Retinal nerve fiber layer thickness remains unchanged following laser-assisted in situ keratomileusis

Abstract

PURPOSE: To evaluate the effect of laser-assisted in situ keratomileusis (LASIK) on retinal nerve fiber layer (RNFL) thickness measurements obtained with scanning laser polarimetry (SLP), optical coherence tomography (OCT), and scanning laser tomography (SLT). DESIGN: Interventional case series. METHODS: Twenty eyes (20 patients) undergoing LASIK were enrolled in this prospective study. SLP, OCT, and SLT examinations were performed 1 week prior to and 1 week and 4 weeks after LASIK surgery. Intraocular pressure was normal at all preoperative and postoperative examinations. SLP, OCT, and SLT mean RNFL thickness values, and SLT RNFL cross sectional area, rim area, and rim volume before and after LASIK were compared by the Student paired t test. RESULTS: Mean patient age was 39.3 ± 9.5 (SD) years (range, 28 to 62 years). Mean preoperative spherical equivalent refractive error was −3.9 ± 1.9 diopters (D) (range, −1.4 to −8.00 D) and mean spherical equivalent refractive surgical correction was 3.6 ± 1.9 D (range, 1.00 to 8.50 D). Mean RNFL thicknesses obtained by SLP were thinner 1 week and 4 weeks after LASIK ( P < 0.01, for all comparisons, paired t test), whereas mean OCT RNFL thickness and SLT RNFL thickness, RNFL cross-section area, rim area, and rim volume measurements were unchanged 1 week and 4 weeks after LASIK ( P ≥ 0.05, for all comparisons, paired t test). CONCLUSIONS: LASIK does not affect RNFL thickness. Alterations in SLP RNFL thickness measurements are due to alterations in corneal architecture rather than an actual LASIK-induced RNFL injury.