The study on the posterior corneal surface topography after LASIK

Objective:To investigate the changes in the posterior corneal surface topography after LASIK and the factors that influence the results.Methods:This study comprised 41 eyes of middle and high myopia(2 patients) that had undergone LASIK. Diopter and radius of curvature of posterior corneal surface were measured by Orbscan before operation, and at 3rd day, 3rd month post operatiion. Eyes were divided into two groups(3mm area and 5mm area) according to the optical diameter of cornea.Results:Significant difference in posterior corneal surface topography existed between pre operation and post operation(P0.05) in corneal center and peripheral(P0.05). There is significant difference in 3 months and 3 days post operation in 3mm area(P0.05). The change in radius of curvature of posterior corneal surface was correlated with corneal thickness after LASIK(r=-0.6,P0.05), but irrelevant to IOP. The change of posterior corneal surface topography was more significant in the corneal thickness less than 350μm(P0.01).Conclusion:LASIK can decrease the radius of curvature of the posterior corneal surface. The corneal thickness after LASIK is a major contributing factor.