The Observation Of Corneal Topography After LASIK

Objective To investigate the changes of corneal topography after myopic LASIK, and its cause, effect.Method Corneal topography was performed on 62 myopic patients (123eyes) before and 1 day, 1 week, 1 month after LASIK surgery. Subjects were divided into groups according to the thickness of residual stromal bed, pre-operative myopic diopter or the ratio of the thickness of residual stromal bed to that of pre-operative cornea.Distance from the top point of posterior surface of the cornea to the perfect spherical surface (posterior Diff value), and its relationship with visual acuity was analyzed. Posterior Diff value was compared between groups and different time. The changes of simulated kdratoscope reading(SimK), 3mm zone irregularity index (3 mmIrrg), 5mm zone irregularity index(5 mmIrrg), anterior chamber depth( ACD) and possible cause were also analyzed.Results Posterior Diff value is higher after LASIK than that of before operation. The value rises if the thickness of residual stromal bed decreases, and it rises if the pre-operative myopic diopter rises. When the thickness of residual stromal bed is more than 300um or the ratio of the thickness of residual stromal bed to that of pre-operative cornea is above 55%,the...