Five RCTs with a total of 476 patients, in which 580 eyes were operated on, were included in the review.
The 5 studies had a mean quality score of 0.73 (range: 0.71 to 0.77).
Uncorrected visual acuity.
There was no statistically significant difference between PRK and LASIK in the odds of having post-operative uncorrected visual acuity of 20/20 or better at a follow-up of at least 6 months ; the ORs were 1.31 (95% CI: 0.77, 2.22) and 1.18 (95% CI: 0.74, 1.88) by PP and ITT analyses, respectively. The trials were not found to be significantly heterogeneous. Uncorrected visual acuity improved significantly faster in patients receiving LASIK than those receiving PRK after 2 weeks; the ORs were 3.20 (95% CI: 1.74, 5.87) and 3.36 (95% CI: 1.81, 6.23) by ITT and PP analyses. There were no significant differences in the rates after 1, 3, 6 and 12 months.
Refractive outcome.
There was a statistically significant difference between PRK and LASIK at a follow-up of at least 6 months for post-operative spherical equivalent refraction within +/- 1.0 diopter (D) (spherical equivalent +/- 1.0 D) of emmetropia when analysed by ITT (OR 0.63, 95% CI: 0.43, 0.92); the PP analysis found no significant difference between the treatments. There was no statistically significant difference between PRK and LASIK at a follow-up of at least 6 months for post-operative spherical equivalent refraction within +/- 0.5 D (spherical equivalent +/- 0.5 D) of emmetropia.
Spectacle-corrected visual acuity.
The possibility of loss of spectacle-corrected visual acuity was significantly less with LASIK than with PRK at a follow-up of at least 6 months; the ORs were 0.31 (95% CI: 0.10, 0.89) and 0.32 (95% CI: 0.11, 0.96) by ITT and PP analyses, respectively.
Subgroup analyses.
In patients with low to moderate myopia (-1.5 to -8.0 D), there were no statistically significant differences between PRK and LASIK for refractive outcome (spherical equivalent +/- 1.0 D and spherical equivalent +/- 0.5 D) and uncorrected visual acuity of 20/20 or better.
Patients with moderate to high myopia (-6.0 to -15.0 D) receiving PRK had a higher percentage of success for refractive outcome (spherical equivalent +/- 1.0 D and spherical equivalent +/- 0.5 D) at a follow-up of at least 6 months than those receiving LASIK; this difference was not significant for spherical equivalent +/- 0.5 D according to the PP analysis. For spherical equivalent +/- 0.1 D, the OR was 0.54 (95% CI: 0.35, 0.84) by ITT analysis and 0.56 (95% CI: 0.33, 0.95) by PP analysis; for spherical equivalent +/- 0.5 D, the ORs were 0.54 (95% CI: 0.32, 0.92) and 0.59 (95% CI: 0.25, 1.37) by ITT and PP analyses, respectively. There were no statistically significant differences between PRK and LASIK for uncorrected visual acuity of 20/20 or better.
Complications.
Different degrees of subepithelial haze were found at 6 and 12 months after PRK. Flap-related complications were reported after LASIK.
The sensitivity analysis found the summary estimates from the fixed- and random-effects models to be very similar.
There was no evidence of publication bias with either test.