Optical quality in low astigmatic eyes with or without cylindrical correction

摘要

PurposeTo investigate whether optical quality could be improved by cylindrical correction for low astigmatic eyes with different amounts and axis orientations in patients with myopia up to - 3.00 diopters (D).MethodsA cross-sectional study enrolling healthy young eyes with 0 to - 3.00 D myopia and - 0.50 to - 0.75 D myopic astigmatism was implemented. With a repeated-measures design, outcome measures were sequentially obtained for each subject under two correction modalities: spherocylindrical correction and spherical correction. Subjective refraction was used to determine the refractive prescriptions accordingly in the two correction modalities to obtain optimal subject-reported visual acuity. Primary outcomes were optical quality parameters including objective scatter index (OSI), modulation transfer function (MTF) cut-off, Strehl ratio (SR), and a simulated contrast visual acuity-optical quality analysis system (OQAS) values (OV) obtained by a double-pass system. Corrected distance visual acuity (CDVA) was measured as a secondary outcome. Outcome comparisons between the two correction modalities were performed by grouping in different amounts (- 0.50 D, - 0.75 D) and axes (with the rule, WTR; against the rule, ATR; oblique, OBL) of astigmatism.ResultsA total of 194 eyes of 194 subjects were evaluated. Significantly better CDVA were shown by spherocylindrical correction for all types of astigmatism except for - 0.50 D WTR astigmatism (P = 0.831). For eyes with - 0.50 D WTR astigmatism, better outcome was only shown in OSI with spherocylindrical correction (P = 0.019). For eyes with - 0.50 D ATR and OBL astigmatism, spherocylindrical correction demonstrated better outcomes in all parameters except for SR (P > 0.05). For eyes with - 0.75 D astigmatism, significantly better outcomes in all optical quality parameters were shown with spherocylindrical correction regardless of the axis (P < 0.05).ConclusionsEyes with ATR or OBL myopic astigmatism may benefit in optical quality and visual acuity by combining a cylindrical correction even with a low amount down to - 0.50 D. However, optical quality and visual acuity improvement are limited for WTR astigmatic eyes when the amount of astigmatism is less than - 0.75 D.