Highter Order Aberrations in Myopia and Myopic Astigmatism Eyes

Objective To analyze the effects of pupil size,myopia and astigmatism on the higher order ocular aberrations in eyes with myopia and myopic astigmatism,and determine relationship between higher order aberrations and best corrective vision acuity (BSCVA). Methods Using a Hartmann-shack method,203 myopia and myopic astigmatism eyes were evaluated before LASIK. According to the degree of myopia and astigmatism,the subjects were divided into following groups:high myopia (-6.00 D),moderate myopia (-3.00 D～-6.00 D) and low myopia (-3.00 D); astigmatism group Ⅰ(≥-0.75 D),astigmatism group Ⅱ(-0.75 D)。 The root mean square (RMS) values of higher order aberrations for each subject with pupil diameters of 4.0 mm,5.0 mm,6.0 mm were calculated. SPSS 11.5 was used for statistical analysis. Results Total higher order aberrations,spherical aberration,horizontal primary coma,and vertical primary coma,were increased significantly with increasing pupil size. However,they were not affected by the degree of myopia. In 5.0 mm and 6.0 mm pupil,astigmatism affected total higher order aberrations and vertical primary coma,but horizontal primary coma and spherical aberration. In 5.0 mm and 6.0 mm pupil,there was a positive relationship between vertical primary coma and BSCVA (r = 0.576,0.695,P 0.01),a negative relationship between spherical aberration and BSCVA(r = -0.580,-0.763,P 0.01). Conclusion Pupil size affected all types of higher order aberrations. Astigmatism affected total higher order aberrations and vertical primary coma. Maintaining vertical primary coma and correcting spherical aberration completely for myopia and myopic astigmatism may be the best choice for customized cornea laser ablation surgery.