: ‐0,06 a ‐0,01; DM de TISA750 ‐0,03; IC del 95%: ‐0,06 a ‐0,01; 91 ojos). La facoemulsificación podría suponer poca o ninguna diferencia en la AV mejor corregida a los 12 meses (DM ‐0,01 unidades logMAR; IC del 95%: ‐0,10 a 0,08; evidencia de certeza baja), y la evidencia es muy incierta acerca de los efectos sobre la PIO a los 12 meses (DM 0,50 mmHg; IC del 95%: ‐2,64 a 3,64; evidencia de certeza muy baja). Se observó una reacción de fibrina posoperatoria en dos participantes del grupo de facoemulsificación y en cuatro del grupo de faco‐VGP. Tres participantes del grupo de faco‐VGP presentaron hipema. No se dispuso de datos sobre la progresión de la pérdida del campo visual ni sobre las mediciones de la calidad de vida a los 12 meses.
Dos estudios compararon la facoemulsificación con la faco‐goniosinequiolisis (faco‐GSL). Evidencia de certeza baja indicó que podría haber poca o ninguna diferencia en la PIO media a los 12 meses (DM ‐0,12 mmHg; IC del 95%: ‐4,72 a 4,48; un estudio; 32 ojos) entre las intervenciones. La facoemulsificación no redujo el número de fármacos reductores de la PIO en comparación con la faco‐GSL a los 12 meses (DM ‐0,38; IC del 95%: ‐1,23 a ‐0,47; un estudio, 32 ojos; evidencia de certeza moderada). Tres ojos del grupo de faco‐GSL desarrollaron hipemas. No se dispuso de datos a los 12 meses sobre la progresión de la pérdida del campo visual, los hallazgos gonioscópicos, la agudeza visual ni sobre las mediciones de la calidad de vida.
Tres estudios compararon la facoemulsificación con facotrabeculectomía combinada, pero solo se dispuso de datos de un estudio (63 ojos). En este estudio, evidencia de certeza baja indicó que hubo poca o ninguna diferencia entre los grupos en el cambio medio de la PIO desde el inicio (DM ‐0,60 mmHg; IC del 95%: ‐1,99 a 0,79), el número de fármacos reductores de la PIO a los 12 meses (DM 0,00; IC del 95%: ‐0,42 a 0,42) y la AV medida por la tabla de Snellen (DM ‐0,03; IC del 95%: ‐0,18 a 0,12). Los participantes del grupo de facoemulsificación presentaron menos complicaciones (razón de riesgos [RR] 0,59; IC del 95%: 0,34 a 1,04), y el grupo de faco‐trabeculectomía requirió más procedimientos de reducción de la PIO (RR 5,81; IC del 95%: 1,41 a 23,88), pero la evidencia fue muy incierta. No hubo datos disponibles para otros desenlaces.
Conclusiones de los autores
Evidencia de certeza moderada mostró que la extracción del cristalino tiene una ventaja sobre la IPL en el tratamiento del GPAC crónico con cristalinos transparentes durante tres años de seguimiento; en última instancia, la decisión de la intervención debe formar parte de un proceso de toma de decisiones compartido entre el médico y el paciente. Para las personas con GPAC crónico y cataratas visualmente significativas, evidencia de certeza baja indicó que la combinación de facoemulsificación con viscogonioplastia o goniosinequiolisis no tiene efectos beneficiosos adicionales a la facoemulsificación sola. No hubo evidencia suficiente para establecer conclusiones importantes con respecto a la facoemulsificación versus la trabeculectomía. Evidencia de certeza baja indicó que la combinación de facoemulsificación con trabeculectomía no confiere efectos beneficiosos adicionales a la facoemulsificación sola y que, en su lugar, podría causar más complicaciones. Estas conclusiones sólo se aplican a los desenlaces a corto y medio plazo; los estudios con períodos de seguimiento más prolongados pueden ayudar a evaluar si estos efectos persisten a largo plazo.
PICO
Resumen en términos sencillos
¿Cuáles son los riesgos y beneficios de la extracción del cristalino para tratar el glaucoma crónico primario de ángulo cerrado?
¿Por qué es importante esta pregunta?
El glaucoma primario de ángulo cerrado (GPAC) es un tipo de glaucoma que constituye una de las principales causas de ceguera en todo el mundo. Se produce cuando hay problemas para drenar el líquido del ojo porque el iris (la parte coloreada del ojo) ha bloqueado los canales de drenaje. La obstrucción puede producirse de forma repentina (GPAC agudo) o gradual (GPAC crónico) y provocar la acumulación de líquido y el aumento la presión dentro del ojo, lo que puede dañar el nervio óptico y causar una pérdida de visión. Entre las opciones terapéuticas se encuentran las gotas para los ojos (colirios), el tratamiento con láser y la cirugía. La "extracción del cristalino" es un tipo de cirugía en la que se sustituye el cristalino natural por una lente artificial. Esto también tiene el efecto de abrir los canales de drenaje y podría ayudar a tratar el GPAC. Se revisó la evidencia de los estudios de investigación para determinar cómo se compara la extracción del cristalino con otros tratamientos del GPAC crónico.
¿Cómo se identificó y evaluó la evidencia?
Se buscaron estudios que compararan la extracción del cristalino con otros tratamientos para el GPAC crónico en la literatura médica, se compararon los resultados y se resumió la evidencia de todos los estudios y se calificó la confianza en la evidencia.
¿Qué se encontró?
Se encontraron ocho estudios con 513 ojos con GPAC crónico que cumplieron los criterios de inclusión. Los estudios hicieron un seguimiento de los participantes durante entre seis y 69 meses, y compararon la extracción del cristalino con:
‐ tratamiento con láser;
‐ extracción del cristalino más una inyección de líquido espeso para romper las adherencias del iris con el objetivo de favorecer el drenaje de líquidos (viscogonioplastia, VGP);
‐ extracción del cristalino más rotura de las adherencias del iris de forma mecánica, lo que se conoce como goniosinequiolisis (GSL);
‐ trabeculectomía (creación de un colgajo para facilitar el drenaje de líquidos); y
‐ extracción del cristalino más trabeculectomía.
Estas son las principales conclusiones de la revisión, centradas en los resultados un año después del tratamiento (a menos que se indique lo contrario).
1. Extracción del cristalino comparada con tratamiento con láser (un estudio)
Cuando se comparó con el tratamiento con láser, la evidencia indica que la extracción del cristalino probablemente:
‐ limita la pérdida del campo visual (la zona que se puede ver cuando el ojo mira de frente);
‐ reduce el número de medicamentos hipotensores necesarios;
‐ abre más el ángulo de drenaje; y
‐ supone poca o ninguna diferencia en la calidad de vida, la claridad de la visión o en la presión del ojo.
Una persona tratada con extracción del cristalino, y tres personas tratadas con láser, experimentaron una pérdida irreversible de 10 o más letras EDTRS de visión en los tres años posteriores al tratamiento.
2. Extracción del cristalino comparada con extracción del cristalino más VGP (un estudio)
Cuando se comparó con la extracción del cristalino más VGP, la evidencia indica que la extracción del cristalino podría:
‐ reducir el número de medicamentos hipotensores necesarios;
‐ abre más el ángulo de drenaje; y
‐ suponer poca o ninguna diferencia en cuanto a la claridad de la visión.
Existe evidencia incierta acerca de si los dos tratamientos tienen efectos diferentes sobre la presión del ojo. El estudio no investigó los efectos sobre la pérdida del campo visual y la calidad de vida.
Se produjo una inflamación ocular en dos personas tratadas con extracción del cristalino, y en cuatro personas tratadas con extracción del cristalino más VGP. Tres personas tratadas con extracción del cristalino más VGP experimentaron sangrado en la parte frontal del ojo.
3. Extracción del cristalino comparada con extracción del cristalino más GSL (dos estudios)
Cuando se comparó con la extracción del cristalino más GSL, la evidencia indica que la extracción del cristalino:
‐ probablemente no reduce el número de medicamentos hipotensores necesarios; y
‐ podría suponer poca o ninguna diferencia en cuanto a la presión ocular.
Los estudios no investigaron los efectos sobre la pérdida del campo visual, el drenaje del ojo, la claridad de la visión ni la calidad de vida.
Tres personas tratadas con extracción del cristalino más GSL experimentaron hemorragia en la parte frontal del ojo.
4. Extracción del cristalino comparada con extracción del cristalino más trabeculectomía (tres estudios)
Cuando se comparó con la extracción del cristalino más trabeculectomía, la evidencia de un estudio indica que la extracción del cristalino podría suponer poca o ninguna diferencia en:
‐ la presión ocular;
‐ el número de medicamentos hipotensores necesarios; y
‐ la claridad de la visión.
Existe evidencia incierta acerca de si un tratamiento provoca más efectos no deseados que otro. Los estudios no investigaron los efectos sobre la pérdida del campo visual, el drenaje del ojo ni la calidad de vida.
¿Qué significa esto?
La evidencia indica lo siguiente:
‐ la extracción del cristalino probablemente es un tratamiento mejor que el láser para el GPAC crónico;
‐ la combinación de la extracción del cristalino con la VGP o la GSL podría no funcionar mejor que la extracción del cristalino sola; y
‐ existe evidencia incierta acerca de si la combinación de la extracción del cristalino con la trabeculectomía supone alguna diferencia.
¿Cuál es el grado de actualización de esta revisión?
La evidencia en esta revisión Cochrane está actualizada hasta el 13 de diciembre de 2019.
Authors' conclusions
Summary of findings
| Phacoemulsification compared with laser peripheral iridotomy for primary angle‐closure glaucoma | ||||||
|---|---|---|---|---|---|---|
| Patient or population: participants with primary angle‐closure glaucoma Settings: 30 hospital eye services in Australia (1), mainland China (1), Hong Kong (2), Malaysia (2), Singapore (2), and the UK (22) Intervention: phacoemulsification Comparison: laser peripheral iridotomy (LPI) | ||||||
| Outcomes | Illustrative comparative risks* (95% CI) | Relative effect | No of eyes | Certainty of the evidence | Comments | |
| Assumed risk | Corresponding risk | |||||
| laser peripheral iridotomy | phacoemulsification | |||||
| Progression of visual field loss (at 12 months) | 165 per 1000 | 65 per 1000 (25 to 152 per 1000) | OR 0.35 (0.13 to 0.91) | 216 | ⊕⊕⊕⊝ | ‐ |
| Mean IOP change from baseline to 12 months | The mean change in IOP in the control group was ‐6.48 mmHg | The mean change in IOP in the intervention group was 0.03 mmHg higher (95% CI ‐2.34 mmHg to 2.32 mmHg) | ‐ | 257 | ⊕⊕⊕⊝ | ‐ |
| Mean number of medications to control IOP (at 12 months) | On average, the number of medications in the control group was 0.98 | On average, the number of medications in the intervention group was 0.70 lower (95% CI ‐0.89 to ‐0.51) | ‐ | 263 | ⊕⊕⊕⊝ | ‐ |
| Gonioscopic findings (at 12 months or later) | The mean angle closure in the control group was 203° | The mean angle closure in the intervention group was 84.93° less (95% CI 38.61° to 131.25°) | 106 | ⊕⊕⊕⊝ | ‐ | |
| Visual acuity (at 12 months) | The mean visual acuity in the control group was 77.4 | The mean visual acuity in the intervention group was 2.03 letters greater (95% CI ‐0.77 to 4.84) | ‐ | 242 | ⊕⊕⊕⊝ | ‐ |
| Adverse effects | No data available | ‐ | ‐ | ‐ | ‐ | |
| Quality of life measures (at 12 months) | The average score on the EQ‐5D in the control group was 2.88 | The average score on the EQ‐5D in the intervention group was 0.04 higher (95% CI ‐0.16 to 0.24) | ‐ | 254 (one study) | ⊕⊕⊕⊝ | ‐ |
| *The assumed risk is based on the estimate in the control group. The corresponding risk (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI). CI: confidence interval; IOP: intraocular pressure; MD: mean difference; OR: odds ratio; EQ‐5D: European Quality of Life‐5 Dimension | ||||||
| GRADE Working Group grades of evidence | ||||||
| aDowngraded one level for imprecision because sample size was not adequately powered (original study was powered to investigate participants with both primary angle closure (PAC) and primary angle‐closure glaucoma (PACG), whereas only participants with PACG were included in this analysis). | ||||||
| Phacoemulsification versus phacoemulsification plus viscogonioplasty for primary angle‐closure glaucoma | ||||||
|---|---|---|---|---|---|---|
| Patient or population: participants with primary angle‐closure glaucoma Settings: university hospital in Iran Intervention: phacoemulsification Comparison: phacoemulsification plus viscogonioplasty (phaco‐VGP) | ||||||
| Outcomes | Illustrative comparative risks* (95% CI) | Relative effect | No of Participants | Certainty of the evidence | Comments | |
| Assumed risk | Corresponding risk | |||||
| phacoemulsification plus viscogonioplasty | phacoemulsification | |||||
| Progression of visual field loss | No data available for this outcome | ‐ | ‐ | ‐ | ‐ | |
| Mean IOP change from baseline to 12 months | The mean change in IOP in the control group was ‐8.8 mmHg | The mean change in IOP in the intervention group was | ‐ | 91 eyes | ⊕⊕⊝⊝ | ‐ |
| Mean number of medications to control IOP (at 12 months) | The mean number of medications to control IOP in the control group was 0.4 | The mean number of medications to control IOP in the intervention groups was 0.1; on average, 0.30 fewer (95% CI ‐0.55 to ‐0.05) | ‐ | 91 eyes | ⊕⊕⊝⊝ | at 6 months: MD ‐0.30 (95% CI ‐0.56 to ‐0.04; 1 study, 91 eyes) |
| Gonioscopic findings (at 12 months or later) | The mean change of angle grading in the control group was 2.0 | The mean change of angle grading in the intervention group was 1.4; on average, 0.60 less (95% CI ‐0.91 to ‐0.29) | ‐ | 91 eyes | ⊕⊕⊝⊝ | ‐ |
| Gonioscopic findings (TISA500) (at 12 months) | The mean TISA500 in the control group was 0.054 | The mean TISA500 in the intervention group was 0.020; on average, 0.03 less (95% CI ‐0.06 to ‐0.01) | ‐ | 91 eyes | ⊕⊕⊝⊝ | ‐ |
| Gonioscopic findings (TISA750) (at 12 months) | The mean TISA750 in the control group was 0.119 | The mean TISA750 in the intervention group was 0.084; on average, 0.03 less (95% CI ‐0.06 to ‐0.01) | ‐ | 91 eyes | ⊕⊕⊝⊝ | ‐ |
| Visual acuity (postoperatively) | The mean best corrected visual acuity in the control group was 0.28 | The mean best corrected visual acuity in the intervention group was 0.27; on average, 0.01 less (95% CI ‐0.10 to 0.08) | ‐ | 91 eyes | ⊕⊕⊝⊝ | ‐ |
| Adverse effects | hyphema (3 eyes), postoperative fibrin reaction (4 eyes) | postoperative fibrin reaction (2 eyes) | ‐ | ‐ | ‐ | |
| Quality of life measures | No data available for this outcome | ‐ | ‐ | ‐ | ‐ | |
| *The assumed risk is based on the estimate in the control group. The corresponding risk (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI). | ||||||
| GRADE Working Group grades of evidence | ||||||
| aDowngraded for high risk of attrition bias | ||||||
| Phacoemulsification versus phacoemulsification plus goniosynechialysis for primary angle‐closure glaucoma | ||||||
|---|---|---|---|---|---|---|
| Patient or population: participants with primary angle closure glaucoma Settings: tertiary eye care center and university hospital in Vietnam, Thailand, and Hong Kong Intervention: phacoemulsification Comparison: phacoemulsification plus goniosynechialysis (phaco‐GSL) | ||||||
| Outcomes | Illustrative comparative risks* (95% CI) | Relative effect | No of Participants | Certainty of the evidence | Comments | |
| Assumed risk | Corresponding risk | |||||
| phacoemulsification plus goniosynechialysis | phacoemulsification | |||||
| Progression of visual field loss | No data available for this outcome | ‐ | ‐ | ‐ | ‐ | |
| Mean IOP change from baseline (at 12 months) | The mean change in IOP in the control group was ‐6.47 mmHg | The mean change in IOP in the intervention group was ‐6.59; on average, 0.12 lower (95% CI ‐4.72 to 4.48) | ‐ | 32 eyes | ⊕⊕⊕⊝ | at 6 months: MD ‐0.04 mmHg (95% CI ‐0.93 to 0.85; 1 study, 64 eyes) |
| Mean number of medications to control IOP (at 12 months) | The mean number of medications to control IOP in the control group was 0.94 | The mean number of medications to control IOP in the intervention groups was 0.56; on average, 0.38 fewer (95% CI ‐1.23 to 0.47) | ‐ | 32 eyes | ⊕⊕⊕⊝ | at 6 months: MD ‐0.35 (95% CI ‐0.63 to ‐0.07; 1 study, 64 eyes) |
| Gonioscopic findings (at 6 months) | See comments | See comments | ‐ | 64 eyes (one study) | ‐ | AOD500: MD ‐0.04° (95% CI ‐0.27 to 0.19) AOD750: MD 0.01° (95% CI ‐0.27 to 0.29) TISA500: MD ‐0.02° (95% CI ‐0.06 to 0.02) TISA750: MD ‐0.03° (95% CI ‐0.17 to 0.11) SSA: MD ‐1.59° (95% CI ‐6.75 to 3.57) |
| Visual acuity | No data available for this outcome | ‐ | ‐ | ‐ | ‐ | |
| Adverse effects | hyphema (3 eyes) | none reported | ‐ | ‐ | ‐ | |
| Quality of life measures | No data available for this outcome | ‐ | ‐ | ‐ | ‐ | |
| *The assumed risk is based on the estimate in the control group. The corresponding risk (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI). AOD: angle opening distance;CI: confidence interval; IOP: intraocular pressure; MD: mean difference; SSA: scleral spur angle; TISA: trabecular iris space area | ||||||
| GRADE Working Group grades of evidence | ||||||
| aDowngraded one level for imprecision due to wide confidence intervals | ||||||
| Phacoemulsification versus phacoemulsification plus trabeculectomy for primary angle‐closure glaucoma | ||||||
|---|---|---|---|---|---|---|
| Patient or population: participants with primary angle‐closure glaucoma Settings: university hospital in Egypt Intervention: phacoemulsification Comparison: phacoemulsification plus trabeculectomy | ||||||
| Outcomes | Illustrative comparative risks* (95% CI) | Relative effect | No of Participants | Certainty of the evidence | Comments | |
| Assumed risk | Corresponding risk | |||||
| Phacoemulsification combined with trabeculectomy | Phacoemulsification | |||||
| Progression of visual field loss (at 12 months) | No data available for this outcome | ‐ | ‐ | ‐ | ||
| Mean IOP change from baseline to 12 months | The mean IOP in the control group was 13.2 mmHg | The mean IOP in the intervention group was 12.6 mmHg; on average, 0.60 mmHg lower (95% CI ‐1.99 to 0.79) | ‐ | 63 eyes (one study) | ⊕⊕⊝⊝ | |
| Mean number of medications to control IOP (at 12 months) | The mean number of medications to control IOP in the control group was 0.5 | The mean number of medications to control IOP in the intervention group was 0.5; on average, there was no difference (95% CI ‐0.42 to 0.42) | ‐ | 63 eyes (one study) | ⊕⊕⊝⊝ | ‐ |
| Gonioscopic findings | No data available for this outcome | ‐ | ‐ | ‐ | ‐ | |
| Mean best corrected visual acuity (at final follow‐up) | The mean best corrected visual acuity in the control group was 0.38 | The mean best corrected visual acuity in the intervention group was 0.35: on average, 0.03 lower (95% CI ‐0.18 to 0.12) | 63 eyes (one study) | ⊕⊕⊝⊝ | ‐ | |
| Adverse effects | Intraoperative and postoperative complications | RR 0.59 (0.34 to 1.04) | 63 eyes (one study) | ⊕⊕⊝⊝ | ||
| 580.6 per 1000 | 343.8 per 1000 | |||||
| Additional IOP‐lowering procedures required | RR 5.81 (1.41 to 23.88) | |||||
| 64.5 per 1000 | 375 per 1000 | |||||
| Quality of life measures (at 12 months) | No data available for this outcome | ‐ | ‐ | ‐ | ‐ | |
| *The assumed risk (e.g. the median control group risk across studies) is based on the estimate in the control group. The corresponding risk (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI). CI: confidence interval; IOP: intraocular pressure; RR: risk ratio | ||||||
| GRADE Working Group grades of evidence | ||||||
| aDowngraded for high risk of attrition bias | ||||||
Background
Description of the condition
Glaucoma is an umbrella term for a group of progressive optic neuropathies that are typically associated with elevated intraocular pressure (IOP), and result in characteristic patterns of visual loss and optic disc cupping. Primary angle‐closure glaucoma (PACG) is a subtype characterized by anatomical iridotrabecular contact, with consequent elevated IOP and glaucomatous optic neuropathy (Casson 2011).
Epidemiology
Glaucoma is the third most common cause of visual impairment, and the most common irreversible cause of blindness worldwide (Stevens 2013). Over 60 million people are living with glaucoma, and the numbers are expected to continue rising (Tham 2014). While primary open‐angle glaucoma is the most common subtype, PACG results in a disproportionately higher prevalence of blindness, accounting for almost half the cases of bilateral blindness due to glaucoma (Baskaran 2015; Dandona 2000; Foster 2001; Quigley 2006).
The prevalence of PACG varies across the globe. It is most common in Asian populations, who comprise up to 86.5% of PACG diagnoses worldwide (Quigley 2006; Tham 2014). Other risk factors include female gender, increasing age, and family history (Amerasinghe 2008; Amerasinghe 2011; Kavitha 2014; Qu 2011; Quigley 2006). Anatomical factors that increase the risk of PACG include hypermetropia, reduced axial length, increased lens thickness, and shallow anterior chamber depth (Devereux 2000; Lowe 1970; Nongpiur 2011; Salmon 1999; Sng 2012). Several potentially responsible candidate genes have been identified, but the relationship is complex, and the mechanisms are as yet unclear (Shastry 2013).
Clinical Presentation and Diagnosis
Chronic PACG presents insidiously – over time, patients may develop visual field defects characteristic of glaucoma if the longstanding pressure damage to the optic nerve is not corrected, which means that it is often asymptomatic until the late stages. Signs include optic disc cupping, elevated IOP, and a narrow or closed iridocorneal angle on gonioscopy. Ultrasound biomicroscopy and anterior segment optical coherence tomography may also be used to assess angle
configuration.
Description of the intervention
PACG treatment aims to lower IOP and thereby arrest optic nerve damage. This can be achieved by a stepped approach, using medical treatment (ocular hypotensive agents), laser (laser peripheral iridotomy, argon laser peripheral iridoplasty, selective laser trabeculoplasty), surgical means (lens extraction, trabeculectomy, goniosynechialysis), or any combination of these treatments.
Lens extraction is increasingly viewed as a viable treatment for PACG. This is typically achieved with phacoemulsification and intraocular lens (IOL) implantation, although older techniques such as extracapsular cataract extraction may uncommonly be used complex cases where phacoemulsification proves difficult, and a variation thereof (manual small incision cataract surgery) is commonly used in developing countries.
How the intervention might work
Relative pupillary block and angle crowding are the two main mechanisms underlying the pathogenesis of PACG (Wright 2015).
In relative pupillary block, there is obstruction of the free flow of aqueous humor from the posterior to the anterior chamber of the eye. The increased pressure gradient across the pupil forces the iris to bow forwards, narrowing the iridocorneal angle, and reducing access to the trabecular meshwork through the apposition of lens and iris at the pupil. Prolonged iridotrabecular contact can also lead to the formation of peripheral anterior synechiae (PAS), which can exacerbate the pupillary block.
Another mechanism is angle crowding, which often coexists with pupillary block, but may also cause PACG by itself. Angle crowding may be due to plateau iris, an anatomical configuration wherein the peripheral iris root is compressed against the trabecular meshwork by more anteriorly positioned ciliary processes, thus predisposing to iridocorneal contact (Ritch 2003; Shukla 2008; Wand 1977). It may also result from other abnormal iris configurations, such as a thick peripheral iris roll (Shabana 2012).
More recent studies have established that exaggerated lens vault plays an important role in the pathogenesis of PACG. Compared to normal eyes, eyes with PACG were found to have thickened crystalline lens with a greater lens vault that displaces the iris anteriorly, thereby reducing the anterior chamber depth (Ozaki 2012; Nongpiur 2011; Shabana 2012). As such, lens extraction can plausibly relieve pupillary block and angle crowding, thus aiding in IOP control. Indeed, there is evidence that replacing the thickened cataractous lens with a synthetic IOL can deepen the anterior chamber depth by 1.0 mm or more (Hayashi 2000; Yang 1997), and early non‐randomized trials showed significant improvement in IOP in PACG patients following cataract extraction (Hayashi 2001; Kubota 2003).
Why it is important to do this review
There is some evidence that lens extraction may help slow the progression of PACG. However, its effectiveness compared to other conventional interventions has not been systematically evaluated. In addition, there is no consensus as to whether lens extraction is sufficiently effective that it should be performed on PACG patients without coexisting cataract (i.e., clear lens extraction), which is important because the surgery is not risk‐free.
The original version of this review did not find any randomized controlled trials on the topic, and the two eligible non‐randomized studies did not provide proof of the effectiveness of lens extraction over other interventions for chronic PACG (Friedman 2006). There has been increasing interest in this subject since then. With the rising disease burden, it is timely for a systematic examination of the evidence on the utility of lens extraction in the treatment of
chronic PACG.
Objectives
To assess the effectiveness of lens extraction compared to other interventions in the treatment of chronic primary angle‐closure glaucoma in people without previous acute angle‐closure attacks.
Methods
Criteria for considering studies for this review
Types of studies
We included only randomized controlled trials (RCT) in the updated review. We excluded the non‐randomized comparative studies from the original version of this review. We did not place any restrictions relating to language, date of publication, or number of participants.
Types of participants
We included studies that enrolled participants diagnosed with chronic primary angle‐closure glaucoma (PACG), defined as gonioscopic evidence of angle closure in association with either glaucomatous optic neuropathy with or without visual field defects, or elevated intraocular pressure (IOP).
We excluded participants with a known history of acute angle‐closure attacks. This population may develop chronic PACG, but the disease may differ substantially from those with asymptomatic disease (Ang 2004; Chen 2012; Tham 2009a). Where studies included both participants with chronic PACG with known symptomatic attacks in the past and those without, we attempted to procure data on the latter group alone. We placed no restrictions on age, gender, ethnicity, comorbidities, use of adjunctive medications, or number of participants.
Types of interventions
We included studies that compared lens extraction with other treatment modalities for chronic PACG, including but not limited to laser iridotomy, medications, and laser iridoplasty.
Types of outcome measures
Primary outcomes
(1) Proportion of participants with evidence of progression of visual field loss at different follow‐up time points. The main primary outcome was at one year of follow‐up. We adopted the criteria in the included studies to define progression of visual field loss as measured using a validated method.
(2) Mean change in IOP from baseline to one year, measured by any method. We also planned to report the mean change in IOP from baseline to different follow‐up time points. If data on mean change from baseline and its standard deviation were not reported in the manuscript and could not be obtained from the authors, we planned to analyze the final mean IOPs at different follow‐up time points.
Secondary outcomes
(1) Mean change in depth of the anterior chamber from baseline in millimeters, measured by any method
(2) Number of medications used to control IOP at six months, one year, and at different follow‐up time points, as reported in the included studies
(3) Gonioscopic findings – we planned to summarize the available information on the examination of the angle, including angle width, from the included studies.
(4) Visual acuity as reported in the included studies.
Adverse effects
We summarized adverse effects related to lens extraction reported in the included studies.
Quality of life measures
We planned to summarize quality of life outcomes reported in the included studies.
Follow‐up
There were no restrictions based on length of follow‐up.
Search methods for identification of studies
Electronic searches
The Cochrane Eyes and Vision Information specialist conducted systematic searches in the following databases for RCTs and controlled clinical trials. We placed no restrictions on language or year of publication. The date of the search was 13 December 2019.
-
Cochrane Central Register of Controlled Trials (CENTRAL; 2019, Issue 12 [which contains the Cochrane Eyes and Vision Trials Register]) in the Cochrane Library (searched 13 December 2019; Appendix 1);
-
MEDLINE Ovid (1946 to 13 December 2019; Appendix 2);
-
Embase Ovid (1980 to 13 December 2019; Appendix 3);
-
LILACS (Latin American and Caribbean Health Sciences Literature Database; 1982 to 13 December 2019; Appendix 4);
-
US National Institutes of Health Ongoing Trials Register ClinicalTrials.gov (www.clinicaltrials.gov; searched 13 December 2019; Appendix 5);
-
World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP; www.who.int/ictrp; searched 13 December 2019; Appendix 6).
Searching other resources
We searched the reference lists of the included studies. We planned to contact the primary investigators of identified RCTs for details of any additional trials not found by our electronic and manual searches. We used the Science Citation Index to search for references that cited the included studies.
Data collection and analysis
Selection of studies
Two review authors independently assessed the titles and abstracts of all reports identified by the electronic and manual searches. We labeled each report as (a) definitely exclude, (b) unsure, or (c) definitely include. We excluded studies labeled as 'definitely exclude'. We assessed studies labeled as 'definitely include' for risk of bias. We assessed the full text of abstracts labelled as 'unsure' according to the inclusion criteria for this review. We recorded the studies excluded after the full‐text review as well as the reasons for exclusion. We resolved any discrepancies between our assessments through discussion.
Data extraction and management
Two review authors independently recorded primary and secondary outcome data in Covidence (Covidence). We resolved discrepancies through discussion. One review author entered the data into Review Manager 5; a second review author verified the accuracy (Review Manager 2014). We contacted study authors to clarify any points of doubt.
Assessment of risk of bias in included studies
For each included trial, two review authors independently assessed the methodological quality and risk of bias according to the guidelines in Chapter 8 of the Cochrane Handbook for Systematic Review of Interventions (Higgins 2011). We assessed the following domains:
1. Sequence generation (selection bias): randomization methods such as computer‐generated random numbers were considered to be at low risk of bias; methods such as alternation were considered to be at high risk of bias; methods using medical record numbers, social security numbers, etc. were considered quasi‐randomized, and were consequently deemed to be at high risk of bias as well.
2. Allocation concealment (selection bias): methods such as central randomization and the use of sequentially numbered sealed envelopes were considered to be at low risk of bias. If participants or investigators were able to foresee upcoming assignments (e.g. using open random allocation schedule, date of birth, alternation etc.), the study was judged as having high risk of bias.
3. Masking (performance bias and detection bias): we assessed masking of outcome assessors where masking was feasible. Masking of participants and physicians was not feasible due to the nature of the intervention studied. If outcome assessors were adequately masked to the assignments, we judged the study as having low risk of bias. If masking was incomplete and outcome measurements were likely to be influenced by lack of masking, the study was judged as having high risk of bias for this domain.
4. Incomplete outcome data (attrition bias): we assessed methods for handling loss to follow‐up and missing data. We judged the study as having low risk of bias if there were no missing outcome data, or where intention‐to‐treat analysis was followed. We judged the study as having high risk of bias if intention‐to‐treat analysis was not followed, or reasons for missing outcome data were likely to be related to true outcome. We attempted to contact trial authors for missing data. Where analyses involved imputing data on participants who dropped out or were lost to follow‐up, we extracted information on methods used for such imputation.
5. Selective outcome reporting (reporting bias): we attempted to assess for evidence of selective reporting of outcomes or analyses on selective populations by comparing the published results to the original protocol. We judged the study as having low risk of reporting bias if the study protocol was published and all pre‐specified outcomes were adequately reported. If not all pre‐specified outcomes or outcomes prescribed in Methods section were reported or outcomes were reported incompletely, we judged the study as having high risk of bias for this domain.
6. Other sources of bias: we evaluated evidence of other sources of bias. We judged high risk of bias for this domain if the study had a potential source of bias due to the specific study design, and judged as low risk of bias if none of such bias was identified. We judged as having unclear risk of bias if there was insufficient information to allow judgement.
Measures of treatment effect
We calculated summary risk ratios (RR) with 95% confidence intervals (CIs) for dichotomous outcomes. In this review, dichotomous outcomes included the primary outcome ‘proportion of patients with evidence of progression of visual field loss.’ For one trial, we presented odds ratio (OR) ‐ one author (SSV) analyzed the individual participant data acquired from the original trial, following its prespecified statistical analysis plan to account for correlation within participants (Azuara‐Blanco 2016). This analysis was performed using Stata (Stata).
We calculated the mean difference (MD) with 95% CIs for normally distributed continuous outcomes. We did not use the standardized mean difference (SMD) because all included studies reported outcomes on the same scale. In this review, continuous outcomes included the primary outcome ‘mean change in IOP’, and the secondary outcomes ‘mean change in anterior chamber depth’, ‘mean change in number of medications used to control IOP’, ‘gonioscopic findings’, and ‘mean change in visual acuity’.
Unit of analysis issues
In one study, the participant was used as the unit of randomization, while the eye was used as the unit of analysis. However, the analysis did not take into account correlation between eyes of the same participant (Moghimi 2015). Another study used the eye as a unit of analysis, without explicitly stating whether one or both eyes of a participant were included (Angmo 2019).
Dealing with missing data
We contacted trial investigators to obtain additional information, individual participant data, or both. We used the published data available when we did not receive a response.
Assessment of heterogeneity
We quantified the proportion of intra‐study variability that could be explained by heterogeneity using the I² statistic (Higgins 2002). We examined the inter‐study variance using Tau². When we observed substantial statistical heterogeneity (defined here as I² > 50%) in a particular outcome, we did not combine the study results in a meta‐analysis, but reported them in a qualitative (narrative) summary instead.
Assessment of reporting biases
For selective outcome reporting, we compared the prespecified outcomes in protocols or trial registries with outcomes reported in published papers. For the studies for which the protocol was not publicly available, we compared the outcomes presented in the Methods section with those reported in the Results section of the published papers. We did not assess for publication bias as we did not include 10 or more studies in meta‐analysis.
Data synthesis
Data analysis followed the guidelines set out in Chapter 9 of the Cochrane Handbook for Systematic Review of Interventions (Deeks 2011).
We planned to conduct a meta‐analysis if there was no substantial heterogeneity. We planned to use the fixed‐effects model for outcomes with fewer than three studies, and the random‐effects model for those containing three or more studies.
Subgroup analysis and investigation of heterogeneity
Where heterogeneity was high (I² > 50%), we planned subgroup analyses to explore the underlying causes. This was conditional on having sufficient data to carry this out.
Sensitivity analysis
Where appropriate, we planned sensitivity analyses to determine the impact of excluding randomized studies of higher risk of bias, quasi‐randomized studies, unpublished studies, or industry‐funded studies from the meta‐analysis. This was ultimately unnecessary because of the limited number of eligible studies.
Summary of findings and assessment of the certainty of the evidence
We created 'Summary of findings' tables for the main comparisons. Two review authors independently graded the quality of the body of evidence for each outcome as one of four levels (i.e. high, moderate, low, or very low) using the GRADE approach (GRADEpro GDT). We resolved disagreement by discussion and obtaining consensus within the review team. We downgraded the certainty of the body of evidence by assessing the following parameters:
-
High risk of bias among included studies;
-
Indirectness of evidence;
-
Unexplained heterogeneity or inconsistency of results;
-
Imprecision of results (i.e. wide confidence intervals);
-
High probability of publication bias.
Results
Description of studies
Results of the search
The electronic searches for the original review were conducted in July 2005 and April 2006; the details were described previously (Friedman 2006). In brief, no relevant randomized controlled trials (RCT) were identified from 395 records at the time. An updated search on 13 December 2019 yielded 2381 records. Five additional records were identified after searching through reference lists. After screening titles and abstracts, we retrieved 52 full‐text reports for further evaluation. After screening the full texts, we included eight relevant studies (17 records); identified one ongoing study (one record), six studies (six records) await classification, and we excluded 28 studies (28 records). In total, we have excluded 45 studies listed in the 'Characteristics of excluded studies' table. We listed six studies in the 'Characteristics of studies awaiting classification' section; we were unable to retrieve two articles, or clarify the eligibility of participants for the remaining four studies (one of which was identified from a manual search). We listed the protocol of an ongoing RCT which commenced in April 2019 under Characteristics of ongoing studies (ChiCTR1900022198). We attempted to contact the relevant authors. We will update the review with relevant information if and when they become available. The flow diagram of the search results is shown in Figure 1.
Study flow diagram
Included studies
Types of studies
The previous version of this review comprised only non‐randomized comparative studies as no eligible RCTs were identified at the time. For this update, we focused solely on RCTs.
We included a total of eight RCTs in this update. Three studies were initially eligible for inclusion in the review (Angmo 2019, El Sayed 2019, Moghimi 2015). Another included participants with both primary angle‐closure glaucoma (PACG) and primary angle closure (PAC), but subsequently provided data for participants with PACG, such that we could perform individual patient data analysis for inclusion in the review (Azuara‐Blanco 2016). Four studies did not meet the eligibility criteria initially, but we obtained data on participants with PACG without a previous history of symptomatic acute angle closure attacks (as per our eligibility criteria) from the trial authors, which we have included below (Husain 2019; Tham 2008; Tham 2009; Tham 2013).
Types of participants
The eight eligible RCTs included comprised 914 eyes in total. Of these, 513 eyes met our inclusion criteria of having PACG without a previous history of acute angle closure attacks. This number does not include three studies, for which the number of eligible eyes was unclear (Tham 2008; Tham 2009; Tham 2013).
Azuara‐Blanco 2016 was a multicenter trial that recruited from across the United Kingdom, Australia, and Southeast Asia (China, Hong Kong, Malaysia, and Singapore). Husain 2019 recruited participants from Southeast Asia (Hong Kong, Singapore, Thailand, Vietnam), as did Tham 2008, Tham 2009, and Tham 2013, all of which recruited from Hong Kong and China. Angmo 2019 took place in India, Moghimi 2015 in Iran, and El Sayed 2019 in Egypt.
PACG was defined as occludable angles (at least 180 degrees of iridotrabecular contact in all studies, apart from Moghimi 2015, which specified at least 270 degrees); glaucomatous visual field loss or glaucomatous optic neuropathy, or both; and elevated IOP. Azuara‐Blanco 2016 enrolled participants who were newly diagnosed with PACG, as well as those with PAC with an intraocular pressure (IOP) of 30 mmHg or higher. Notably, study participants did not have symptomatic cataracts. This was also the case for Tham 2013, which only evaluated participants with medically uncontrolled PACG without cataracts. Conversely, all participants in Angmo 2019, Husain 2019; Moghimi 2015, Tham 2008; Tham 2009 had PACG as well as visually significant cataracts in the study eye. The final study comprised a mix of eyes with PACG with and without cataracts (El Sayed 2019).
Four studies included participants with a previous history of acute angle closure attacks (Husain 2019; Tham 2008; Tham 2009; Tham 2013). We obtained data for those with PACG without such a history through private correspondence with the authors of these studies.
All eight studies had two study arms, and all the baseline characteristics were equivalent in both arms, apart from Husain 2019, which reported a discrepancy in the mean central corneal thickness across study arms.
Types of interventions
Azuara‐Blanco 2016 compared phacoemulsification (clear lens extraction) and standard care (laser peripheral iridotomy). For the phacoemulsification group, synechialysis was allowed according to local practice. For the standard care group, laser iridoplasty was subsequently allowed if angle closure persisted, and participants could undergo lens extraction only if they subsequently developed a visually significant cataract or if their ophthalmologist recommended this to help with IOP control.
Moghimi 2015 compared phacoemulsification and phacoemulsification combined with viscogonioplasty (phaco‐VGP), a technique for breaking the PAS using a cohesive viscoelastic. This was injected near the iridocorneal angle twice for 360°, without touching the angle with the cannula, i.e. no surgical instruments were used to mechanically break the PAS, in contrast to phaco‐GSL.
Both Angmo 2019 and Husain 2019 compared phacoemulsification and phacoemulsification combined with goniosynechialysis (phaco‐GSL). The surgeons in Angmo 2019 used a viscoelastic cannula to mechanically break the PAS along approximately 270 degrees of the iridocorneal angle. In Husain 2019, GSL was performed using an iris repositor or similar.
Three studies compared phacoemulsification versus combined phaco‐trabeculectomy (El Sayed 2019; Tham 2008; Tham 2009).
One compared phacoemulsification versus trabeculectomy with adjunctive mitomycin C (MMC) (Tham 2013).
Types of outcomes
Primary outcomes
Two studies evaluated the proportion of participants with evidence of progression of visual field loss at 24 months (Tham 2008; Tham 2009). None of the eight studies assessed this parameter at 12 months postoperatively, although Azuara‐Blanco 2016 reported progression in visual field loss at 12, 24, and 36 months.
Two studies reported the mean change in IOP from baseline to 12 months (Husain 2019; Moghimi 2015). The remaining six reported the final mean IOP at various time points: Angmo 2019 up to six months; El Sayed 2019 up to 12 months; three up to 24 months, including at 12 months (Tham 2008; Tham 2009; Tham 2013); Azuara‐Blanco 2016 up to 36 months (including at 12 months). We also obtained the raw data from the authors of Azuara‐Blanco 2016 to calculate the mean change in IOP from baseline to 12 months.
Secondary outcomes
None of the eight studies reported the mean change in anterior chamber depth (ACD) from baseline.
All eight studies evaluated the mean number of IOP‐lowering medications required at various follow‐up intervals: Angmo 2019 at six months; Azuara‐Blanco 2016 at 6,12, 24, and 36 months; El Sayed 2019 and Moghimi 2015 at 1, 3, 6, and 12 months; Husain 2019 at 12 months; and Tham 2008, Tham 2009, and Tham 2013 at 3‐monthly intervals up to 24 months.
Two studies reported the mean change in gonioscopic grading from baseline: one at 12 months postoperatively (Husain 2019), and the other at the last follow‐up visit, which appears to have varied for each participant (Moghimi 2015). Azuara‐Blanco 2016 reported the degree of appositional and synechial angle closure at 36 months postoperatively. Two studies also measured changes in the iridocorneal angle in terms of quantitative anterior segment optical coherence tomography (AS‐OCT) parameters (Angmo 2019; Moghimi 2015).
Five studies described the best corrected visual acuity (BCVA) at various time points: Azuara‐Blanco 2016 at 12 and 36 months; El Sayed 2019 at the final follow‐up (varying intervals after 12 months for each individual); and Tham 2008, Tham 2009, and Tham 2013 at 12 and 24 months postoperatively.
Adverse effects
Seven studies reported both intraoperative and postoperative complications in both treatment arms (Azuara‐Blanco 2016; El Sayed 2019; Husain 2019; Moghimi 2015; Tham 2008; Tham 2009; Tham 2013). One described only postoperative complications, and it was unclear whether intraoperative complications were documented (Angmo 2019).
Quality of life measures
Only one study included self‐reported quality of life as an outcome. Azuara‐Blanco 2016 measured health status using the European Quality of Life‐5 Dimensions (EQ‐5D), as well as vision‐related quality of life, using the National Eye Institute Visual Function Questionnaire‐25 and the Glaucoma Utility Index.
Excluded studies
The 45 studies excluded after full text review are briefly described in the 'Characteristics of excluded studies' section. In summary, we excluded 29 studies due to incorrect study design (not RCTs), ten studies due to ineligible participants (not participants with chronic PACG), and six studies due to interventions.
Risk of bias in included studies
We summarized the risk of bias assessments in Figure 2.
'Risk of bias' summary: review authors' judgements about each 'Risk of bias' item for each included study
Allocation
All eight studies reported adequate methods of generating the randomization schedule. Five studies used random number tables (Angmo 2019; El Sayed 2019; Tham 2008; Tham 2009; Tham 2013) ; one used computer‐generated random blocks (Moghimi 2015); one randomized participants in a 1:1 ratio by way of a random‐number generator (Husain 2019); while one created a randomization schedule with the aid of a web‐based application that used sex, center, ethnic origin, diagnosis, and one or both eyes suitable for treatment as minimization covariates (Azuara‐Blanco 2016).
Two studies used appropriate allocation concealment methods (Azuara‐Blanco 2016; Moghimi 2015). It was unclear from the text whether allocation concealment took place in the remaining six studies.
Blinding
Three studies were at low risk of detection bias as they blinded both participants and outcome assessors to the intervention performed (Angmo 2019; Husain 2019; Moghimi 2015).
For the remaining five studies, the inherent differences in the interventions compared meant that it was difficult to mask participants and study personnel, particularly the surgeons performing the intervention. Azuara‐Blanco 2016 took steps to counteract this, undertaking a rigorous standardized masking protocol to minimize detection bias for IOP assessment. One study reported that the study personnel were not masked (Tham 2009), while this was not mentioned in three studies (El Sayed 2019; Tham 2008; Tham 2013).
Incomplete outcome data
We judged three studies to be at low risk of bias because intention‐to‐treat analyses were performed as planned in their study protocol (Azuara‐Blanco 2016; Husain 2019; Tham 2013). This was presumed to be the case for a further two that had no apparent losses to follow‐up (Tham 2008; Tham 2009).
We judged three studies to be at high risk of attrition bias (Angmo 2019; El Sayed 2019; Moghimi 2015). Only data from participants who completed follow‐up were analyzed and presented; missing participants were excluded from the outcomes and baseline data completely, and their reasons for dropping out were not elucidated.
Selective reporting
We deemed three studies to be at low risk of reporting bias as the results of all outcomes described in their protocols were duly reported (Angmo 2019; Azuara‐Blanco 2016; Husain 2019).
One study was at risk of reporting bias ‐ the results of several prespecified outcome measures described in the protocol were not reported (Tham 2013).
The risk was unclear for four studies because we had no protocol to compare the results against (El Sayed 2019; Moghimi 2015; Tham 2008; Tham 2009).
Other potential sources of bias
One study was at unclear risk because it is still ongoing and only the interim report was available (Angmo 2019). We judged the remaining studies to be at low risk of bias.
Effects of interventions
See: Summary of findings 1 Phacoemulsification compared with laser peripheral iridotomy for primary angle‐closure glaucoma; Summary of findings 2 Phacoemulsification versus phacoemulsification plus viscogonioplasty for primary angle‐closure glaucoma; Summary of findings 3 Phacoemulsification versus phacoemulsification plus goniosynechialysis for primary angle‐closure glaucoma; Summary of findings 4 Phacoemulsification versus phacoemulsification plus trabeculectomy for primary angle‐closure glaucoma
Meta‐analysis was not possible due to the absence of equivalent intervention groups, relevant data, and follow‐up periods. We therefore presented the results narratively. We show the summary of results for each comparison in Table 1.
| Intervention | Phacoemulsification | Phacoemulsification | Phacoemulsification | Phacoemulsification | Phacoemulsification |
|---|---|---|---|---|---|
| Comparison | Laser peripheral iridotomy (LPI) | Phacoemulsification plus viscogonioplasty | Phacoemulsification plus goniosynechialysis (phaco‐GSL) | Phacoemulsification plus trabeculectomy | Trabeculectomy |
| Study ID | |||||
| Progression of visual field loss | OR 0.49 (95% CI 0.24 to 0.92) at 6 months; OR 0.35 (95% CI 0.13 to 0.91) at 12 months; OR 0.37 (95% CI 0.17 to 0.82) at 24 months; OR 0.42 (95% CI 0.20 to 0.87) at 36 months | NR | NR | Unable to complete analysis to compare between groups | Unable to complete analysis to compare between groups |
| Mean change in IOP (in mmHg) | MD ‐0.65 mmHg (95% CI ‐3.12 to 1.82) at 6 months; MD ‐0.03 mmHg (95% CI ‐2.34 to 2.32) at 12 months; MD 0.74 mmHg (95% CI ‐1.66 to 3.13) at 24 months; MD 1.04 mmHg (95% CI ‐1.22 to 3.31) at 36 months | MD 0.50 mmHg (95% CI ‐2.64 to 3.64; 91 eyes) at 12 months | MD ‐0.04 mmHg (95% CI ‐0.93 to 0.85; 1 study, 64 eyes) at 6 months; MD ‐0.12 mmHg (95% CI ‐4.72 to 4.48; 1 study, 32 eyes) at 12 months | MD 0.50 mmHg (95% CI ‐1.95 to 2.95) at 1 month; MD 0.00 mmHg (95% CI ‐2.36 to 2.36) at 3 months; MD ‐0.30 mmHg (95% CI ‐1.89 to 1.29) at 6 months; MD ‐0.60 mmHg (95% CI ‐1.99 to 0.79) at 12 months | Unable to complete analysis to compare between groups |
| Mean change in anterior chamber depth | NR | NR | NR | NR | NR |
| Number of medications used to control IOP | MD ‐0.65 (95% CI ‐0.85 to ‐0.45) at 6 months; MD ‐0.70 (95% CI ‐0.89 to ‐0.51) at 12 months; MD ‐0.73 (95% CI ‐0.94 to ‐0.52) at 24 months; MD ‐0.65 (95% CI ‐0.87 to ‐0.43) at 36 months | MD ‐0.30 (95% CI ‐0.56 to ‐0.04; 91 eyes) at 6 months; MD ‐0.30 (95% CI ‐0.55 to ‐0.05; 91 eyes) at 12 months | MD ‐0.35 (95% CI ‐0.63 to ‐0.07; 1 study, 64 eyes) at 6 months; MD ‐0.38 (95% CI ‐1.23 to 0.47; 1 study, 32 eyes) at 12 months | MD 0.30 (95% CI 0.01 to 0.59) at 1 month; MD 0.40 (95% CI 0.06 to 0.74) at 3 months; MD 0.20 (95% CI ‐0.15 to 0.55) at 6 months; MD 0.00 (95% CI ‐0.42 to 0.42) at 12 months | Unable to complete analysis to compare between groups |
| Gonioscopic findings (measured in degrees) | Appositional angle closure MD ‐74.16° (95% CI ‐121.34 to ‐26.98) at 36 months Synechial angle closure MD ‐69.63° (95% CI, ‐104.34 to ‐16.92) at 12 months; MD 1.12 (95% CI, ‐42.37 to 44.62) at 36 months | Angle width TISA500 TISA750 | AOD500 AOD750 TISA500 TISA750 SSA | Unable to complete analysis to compare between groups | Unable to complete analysis to compare between groups |
| Best corrected visual acuity | MD 2.03 (95% CI ‐0.77 to 4.84) at 12 months; MD 4.30 (95% CI 0.74 to 7.87) at 36 months | MD ‐0.01 (95% CI ‐0.10 to 0.08; 91 eyes) postoperatively | NR | MD ‐0.03 (95% CI ‐0.18 to 0.12; 1 study, 63 eyes) | Unable to complete analysis to compare between groups |
| Adverse effects | Phacoemulsification group: malignant glaucoma (1 eye); irreversible loss of vision of more than 10 ETDRS letters (1 eye); other related adverse events (1 eye). LPI group: lost ten or more ETDRS letters irreversibly (3 eyes); other related adverse events (10 eyes). | Phaco‐GSL group hyphema (3 eyes) | Less risk of: Intra‐ and post‐operative complications (RR 0.59, 95% CI 0.34 to 1.04); additional IOP‐lowering procedures (RR 5.81, 95% CI 1.41 to 23.88) in the phacoemulsification group | none | |
| Quality of life measures (European Quality of Life‐5 Dimension) | MD 0.03 (95% CI ‐0.16 to 0.22) at 6 months; MD 0.04 (95% CI ‐0.16 to 0.24) at 12 months; MD 0.005 (95% CI ‐0.19 to 0.20) at 24 months; MD ‐0.04 (95% CI ‐0.24 to 0.16) at 36 months | NR | NR | NR | NR |
AOD: angle opening distance; CI: confidence interval; IOP: Intraocular pressure; NR: not reported; MD: mean difference; OR: odds ratio; RR: risk ratio; SSA: scleral spur angle; TISA: trabecular iris space area
Phacoemulsification versus laser peripheral iridotomy (LPI)
One study compared phacoemulsification with standard care (LPI) in participants with both PAC and PACG without cataracts (i.e. clear lens extraction) (Azuara‐Blanco 2016). We obtained the raw study data and repeated the analysis for participants with PACG only, using the statistical analysis plan published and provided by the trial investigators. We include a caveat here: the following results should be interpreted with caution because the study was not powered to investigate participants with PACG alone, and we have adjusted the GRADE score accordingly. Of those with PACG, 127 eyes underwent phacoemulsification and 136 had LPI. See summary of findings Table 1.
Primary outcomes
Progression of visual field loss
The proportion of participants with evidence of progression of visual field loss was lower in the phacoemulsification group than the LPI group at six months (odds ratio [OR] 0.49, 95% confidence interval [CI] 0.24 to 0.92; 216 eyes), 12 months (OR 0.35, 95% CI 0.13 to 0.91; 216 eyes), 24 months (OR 0.37, 95% CI 0.17 to 0.82; 216 eyes), and 36 months (OR 0.42, 95% CI 0.20 to 0.87; 216 eyes). We graded the certainty of the evidence as moderate, having downgraded one level for imprecision (‐1) because the study cohort was not adequately powered to evaluate participants with PACG alone.
Mean change in IOP from baseline to one year
There was no observable difference in change from baseline IOP between the intervention groups at any time point. The mean difference between the groups was ‐0.65 mmHg (95% CI ‐3.12 to 1.82; 257 eyes) at 6 months; ‐0.03 mmHg (95% CI ‐2.34 to 2.32; 257 eyes) at 12 months; 0.74 mmHg (95% CI ‐1.66 to 3.13; 257 eyes) at 24 months; and 1.04 mmHg (95% CI ‐1.22 to 3.31; 257 eyes) at 36 months. We graded the certainty of evidence as moderate for this outcome, downgrading one level for imprecision (‐1) because the study cohort was not adequately powered to evaluate participants with PACG alone.
Secondary outcomes
Mean change in depth of the anterior chamber
Not reported.
Number of medications used to control IOP
The phacoemulsification group required fewer IOP‐lowering medications than the LPI group at 6 months (mean difference [MD] ‐0.65, 95% CI ‐0.85 to ‐0.45; 263 eyes); 12 months (MD ‐0.70, 95% CI ‐0.89 to ‐0.51; 263 eyes); 24 months (MD ‐0.73, 95% CI ‐0.94 to ‐0.52; 263 eyes); and 36 months (MD ‐0.65, 95% CI ‐0.87 to ‐0.43; 263 eyes). We graded the certainty of evidence as moderate for this outcome, downgrading one level for imprecision (‐1) because the study cohort was not adequately powered to evaluate participants with PACG alone.
Gonioscopic findings
Gonioscopic findings favored the phacoemulsification group, which had less appositional angle closure at 12 months (MD ‐84.93°, 95% CI ‐131.25° to ‐38.61°; 106 eyes) and 36 months (MD ‐74.16°, 95% CI ‐121.34° to ‐26.98°; 101 eyes) compared to the LPI group. The phacoemulsification group also had less synechial angle closure (extent of PAS) at 12 months (MD ‐69.63°, 95% CI ‐104.34° to ‐16.92°, 51 eyes) compared to the LPI group, with similar outcomes at 36 months (MD 1.12°, 95% CI ‐42.37° to 44.62°, 52 eyes). We graded the certainty of evidence as moderate for this outcome, downgrading one level for imprecision (‐1) because the study cohort was not adequately powered to evaluate participants with PACG alone.
Visual acuity
Best corrected visual acuity, measured using the Early Treatment Diabetic Retinopathy Study (EDTRS) letter chart, was comparable between the groups at 12 months (MD 2.03, 95% CI ‐0.77 to 4.84; 242 eyes) but favored the LPI group at 36 months (MD 4.30, 95% CI 0.74 to 7.87; 242 eyes). We graded the certainty of evidence as low for this outcome, downgrading by one level because of imprecision (‐1) because the study cohort was not adequately powered to evaluate participants with PACG alone.
Adverse effects
At six months, malignant glaucoma was reported in one eye of one participant in each of the phacoemulsification and LPI groups; irreversible loss of vision of more than ten ETDRS letters was reported in one eye of one participant in the phacoemulsification group; and other related adverse events were reported in five eyes in the phacoemulsification group, and three eyes in the LPI group. The analysis included 118 eyes of 118 participants in the phacoemulsification group, and 132 eyes of 132 participants in the LPI group for all outcomes except malignant glaucoma (117 eyes in 117 participants in the phacoemulsification group and 131 eyes in 131 participants in the LPI group), and other related adverse events (81 eyes in 81 participants in the phacoemulsification group, and 92 eyes in 92 participants in the LPI group).
At 36 months, malignant glaucoma was reported in one eye of one participant in the phacoemulsification group, irreversible loss of vision of more than ten ETDRS letters was reported in one eye of one participant in the phacoemulsification group and three eyes of three participants in the LPI group, and other related adverse events were reported in one eye in the phacoemulsification group and ten eyes in the LPI group. The analysis included 112 eyes of 112 participants in the phacoemulsification group and 121 eyes of 121 participants in the LPI group for all outcomes except other related adverse events (85 eyes of 85 participants in the phacoemulsification group and 88 eyes in 88 participants in the LPI group).
We graded the certainty of evidence as moderate for this outcome, downgrading by one level because of imprecision (‐1).
Quality of life measures
The study used the European Quality of Life‐5 Dimension (EQ‐5D), with three rating scales in five dimensions of health, to assess health status; higher score means better quality of life. There was no evidence of difference between the two groups at 6 months (MD 0.03, 95% CI ‐0.16 to 0.22; 254 eyes), 12 months (MD 0.04, 95% CI ‐0.16 to 0.24; 254 eyes), 24 months (MD 0.005, 95% CI ‐0.19 to 0.20; 254 eyes), or 36 months (MD ‐0.04, 95% CI ‐0.24 to 0.16; 254 eyes). We graded the certainty of evidence as moderate, downgraded by one level because of imprecision (‐1).
Phacoemulsification versus phacoemulsification with viscogonioplasty (phaco‐VGP)
Moghimi 2015 compared phacoemulsification and phaco‐VGP in eyes with PACG and co‐existing cataracts, reporting the results for 46 eyes in the phacoemulsification group and 45 in the phaco‐VGP group for participants who had completed at least 12 months of follow‐up. See summary of findings Table 2.
Primary outcomes
Progression of visual field loss
Not reported.
Mean change in IOP from baseline to one year
Reduction in IOP was observed in both the phacoemulsification (‐8.3 mmHg ± 6.8 mmHg) and phaco‐VGP (‐8.8 mmHg ± 8.4 mmHg) groups at one year; there was no evidence of difference between groups (MD 0.50 mmHg, 95% CI ‐2.64 to 3.64; 91 eyes; Analysis 1.1). We graded the certainty of evidence as low for this outcome, downgrading by two levels because of high risk of attrition bias (‐1) and imprecision due to wide confidence intervals (‐1).
Secondary outcomes
Mean change in depth of the anterior chamber
Not reported.
Number of medications used to control IOP
Fewer IOP‐lowering medications were used in the phacoemulsification group (0.1 ± 0.4) compared to the phaco‐VGP group (0.4 ± 0.8) at 6 months (MD ‐0.30, 95% CI ‐0.56 to ‐0.04; 91 eyes; Analysis 1.2), and 12 months (0.1 ± 0.3 versus 0.4 ± 0.8; MD ‐0.30, 95% CI ‐0.55 to ‐0.05; 91 eyes; Analysis 1.2). We graded the certainty of evidence as low for this outcome, downgrading by two levels because of high risk of attrition bias (‐1) and wide confidence intervals (‐1).
Gonioscopic findings
There was increased angle width in both the phacoemulsification and phaco‐VGP groups, which was higher in the phaco‐VGP group (1.4 ± 0.8 versus 2.0 ± 0.7; MD ‐0.60, 95% CI ‐0.91 to ‐0.29; 91 eyes; Analysis 1.3). This was measured at the last follow‐up visit (at 12 months or later) which varied for each individual.
Changes in anterior segment optical coherence tomography (AS‐OCT) parameters were also described: both phacoemulsification and phaco‐VGP groups had changes in the trabecular iris space area (TISA500 [0.020 ± 0.084 versus 0.054 ± 0.033]) and TISA750 (0.084 ± 0.057 versus 0.119 ± 0.061) at 12 months; this increase was higher in the phaco‐VGP group (MD ‐0.03, 95% CI ‐0.06 to ‐0.01 in TISA500, and MD ‐0.03, 95% CI ‐0.06 to ‐0.01 in TISA750; 91 eyes; Analysis 1.3). We graded the certainty of evidence as low for this outcome, downgrading by two levels because of high risk of attrition bias (‐1) and imprecision due to wide confidence intervals (‐1).
Visual acuity
The mean logMAR best‐corrected visual acuity (BCVA) was comparable at baseline (0.49 ± 0.28 in the phacoemulsification group versus 0.49 ± 0.35 in the phaco‐VGP group; MD 0.00, 95% CI ‐0.13 to 0.13; 91 eyes), and postoperatively (0.27 ± 0.2 in the phacoemulsification group versus 0.28 ± 0.23 in the phaco‐VGP group; MD ‐0.01, 95% CI ‐0.10 to 0.08; 91 eyes; Analysis 1.4). We graded the certainty of evidence as moderate for this outcome, downgrading by two levels due to high risk of attrition bias (‐1) and imprecision from wide confidence intervals (‐1).
Adverse effects
Three participants in the phaco‐VGP group developed postoperative hyphema that was successfully managed with viscotamponade. Four participants in the phaco‐VGP group and two in the phacoemulsification alone group developed a postoperative fibrin reaction that resolved after a few days. No other adverse effects were reported.
Quality of life measures
Not measured.
Phacoemulsification versus phacoemulsification with goniosynechialysis (phaco‐GSL)
Two studies compared phacoemulsification alone with combined phaco‐GSL (Angmo 2019; Husain 2019). Angmo 2019 comprised 30 eyes in the phacoemulsification group and 34 in the phaco‐GSL group. Husain 2019 included participants with both PAC and PACG with and without a previous history of acute angle closure attacks. We obtained the raw study data from the lead author and repeated the analysis for only participants with PACG without previous acute angle closure attacks. This gave us 16 eyes in the phacoemulsification group and 16 in the phaco‐GSL group. We were unable to conduct any meta‐analyses because the outcomes were measured at different time points in both studies. See summary of findings Table 3.
Primary outcomes
Progression of visual field loss
Not reported by either study.
Mean change in IOP from baseline to one year
Angmo 2019 did not report the mean change in IOP from baseline. However, there was no evidence of difference in mean IOP at six months between the phacoemulsification and phaco‐GSL groups (13.17 mmHg ± 1.66 mmHg versus 13.21 mmHg ± 1.97 mmHg; MD ‐0.04 mmHg, 95% CI ‐0.93 to 0.85; 64 eyes; Analysis 2.1). We graded the certainty of evidence as low for this outcome, downgrading by one level each because of high risk of attrition bias (‐1) and imprecision due to wide confidence intervals (‐1).
In Husain 2019, the mean change in IOP from baseline to 12 months was comparable between the phacoemulsification and phaco‐GSL groups (‐6.59 mmHg ± 6.72 mmHg versus ‐6.47 mmHg ± 6.57 mmHg; MD ‐0.12 mmHg, 95% CI ‐4.72 to 4.48; 32 eyes; Analysis 2.1). We graded the certainty of evidence as moderate for this outcome, downgrading by one level because of imprecision due to wide confidence intervals (‐1).
Secondary outcomes
Mean change in depth of the anterior chamber
Not reported by either study.
Number of medications used to control IOP
In Angmo 2019, the phacoemulsification group required fewer IOP‐lowering medications at six months compared to the phaco‐GSL group (1.70 ± 0.66 versus 2.05 ± 0.46; MD ‐0.35, 95% CI ‐0.63 to ‐0.07; 64 eyes; Analysis 2.2). We graded the certainty of evidence as low for this outcome, downgrading by one level each because of high risk of attrition bias (‐1) and imprecision due to small sample size (‐1).
In Husain 2019, the phacoemulsification and phaco‐GSL groups required a comparable number of IOP‐lowering medications at 12 months (0.56 ± 1.09 versus 0.94 ± 1.34; MD ‐0.38, 95% CI ‐1.23 to 0.47; 32 eyes; Analysis 2.2). We graded the certainty of evidence as moderate for this outcome, downgrading by one level because of imprecision due to wide confidence intervals (‐1).
Gonioscopic findings
Angmo 2019 described the iridocorneal angle changes in terms of quantitative anterior segment optical coherence tomography (AS‐OCT) findings at six months postoperatively. While there was an improvement in angle opening for both groups, there was no evidence of difference for the five parameters, measured between the phacoemulsification and phaco‐GSL groups: angle opening distance (AOD)500 (0.48 ± 0.21 versus 0.52 ± 0.65; MD ‐0.04, 95% CI ‐0.27 to 0.19; 64 eyes); AOD750 (0.72 ± 0.3 versus 0.71 ± 0.77; MD 0.01, 95% CI ‐0.27 to 0.29; 64 eyes); trabecular iris space area (TISA)500 (0.15 ± 0.06 versus 0.17 ± 0.10; MD ‐0.02, 95% CI ‐0.06 to 0.02; 64 eyes); TISA750 (0.30 ± 0.12 versus 0.33 ± 0.40; MD ‐0.03, 95% CI ‐0.17 to 0.11; 64 eyes); scleral spur angle (SSA) (31.47 ± 10.84 versus 33.06 ± 10.11; MD ‐1.59, 95% CI ‐6.75 to 3.57; 64 eyes; Analysis 2.3).
Visual acuity
Not reported by either study.
Adverse effects
Angmo 2019 reported three cases of postoperative hyphema in the phaco‐GSL group. These data were not available for the subgroup in Husain 2019.
Quality of life measures
Not reported by either study.
Phacoemulsification versus combined phaco‐trabeculectomy
Three studies compared phacoemulsification alone with phaco‐trabeculectomy in 63 eyes of 63 participants with chronic PACG (El Sayed 2019), 72 eyes of 72 participants with medically controlled chronic PACG with coexisting cataract (Tham 2008), and 51 eyes of 51 participants with medically uncontrolled chronic PACG with coexisting cataract (Tham 2009). The latter two studies also included participants with previous acute angle‐closure attacks. We requested the data for the subgroup of participants who did not have a history of acute angle‐closure attacks from the trial investigators, but could not incorporate them, because they only provided the data for the phacoemulsification group. This comprised 26 eyes (Tham 2008), and 20 eyes (Tham 2009) in the phacoemulsification groups that did not have a previous acute angle‐closure attack. Participants who did not complete the 12‐month follow‐up were excluded from analysis (number unknown). See summary of findings Table 4.
Primary outcomes
Progression of visual field loss
One (3.8%) participant (Tham 2008), and 10 (50%) participants (Tham 2009) in the phacoemulsification groups had progression of visual field loss at 24 months. Visual field loss was not reported by El Sayed 2019.
Mean change in IOP from baseline to one year
The mean IOP at 12 months in the phacoemulsification groups was 14.2 mmHg ± 2.8 mmHg in Tham 2008, and 15.8 mmHg ± 3.4 mmHg in Tham 2009.
El Sayed 2019 did not report the mean change in IOP from baseline. The mean IOP between the phacoemulsification and phaco‐trabeculectomy groups were statistically similar at baseline (21.6 mmHg ± 9.2 mmHg in phacoemulsification group versus 25.6 mmHg ± 11.1 mmHg in phaco‐trabeculectomy group; MD ‐4.00 mmHg, 95% CI ‐9.04 to 1.04; 63 eyes). The mean IOP remained statistically comparable at all time points measured postoperatively: at 1 month (14.4 mmHg ± 3.6 mmHg versus 13.9 mmHg ± 6.0 mmHg; MD 0.50 mmHg, 95% CI ‐1.95 to 2.95; 63 eyes), 3 months (13.0 mmHg ± 5.4 mmHg versus 13 mmHg ± 4.1 mmHg; MD 0.00 mmHg, 95% CI ‐2.36 to 2.36; 63 eyes), 6 months (12.4 mmHg ± 2.5 mmHg versus 12.7 mmHg ± 3.8 mmHg; MD ‐0.30 mmHg, 95% CI ‐1.89 to 1.29; 63 eyes), and 12 months (12.6 mmHg ± 2.6 mmHg versus 13.2 mmHg ± 3.0 mmHg; MD ‐0.60 mmHg, 95% CI ‐1.99 to 0.79; 63 eyes; Analysis 3.1). We graded the certainty of evidence as low for this outcome, downgrading by one level each because of high risk of attrition bias (‐1) and imprecision due to wide confidence intervals (‐1).
Mean change in depth of the anterior chamber (ACD)
The ACD data was not available for the subgroup of participants without previous acute angle‐closure attacks in Tham 2008 and Tham 2009, and was not reported by El Sayed 2019.
Secondary outcomes
Number of medications used to control IOP
In El Sayed 2019, the mean number of IOP‐lowering medications was 2.3 (SD 0.9) in the phacoemulsification group and 2.8 (SD 1) in the phaco‐trabeculectomy group preoperatively. This was lower in the phaco‐trabeculectomy group than the phacoemulsification group at 1 month (0.1 ± 0.2 versus 0.4 ± 0.8; MD 0.30, 95% CI 0.01 to 0.59; 63 eyes), and at 3 months (0.1 ± 0.4 versus 0.5 ± 0.9; MD 0.40, 95% CI 0.06 to 0.74; 63 eyes); but comparable between groups at 6 months (0.5 ± 0.8 in the phacoemulsification group versus 0.3 ± 0.6 in the phaco‐trabeculectomy group; MD 0.20, 95% CI ‐0.15 to 0.55; 63 eyes), and 12 months (0.5 ± 0.8 versus 0.5 ± 0.9; MD 0.00, 95% CI ‐0.42 to 0.42; 63 eyes; Analysis 3.2).
The number of IOP‐lowering medications was not available for the subgroup of participants without previous acute angle‐closure attacks in Tham 2008 or Tham 2009.
We graded the certainty of evidence as low for this outcome, downgrading by one level each because of high risk of attrition bias (‐1) and imprecision due to wide confidence intervals (‐1).
Gonioscopic findings
Gonioscopic findings were not available for the subgroup of participants without previous acute attacks of angle closure in Tham 2008 and Tham 2009, and were not reported by El Sayed 2019.
Visual acuity
For El Sayed 2019, the best corrected visual acuity was comparable between the phacoemulsification and phaco‐trabeculectomy groups at baseline (0.29 ± 0.3 versus 0.27 ± 0.25; MD 0.02, 95% CI ‐0.12 to 0.16; 63 eyes), and at the final follow‐up visit (variable time scale for each participant) (0.35 ± 0.31 versus 0.38 ± 0.3; MD ‐0.03, 95% CI ‐0.18 to 0.12; 63 eyes; Analysis 3.3).
Visual acuity data were not available for the subgroup of participants without previous acute angle‐closure attacks in Tham 2008 or Tham 2009.
We graded the certainty of evidence as low for this outcome, downgrading by one level each because of high risk of attrition bias (‐1) and imprecision due to wide confidence intervals (‐1).
Adverse effects
El Sayed 2019 reported that the phacoemulsification group experienced fewer complications than the phaco‐trabeculectomy group overall (risk ratio [RR] 0.59, 95% CI 0.34 to 1.04; 63 eyes; Analysis 3.4). Phacoemulsification resulted in one case of intraoperative posterior capsular tear with vitreous loss, nine of corneal edema, and one of pupillary membrane; whereas, phaco‐trabeculectomy resulted in 18 complications, including intraoperative hyphema (1), corneal edema (6), corneal ulcer (1), hypotony (3), choroidal detachment (1), conjunctival retraction (1), shallow anterior chamber (2), pupillary membrane (2), and wipe‐out (1). In addition, more eyes in the phaco‐trabeculectomy group required further IOP‐lowering procedures (eleven needed one or more needle bleb revisions, and one underwent cyclodiode laser) than the phacoemulsification group (two eyes required trabeculectomy) (RR 5.81, 95% CI 1.41 to 23.88; 63 eyes; Analysis 3.4).
Two of 26 eyes in Tham 2008 and two of 20 eyes in Tham 2009 had intraoperative complications in the phacoemulsification group. They did not observe any postoperative complications.
We graded the certainty of evidence as low for this outcome, downgrading by one level each because of high risk of attrition bias (‐1) and imprecision due to wide confidence intervals (‐1).
Quality of life measures
Not reported by any study.
Phacoemulsification versus trabeculectomy
Tham 2013 compared phacoemulsification with trabeculectomy in participants with medically uncontrolled chronic angle‐closure glaucoma without cataract. We obtained the data for a subgroup of participants without history of acute angle‐closure attacks from the trial investigators. Of 26 participants originally randomized to phacoemulsification, 16 did not have previous acute attacks. The data in the trabeculectomy group were not provided, and as such, we were unable to analyze the between‐group differences.
Discussion
Summary of main results
We identified eight randomized controlled trials (RCT) comprising 513 eyes (total number of participants unknown) that addressed the utility of lens extraction in treating chronic angle‐closure glaucoma. The participants were recruited from a diverse range of countries and were followed up for a minimum of 12 months.
One RCT compared phacoemulsification with laser peripheral iridotomy (LPI) in chronic primary angle‐closure glaucoma (PACG) with clear crystalline lenses. A smaller proportion of participants who had phacoemulsification experienced progression of visual field loss than those who had LPI at 12 months. There was greater widening of the iridocorneal angle in participants in the phacoemulsification group compared with those in the LPI group, but no evidence of difference in intraocular pressure (IOP) reduction at all time points up to 3 years. However, the phacoemulsification group required fewer IOP‐lowering medications to achieve this reduction. There was no evidence of difference between phacoemulsification and LPI for health‐related quality of life, or for adverse events in the hands of experienced surgeons. All these findings, together with moderate certainty of evidence, suggest a clinical benefit to phacoemulsification over LPI. It is also important to note that this study was not powered to look only at those with PACG and this is a sub‐analysis; lack of significance for some findings could be perhaps be attributed to the small sample size. In addition, these results are applicable over a three‐year time period, and longer term comparisons are not yet known.
Only one study compared phacoemulsification with trabeculectomy, but we did not have the data to analyze and draw conclusions.
Three studies compared phacoemulsification with phacoemulsification and trabeculectomy. There were limited data on progression of visual field loss, change in ACD, or iridocorneal angle within these studies. There was no evidence of difference between groups for IOP, or the number of medications used to control IOP. However, there was evidence that phacoemulsification was associated with a reduced risk of complications compared with phacoemulsification plus trabeculectomy in one trial (El Sayed 2019) (low certainty of evidence).
The remaining three studies compared phacoemulsification alone versus phacoemulsification (phaco) plus supplemental interventions (viscogonioplasty [VGP] or goniosynechialysis [GSL]). All these trials included 6‐month or 12‐month follow‐up. There were no data on progression of visual field loss in these trials. Moderate to low certainty evidence suggest that there may be little or no evidence of additional benefit with the supplemental procedures compared with phacoemulsification alone for reducing IOP or medications to control IOP, increasing width of the iridocorneal angle, or visual acuity. While more complications were reported among participants in the phacoemulsification plus supplemental procedure groups than in the phacoemulsification groups, there were insufficient data to draw conclusions with certainty. Until further evidence becomes available, these supplemental procedures may be left to the discretion of the surgeon or local protocols.
Overall completeness and applicability of evidence
Overall, the review possesses good external validity. The definition of chronic PACG used in each study was generally similar across the board. The overall study population appropriately reflected the real‐world distribution of PACG. In addition, participants included those with medically controlled and uncontrolled PACG, which is similarly a representative microcosm of the wider population with PACG. The eight studies reported on chronic PACG patients with cataractous as well as clear lenses, providing a broad perspective on the utility of lens extraction in PACG. The studies encompassed a wide range of clinically relevant interventions, including one that compared lens extraction against standard care, enabling the evaluation of lens extraction's true effectiveness as a treatment modality. The majority of the included studies assessed both IOP measurements and IOP‐lowering medications, which are clinically important in terms of arresting glaucoma progression. However, the ultimate goal of PACG treatment is also to prevent additional damage to the optic nerve in order to slow or arrest visual field loss, and IOP alone may not be sufficient to assess this. Even so, few studies included progression of visual field loss as an outcome measure. In addition, the impact of the interventions on participants' health‐related quality of life was not always sought. Future studies will want to consider assessing the impact of interventions on both visual field and quality of life.
The potential differences between RCT and real world outcomes is also worth noting. Compared to a routine phacoemulsification case, eyes with PACG tend to have anatomical differences including shallower anterior chambers, shorter axial lengths, and thicker and more anteriorly positioned crystalline lenses, among others. Phacoemulsification in PACG eyes may therefore be a more challenging endeavour, thereby increasing the innate risks of intraoperative complications. While it is reassuring that the complication rates in the included studies were rates were modest, an important caveat to note is that these surgeries were invariably performed by highly experienced surgeons, whereas this may not necessarily hold true in a real world setting.
Finally, where outcomes of interest were inadequately reported, we wrote to the study authors to seek further clarification, and thereby, ensure that the review was as complete as possible. However, we were regrettably unable to obtain comparative data for three studies, and complete safety data for a few others (Tham 2008; Tham 2009; Tham 2013).
Quality of the evidence
The quality of evidence varied among the included studies. We graded the certainty of evidence to be moderate or low due to risk of bias and imprecision related to the small number of participants included in each comparison of interventions. Although randomization was adequate and there were minimal conflicts of interest across the board, the remaining risk of bias domains were problematic, primarily due to poor adherence to the CONSORT guidelines (Moher 2010). Allocation concealment and masking were generally poorly reported. In addition, loss to follow‐up was inadequately documented, and three studies lacked intention‐to‐treat analyses, instead excluding missing patients entirely. For the comparison of phacoemulsification and phaco‐VGP or phaco‐GSL in particular, variability in outcome reporting also hampered the synthesis of information. All these reduce confidence in the validity of the findings, which should therefore be interpreted with caution.
Potential biases in the review process
The review team used standard Cochrane methodology, including a comprehensive search strategy designed by experienced information specialists. Two review authors, including at least one clinician and one methodologist, independently assessed the search results for eligibility and extracted data. In addition, we reached out to the authors to seek clarification on the eligibility of the study for inclusion, as well as points of contention. As there were no language restrictions, multiple publications available only in Chinese were carefully reviewed in the screening process, which was important because a fair proportion of people with PACG reside in Chinese‐speaking regions. As such, we can confidently conclude that we have identified most, if not all, pertinent results in this review. However, it is important to note that the results should be interpreted with caution, as we obtained data for participants meeting our inclusion criteria only (chronic PACG, no previous acute angle‐closure attacks) to conduct several analyses, meaning that the data might not be adequately powered to answer the clinical question posed.
One of the review authors (DSF) co‐authored one study included in this review (Azuara‐Blanco 2016). However, two other review authors (AYO and SMN) independently assessed the study eligibility, extracted the data, and judged risk of bias following Cochrane standard methodology, and a third (VSS) performed the statistical analyses for this study. We consider the risk of bias induced by this association to be minimal.
Agreements and disagreements with other studies or reviews
This review demonstrates evidence for the benefits of lens extraction in terms of improving IOP control, increasing ACD, and reducing the number of IOP‐lowering medications required in people with chronic PACG. This is consistent with findings from previous non‐comparative studies, which demonstrated similar IOP reduction and increased ACD after lens extraction in participants with PACG, primary angle closure (PAC), or even normal non‐glaucomatous eyes (Atalay 2017; Kashiwagi 2006; Siak 2016). Masis 2017 published a systematic meta‐analysis of the final change in IOP following phacoemulsification in 597 eyes with PACG. They reported an absolute change of ‐6.4 mmHg (95% confidence interval [CI] ‐9.4 to ‐3.4; IV = 99%) at the final follow‐up visit. While synthesizing these results to determine the absolute effect of phacoemulsification was out of the scope of this review, it is worth mentioning that Masis 2017 included a mix of retrospective and prospective non‐randomized studies in addition to RCTs. Further, participants with previous acute angle‐closure attacks were eligible for inclusion in the review, and IOP was measured at the final follow‐up visit, which would vary between participants, as well as across each study. While this lends credence to the hypothesis that the lens may indeed play an important role in the pathophysiology of chronic PACG, it is possible that the true effect may differ from that described.
The role of goniosynechialysis is also worth discussing further. This review suggests that there may be little or no evidence of additional benefit with of supplemental goniosynechialysis or viscogonioplasty compared with phacoemulsification alone for reducing IOP or medications to control IOP, increasing width of the iridocorneal angle, or visual acuity. Ahmed 2019 reviewed a range of studies, including both comparative and non‐comparative studies, as well as participants with both PAC and PACG. Ahmed 2019 highlights the confounding effect that phacoemulsification may have in itself releasing peripheral anterior synechiae (PAS), the fact that a successful outcome depends not simply on performing the procedure, but also on the amount of residual PAS, and finally, the lack of sufficient intraoperative gonioscopy in establishing an accurate baseline and outcome in terms of PAS. These are all important considerations that should be considered in future studies, before dismissing goniosynechialysis or viscogonioplasty out of hand.
In their systematic review and meta‐analysis comparing phacoemulsification, trabeculectomy, and phaco‐trabeculectomy in the treatment of 1495 eyes with PACG, Deng 2011 concluded that phacotrabeculectomy was superior to both trabeculectomy and phacoemulsification in reducing IOP. Wang 2016 published a separate review and meta‐analysis comparing phacoemulsification and phaco‐trabeculectomy in 468 eyes, which concluded that phacoemulsification alone had a better effect on IOP reduction than phaco‐trabeculectomy. Interestingly, the studies included in Wang 2016 overlapped with that of Deng 2011. Our findings differ from the conclusions from both reviews – while we were unable to draw any meaningful conclusions regarding phacoemulsification
and trabeculectomy, we found some evidence to suggest that there was no significant benefit for phaco‐trabeculectomy over phacoemulsification alone, with the former more likely to produce more complications and result in further interventions. There are several methodological differences worth noting here: both Deng 2011 and Wang 2016 included non‐randomized retrospective studies, thereby increasing the potential for bias, and result in a less robust estimate of effect (Reeves 2019). Finally, neither review downgraded for risk of bias in the included studies.
Study flow diagram
'Risk of bias' summary: review authors' judgements about each 'Risk of bias' item for each included study
Comparison 1: Phacoemulsification versus phaco‐viscogonioplasty (phaco‐VGP), Outcome 1: Mean IOP change from baseline
Comparison 1: Phacoemulsification versus phaco‐viscogonioplasty (phaco‐VGP), Outcome 2: Mean number of medications to control IOP
Comparison 1: Phacoemulsification versus phaco‐viscogonioplasty (phaco‐VGP), Outcome 3: Gonioscopic findings
Comparison 1: Phacoemulsification versus phaco‐viscogonioplasty (phaco‐VGP), Outcome 4: Mean visual acuity
Comparison 2: Phacoemulsification versus phacoemulsification with goniosynechialysis (phaco‐GSL), Outcome 1: Mean IOP change from baseline
Comparison 2: Phacoemulsification versus phacoemulsification with goniosynechialysis (phaco‐GSL), Outcome 2: Mean number of medications to control IOP
Comparison 2: Phacoemulsification versus phacoemulsification with goniosynechialysis (phaco‐GSL), Outcome 3: Gonioscopic findings
Comparison 3: Phacoemulsification versus combined phaco‐trabeculectomy, Outcome 1: Mean IOP
Comparison 3: Phacoemulsification versus combined phaco‐trabeculectomy, Outcome 2: Mean number of medications to control IOP
Comparison 3: Phacoemulsification versus combined phaco‐trabeculectomy, Outcome 3: Mean visual acuity
Comparison 3: Phacoemulsification versus combined phaco‐trabeculectomy, Outcome 4: Adverse effects
| Phacoemulsification compared with laser peripheral iridotomy for primary angle‐closure glaucoma | ||||||
|---|---|---|---|---|---|---|
| Patient or population: participants with primary angle‐closure glaucoma Settings: 30 hospital eye services in Australia (1), mainland China (1), Hong Kong (2), Malaysia (2), Singapore (2), and the UK (22) Intervention: phacoemulsification Comparison: laser peripheral iridotomy (LPI) | ||||||
| Outcomes | Illustrative comparative risks* (95% CI) | Relative effect | No of eyes | Certainty of the evidence | Comments | |
| Assumed risk | Corresponding risk | |||||
| laser peripheral iridotomy | phacoemulsification | |||||
| Progression of visual field loss (at 12 months) | 165 per 1000 | 65 per 1000 (25 to 152 per 1000) | OR 0.35 (0.13 to 0.91) | 216 | ⊕⊕⊕⊝ | ‐ |
| Mean IOP change from baseline to 12 months | The mean change in IOP in the control group was ‐6.48 mmHg | The mean change in IOP in the intervention group was 0.03 mmHg higher (95% CI ‐2.34 mmHg to 2.32 mmHg) | ‐ | 257 | ⊕⊕⊕⊝ | ‐ |
| Mean number of medications to control IOP (at 12 months) | On average, the number of medications in the control group was 0.98 | On average, the number of medications in the intervention group was 0.70 lower (95% CI ‐0.89 to ‐0.51) | ‐ | 263 | ⊕⊕⊕⊝ | ‐ |
| Gonioscopic findings (at 12 months or later) | The mean angle closure in the control group was 203° | The mean angle closure in the intervention group was 84.93° less (95% CI 38.61° to 131.25°) | 106 | ⊕⊕⊕⊝ | ‐ | |
| Visual acuity (at 12 months) | The mean visual acuity in the control group was 77.4 | The mean visual acuity in the intervention group was 2.03 letters greater (95% CI ‐0.77 to 4.84) | ‐ | 242 | ⊕⊕⊕⊝ | ‐ |
| Adverse effects | No data available | ‐ | ‐ | ‐ | ‐ | |
| Quality of life measures (at 12 months) | The average score on the EQ‐5D in the control group was 2.88 | The average score on the EQ‐5D in the intervention group was 0.04 higher (95% CI ‐0.16 to 0.24) | ‐ | 254 (one study) | ⊕⊕⊕⊝ | ‐ |
| *The assumed risk is based on the estimate in the control group. The corresponding risk (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI). CI: confidence interval; IOP: intraocular pressure; MD: mean difference; OR: odds ratio; EQ‐5D: European Quality of Life‐5 Dimension | ||||||
| GRADE Working Group grades of evidence | ||||||
| aDowngraded one level for imprecision because sample size was not adequately powered (original study was powered to investigate participants with both primary angle closure (PAC) and primary angle‐closure glaucoma (PACG), whereas only participants with PACG were included in this analysis). | ||||||
| Phacoemulsification versus phacoemulsification plus viscogonioplasty for primary angle‐closure glaucoma | ||||||
|---|---|---|---|---|---|---|
| Patient or population: participants with primary angle‐closure glaucoma Settings: university hospital in Iran Intervention: phacoemulsification Comparison: phacoemulsification plus viscogonioplasty (phaco‐VGP) | ||||||
| Outcomes | Illustrative comparative risks* (95% CI) | Relative effect | No of Participants | Certainty of the evidence | Comments | |
| Assumed risk | Corresponding risk | |||||
| phacoemulsification plus viscogonioplasty | phacoemulsification | |||||
| Progression of visual field loss | No data available for this outcome | ‐ | ‐ | ‐ | ‐ | |
| Mean IOP change from baseline to 12 months | The mean change in IOP in the control group was ‐8.8 mmHg | The mean change in IOP in the intervention group was | ‐ | 91 eyes | ⊕⊕⊝⊝ | ‐ |
| Mean number of medications to control IOP (at 12 months) | The mean number of medications to control IOP in the control group was 0.4 | The mean number of medications to control IOP in the intervention groups was 0.1; on average, 0.30 fewer (95% CI ‐0.55 to ‐0.05) | ‐ | 91 eyes | ⊕⊕⊝⊝ | at 6 months: MD ‐0.30 (95% CI ‐0.56 to ‐0.04; 1 study, 91 eyes) |
| Gonioscopic findings (at 12 months or later) | The mean change of angle grading in the control group was 2.0 | The mean change of angle grading in the intervention group was 1.4; on average, 0.60 less (95% CI ‐0.91 to ‐0.29) | ‐ | 91 eyes | ⊕⊕⊝⊝ | ‐ |
| Gonioscopic findings (TISA500) (at 12 months) | The mean TISA500 in the control group was 0.054 | The mean TISA500 in the intervention group was 0.020; on average, 0.03 less (95% CI ‐0.06 to ‐0.01) | ‐ | 91 eyes | ⊕⊕⊝⊝ | ‐ |
| Gonioscopic findings (TISA750) (at 12 months) | The mean TISA750 in the control group was 0.119 | The mean TISA750 in the intervention group was 0.084; on average, 0.03 less (95% CI ‐0.06 to ‐0.01) | ‐ | 91 eyes | ⊕⊕⊝⊝ | ‐ |
| Visual acuity (postoperatively) | The mean best corrected visual acuity in the control group was 0.28 | The mean best corrected visual acuity in the intervention group was 0.27; on average, 0.01 less (95% CI ‐0.10 to 0.08) | ‐ | 91 eyes | ⊕⊕⊝⊝ | ‐ |
| Adverse effects | hyphema (3 eyes), postoperative fibrin reaction (4 eyes) | postoperative fibrin reaction (2 eyes) | ‐ | ‐ | ‐ | |
| Quality of life measures | No data available for this outcome | ‐ | ‐ | ‐ | ‐ | |
| *The assumed risk is based on the estimate in the control group. The corresponding risk (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI). | ||||||
| GRADE Working Group grades of evidence | ||||||
| aDowngraded for high risk of attrition bias | ||||||
| Phacoemulsification versus phacoemulsification plus goniosynechialysis for primary angle‐closure glaucoma | ||||||
|---|---|---|---|---|---|---|
| Patient or population: participants with primary angle closure glaucoma Settings: tertiary eye care center and university hospital in Vietnam, Thailand, and Hong Kong Intervention: phacoemulsification Comparison: phacoemulsification plus goniosynechialysis (phaco‐GSL) | ||||||
| Outcomes | Illustrative comparative risks* (95% CI) | Relative effect | No of Participants | Certainty of the evidence | Comments | |
| Assumed risk | Corresponding risk | |||||
| phacoemulsification plus goniosynechialysis | phacoemulsification | |||||
| Progression of visual field loss | No data available for this outcome | ‐ | ‐ | ‐ | ‐ | |
| Mean IOP change from baseline (at 12 months) | The mean change in IOP in the control group was ‐6.47 mmHg | The mean change in IOP in the intervention group was ‐6.59; on average, 0.12 lower (95% CI ‐4.72 to 4.48) | ‐ | 32 eyes | ⊕⊕⊕⊝ | at 6 months: MD ‐0.04 mmHg (95% CI ‐0.93 to 0.85; 1 study, 64 eyes) |
| Mean number of medications to control IOP (at 12 months) | The mean number of medications to control IOP in the control group was 0.94 | The mean number of medications to control IOP in the intervention groups was 0.56; on average, 0.38 fewer (95% CI ‐1.23 to 0.47) | ‐ | 32 eyes | ⊕⊕⊕⊝ | at 6 months: MD ‐0.35 (95% CI ‐0.63 to ‐0.07; 1 study, 64 eyes) |
| Gonioscopic findings (at 6 months) | See comments | See comments | ‐ | 64 eyes (one study) | ‐ | AOD500: MD ‐0.04° (95% CI ‐0.27 to 0.19) AOD750: MD 0.01° (95% CI ‐0.27 to 0.29) TISA500: MD ‐0.02° (95% CI ‐0.06 to 0.02) TISA750: MD ‐0.03° (95% CI ‐0.17 to 0.11) SSA: MD ‐1.59° (95% CI ‐6.75 to 3.57) |
| Visual acuity | No data available for this outcome | ‐ | ‐ | ‐ | ‐ | |
| Adverse effects | hyphema (3 eyes) | none reported | ‐ | ‐ | ‐ | |
| Quality of life measures | No data available for this outcome | ‐ | ‐ | ‐ | ‐ | |
| *The assumed risk is based on the estimate in the control group. The corresponding risk (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI). AOD: angle opening distance;CI: confidence interval; IOP: intraocular pressure; MD: mean difference; SSA: scleral spur angle; TISA: trabecular iris space area | ||||||
| GRADE Working Group grades of evidence | ||||||
| aDowngraded one level for imprecision due to wide confidence intervals | ||||||
| Phacoemulsification versus phacoemulsification plus trabeculectomy for primary angle‐closure glaucoma | ||||||
|---|---|---|---|---|---|---|
| Patient or population: participants with primary angle‐closure glaucoma Settings: university hospital in Egypt Intervention: phacoemulsification Comparison: phacoemulsification plus trabeculectomy | ||||||
| Outcomes | Illustrative comparative risks* (95% CI) | Relative effect | No of Participants | Certainty of the evidence | Comments | |
| Assumed risk | Corresponding risk | |||||
| Phacoemulsification combined with trabeculectomy | Phacoemulsification | |||||
| Progression of visual field loss (at 12 months) | No data available for this outcome | ‐ | ‐ | ‐ | ||
| Mean IOP change from baseline to 12 months | The mean IOP in the control group was 13.2 mmHg | The mean IOP in the intervention group was 12.6 mmHg; on average, 0.60 mmHg lower (95% CI ‐1.99 to 0.79) | ‐ | 63 eyes (one study) | ⊕⊕⊝⊝ | |
| Mean number of medications to control IOP (at 12 months) | The mean number of medications to control IOP in the control group was 0.5 | The mean number of medications to control IOP in the intervention group was 0.5; on average, there was no difference (95% CI ‐0.42 to 0.42) | ‐ | 63 eyes (one study) | ⊕⊕⊝⊝ | ‐ |
| Gonioscopic findings | No data available for this outcome | ‐ | ‐ | ‐ | ‐ | |
| Mean best corrected visual acuity (at final follow‐up) | The mean best corrected visual acuity in the control group was 0.38 | The mean best corrected visual acuity in the intervention group was 0.35: on average, 0.03 lower (95% CI ‐0.18 to 0.12) | 63 eyes (one study) | ⊕⊕⊝⊝ | ‐ | |
| Adverse effects | Intraoperative and postoperative complications | RR 0.59 (0.34 to 1.04) | 63 eyes (one study) | ⊕⊕⊝⊝ | ||
| 580.6 per 1000 | 343.8 per 1000 | |||||
| Additional IOP‐lowering procedures required | RR 5.81 (1.41 to 23.88) | |||||
| 64.5 per 1000 | 375 per 1000 | |||||
| Quality of life measures (at 12 months) | No data available for this outcome | ‐ | ‐ | ‐ | ‐ | |
| *The assumed risk (e.g. the median control group risk across studies) is based on the estimate in the control group. The corresponding risk (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI). CI: confidence interval; IOP: intraocular pressure; RR: risk ratio | ||||||
| GRADE Working Group grades of evidence | ||||||
| aDowngraded for high risk of attrition bias | ||||||
| Intervention | Phacoemulsification | Phacoemulsification | Phacoemulsification | Phacoemulsification | Phacoemulsification |
|---|---|---|---|---|---|
| Comparison | Laser peripheral iridotomy (LPI) | Phacoemulsification plus viscogonioplasty | Phacoemulsification plus goniosynechialysis (phaco‐GSL) | Phacoemulsification plus trabeculectomy | Trabeculectomy |
| Study ID | |||||
| Progression of visual field loss | OR 0.49 (95% CI 0.24 to 0.92) at 6 months; OR 0.35 (95% CI 0.13 to 0.91) at 12 months; OR 0.37 (95% CI 0.17 to 0.82) at 24 months; OR 0.42 (95% CI 0.20 to 0.87) at 36 months | NR | NR | Unable to complete analysis to compare between groups | Unable to complete analysis to compare between groups |
| Mean change in IOP (in mmHg) | MD ‐0.65 mmHg (95% CI ‐3.12 to 1.82) at 6 months; MD ‐0.03 mmHg (95% CI ‐2.34 to 2.32) at 12 months; MD 0.74 mmHg (95% CI ‐1.66 to 3.13) at 24 months; MD 1.04 mmHg (95% CI ‐1.22 to 3.31) at 36 months | MD 0.50 mmHg (95% CI ‐2.64 to 3.64; 91 eyes) at 12 months | MD ‐0.04 mmHg (95% CI ‐0.93 to 0.85; 1 study, 64 eyes) at 6 months; MD ‐0.12 mmHg (95% CI ‐4.72 to 4.48; 1 study, 32 eyes) at 12 months | MD 0.50 mmHg (95% CI ‐1.95 to 2.95) at 1 month; MD 0.00 mmHg (95% CI ‐2.36 to 2.36) at 3 months; MD ‐0.30 mmHg (95% CI ‐1.89 to 1.29) at 6 months; MD ‐0.60 mmHg (95% CI ‐1.99 to 0.79) at 12 months | Unable to complete analysis to compare between groups |
| Mean change in anterior chamber depth | NR | NR | NR | NR | NR |
| Number of medications used to control IOP | MD ‐0.65 (95% CI ‐0.85 to ‐0.45) at 6 months; MD ‐0.70 (95% CI ‐0.89 to ‐0.51) at 12 months; MD ‐0.73 (95% CI ‐0.94 to ‐0.52) at 24 months; MD ‐0.65 (95% CI ‐0.87 to ‐0.43) at 36 months | MD ‐0.30 (95% CI ‐0.56 to ‐0.04; 91 eyes) at 6 months; MD ‐0.30 (95% CI ‐0.55 to ‐0.05; 91 eyes) at 12 months | MD ‐0.35 (95% CI ‐0.63 to ‐0.07; 1 study, 64 eyes) at 6 months; MD ‐0.38 (95% CI ‐1.23 to 0.47; 1 study, 32 eyes) at 12 months | MD 0.30 (95% CI 0.01 to 0.59) at 1 month; MD 0.40 (95% CI 0.06 to 0.74) at 3 months; MD 0.20 (95% CI ‐0.15 to 0.55) at 6 months; MD 0.00 (95% CI ‐0.42 to 0.42) at 12 months | Unable to complete analysis to compare between groups |
| Gonioscopic findings (measured in degrees) | Appositional angle closure MD ‐74.16° (95% CI ‐121.34 to ‐26.98) at 36 months Synechial angle closure MD ‐69.63° (95% CI, ‐104.34 to ‐16.92) at 12 months; MD 1.12 (95% CI, ‐42.37 to 44.62) at 36 months | Angle width TISA500 TISA750 | AOD500 AOD750 TISA500 TISA750 SSA | Unable to complete analysis to compare between groups | Unable to complete analysis to compare between groups |
| Best corrected visual acuity | MD 2.03 (95% CI ‐0.77 to 4.84) at 12 months; MD 4.30 (95% CI 0.74 to 7.87) at 36 months | MD ‐0.01 (95% CI ‐0.10 to 0.08; 91 eyes) postoperatively | NR | MD ‐0.03 (95% CI ‐0.18 to 0.12; 1 study, 63 eyes) | Unable to complete analysis to compare between groups |
| Adverse effects | Phacoemulsification group: malignant glaucoma (1 eye); irreversible loss of vision of more than 10 ETDRS letters (1 eye); other related adverse events (1 eye). LPI group: lost ten or more ETDRS letters irreversibly (3 eyes); other related adverse events (10 eyes). | Phaco‐GSL group hyphema (3 eyes) | Less risk of: Intra‐ and post‐operative complications (RR 0.59, 95% CI 0.34 to 1.04); additional IOP‐lowering procedures (RR 5.81, 95% CI 1.41 to 23.88) in the phacoemulsification group | none | |
| Quality of life measures (European Quality of Life‐5 Dimension) | MD 0.03 (95% CI ‐0.16 to 0.22) at 6 months; MD 0.04 (95% CI ‐0.16 to 0.24) at 12 months; MD 0.005 (95% CI ‐0.19 to 0.20) at 24 months; MD ‐0.04 (95% CI ‐0.24 to 0.16) at 36 months | NR | NR | NR | NR |
| AOD: angle opening distance; CI: confidence interval; IOP: Intraocular pressure; NR: not reported; MD: mean difference; OR: odds ratio; RR: risk ratio; SSA: scleral spur angle; TISA: trabecular iris space area | |||||
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
| 1.1 Mean IOP change from baseline Show forest plot | 1 | Mean Difference (IV, Fixed, 95% CI) | Totals not selected | |
| 1.1.1 at 12 months | 1 | Mean Difference (IV, Fixed, 95% CI) | Totals not selected | |
| 1.2 Mean number of medications to control IOP Show forest plot | 1 | Mean Difference (IV, Fixed, 95% CI) | Totals not selected | |
| 1.2.1 at 6 months | 1 | Mean Difference (IV, Fixed, 95% CI) | Totals not selected | |
| 1.2.2 at 12 months | 1 | Mean Difference (IV, Fixed, 95% CI) | Totals not selected | |
| 1.3 Gonioscopic findings Show forest plot | 1 | Mean Difference (IV, Fixed, 95% CI) | Totals not selected | |
| 1.3.1 Change of angle grading at 12 months or later | 1 | Mean Difference (IV, Fixed, 95% CI) | Totals not selected | |
| 1.3.2 TISA500 | 1 | Mean Difference (IV, Fixed, 95% CI) | Totals not selected | |
| 1.3.3 TISA750 | 1 | Mean Difference (IV, Fixed, 95% CI) | Totals not selected | |
| 1.4 Mean visual acuity Show forest plot | 1 | Mean Difference (IV, Fixed, 95% CI) | Totals not selected | |
| 1.4.1 at baseline | 1 | Mean Difference (IV, Fixed, 95% CI) | Totals not selected | |
| 1.4.2 postoperatively | 1 | Mean Difference (IV, Fixed, 95% CI) | Totals not selected | |
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
| 2.1 Mean IOP change from baseline Show forest plot | 2 | Mean Difference (IV, Fixed, 95% CI) | Totals not selected | |
| 2.1.1 at 6 months | 1 | Mean Difference (IV, Fixed, 95% CI) | Totals not selected | |
| 2.1.2 at 12 months | 1 | Mean Difference (IV, Fixed, 95% CI) | Totals not selected | |
| 2.2 Mean number of medications to control IOP Show forest plot | 2 | Mean Difference (IV, Fixed, 95% CI) | Totals not selected | |
| 2.2.1 at 6 months | 1 | Mean Difference (IV, Fixed, 95% CI) | Totals not selected | |
| 2.2.2 at 12 months | 1 | Mean Difference (IV, Fixed, 95% CI) | Totals not selected | |
| 2.3 Gonioscopic findings Show forest plot | 1 | Mean Difference (IV, Fixed, 95% CI) | Totals not selected | |
| 2.3.1 AOD500 | 1 | Mean Difference (IV, Fixed, 95% CI) | Totals not selected | |
| 2.3.2 AOD750 | 1 | Mean Difference (IV, Fixed, 95% CI) | Totals not selected | |
| 2.3.3 TISA500 | 1 | Mean Difference (IV, Fixed, 95% CI) | Totals not selected | |
| 2.3.4 TISA750 | 1 | Mean Difference (IV, Fixed, 95% CI) | Totals not selected | |
| 2.3.5 SSA | 1 | Mean Difference (IV, Fixed, 95% CI) | Totals not selected | |
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
| 3.1 Mean IOP Show forest plot | 1 | Mean Difference (IV, Fixed, 95% CI) | Totals not selected | |
| 3.1.1 at baseline | 1 | Mean Difference (IV, Fixed, 95% CI) | Totals not selected | |
| 3.1.2 at 1 month | 1 | Mean Difference (IV, Fixed, 95% CI) | Totals not selected | |
| 3.1.3 at 3 months | 1 | Mean Difference (IV, Fixed, 95% CI) | Totals not selected | |
| 3.1.4 at 6 months | 1 | Mean Difference (IV, Fixed, 95% CI) | Totals not selected | |
| 3.1.5 at 12 months | 1 | Mean Difference (IV, Fixed, 95% CI) | Totals not selected | |
| 3.2 Mean number of medications to control IOP Show forest plot | 1 | Mean Difference (IV, Fixed, 95% CI) | Totals not selected | |
| 3.2.1 at baseline | 1 | Mean Difference (IV, Fixed, 95% CI) | Totals not selected | |
| 3.2.2 at 1 month | 1 | Mean Difference (IV, Fixed, 95% CI) | Totals not selected | |
| 3.2.3 at 3 months | 1 | Mean Difference (IV, Fixed, 95% CI) | Totals not selected | |
| 3.2.4 at 6 months | 1 | Mean Difference (IV, Fixed, 95% CI) | Totals not selected | |
| 3.2.5 at 12 months | 1 | Mean Difference (IV, Fixed, 95% CI) | Totals not selected | |
| 3.3 Mean visual acuity Show forest plot | 1 | Mean Difference (IV, Fixed, 95% CI) | Totals not selected | |
| 3.3.1 preoperatively | 1 | Mean Difference (IV, Fixed, 95% CI) | Totals not selected | |
| 3.3.2 at the final follow‐up | 1 | Mean Difference (IV, Fixed, 95% CI) | Totals not selected | |
| 3.4 Adverse effects Show forest plot | 1 | Risk Ratio (M‐H, Fixed, 95% CI) | Totals not selected | |
| 3.4.1 Intra‐ and post‐operative complications | 1 | Risk Ratio (M‐H, Fixed, 95% CI) | Totals not selected | |
| 3.4.2 Additional IOP‐lowering procedures | 1 | Risk Ratio (M‐H, Fixed, 95% CI) | Totals not selected | |
