The effect of soft contact lens wear and time from blink on wavefront aberration measurement variation

Advances in contact lens design technology allow incorporation of correction of higher-order aberrations to improve or manipulate the eye's optical quality. Repeatability of aberration measurements in vivo with contact lens wear has not been established.

Higher-order aberrations were measured using the COAS aberrometer (Wavefront Sciences, USA) in 23 participants who were free from external eye pathology. Cycloplegia with 1% Cyclopentolate HCl ensured control of accommodation and that pupil diameters exceeded analysis diameter. Tear film characteristics were assessed with the phenol red thread test and Keeler Tearscope. Variability in wavefront aberrations was assessed with and without a low powered soft contact lens. The effect of time after the blink and tear film characteristics were also investigated.

Standard deviations differed significantly for some fifth-order terms (p < or = 0.003) with contact lens wear. Coefficient of variation did not increase significantly with contact lens wear. Time from blink increased standard deviations in the third-order (p < or = 0.003). The effect of contact lens wear and time from blink differed between groups with different tear film characteristics.

Variability in measurements of aberrations increased significantly for odd-order aberrations when a contact lens was worn or between blinks. Fourth-order aberrations showed less effect of contact lens wear. Therefore, verification of the performance of lenses with aspheric optics on eye is feasible. Accurate assessment of higher-order aberrations is more difficult when a contact lens is worn. Both contact lens wear and time from blink increase variability in aberrations, which suggests a role for the tear film in increased aberrations with soft contact lens wear.