Abstract
Purpose :
To compare the effect of toric contact lenses versus spherical soft contact lenses on the reading performance of novel contact lens users with low astigmatism.
Methods :
The reading test consisted of two paragraphs of 92 and 97 words divided into six lines (Arial 10 font) shown on a 23.6” screen at a reading distance of 60 cm. Reading performance parameters (reading time, number of fixations, number of regressions and magnitude of saccades) were recorded using an eye-tracking device (GP3 HD, Gazepoint, Vancouver, Canada) at a frequency of 150 Hz. Additionally, contrast sensitivity (CS) was measured with a Visual Adaptative Optics simulator (VAO; Voptica SL, Murcia, Spain) at frequencies of 9 and 15 cpd, respectively. Nineteen first-year university students were recruited. They were all contact lens neophytes, divided into two groups, matched by age and refractive error (no statistically significant differences). Subjects in group one (N=10; age 19 ± 2 years; sphere -2.3 ± 0.7 D; cylinder -0.9 ± 0.3 D) were monocularly fitted with a spherical contact lens (Precision1, Alcon Laboratories, Inc, Fort Worth, TX) while subjects in group two (N=9; age 21 ± 3 years; sphere -2.3 ± 1.3 D; cylinder -1.0 ± 0.4 D) were fitted with a toric lens (Precision1 for Astigmatism).
Results :
Saccadic regressions during reading were larger (p<0.05) in the group of spherical lenses (mean 22 ± 15) than in the group of toric lenses (mean 14 ± 6). On average, all parameters that characterize reading performance showed a similar tendency, being slightly worse and showing more variability in the spherical group than in the toric group of subjects. For instance, the number of fixations, saccade magnitude and reading time reduced by 10%, 9% and 7%, respectively in the toric group compared to the spherical group. We also observed a significant reduction (p<0.05) of the contrast sensitivity threshold at 9 cpd from 9 ± 7% in the spherical group to 4 ± 1% in the toric group and also at 15 cpd, with a 52% reduction of the threshold in the toric group.
Conclusions :
A full correction of astigmatism with a toric CL (Precision1 for Astigmatism) improved visual performance in a broad sense, with better CS but also better reading performance. These results may suggest instantaneous visual benefits of fitting toric lenses versus spherical lenses in contact lens neophytes with low astigmatism.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.