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D. A. Berntsen, M. M. Merchea, C. J. Mack, K. Richdale, J. T. Barr; Higher-Order Aberrations With Spherical and Toric Soft Contact Lens Designs. Invest. Ophthalmol. Vis. Sci. 2007;48(13):5372.
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To determine the effect of spherical and toric contact lens design on higher-order aberrations.
Thirty eyes (15 subjects) entered a masked, randomized, cross-over study. Each eye was fitted with both the spherical and toric lenses of the following brands in random order: Acuvue Advance, Biomedics, Frequency, and SofLens. Higher-order aberrations (HOA) were measured using the Zywave II Aberrometer over a 6-mm aperture up to the fifth order. A linear model accounting for the fixed effect of lens type and the random effects of subject and eye was created. Pair wise t-tests were completed between lens brands within each of the spherical and toric lenses. Paired t-tests were used to compare between the spherical and toric lenses within brands. Statistical significance was set at p < 0.01 and clinical significance was considered a change greater than 0.1 µm. Photopic and mesopic high- and low-contrast best-corrected logMAR visual acuity (BCVA) was measured with a 6 mm aperture. Repeated-measures ANOVAs were used to analyze visual acuity data with appropriate corrected post-hoc t-tests.
No clinically significant differences in total HOAs were found between the spherical and toric lenses. Positive spherical aberration (SA) was reduced by all spherical and toric lenses compared to wearing no lens by between 0.07 to 0.23 µm (p<0.0001). Frequency 55 Toric induced the greatest change in SA. Toric Acuvue Advance had significantly less vertical coma (-0.04 µm) than the three prism ballast design toric lenses (0.11 to 0.23 µm; p<0.0001). SofLens Toric had the greatest amount of vertical coma. With the exception of Acuvue Advance, all toric lenses had significantly more vertical coma than their sphere counterparts (p<0.002). No other significant HOA differences were measured. BCVA with spherical lenses on astigmatic eyes was not significantly different between lens brands (all p>0.24). Photopic, high-contrast BCVA was better with toric Biomedics and SofLens than with Acuvue Advance (p=0.01). Photopic, low-contrast BCVA was better with toric SofLens than Acuvue Advance (p=0.03).
Toric contact lenses with prism ballast demonstrated more vertical coma, but better photopic BCVA. In general, positive SA is reduced by both sphere and toric lenses. The visual effect of lens design related HOAs needs further investigation.
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