Higher-order aberrations when wearing sphere and toric soft contact lenses

Abstract

Purpose: To determine the on-eye effect of spherical and toric contact lens design on higher-order aberrations (HOA).

Methods: Thirty eyes (15 subjects) entered a masked, randomized, cross-over study. Each eye was fitted with the spherical and toric lens of the following brands in random order: Acuvue Advance, Biomedics 55, Frequency 55, and SofLens 66. HOAs were measured using the Zywave II Aberrometer over a 6-mm aperture up to fifth order. A linear model accounting for the fixed effect of lens type and random effects of subject and eye was created. Paired t-tests were completed between lens brands within the spherical and toric lenses and between the spherical and toric lens within each brand. Best-corrected visual acuity (VA) was measured and compared.

Results: No clinically meaningful differences in total HOAs were found between brands or between the spherical and toric lens within a brand. Positive spherical aberration (SA) was reduced by all spherical and toric lenses compared to wearing no lens by 0.07 to 0.23 microm (p < 0.0001). Frequency toric induced the greatest change in SA. The thin-zone design lens (Acuvue Advance for Astigmatism) had a statistically different amount of vertical coma (-0.04 microm) than the three prism-balast toric lenses (0.11 to 0.23 microm; p < 0.0001). SofLens toric had the greatest amount of vertical coma, but better VA than Acuvue Advance for Astigmatism and Frequency toric. With the exception of Acuvue Advance for Astigmatism, toric lenses had greater absolute magnitude of vertical coma than their sphere counterparts (all p < 0.002). No other significant HOA differences were observed.

Conclusions: Toric contact lenses with prism-ballast designs demonstrated more vertical coma, but better VA. Positive SA was reduced by spherical and toric contact lenses. The visual quality effect of lens design and material on induced HOAs warrants further investigation.

Figure 1

Total higher-order aberration findings for spherical and toric soft contact lenses tested. No clinically meaningful differences were found. (Error bars represent 95% Confidence Interval)

Figure 2

Third-order (a), fourth-order (b), and fifth-order (c) aberration findings for spherical and toric soft contact lenses tested. No clinically meaningful differences were found. (Error bars represent 95% Confidence Interval)

Figure 2

Third-order (a), fourth-order (b), and fifth-order (c) aberration findings for spherical and toric soft contact lenses tested. No clinically meaningful differences were found. (Error bars represent 95% Confidence Interval)

Figure 2

Third-order (a), fourth-order (b), and fifth-order (c) aberration findings for spherical and toric soft contact lenses tested. No clinically meaningful differences were found. (Error bars represent 95% Confidence Interval)

Figure 3

Spherical Aberration (Z⁴₀) for spherical contact lenses, toric contact lenses, and no lens. Positive spherical aberration was reduced by all spherical and toric lenses compared to wearing no lens. (Error bars represent 95% Confidence Interval)

Figure 4

Vertical coma (Z³₋₁) for spherical and toric soft contact lenses tested. Acuvue Advance for Astigmatism (a thin-zone toric lens) had significantly less vertical coma than the other three prism-ballast toric lenses). (Error bars represent 95% Confidence Interval)

Figure 5

Vertical contact lens decentration for spherical and toric contact lenses tested. Among the spherical lenses, the vertical decentration of the Acuvue Advance sphere was significantly different than the other spherical lens brands. No significant differences in vertical decentration were present among the toric lens brands. (Error bars represent 95% Confidence Interval)