title: Contrast sensitivity after epikeratophakia.
abstract: Epikeratophakia is a rapidly evolving surgical procedure for the refractive correction of aphakia. Even when Snellen acuity after epikeratophakia is normal, patients often report a subjective degradation of the visual image through the surgically corrected eye. To further define visual performance in the patient with optically successful epikeratophakia, we examined contrast sensitivity in two patients surgically corrected for monocular aphakia. Contrast thresholds were measured over a range of spatial frequencies using both computer-generated sinusoidal gratings and a commercially available wall chart system. The eye with epikeratophakia in each case was compared with the opposite normal eye with comparable acuity. One patient was also tested prospectively in the same eye both before and after surgery. Data demonstrate a depression of the contrast sensitivity function in the middle and high spatial frequencies induced by the placement of an epikeratophakia lenticule when compared with the normal eye or contact lens-corrected, preoperative aphakic eye with comparable good acuity. These findings may explain the subjective experience of epikeratophakia patients.
authors.affiliation: Cornea and External Disease Service, University of California, Davis 95816.
authors.forename: M J
authors.initials: MJ
authors.lastname: Mannis
authors.forename: K
authors.initials: K
authors.lastname: Zadnik
authors.forename: C
authors.initials: C
authors.lastname: Johnson
authors.forename: C
authors.initials: C
authors.lastname: Adams
mesh_terms: D000328:Adult; D001035:Aphakia / Q000601:surgery*; D002387:Cataract Extraction; D003261:Contact Lenses; D015350:Contrast Sensitivity; D006801:Humans; D008297:Male; D008875:Middle Aged; D014792:Visual Acuity