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Clinical and Corneal Biomechanical Changes After Collagen Cross-Linking With Riboflavin and UV Irradiation in Patients With Progressive Keratoconus: Results After 2 Years of Follow-up

Goldich, Yakov MD; Marcovich, Arie L. MD; Barkana, Yaniv MD; Mandel, Yossi MD; Hirsh, Ami MD; Morad, Yair MD; Avni, Isaac MD; Zadok, David MD

doi: 10.1097/ICO.0b013e318226bf4a
Clinical Science

Purpose: To assess the biomechanical and keratometric effects and the safety of treatment of progressive keratoconus with UV–riboflavin collagen cross-linking (CXL).

Methods: This is a prospective clinical controlled study. Fourteen eyes of 14 patients with progressive keratoconus were treated with CXL after corneal deepithelization. Patients were assessed preoperatively, at week 1 and at months 1, 3, 6, 9, 12, and 24 after treatment. We measured uncorrected visual acuity (UCVA) and best spectacle–corrected visual acuity (BSCVA) (logarithm of the minimum angle of resolution), refraction, biomicroscopy and fundus examination, intraocular pressure, axial length, endothelial cell density, corneal topography, minimal corneal thickness, macular optical coherence tomography, and corneal biomechanics with the ocular response analyzer.

Results: Comparing the preoperative results with 24-month postoperative results, we observed significant improvement in BCVA (0.21 ± 0.1 to 0.14 ± 0.1, P = 0.002) and stability in UCVA (0.62 ± 0.5 and 0.81 ± 0.49, P = 0.475). We observed a significant decrease in steepest-meridian keratometry (diopters) (53.9 ± 5.9 to 51.5 ± 5.4, P = 0.001) and in mean cylinder (diopters) (10.2 ± 4.1 to 8.1 ± 3.4, P = 0.001). Significant elongation of the eyes was observed, from 24.39 ± 1.7 mm to 24.71 ± 1.9 mm (P = 0.007). No significant change was observed in mean simulated keratometry, minimal corneal thickness, endothelial cell density, corneal hysteresis, and corneal resistance factor or foveal thickness.

Conclusions: Two years after CXL, the observation of stable UCVA, improved BCVA, and reduced keratometry suggests stabilization in progression of keratoconus. Unchanged corneal thickness, endothelial cell density, and foveal thickness suggest the long-term safety of this procedure. The observed increase in axial length and stability in corneal biomechanical parameters measured with the ocular response analyzer require further study for verification and explanation.

*Department of Ophthalmology, Assaf Harofeh Medical Center, Zerifin, Israel

Department of Ophthalmology, Kaplan Medical Center, Rehovot, Israel

Center for Bioengineering in the Service of Humanity and Society, Hebrew University, Jerusalem, Israel

§Einaim Refractive Surgery Centers, Israel.

The authors state that they have no financial or conflicts of interest to disclose.

Reprints: Yakov Goldich, Department of Ophthalmology, Assaf Harofeh Medical Center, Beer Yaakov, Zerifin 70300, Israel (e-mail:

Received August 19, 2010

Accepted May 28, 2011

Copyright © 2012 Wolters Kluwer Health, Inc. All rights reserved.