Laser in situ keratomileusis and scanning laser ophthalmoscopy: Originalien

Background. To determine the influence of Laser in situ keratomileusis (LASIK) on the measurements of retinal thickness and optic nerve head topography using the Retinal Thickness Analyzer (RTA). Methods. RTA measurements were performed before and after LASIK. Forty-eight eyes of 25 healthy subjects were included. Mean age was 40.0 +/- 10.6 years. Mean preoperative refractive error (spherical equivalent) was -3.3 +/- 3.6 dpt, and 0.2 +/- 0.9dpt postoperatively. Correlation between ablation depth and duration and change of retinal thickness postoperatively was performed. All patients received a pachymetry preoperatively. Results. Postoperatively, mean retinal nerve fiber layer thickness (MRNFL) and cross sectional area (RNFL cross section area) significantly decreased after LASIK (MRNFL preop: 0.18 mm, postop: 0.11 mm, P =0.026, RNFL cross section preop: 1.17 mm(2), postop: 0.71 mm2, P = 0.015). Ablation depth revealed a significant correlation with changes in retinal thickness measurements postoperatively (Delta MRNFL: Ablation depth, P = 0.001, r = -0.5). Duration of the ablation was not significantly correlated to the MRNFL measurements postoperatively (P = 0.27, r = -0.08). No correlation was found between the central corneal thickness and the change in retinal thickness after LASIK (P = 0.51). Conclusion. Due to changes in corneal architecture after LASIK, measurements using RTA reveal a decrease in MRNFL and RNFL cross section area. These changes are likely artifacts. Further studies with a longer follow-up are desirable.