LAUSR

PURPOSE To investigate the effect of refractive astigmatism on all-distance visual acuity (VA) in eyes implanted with a diffractive trifocal or bifocal intraocular lens (IOL). DESIGN Cross-sectional study METHODS: Fifty eyes with trifocal IOLs (Alcon PanOptix), and 50 eyes with bifocal IOLs (ReSTOR +3D) were enrolled. After simulating astigmatism by adding cylindrical lenses of 0, 0.5, 0.75, 1.0, and 1.5 diopters (D), the corrected logarithm of minimal angle of resolution (logMAR) VA was measured using an all-distance vision tester. RESULTS Mean VAs at most distances significantly worsened in proportion to the added astigmatism (P≤0.0111) with no significant difference in near VA at 0.3 m in the trifocal group or in intermediate VA at 0.7 m in the bifocal group. Mean intermediate VA at 0.5 m was significantly better in the trifocal group than in the bifocal group when the astigmatism was 0.75D or less (P≤ 0.0472), but distance VA at ∞ and 5.0 m was significantly worse in the trifocal group when the astigmatism was 0.5D or more (P≤0.0457). Useful mean logMAR VA of 0.20 at all distances was achieved when the astigmatism was 0.75D or less in the trifocal group and 1.0D or less in the bifocal group. CONCLUSIONS All-distance VA, particularly distance VA, worsened more in proportion to astigmatism with a trifocal IOL than with a bifocal IOL. Useful VA was achieved when the astigmatism was 0.75D or less with a trifocal IOL, suggesting that astigmatism correction is necessary when astigmatism is more than 0.75D.