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Pars plana vitrectomy combined with scleral buckle versus pars plana vitrectomy for giant retinal tear

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Versión publicada: 26 abril 2017 Historial de versiones

https://doi.org/10.1002/14651858.CD012646

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Abstract

This is a protocol for a Cochrane Review (Intervention). The objectives are as follows:

To assess the effectiveness and safety of pars plana vitrectomy combined with scleral buckle versus pars plana vitrectomy alone for eyes with giant retinal tear.

Background

Description of the condition

A giant retinal tear (GRT) is a full‐thickness neurosensory retinal break extending for 90° or more in the presence of a posterior vitreous detachment (Freeman 1978; Glasspool 1973; Kanski 1975; Schepens 1967; Scott 1975).

The annual incidence of GRT in the general population is estimated to be between 0.094 and 0.15 per 100,000 individuals (Ang 2010; Mitry 2011). The mean age of people with GRT ranges from 30 to 53 years (Ambresin 2003; Freeman 1981; Ghosh 2004; Goezinne 2008; Lee 2009; Norton 1969; Sirimaharaj 2005; Wolfensberger 2003). By gender, men represent more cases of GRT, up to 91% of all cases (Ang 2010). GRTs are estimated to be the cause of rhegmatogenous retinal detachment in 0.5% to 8.3% of cases (Chou 2007; Freeman 1978; Malbran 1990; Yorston 2002).

GRTs can be classified as primary or secondary. Primary GRTs are idiopathic, while secondary GRTs can be caused by trauma, peripheral retinal degeneration (lattice‐related and white‐without‐pressure), hereditary vitreoretinopathies, such as Sticklers (Donoso 2003; Stickler 2001), Ehlers‐Danlos and Marfan syndrome (Dotrelova 1997); high myopia (greater than 6 diopters) (Ang 2010); or as a complication of other surgical procedures, such as pars plana vitrectomy (PPV) (Shinoda 2008), refractive surgery (Navarro 2005; Ozdamar 1998; Schipper 2000; Vilaplana 1999), excessive diathermy, or photocoagulation (Schepens 1962). The majority of GRTs are judged to be idiopathic (55% to 66%); next in frequency are trauma (31%) (Ghosh 2004; Goezinne 2008; Holland 1977; Kanski 1975; Leaver 1981; Leaver 1984; Norton 1969; Sirimaharaj 2005; Vidaurri‐Leal 1984), high myopia (9%) (Holland 1977; Kanski 1975; Lee 2009), and hereditary vitreoretinopathies (1%) (Donoso 2003; Stickler 2001). Other rare associations have included aniridia, lens coloboma, buphthalmos, microspherophakia, retinitis pigmentosa, endogenous endophthalmitis and acute retinal necrosis (Cahill 1998; Cooling 1980; Dowler 1995; Hovland 1968; Pal 2005).

Between 0% and 13% of GRTs present as bilateral, nontraumatic tears (Ambresin 2003; Ang 2012; Freeman 1978; Ghosh 2004; Goezinne 2008; Holland 1977; Kanski 1975; Leaver 1984; Lee 2009; Schepens 1962; Schepens 1967; Sirimaharaj 2005; Vidaurri‐Leal 1984). Nearly 10% of cases of GRT have been associated with an earlier GRT in the fellow eye (Ang 2012). GRTs frequently are found just posterior to the ora serrata. In cases of blunt trauma, the GRT usually appears at the superonasal quadrant associated with vitreous base avulsion; secondary to anterior‐to‐posterior compression followed by transverse distension of the globe (Schepens 1967). When GRTs are presented at the equatorial zone with posterior extensions, the slits at either end of the GRT may extend further posteriorly in a radial fashion (Scott 1976), giving the tear's edge increased independent mobility that tends to make it invert or fold on itself.

At diagnosis, visual acuity varies widely from counting fingers and light perception to, in some cases, visual acuity better than 20/40 (Ang 2010). More than 50% of all cases with GRT are associated with retinal detachment in which the fovea is compromised (fovea‐off retinal detachment). People with GRT usually present with acute, painless loss of vision, that may be preceded by the perception of lights, floaters, a shadow over the field of vision, or a combination of these symptoms (Ambresin 2003; Ang 2012; Aylward 1993; Ghosh 2004; Goezinne 2008; Leaver 1984).

Surgical management of GRT can be extremely challenging because of the high incidence of scarring on both retinal surfaces and in the vitreous cavity following retinal detachment, which may lead to surgical failure even following initially successful surgical repair. Proliferative vitreous retinopathy may be due to retinal pigment epithelium (RPE) cells from the large area of exposed RPE and blood‐borne cells from any concurrent clinical or subclinical associated vitreous hemorrhage. RPE cells migrate towards the vitreous cavity and proliferate into the epiretinal and subretinal space with an increase in cytokine production followed by formation of cellular membranes, which may grow and contract (Duquesne 1996; Girard 1994; Kon 1999; Leaver 1984; Malbran 1990; Miller 1986; Ryan 1985; Tseng 2004; Weller 1990; Wiedemann 1988; Yeung 2008; Yoshino 1989). Proliferative vitreous retinopathy has been estimated to cause up to 49% of recurrent retina detachment of GRT cases (Ghosh 2004; Kertes 1997; Malbran 1990; Rofail 2005; Scott 2002).

There has been a long‐standing debate over the role of the scleral buckle procedure combined with PPV in the surgical management of GRT. Management includes complete vitrectomy, unfolding the retinal flap, sealing the tear with chorioretinal adhesion, and providing long‐term intraocular tamponade (Adelman 2013; Chang 1989; Kreiger 1992).

The role of scleral buckling is controversial. Some surgeons consider it a beneficial procedure to help attachment of the retina because it reduces early and late vitreoretinal tractions, supports areas where unrecognized retinal breaks developed after surgery and counteracts late tractions on peripheral retina from contracture of residual vitreous gel. There are surgeons who consider it to complicate the closure of GRT by causing a gaping of retinal tissue, redundant retinal folds, being a real cause of posterior retinal slippage due to its role in changing ocular contour and scleral shortening relative to retina. Alternatively, some surgeons consider performing a scleral buckle only for recurrent cases of GRT. This remains an ongoing discussion between experienced surgeons (Al‐Khairi 2008; Hoffman 1986; May 1992; Scott 2002).

Description of the intervention

Two surgical interventions are used to repair GRTs: PPV combined with scleral buckle or PPV alone.

PPV is a surgical procedure that involves removal of the vitreous gel. Perfluorocarbon liquids are then used to unfold the retina and provide countertraction and retinal stabilization during removal of fibrous membranes adherent to the retina (epiretinal and subretinal membranes) (Machemer 1972). Once retina reattachment is complete, the surgeon performs two or three rows of endophotocoagulation under air or a perfluorocarbon liquid bubble at the border of the tear. At the end of the PPV, silicone oil or a gas bubble is usually injected into the eye to provide retinal tamponade while the retina heals and reattaches (Chang 1989; Machemer 1972; Mathis 1992).

Scleral buckle procedures involve the use of an explant made of silicon sponge or a solid silicone band sutured to the sclera circumferentially around the equator of the eye (Wilkinson 1999; Williams 2006).

Scleral buckle and PPV may be combined for treatment of GRTs (Goezinne 2008; Holland 1977; Weichel 2006).

How the intervention might work

In PPV, the vitreous body and the vitreous base are removed; intraoperatively perfluorocarbon liquids (perfluoro n‐octano) are used to unfold the retina. Fibrous membranes are removed to relieve the vitreoretinal traction while the retina flattens. Once the retina is flattened, the tear is sealed by chorioretinal adhesion induced by endophotocoagulation. At the end of the procedure, the vitreous cavity is filled with silicone oil or a gas bubble to promote the adhesion between the retina and the RPE (Ambresin 2003; Freeman 1981; Leaver 1981; Leaver 1984; Sirimaharaj 2005).

The scleral buckle creates an indentation in the wall of the eye, which brings the detached retina closer to the eye wall and relieves the vitreoretinal traction by supporting the vitreous base. Thus, the combined procedure may hasten healing and result in better postsurgery anatomical and visual outcomes (Goezinne 2008; Holland 1977; Weichel 2006).

Why it is important to do this review

GRTs are an uncommon cause of retinal detachment. Even though primary and final retinal reattachment rates are achieved in up to 90% of cases (Chang 1989; Goezinne 2008), visual recovery may be limited. Because of the extensive area of RPE exposed, GRTs usually progress rapidly to proliferative vitreous retinopathy leading to surgical failure or reduced vision. The surgical management of a GRT may be challenging; recurrent retinal detachment secondary to proliferative vitreous retinopathy occurs in up to 40% of cases (Ghosh 2004; Kertes 1997; Malbran 1990; Rofail 2005; Scott 2002).

GRT currently is managed with PPV; the use of adjunctive scleral buckling is debated because it is unclear whether applying a scleral buckle provides anatomical or visual advantage. Although there is general consensus that favors the combined procedure in cases of GRT with proliferative vitreous retinopathy, some surgeons choose not to use scleral buckling because it may distort the shape of the eye and enhance the risks of slippage of the retina posteriorly, secondary axial lengthening, gaping of retinal tissue, redundant retinal folds and fish mouthing (Chang 1989; Machemer 1972; Mathis 1992). Other surgeons favor the combined procedure because it is thought to reduce early and late traction within the vitreous base, thus decreasing the risk of recurrent retinal detachment (Goezinne 2008; Holland 1977; Weichel 2006).

It is therefore important to review the current evidence to compare PPV alone or combined with scleral buckling to determine the better option that results in higher rates of surgery success, while reducing the number of secondary surgeries and adverse events. A separate Cochrane Review has been published about interventions for prevention of GRT in the fellow eye because people with unilateral GRT are at high risk of developing retinal tears and retinal detachment in the other eye (Ang 2012).

Objectives

To assess the effectiveness and safety of pars plana vitrectomy combined with scleral buckle versus pars plana vitrectomy alone for eyes with giant retinal tear.

Methods

Criteria for considering studies for this review

Types of studies

We will include only randomized controlled trials (RCTs) and exclude quasi‐randomized and nonrandomized trials. We will include trials irrespective of their publication status or language.

Types of participants

We will include trials that enrolled participants with either unilateral or bilateral GRT. We will define GRT as a full‐thickness retinal break extending circumferentially for 90° or greater in the presence of a posterior vitreous detachment, or as defined by eligible trials. We will include trials with more than three months of follow‐up, regardless of the age, gender, ethnicity, lens status (e.g. phakic or pseudophakic eyes) of the affected eye(s), or etiology of GRT among participants enrolled in the trials.

Types of interventions

We will include trials that compared PPV combined with scleral buckle versus PPV alone for GRT.

Types of outcome measures

Primary outcomes

  1. Primary surgical success defined as primary retinal reattachment, or as defined by the trial investigators, after initial surgery. As we anticipate trials will report different postsurgery follow‐up, we will consider outcomes reported at different time points: less than six months, six to 12 months and more than 12 months' follow‐up.

Secondary outcomes

  1. Mean change in best corrected visual acuity (BCVA) in logMAR units from baseline to last follow‐up visit reported at different time points (less than six months, six to 12 months and more than 12 months' follow‐up).

  2. Proportion of study eyes that required a second surgery for retinal reattachment after the initial surgery. We will analyze second surgeries reported from day one up to last reported follow‐up visit after surgery.

Adverse events

We will investigate the proportion of study eyes with adverse events after the surgeries such as retinal detachment recurrence, elevation of intraocular pressure above 21 mmHg, choroidal detachment, cystoid macular edema, macular pucker, vitreoretinal proliferation, progression of cataract in initially phakic eyes and any other adverse events reported from the included trials at any time from day one up to last reported follow‐up visit after surgery.

Economic outcomes

We will compare costs between treatment groups when data are available.

Search methods for identification of studies

Electronic searches

The Cochrane Eyes and Vision Information Specialist will search the following electronic databases for randomised controlled trials and controlled clinical trials. There will be no language or publication year restrictions.

  • Cochrane Central Register of Controlled Trials (CENTRAL) (which contains the Cochrane Eyes and Vision Trials Register) in the Cochrane Library (latest issue) (Appendix 1);

  • MEDLINE Ovid (1946 to present) (Appendix 2);

  • Embase.com (1947 to present) (Appendix 3);

  • LILACS (Latin American and Caribbean Health Science Information Database (1982 to present) (Appendix 4);

  • PubMed (1948 to present) (Appendix 5);

  • US National Institutes of Health Ongoing Trials Register ClinicalTrials.gov (www.clinicaltrials.gov) (Appendix 6);

  • World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp) (Appendix 7);

Searching other resources

For this review, we will not search conference proceedings because these are handsearched by Cochrane Eyes and Vision (CEV) and included in CENTRAL.

Data collection and analysis

Selection of studies

Two authors will independently assess the titles and abstracts of all records identified by the electronic and manual searches. Each author will label the study referenced in each citation as "definitely relevant," "unsure" or "definitely not relevant." We will exclude trials classified as "definitely not relevant" from the review. Two authors will independently reassess the full‐text of trials labeled as "unsure" and "definitely relevant" according to the inclusion criteria for this review and classify them as "definitely include" or "definitely exclude." We will assess the trials labeled as "definitely include" for methodological quality. We will resolve any differences in classification between the two authors by discussion at both stages of screening process. We will document excluded trials after review of the full‐text report and provide the reasons for exclusion in the 'Characteristics of excluded studies' table.

Data extraction and management

Two authors will extract data independently using online web‐based data extraction forms developed by Cochrane Eyes and Vision, using Systematic Review Data Repository (SRDR) or Covidence. Two authors will record the data independently and reach consensus before entering data into Review Manager 5 (RevMan 5) (Review Manager 5 2014). One author will enter the data into Review Manager 5 and a second author will verify the entered data as correct.

We will collect the following information from the included trials: study methods, participants, interventions and outcomes. If data on included trials are missing or unclear, we will contact the study authors or organizations involved to obtain clarification. When possible, we will contact trial authors to ask if they are able to provide numeric data when it is only provided in a graphic format.

Assessment of risk of bias in included studies

We will assess each included trial for the risks of bias according to the guidelines in Chapter 8 of the Cochrane Handbook for Systematic Reviews of Interventions (Higgins 2011). We will consider the following criteria when assessing bias.

  1. Random sequence generation: we will assess the method used to generate the allocation sequence generation and allocation concealment method used before randomization.

  2. Masking (blinding) of participants and outcome assessors: we will assess the methods used to mask participants and outcome assessors.

  3. Incomplete outcome data: we will assess exclusions after randomization, rates of follow‐up, reasons for losses to follow‐up and deviations from intention‐to‐treat analysis of outcomes.

  4. Selective outcome reporting: we will assess selective outcome reporting by comparing protocols and other design documents with trial reports and note outcomes that were measured but not reported.

  5. Other bias: for example, industry funding.

We will grade each of the above bias criteria as:

  1. high risk of bias: when plausible bias seriously weakens the study results;

  2. low risk of bias: when plausible bias is unlikely to alter the study results; or

  3. unclear risk of bias: when plausible bias raises some doubt about the study results.

For all trials assessed graded as "unclear risk of bias" because of the doubt about the study on methods, results or missing data, we will contact the investigators of the RCTs to request additional information. If we are unable to communicate with the study investigators or do not receive a response within two weeks, we will assess the risks of bias of that trial based on the available information and note the lack of response from study investigators. We will resolve any disagreements between the authors regarding bias assessment through discussion until a consensus is reached.

Measures of treatment effect

We will estimate the risk ratio (RR) and its 95% confidence interval (CI) after surgery (PPV combined with scleral buckle compared with PPV alone) of the following dichotomous outcomes.

  1. Primary surgical success.

  2. Second surgery for retinal reattachment.

  3. Develop of adverse events such as retinal detachment recurrence, elevation of intraocular pressure above 21 mmHg, choroidal detachment, cystoid macular edema, macular pucker, vitreoretinal proliferation, progression of cataract in initially phakic eyes and any other adverse events reported from the included trials at any time from day one up to last reported follow‐up visit after surgery.

We will estimate means and standard deviation of absolute and relative change after surgery (PPV combined with scleral buckle compared with PPV alone) of the following outcomes.

  1. Absolute and relative change on visual acuity in LogMAR from baseline to follow‐up visits in both surgery groups.

  2. Absolute and relative change on retinal detachment in GRT from baseline to follow‐up visits in both surgery groups.

To avoid the phenomenon of regression to the mean for the absolute change, we will perform an analysis of covariance were the change is defined relative to the value of 'y' at baseline.

Unit of analysis issues

For this review, the unit of analysis will be eyes, then all statistical estimations will be including within individual correlation. Among the analyses that we will use are analysis of covariance and lineal regression for repeated measures.

For trials that enrolled both eyes of participants with bilateral GRT and used a paired‐eye design in which one eye was randomized to receive PPV alone and the fellow eye received the combined procedure, the unit of analysis will be the eye. If enough data are provided on paired‐eye design trials such as covariances or paired tabulation, we will use a paired‐sample t‐test or a McNemar test to assess the differences between paired eye outcomes.

Dealing with missing data

If trials are not analyzed using an intention‐to‐treat analysis, or where data are unclear or missing, we will contact the trial authors for clarification and further information. We will make two attempts to contact trial authors and allow two weeks for the trial authors to respond, and if we do not receive a response, we will use the available information.

Assessment of heterogeneity

We will evaluate the heterogeneity of the trials using the Cochrane Q and I2 tests. The Q value has a Chi2 distribution with the null hypothesis that the likelihood ratio is the same for all studies. The I2 test evaluates the variability on the effect. We will consider values higher than 50% as evidence of substantial heterogeneity (Deeks 2011). If substantial heterogeneity or inconsistency is present, we will not report the pooled analysis, we will instead report a narrative summary of the results.

We expect methodological and clinical sources of heterogeneity from differences in participant characteristics, types or timing of outcome measurement, and intervention characteristics such as surgical methods used like number of surgeons, PPV gauge number, scleral buckle type (silicon band/silicon sponge), preoperative lens status (phakic, pseudophakic, aphakic) and vitreous substitute endotamponade (gas/silicon oil).

Assessment of reporting biases

When possible, we will obtain published protocols or methods papers to compare the intended outcomes with reported outcomes. When there are 10 or more RCTs, we will use funnel plots to judge asymmetry that may indicate publication bias in one or more reported studies in a meta‐analysis.

Data synthesis

We will perform data analysis according to the guidelines set out in Chapter 9 of the Cochrane Handbook for Systematic Reviews of Interventions (Deeks 2011). We will compare PPV combined with scleral buckle versus PPV alone for GRT. When the number of trials is fewer than three, we will use a fixed‐effect model, otherwise we plan to use a random‐effects model. If there is evidence of substantial heterogeneity, or there is a large amount of diversity in participant characteristics and trial methodology, we may choose to present only a narrative summary of the results. We will perform a meta‐analysis for all the outcomes under Types of outcome measures.

Subgroup analysis and investigation of heterogeneity

We will investigate potential explanations of clinical or statistical heterogeneity by comparing outcomes within subgroups to compare the relative effect of PPV combined with scleral buckle and PPV alone by the type of tamponade used in surgery (silicon oil or gas), participant age, retinal tear etiology, duration of symptoms, grades or quadrants of retinal tear extension (90° to 180° or one or two quadrants, 180° to 270° or two or three quadrants, and 270° to 360° or three or four quadrants), lens status (phakic, pseudophakic or aphakic) and presence of proliferative vitreoretinopathy (grade C) according to the Retinal Society classification (Machemer 1991), whenever sufficient data are reported.

Sensitivity analysis

We will examine the impact of excluding trials with high risk of bias in all the following domains incomplete data, unpublished data and industry funding to assess the robustness of estimates with respect to these factors.

'Summary of findings' table

We will produce a 'Summary of findings' table for the following outcomes: primary surgical success, mean change in BCVA from baseline measured in logMAR units, proportion of study eyes that required a second surgery for retinal reattachment, adverse events, and economic outcomes. We will use the GRADE approach to assess the quality of the evidence (Guyatt 2011). Given the certainty, we will consider limitations in any included studies, the consistency of the effect, imprecision of results, indirectness of results and publication bias.