Effect of Refractive Astigmatism on All-Distance Visual Acuity in Eyes With a Trifocal Intraocular Lens.

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 (PanOptix; Alcon) 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 ≤ .0111) with no significant differences 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 0.75 D or less (P ≤ .0472), but VA at distances of ∞ and 5.0 m were significantly worse in the trifocal group when the astigmatism was 0.5 D or more (P ≤ .0457). Useful mean logMAR VA of 0.20 was achieved at all distances when the astigmatism was 0.75 D or less in the trifocal group and 1.0 D 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 0.75 D or less with a trifocal IOL, suggesting that astigmatism correction is necessary when astigmatism is more than 0.75 D.