Effects of Toric and Soft Spherical Contact Lenses on Visual Performance and Wavefront Aberrations in Patients with Low Levels of Astigmatism

Purpose:

To investigate the effects of toric and soft spherical contact lenses on the visual performance and wavefront aberrations in cases of low astigmatism.

Material and Method:

Twenty-four eyes of 14 contact lens users with cylindirical refractive error of -1.25 diopters or less were included in this prospective study. The subjects wore spherical (lotrafilcon B) and toric (galyfilcon A) lenses for eight hours with a one-week interval. The best-corrected visual acuity and contrast sensitivity were measured before and after 8 hours of contact lens wear. Corneal topography and wavefront analysis were also performed. Zernike coefficients were used to calculate the aberrations at a 6-mm pupil diameter. Total and higher-order root mean square (RMS) values as well as spherical and coma aberrations were measured.

Result:

The mean spherical refractive error of the cases was -2.52±1.25 (range: from -0.50 to -6.0) D. The mean best- corrected visual acuity was significantly higher with both types of contact lenses than with glasses (p=0.017), however, no statistical difference was observed between the two types of contact lenses (p=0.470). The mean high-frequency contrast sensitivity value was lower with toric lenses (p=0.038). The mean higher-order RMS value was higher with both types of contact lenses (p=0.021), but with no difference between them (p>0.05). The mean spherical aberration value did not differ among glasses, toric or soft spherical contact lenses (p>0.05). The mean coma aberrations were high with both types of contact lenses (p=0.041); no difference was observed between the two lens types (p>0.05).

Discussion:

In this study, it was demonstrated that in cases of low astigmatism, soft spherical and toric contact lenses increase visual acuity, total higher-order aberrations, and coma aberrations, but decrease high-frequency contrast sensitivity. There was no difference between the two types of contact lenses. (Turk J Ophthalmol 2011; 41: 22-5)