In a recent study, toric contact lenses improved visual acuity by roughly one line compared with spherical contact lenses for patients with low-to-moderate (-0.75D to -1.75D) astigmatism. Eyestrain measured with electromyography was less with toric vs. spherical contact lenses at the initial fit, but not at follow-up.
Researchers examined the benefits of toric contact lenses on objective measures of visual performance using visual acuity and electromyography of the orbicularis oculi. Of the 60 participants, researchers fit 29 with toric lenses and 31 with spherical lenses. High- and low-contrast visual acuities significantly improved with toric lenses compared with spherical lenses at both fitting and follow-up. Electromyography recordings showed less orbicularis muscle activity with toric contact lenses compared with spherical contact lenses; however, the difference was only different at the fitting visit.
The study calls for further development of electromyography to ensure that eyestrain is minimized for patients in a world closely associated with electronic devices. The authors propose using the technique to assess eyestrain at a computer and also while contact lens wearers are reading. They conclude that studies should consider the impact of astigmatism correction in relation to other factors commonly associated with computer vision syndrome, such as tear film instability and binocular vision disorders.
|Berntsen DA, Cox SM, Bickle KM, et al. A randomized trial to evaluate the effect of toric versus spherical contact lenses on vision and eyestrain. Eye Contact Lens. 2019;45(1)28-33.|