Relationship between the distance from thinnest point to pupil center and unevenness of corneal thickness and the influence of the unevenness on correction of astigmatism by LASEK

Abstract

Objective To observe relationship between the distance from thinnest point to pupil center (DTP) and unevenness of distribution of corneal thickness using Pentacam,and to investigate influence of unevenness of distribution on the correction of astigmatism by LASEK.Methods One hundred and six myopic astigmatism eyes treated with LASEK were divided into two groups,low-midrange astigmatism (-0.25D～-2.00D) group and high astigmatism (-2.25D～-4.00D) group.The following-up period was for 6 months.The DTP,and the unevenness of distribution of corneal thickness of 3.0mm (D3.0mm) and 6.5ram (D6.5mm) area were calculated.The correction of myopic astigmatism by LASEK based on standard vector analysis was evaluated.Results The DTP was (0.64±0.23) mm,D6.5mm was (55.61±18.57) tm and D3.0mm was (16.71±4.45) μm in 106 eyes.The D6.5mm of low-midrange astigmatism group was significant lower than that of high astigmatism group (P ＜0.05).In 106 eyes,the DTP was positively correlated with D6.5mm and D3.0mm respectively (r =0.43,0.49,P ＜0.01).The D6.5mm was positively correlated with D3.0mm (r =0.42,P ＜0.01).The | EV | (absolute error vector) of low-midrange astigmatism group was significant lower than that of high astigmatism group (P ＜0.05).The | EV | of high astigmatism group was positively correlated with D6.5mm (r =0.47,P ＜0.05).Conclusions The distance from thinnest point to pupil center is correlated with the unevenness of distribution of corneal thickness.The unevenness of distribution of corneal thickness may influence the outcome of correction of myopia with high astigmatism by LASEK. Key words: Corneal thickness ; Pupil ; Vector analysis ; Astigmatism ; Excimer laser ;