SCARRING AND VISUAL ACUITY IN KERATOCONUS

Title SCARRING AND VISUAL ACUITY IN KERATOCONUS
Author, Co-Author Karla Zadnik, Joseph Barr, Timothy Edrington, Mae Gordon, The Study Group
Topic
Year
1993
Day
Saturday
Program Number
3:30 pm
Room
Salon E
Affiliation
Abstract Conventional wisdom holds that keratoconus patients progressively lose visual acuity with time, that rigid contact lenses are necessary for best visual acuity, and that subjective refraction results are not meaningful for spectacle correction due to poor visual acuity. We have screened almost 2,000 patients with the diagnosis of keratoconus in planning the Contact Lens Evaluation in Keratoconus (CLEK) Study, an investigation of flat versus steep fitting methods in keratoconus. Examination of the cross-sectional screening data on the relationship between scarring and visual acuity yielded the following results. The median visual acuity with contact lens correction was 20/20 to 20/25 for unscarred corneas (n=1,509 eyes) and 20/25 to 20/30 for scarred corneas (n=861 eyes). The median visual acuity with subjective refraction was 20/25 to 20/30 for unscarred corneas (n=1,712 eyes) and 20/65 to 20/70 for scarred corneas (n=755 eyes). Further, 58% of 1,579 keratoconic eyes could achieve at least 20/40 visual acuity with manifest refraction; these refraction results have not been evaluated for stability with time. These results indicate that subjective refraction and prescription of spectacles for occasional or emergency use should be attempted in keratoconus, but that the presence of corneal scarring adversely affects the expected visual acuity. The effect of covariates such as age, duration of disease, corneal curvature, and corneal irregularity or distortion on visual acuity and scarring in keratoconus will also be discussed. Supported by NEI grants EY08652 and EY02687, an unrestricted grant from Paragon Vision Sciences, an unrestricted grant from CIBA Vision Corporation, and the Ohio Lions Eye Research Foundation.
Affiliation of Co-Authors
Outline