Accommodation and convergence with spherical and toric soft contact lenses in astigmatic eyes

To evaluate the accommodation and convergence in astigmatic eyes with spherical and toric contact lenses.

Total of 50 non-contact lens wearers, aged between 18 and 30 years with -0.75 to -2.00 D of astigmatism were enrolled in a double-masked, randomized, crossover study. Participants attended three clinical visits and were fitted with Purevision 2 Sphere and Toric (Bausch and Lomb Inc, Rochester, NY) contact lenses in a randomized order. The amplitude of accommodation was measured using a push-up technique with a Royal Air Force Ruler, and the near point of convergence was assessed using a vertical row of letters attached to a pen torch. All participants completed the Near ActivityVisual Questionnaire (NAVQ) and a forced-choice lens preference test.

The amount of amplitude of accommodation was significantly lower with toric contact lenses (7.86 ± 0.94 D) compared to spherical contact lenses (10.6 ± 0.84 D, p < 0.001). Similarly, near point of convergence was also significantly better with toric correction than with spherical correction (10.99 ± 1.06 cm vs. 12.78 ± 1.19 cm, p < 0.001). Participants reported improved near-visual performance with toric lenses (p < 0.001), and ninety percent (45 of 50) of participants preferred toric lenses (p < 0.0001).

Astigmatic eyes showed reduced accommodative stress and improved convergence stability with toric contact lenses. This study emphasizes the importance of correcting astigmatism to optimize binocular vision and minimize visual fatigue in contact lens wearers.