A Randomized Controlled Trial of Corneal Collagen Cross-linking in Progressive Keratoconus: Preliminary Results

<h4>PURPOSE</h4><p>This prospective, randomized, controlled trial aims to provide evidence in relation to the efficacy and safety of corneal collagen cross-linking (CXL) in the management of progressive keratoconus. </p> <h4>METHODS</h4><p>Eligible eyes were separately randomized into either treatment or control groups. Collagen cross-linking was performed using 0.1% riboflavin (in 20% dextran T500) and ultraviolet A (UVA) irradiation (370 nm,3 mW/cm², 30 min) in accordance with a previously published protocol. At each review, a full clinical ophthalmic examination was performed including endothelial cell count and confocal microscopy.</p> <h4>RESULTS</h4><p>To date, 66 eyes of 49 patients with documented progression of keratoconus have been enrolled and randomized. Interim analysis of treated eyes showed a flattening of the steepest simulated keratometry value (K-max) by an average of 0.74 diopters (D) (<i>P</i>=.004) at 3 months, 0.92 D (<i>P</i>=.002) at 6 months, and 1.45 D (<i>P</i>=.002) at 12 months. A trend toward improvement in best spectacle-corrected visual acuity was also observed. In the control eyes, mean K-max steepened by 0.60 D (<i>P</i>=.041) after 3 months, by 0.60 D (<i>P</i>=.013) after 6 months, and by 1.28 D (<i>P</i><u><</u>.0001) after 12 months. Best spectacle-corrected visual acuity decreased by logMAR 0.003 (<i>P</i>=.883) over 3 months, 0.056 (<i>P</i>=.092) over 6 months, and 0.12 (<i>P</i>=.036) over 12 months. No statistically significant changes were found for spherical equivalent or endothelial cell density.</p> <h4>CONCLUSIONS</h4><p>Preliminary results of this randomized controlled trial suggest a temporary stabilization of all treated eyes after CXL. [<cite>J Refract Surg.</cite> 2008;24:S720-S725.]</p> <h4>ABOUT THE AUTHORS</h4> <p>From Centre for Eye Research Australia (Wittig-Silva, Lamoureux, Snibson) and Royal Victorian Eye & Ear Hospital (Wittig-Silva, Whiting, Sullivan, Snibson), East Melbourne; and Victorian College of Optometry (Lindsay), Carlton, Australia.</p> <p>Grant support provided by Royal Victorian Eye & Ear Hospital Research Fund, Eye Research Australia Foundation, Scholarship for Postgraduate Studies (Faculty of Medicine and University of Melbourne), and Contact Lens Society of Australia.</p> <p>The authors have no financial interest in the materials presented herein.</p> <p>Presented in part at the International Congress of Corneal Cross-Linking; December 7-8, 2007; Zurich, Switzerland.</p> <p>The authors acknowledge Institute of Refractive and Ophthalmic Surgery and Peschke Meditrade GmbH for the use of the UV-X device and general advice; Medical Photographic Imaging Centre, Royal Victorian Eye & Ear Hospital for their consistently excellent photographic work; the Pharmacy Department, Royal Victorian Eye & Ear Hospital for their outstanding support and expertise; Mr Marios Constantinou for his assistance with the database and clinical work; and Prof Lawrie Hirst for his valuable advice and support.</p> <p>Correspondence: Grant R. Snibson, FRANZCO, Centre for Eye Research Australia (CERA), 32 Gisborne St, East Melbourne 3002 VIC, Australia. Tel: 613 9416 0695; Fax: 613 9416 1816; E-mail: <a href="mailto:gsnibson@eyesurgery.com.au">gsnibson@eyesurgery.com.au</a></p>