Evaluating the Cryotherapy for Retinopathy of Prematurity Study (CRYO-ROP).

ease than in zone 2 disease, where fortunately greater than 75% of the disease occurs. It is important to note that unfavorable outcomes as stage 5 (total retinal detachment) outnumbered stage 4B (a retinal fold extending through the macula) by a ratio of 13 to 1. The treated unfavorable results were far more common proportionately in zone 1 disease than in zone 2 disease. The results of this study proved for the first time the availability of a treatment that improved the outlook for vision significantly over the natural history of the disease. The results of the study were quickly adopted both in the United States and worldwide as the standard of care, a tribute to the meticulous planning and execution by the investigators involved in carrying it out. Treatment took a further step forward when the indirect diode laser became available and was shown in a number of observational studies to be as effective as cryotherapy and easier in application for the infant and therapist. The CRYO-ROP trial proved to be the template for studies to follow. It also furnished a cadre of ophthalmologists trained in the design and implementation of randomized trial methods and the application of the methods to other problems in pediatric ophthalmology as they arose. It stands as one of the most successful trials undertaken with support of the National Eye Institute. Submitted for Publication: November 22, 2006; accepted November 22, 2006. Correspondence: John T. Flynn, MD, Department of Ophthalmology, Harkness Eye Institute, 635 W 165th St, New York, NY 10032 ([email protected]). Financial Disclosure: None reported. Funding/Support: This work was supported in part by the Communities Foundation of Texas.