Spherical aberration in relation to visual performance in contact lens wear

Introduction: The aim of the present study was to evaluate changes in spherical aberration and their effect on visual quality (visual acuity and contrast sensitivity) in both distance and near with different non-custom-made contact lenses. Methods: A wavefront analyser was used to measure the aberrations in each subject's eyes uncorrected and with the contact lenses: a standard lens and two aspherical contact lenses. High-contrast visual acuity at distance was measured with Test-Chart 2000(100% contrast) and at near with Sloan ETDRS Near Point chart (100% contrast). Low-contrast visual acuity at distance was measured with Test-Chart 2000 (10% contrast) and contrast measurements at near with Mars letter contrast sensitivity chart. Results: Mean spherical aberration was positive for all pupil sizes in the uncorrected eye, residual spherical aberration was close to zero with the standard lens for all pupil sizes, whereas the two aspheric contact lenses over-corrected spherical aberration. The changes in aberration were statistically significant (p < 0.05) with all lenses. No significant difference could be detected between trial frame correction, spherical and aspherical soft contact lens designs with respect to visual quality. This was the case for both distance and near. Conclusion: The results are in line with previous studies and indicate that non-custom-made spherical aberration control contact lenses have little effect on visual quality as defined in this study. (C) 2010 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.