Correlation of contrast visual acuity with higher-order aberrations in myopia and myopic astigmatism

Abstract

Objective It has been shown that visual performance and aberration are related to pupil diameter. This study investigated the correlation between visual performance and higher-order aberration for corresponding pupil sizes under bright and dark backgrounds in patients with myopia and myopic astigmatism. Methods This was a prospective clinical study. One hundred and twenty-three right eyes of 123 subjects with a spherical equivalent refraction (SE) from-0.5 D to-10.00 D were enrolled in this study. An iTrace wavefront aberrometer was used to measure the aberration. MFVA-100 was used to measure contrast visual acuities. 100%, 25%, 10% and 5% contrast visual acuities under bright and dark backgrounds, and the pupil size for corresponding conditions were recorded with a Pupillometer. The root mean square (RMS) values of the wavefront aberrations under the corresponding pupil sizes were calculated. The relationship between higher-order aberrations and contrast visual acuity under bright and dark backgrounds were analyzed. A paired t test and multiple linear regression analysis was performed. Results Under a bright background, contrast visual acuities of 100%, 25%, 10%, 5% were 5.155, 4.989, 4.759, 4.665; Under a dark background, the corresponding contrast visual acuities were 5.068, 4.875, 4.665, 4.439, the differences between the two backgrouds were significant of the same contrast (t=20.095, 18.241, 12.422, 28.538, P＜ 0.01). Under the same background, visual acuities among different contrast were significant (F= 500.564, 842.708, P＜0.01). Under a bright background, the RMS of coma (both the horizontal and vertical coma) was significantly associated with four different contrast visual acuities (r2=0.072, 0.124, 0.104, 0.119, P＜0.01 for all). Under a dark background, RMS of the fourth-order Zernike coefficients was significantly associated with contrast visual acuity (r2=0.045, 0.123, 0.161, 0.067, P＜0.05 for all). Conclusion The link between visual performance and aberration depends on the variation in pupil size. Under a bright background, coma is the main factor affecting visual performance. Under a dark background, fourth-order Zernike coefficients contributes to the degradation of the contrast visual acuity because of the larger pupil size. Key words: Aberrations; Contrast sensitivity; Photophic stimulation