Abstract
Eyes with keratoconus have abnormal corneal optics that reduce spatial contrast sensitivity. The vision of keratoconus patients has been studied at high light levels; however, losses in contrast sensitivity should be more pronounced when the pupil is large because the steepest portion of the cornea is often located peripherally. We measured contrast sensitivity at low luminance in several subjects with mild cases of keratoconus, and compared sensitivity to retinal image quality measured by an objective method. The contrast sensitivity deficit at low to middle spatial frequencies became more pronounced at low luminance. Retinal image quality was also reduced in keratoconus, even for moderate pupil sizes. Wave-front aberrations in the pupil plane were also measured on two subjects. The dominant aberrations were astigmatism and coma, but higher order aberrations were present. Rigid contact lenses corrected most of the aberrations and improved sensitivity, particularly at low luminance.
© 2000 Optical Society of America
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