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Treatment of Progressive Keratoconus by Riboflavin-UVA-Induced Cross-Linking of Corneal Collagen: Ultrastructural Analysis by Heidelberg Retinal Tomograph II In Vivo Confocal Microscopy in Humans

Mazzotta, Cosimo PhD; Balestrazzi, Angelo PhD; Traversi, Claudio MD; Baiocchi, Stefano PhD; Caporossi, Tomaso MD; Tommasi, Cristina MD; Caporossi, Aldo MD

doi: 10.1097/ICO.0b013e318030df5a
Clinical Science

Purpose: To assess ultrastructural stromal modifications after riboflavin-UVA-induced cross-linking of corneal collagen in patients with progressive keratoconus.

Methods: This was a second-phase prospective nonrandomized open study in 10 patients with progressive keratoconus treated by riboflavin-UVA-induced cross-linking of corneal collagen and assessed by means of Heidelberg Retinal Tomograph II Rostock Corneal Module (HRT II-RCM) in vivo confocal microscopy. The eye in the worst clinical condition was treated for each patient. Treatment under topical anesthesia included corneal deepithelization (9-mm diameter) and instillation of 0.1% riboflavin phosphate-20% dextran T 500 solution at 5 minutes before UVA irradiation and every 5 minutes for a total of 30 minutes. UVA irradiation was 7 mm in diameter. Patients were assessed by HRT II-RCM confocal microscopy in vivo at 1, 3, and 6 months after treatment.

Results: Rarefaction of keratocytes in the anterior and intermediate stroma, associated with stromal edema, was observed immediately after treatment. The observation at 3 months after the operation detected keratocyte repopulation in the central treated area, whereas the edema had disappeared. Cell density increased progressively over the postoperative period. At ∼6 months, keratocyte repopulation was complete, accompanied by increased density of stromal fibers. No endothelial damage was observed at any time.

Conclusions: Reduction in anterior and intermediate stromal keratocytes followed by gradual repopulation has been confirmed directly in vivo in humans by HRT II-RCM confocal microscopy after riboflavin-UVA-induced corneal collagen cross-linking.

From the *Department of Ophthalmology and Neurosurgery, University of Siena, Siena, Italy; and the †Ophthalmology Institute, Catholic University, Rome, Italy.

Received for publication June 5, 2006; revision received November 8, 2006; accepted November 21, 2006.

The authors state that they have no proprietary interest in the products named in this article.

Reprints: Angelo Balestrazzi, Dipartimento di Scienze Oftalmologiche e Neurochirurgiche, Università di Siena, Viale Bracci 1, 53100 Siena, Italy (e-mail: balestrazzi@unisi.it).

Copyright © 2007 Wolters Kluwer Health, Inc. All rights reserved.