Laser epithelial keratomileusis (LASEK) compared with photorefractive keratectomy (PRK) for myopia

Population: adult participants (≥ 18 years) with myopia

Settings: surgical procedure

Intervention: LASEK

Comparison: PRK

UCVA of 20/20 or better
at 12 months post treatment

RR 0.98
(0.92 to 1.05)

102
(1 trial )

⊕⊕⊝⊝
Low^a

RR < 1 favors PRK

Within ± 0.50 D of target refraction

at 12 months post treatment

RR 0.93 (0.84 to 1.03)

152
(2 studies)

⊕⊕⊝⊝
Low^b,c

RR < 1 favors PRK

Loss of 1 or more lines of BSCVA
at 12 months post treatment

RR 3.00

(0.13 to 71.96)

102
(1 trial)

⊕⊝⊝⊝
Very low^a,c

No event in the PRK group compared with one event in the LASEK group observed; RR > 1 favors PRK

Mean spherical equivalent
at 12 months post treatment

386
(3 studies)

⊕⊕⊕⊝
Moderate^b

Adverse outcomes ‐ corneal haze score at 12 months

(grade 1.0 ‐ more prominent haze that does not interfere with visibility of fine iris details;

grade 2.0 ‐ mild obscuration of iris details;

grade 3.0 ‐ moderate obscuration of iris and lens; and

grade 4.0 ‐ completely opaque stroma in the area of ablation)

284 eyes
(3 studies)

⊕⊝⊝⊝
Very low^b,c,d

The 3 included studies showed inconsistent results, so no pooled analysis was done. One study showed little or no difference in corneal haze score between LASEK and PRK, one study reported that corneal haze scores were lower in the LASEK group than in the PRK group, and one study did not report analyzable data for the PRK group, so we could not estimate the treatment effect for this trial.

Adverse outcomes ‐ glare and halo scores at 3 months

(grade 0 ‐ none;

grade 1 ‐ very low;

grade 2 ‐ low;

grade 3 ‐ moderate;

grade 4 ‐ high; and

grade 5 ‐ very high)

64 eyes
(1 study)

⊕⊝⊝⊝
very low^a,c

Only 1 included study reported these adverse effects; below are the reported estimates

For glare score:

MD ‐0.04, 95% CI ‐0.61 to 0.53

For halo score:

MD ‐0.09, 95% CI ‐0.72 to 0.54

*The basis for the assumed risk is provided in footnotes. 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)

**Both eyes of participants were included for all studies (i.e. all studies used a paired‐eye design in which 1 eye received PRK and the fellow eye received LASEK)
BSCVA: best spectacle‐corrected visual acuity; CI: confidence interval; D: diopters; LASEK: laser epithelial keratomileusis;MD: mean difference; PRK: photorefractive keratectomy; RR: risk ratio; UCVA: uncorrected visual acuity

GRADE (Grades of Recommendation, Assessment, Development and Evaluation) Working Group grades of evidence
High quality: Further research is very unlikely to change our confidence in the estimate of effect
Moderate quality: Further research is likely to have an important impact on our confidence in the estimate of effect and may change the estimate
Low quality: Further research is very likely to have an important impact on our confidence in the estimate of effect and is likely to change the estimate
Very low quality: We are very uncertain about the estimate