Author, Co-Author Karla Zadnik, Kenneth Schechtman, Jason Nichols, Barbara Fink, Julie Tyler, Carol Rosenstiel, Julie Shin, Karen Steger-May, The Study Group
Program Number
1:00 pm
Northern Hemisphere A 3-4
Ohio State University
Abstract PURPOSE. Keratoconus is classically described as an asymmetric disease, but data supporting this clinical assertion are sparse. We report baseline differences between eyes on key variables in the Collaborative Longitudinal Evaluation of Keratoconus (CLEK) Study cohort compared to a retrospective group of contact lens wearers.

METHODS. A total of 1,091 nonsurgical keratoconus patients were enrolled and examined at baseline. We measured corneal curvature (keratometry); visual acuity; refractive error (manifest refraction); and corneal scarring.

RESULTS. We classify these patients as having moderate-severe keratoconus with the steep keratometric reading in the worse eye of 52.84 +/- 5.74 D and in the better eye of 48.49 +/- 4.48 D. They have reasonably good visual acuity on average with high contrast entrance visual acuity of 37.43 (20/32) +/- 17.50 letters in the worse eye and 49.61 (20/16) +/- 8.58 letters in the better eye. The mean differences are as follows. Flat keratometry: 3.58 +/- 4.44 D and steep keratometry: 4.35 +/- 4.41 D; high contrast entrance VA: 12.18 ± 14.94 letters; low contrast entrance VA: 13.22 ± 14.42 letters; high contrast best corrected VA: 7.93 +/- 8.82 letters; low contrast best corrected VA: 9.75 ± 10.36 letters; spherical equivalent: 3.16 +/- 3.83 D. However, among those patients wearing rigid contact lenses, contact lens wearing time does not differ between eyes (0.28 +/- 1.68 hours). Twenty-one percent of the patients had corneal scarring in only one eye. Only 2% of the patients report vigorously rubbing only one eye.

CONCLUSIONS. Keratoconus is asymmetric in the CLEK Study sample. Differences between eyes average at least 4.00 D of corneal curvature, two lines of visual acuity, and 3.00 D of refractive error. Supported by NIH-NEI grants U10 EY10419, EY10069, EY10077, EY12656 and by Conforma Contact Lenses, Paragon Vision Sciences, CIBA Vision Corporation, and the Ohio Lions Eye Research Foundation.
Affiliation of Co-Authors Ohio State University, Washington University Medical School, Ohio State University, Nova Southeastern University, University of Alabama at Birmingham, Southern California College of Optometry, Washington University Medical School, Washington University Medical School