Impact of Simulated Astigmatism on Visual Acuity, Stereopsis, and Reading in Young Adults

This study investigated the functional visual impact of simulated astigmatic blur using cylindrical powers of 0.50 D, 1.00 D, and 2.00 D, applied in against-the-rule (ATR), with-the-rule (WTR), and oblique (OBL) axes, in adults aged 18 to 35 years with no known ocular disease. Forty-five young adults were randomly divided into three groups (n = 15). Binocular best-corrected visual acuity (distance and near) was recorded in logMAR using the ETDRS acuity chart at 5 m and 40 cm, supported by acuity optotypes displayed in a Bailey-Lovie chart format. Depth-fusion and disparity discrimination were measured using polarized stereopsis thresholds with the Randot^® Stereo Test from Stereo Optical Company, Inc. Reading performance was quantified as a continuous binocular rate metric (words per minute) using the validated Portuguese digital reading curve provided by the MNREAD iPad App by Precision Vision at 40 cm. The results were preserved verbatim as follows: Distance and near BCVA were significantly affected by ATR astigmatisms (-0.50 + 1.00 90°, -1.00 + 2.00 90°), WTR astigmatisms (-0.25 + 0.50 180°, -0.50 + 1.00 180°, -1.00 + 2.00 180°), and OBL astigmatisms (OD: -0.25 + 0.50 45°, OS: -0.25 + 0.50 135°; OD: -0.50 + 1.00 45°, OS: -0.50 + 1.00 135°; OD: -1.00 + 2.00 45°, OS: -1.00 + 2.00 135°). Stereopsis was significantly influenced by high-power OBL astigmatism (-1.00 + 2.00). Reading rate was also negatively impacted by OBL astigmatisms ≥1.00 D. Simulated astigmatism of different powers and axes reduced high-contrast distance and near BCVA, stereopsis, and reading speed in adults aged 18-35 years. Higher-power astigmatism, particularly along oblique axes, caused the most significant functional impairment.