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Effects of Corneal Cross-linking on Contrast Sensitivity, Visual Acuity, and Corneal Topography in Patients With Keratoconus

Lamy, Ricardo MD, PhD*,†; Netto, Camila F. MD*; Reis, Ricardo G. MD*; Procopio, Bruno MD*; Porco, Travis C. PhD, MPH; Stewart, Jay M. MD; Dantas, Adalmir M. MD, PhD*; Moraes, Haroldo V. Jr MD, PhD*

doi: 10.1097/ICO.0b013e31826672e2
Clinical Science

Purpose: To assess the effects of corneal collagen cross-linking (CXL) on contrast sensitivity (CS), visual acuity, and corneal topography investigating possible predictors of efficacy.

Methods: Sixty-eight eyes of 34 patients with progressive keratoconus were enrolled in this prospective study. CXL was performed in one eye and the other eye was left untreated as a control. CS, best spectacle–corrected visual acuity (BSCVA), simulated keratometry in the steepest meridian (SimK-s), mean power in the central 3-mm zone (C-MP), mean power in the paracentral 3- to 5-mm zone (P-MP), maximum keratometric power in the central zone (C-Kmax), and maximum keratometric power in the paracentral zone (P-Kmax) were evaluated at baseline, 40 days, 3 months, 6 months, 1 year, and after 2 years of follow-up.

Results: Treated eyes showed an improvement (P < 0.001) of +0.16 logCS and −0.16 logarithm of the minimum angle of resolution (logMAR) and a reduction in SimK-s of −0.61 diopter (D), C-Kmax −1.11 D, P-Kmax −0.99 D, C-MP −0.39 D, and P-MP −0.30 D. Of the treated eyes, 43.3% had a decrease in C-Kmax greater than 1 D, 50% by 0 to 0.99 D, and 6.7% had an increase of up to +0.89 D. Treated eyes with keratometric apex in the central 3-mm zone (CKA) improved BSCVA −0.19 logMAR and CS +0.19 logCS; whereas in treated eyes with paracentral keratometric apex (PKA), the improvement was −0.13 logMAR and +0.16 logCS.

Conclusions: CXL with riboflavin and UV-A improved CS and inhibited the progression of keratoconus. As a predictor of treatment efficacy, eyes with CKA showed greater improvement in BSCVA after CXL when compared with eyes with PKA.

Author Information

*Department of Ophthalmology, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil

Department of Ophthalmology, University of California, San Francisco, CA.

Reprints: Ricardo Lamy, Department of Ophthalmology, Federal University of Rio de Janeiro, Rio de Janeiro 21941-913, Brazil (e-mail:

The authors have no funding or conflicts of interest to disclose.

Received February 13, 2012

Accepted June 24, 2012

© 2013 by Lippincott Williams & Wilkins.