The Effect Of Laser In Situ Keratomileusis On The Retinal Structures And Functions

PURPOSE: To evaluate the effects of laser in situ keratomileusis (LASIK) on the retinal structures and functions.METHODS: 40 eyes of 20 patients undergoing LASIK were enrolled in this prospective study. Optical coherence tomography(OCT) and perimetry were performed before and 1 day, 1 month, 3 months, 6months after LASIK surgery. The retinal neuroepithelial layer of macular and retinal nerve fiber layer(RNFL) thickness values before and after LASIK were obtained by OCT. At the same time, perimetry was performed by HumphreyII-750 visual field analysis. We used the central 30-2 fast threshold program to examine the change in central 30 degree. Mean defect(MD) and pattern standard deviation(PSD) were record. Statistical analyses were performed by SPSS for Windows (version 11.5) using the randomized complete block design ANOVA (two factors analysis of variance). Differences among variables were evaluated by q-test ( Student-Newman-Kueuls method).RESULTS: The mean neuroepithelial layer and RNFL thicknesses obtained by OCT were unchanged before and after LASIK(P>0.05, for all comparisons).Of the indices of perimetry, mean defect(MD) has a significant differences among preoperative and postoperative values; and was correlated with visual acuity post-LASIK significantly. While pattern standard deviation(PSD) did not showsignificant differences before and after LASIK(P>0.05) and was not correlated with visual acuity post-LASIK. All of the changes in the thickness of neuroepithelial layer, RNFL and the indexes of visual field were not correlated with the degree of myopia and the other surgical parameters (P>0.05).CONCLUSION: The thickness of neuroepithelial layer of macular and RNFL were unchanged before and after surgery. The indexes of visual field, MD and PSD, were not significantly affected pre-LASIK and post-LASIK. LASIK does not affect the retinal structures and normal physiological functions.