Does cryotherapy affect refractive error? Results from treated versus control eyes in the cryotherapy for retinopathy of prematurity trial1☆
Presented in part at the annual meeting of The Association for Research in Vision and Ophthalmology, May 1998, Fort Lauderdale, Florida.
Received 30 December 1999; accepted 12 September 2000.
Abstract
Purpose
To evaluate the effect of cryotherapy on refractive error status between ages 3 months and 10 years in children with birth weights of less than 1251 g in whom severe retinopathy of prematurity (ROP) developed in one or both eyes during the neonatal period.
Design
Randomized clinical trial.
Participants
Two hundred ninety-one children in whom severe ROP developed during the neonatal period.
Intervention
Cryotherapy for ROP.
Main outcome measures
Cycloplegic Refraction
Methods
The children underwent repeated follow-up eye examinations, including cycloplegic retinoscopy, between 3 months and 10 years after term due date. Refractive error data from all eyes that were randomized to cryotherapy were compared with data from all eyes that were randomized to serve as controls. Refractive error data were also compared for a subset of children who had both a treated and a control eye that could be refracted.
Results
At all ages, the proportion of treated eyes that were unable to be refracted because of retinal detachment, media opacity, or pupillary miosis was approximately half the proportion of the control eyes that were unable to be refracted. When data from all eyes that could be refracted were considered, the distribution of refractive errors between fewer than 8 diopters (D) of myopia and more than 8 D of hyperopia was similar for treated and control eyes at all ages. The proportion of eyes with 8 D or more of myopia was much higher in treated than in control eyes at all ages after 3 months. In the subset of children who had a treated eye and a control eye that could be refracted, distributions of refractive errors in treated versus control eyes were similar at most ages.
Conclusions
In both treated and control eyes, there was an increase in the prevalence of high myopia between 3 and 12 months of age. Between 12 months and 10 years of age, there was little change in distribution of refractive error in treated or control eyes. The higher prevalence of myopia of 8 D or more in treated eyes, as compared with control eyes, may be the result of cryotherapy’s preservation of retinal structure in eyes that, in the absence of cryotherapy, would have progressed to retinal detachment.
Manuscript no. 99855.
1Division of Pediatric Ophthalmology, The Children’s Hospital of Philadelphia and Scheie Eye Institute, University of Pennsylvania Health System, Philadelphia, Pennsylvania, USA
2Departments of Ophthalmology and Psychology, University of Arizona, Tucson, Arizona, USA
3Department of Ophthalmology, University of Oklahoma, Oklahoma City, Oklahoma, USA
4University of Texas Health Science Center at Houston, School of Public Health, Houston, Texas, USA
5Department of Ophthalmology, Medical College of Wisconsin, Milwaukee, Wisconsin, USA
6Casey Eye Institute, Oregon Health Sciences University, Portland, Oregon, USA
7Departments of Pediatrics and Ophthalmology, University of Rochester, Rochester, New York, USA
8Wilmer Eye Institute, The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
9Departments of Ophthalmology and Pediatrics, University of Minnesota, Minneapolis, Minnesota, USA
Correspondence to Graham E. Quinn, MD, Division of Pediatric Ophthalmology, The Children’s Hospital of Philadelphia, One Children’s Center, Philadelphia, PA 19104
☆ Supported by the National Eye Institute, Bethesda, Maryland (cooperative agreement no. U10 EY05874).
1 A listing of cooperative group participants can be found in Archives of Ophthalmology 1996;114:417–24.
2 Reprint requests to CRYO-ROP Study Headquarters, Oregon Health Sciences University, Department of Ophthalmology, L467, 3375 SW Terwilliger Boulevard, Portland, OR 97201-4197 (Earl A. Palmer, MD).
ABSTRACT