Prediction of distance visual acuity in presbyopic astigmatic subjects

Abstract

Abstract This study was aimed to determine the effect of the amount of astigmatism on distance visual acuity, and to provide a prediction formula of visual acuity according to astigmatism, in a presbyopic population. We comprised 318 eyes of 318 consecutive patients (158 phakic and 160 pseudophakic subjects) without any eye diseases, except for refractive errors with astigmatism of 3 diopter or less. We assessed the relationship of the spherical equivalent visual acuity (SEVA) with astigmatism, and also provided a regression formula of visual acuity according to astigmatism in such subjects. We found a significant correlation between the SEVA and the amount of astigmatism (r = 0.715, p < 0.001) in the entire study population. We obtained similar results, not only in phakic eyes (r = 0.718, p < 0.001), but also in pseudophakic eyes (r = 0.717, p < 0.001). The regression formula was expressed as follows: y = 0.017x2 + 0.125x − 0.116 (R2 = 0.544), where y = logMAR SEVA, and x = astigmatism. We also found no significant differences in the SEVA for matched comparison among the with-the-rule (WTR), against-the-rule (ATR), and oblique (OBL) astigmatism subgroups (p = 0.922). These regression formulas may be clinically beneficial not only for estimating the visual prognosis after astigmatic correction, but also for determining the surgical indication of astigmatic correction.