Visual acuity in contact lens wearers

Purpose. The difference between high- and low-contrast visual acuity provid es a sensitive indicator of vision loss in ocular disease; however, the eff ect of refractive error correction on this difference is still debated. Met hods. High- and low-contrast visual acuity was measured in 116 rigid gas pe rmeable contact lens wearers, 51 spectacle wearers, and 50 soft contact len s wearers with habitual and best correction. Twenty-nine of the soft contac t lens wearers reported that they wore disposable contact lenses (discarded on a monthly or more frequent basis), whereas the other 21 soft contact le ns wearers wore traditional soft contact lenses. Results. Rigid gas permeab le contact lens wearers had statistically worse high-contrast habitual visu al acuity than spectacle wearers (Tukey-Kramer, p = 0.0075). Traditional so ft contact lens wearers had significantly worse low-contrast visual acuity compared with all other groups (Tukey-Kramer, p < 0.02 for each comparison) . Traditional soft contact lens wearers had a significantly larger differen ce between high- and low-contrast visual acuity with best correction compar ed with rigid gas permeable wearers (Tukey-Kramer, p = 0.0099). Conclusions . Rigid gas permeable contact lens wearers had statistically worse habitual high-contrast visual acuity compared with spectacle wearers, but no differ ence was present under best-corrected conditions. We hypothesize that rigid gas permeable contact lens wearers were not wearing their optimal correcti on habitually. Traditional soft contact lens wearers had significantly wors e low-contrast visual acuity. They also had a larger difference between the ir best-corrected high- and low-contrast visual acuity scores compared with rigid gas permeable contact lens wearers.