Spherical aberration and higher order aberrations with Balafilcon A (PureVision) and Comfilcon A (Biofinity)

Advances in the optical design of soft contact lenses have seen certain manufacturers incorporate aspheric optics into soft lenses in an attempt to reduce spherical aberration, to provide superior visual performance. The aim of this study is to determine the on-eye differences in spherical aberration and higher order aberrations (HOA) between the Bausch and Lomb PureVision (Balafilcon A) and the CooperVision Biofinity (Comfilcon A).

Twenty subjects were recruited in a prospective, randomized, unilateral study. The right eye was dilated and HOA measured with the NIDEK OPD-Scan. Each eye was fitted randomly with a -3.00D PureVision and a -3.00D Biofinity, and HOA were measured with lenses in situ across a 6 mm pupil. Paired t-tests were performed to determine HOA differences with the lenses in situ compared to baseline.

Aberrometry was successfully performed on all subjects. Statistical analysis indicated no changes in spherical aberration, but changes in other HOA. With the PureVision, there were increases in Zernike terms Z (3) (1) (from 0.01 μm to -0.11 μm), Z (4) (-2) (from 0.01 μm to 0.13 μm) and Z (5) (-1) (from -0.01 μm to 0.03 μm). With the Biofinity there was an increase in Zernike term Z (3) (3) (from 0.00 μm to 0.09 μm).

No statistically significant changes occurred in spherical aberration. The PureVision caused statistically significant increases in Z (3) (1) , Z (4) (-2) and Z (5) (-1) , and the Biofinity caused an increase in Z (3) (3) . Clinically significant changes (>0.1 μm) occurred with terms Z (3) (1) and Z (4) (-2) with the PureVision only.