放射状角膜切开术前后的角膜地形图分析

CORNEAL TOPOGRAPHY ANALYSIS BEFORE AND AFTER RADIAL KERATOTOMY

应用计算机辅助的角膜地形图仪对轻、中度近视４２例（５８只眼）于放射状角膜切开术（ｒａ－ｄｉａｌｋｅｒａｔｏｔｏｍｙ，ＲＫ）前、后行角膜地形图检测。结果表明，ＲＫ前大多数（７６％）的近视眼角膜呈正性非球面性；ＲＫ后角膜绝大多数向负性非球面过渡。ＲＫ前近视眼的角膜地形图６７％患者呈对称或不对称的蝴蝶结状；ＲＫ后角膜中央变扁区的主要形态为圆形或椭圆形、哑铃状与带状。ＲＫ前后角膜平均表面规则指数无显著改变，而角膜平均表面不规则指数则有显著改变。ＲＫ使角膜中央及中周部变扁，ＲＫ效应最显著的区域位于距光学中心１．１４０±０．０９０ｍｍ附近。ＲＫ前后角膜地形图的检测与分析不仅对ＲＫ设计提供准确的客观依据，也使客观定量评估ＲＫ效应、使精确ＲＫ疗效预测性及有效改进ＲＫ质量成为可能。

Corneal topographic analyses were conducted on 58 eyes of 42 cases with mild or moder-ate myopia by computer-assisted photokeratography before and after radial keratotomy(RK).The re-sults indicate that the corneal surfaces of most examined eyes(76%)are positive aspheric shape beforeRK,while after RK they are changed to negative aspheric shape.Before RK, the corneal topography ofmost examined eyes(67%)is symmetric bow tie pattern or asymmetric bow tie pattern;after RK,theforms of central flattened regions are mainly round or approximately round,dumbbell and belt-shaped. Before and after RK there is no significant change in surface regularity index(SRI),but surface asym-metry index(SAI)is changed significantly.RK makes the central and central peripheral parts of thecornea flattened.The most significant RK effect is found at the region 1.140±0.090 mm away fromthe corneal optical center.Examination and analysis on the corneal topography before and after RK notonly provide an accurate and objective basis for RK operational plan,but also make it possible to objec-tively and quantitatively evaluate the RK effect,to accurately predict the RK clinical effects,and to ef-fectively improve the RK clinical quality.