PRK切削中心偏离的临床观察

A clincal study of ablation decentration in PRK

为研究准分子激光屈光性角膜切削术（ＰｈｏｔｏｒｅｆｒａｃｔｉｖｅＫｅｒａｔｅｃｔｏｍｙ，ＰＲＫ）切削中心偏离对角膜散光与欠矫的影响。对ＰＲＫ术后２１０眼行角膜地形图检查后发现，ＰＲＫ切削偏心小于０５０ｍｍ者为３７２％，０５０～１００ｍｍ者为５３３％，１０ｍｍ以上者为９５％，切削偏心平均为０７６ｍｍ，欠矫平均为１４１Ｄ，散光无明显改变。切削偏心能直接导致欠矫的发生，但对角膜散光无明显影响，减小偏心可以避免欠矫的发生。

ffects on corneal astigmatism and undercorrection by ablation decentration from the pupil center were evaluated by corneal topography.An investigation was taken among 210 eyes followed up for more than 3 months.The results were:37 2% were decentered 0 50mm or less,53 3%>0 50mm and ≤1 00mm,and 9 5%>1 00mm.mean ablation decentration was 0 76mm,mean undercorrection was 1 41D,while corneal astigmatism didnot change obviously It is revealed that the ablation decentration could directly result in undercorrection,but it has no effect on corneal astigmatism.Decreasing decentration is an important measure to avoid undercorrection.