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Swift Treatment Prevents Childhood Blindness
School of Public Health researchers play central role in $13 million national clinical trial
Betty Tung and Bob Hardy, School of Public Health, developed a riskassessment program that guided treatment of infants in a study of retinopathy of prematurity.
Photo by Scott Merville
Tiny premature babies threatened by a major cause of childhood blindness benefit from early treatment of the disease guided by a risk assessment program developed at The University of Texas School of Public Health at Houston (SPH).
The National Eye Institute of the National Institutes of Health (NIH) in December 2003 announced research results and new guidelines for treating retinopathy of prematurity (ROP), a notoriously unpredictable disease that heals spontaneously in most cases but also leaves some infants facing a lifetime of blindness.
At the center of the study were Professor of Biometry Robert L. Hardy, Ph.D., Project Manager Betty Tung, and the staff of the SPH Coordinating Center for Clinical Trials, who have been instrumental in unraveling the disease’s secrets for 20 years.
“Premature, low birth weight infants face a host of medical complications with lifelong consequences. The results of this study allow us to improve treatment for ROP and, hopefully, the quality of life for children who most need sight-saving therapy,” said Paul A. Sieving, M.D., Ph.D., director of the National Eye Institute (NEI), the study’s sponsor.
“This is a great step forward in research to treat blinding eye diseases,” said NIH Director Elias Zerhouni, M.D.
Hardy and colleagues coordinated the trial, which showed that early treatment can reduce the likelihood of poor vision by 25 percent and the risk of serious eye damage by 33 percent. Hardy’s team received $12.1 million of the $13.1 million that the NEI spent on the study, which included 26 clinical sites. But more importantly, they developed the risk assessment technique that was essential to conducting the test of early treatment.
“The challenge is knowing which babies to treat for ROP and which to keep under observation,” said Hardy, who also is the Allan King Professor in Public Health. Hardy, Tung and Charlie Cooper used a painstaking analysis of children in an earlier ROP study to develop a computer program that identifies infants at high risk of blindness.
“This new risk assessment model proved invaluable in the early detection of infants who have a high risk of blindness and may require treatment. It also allowed us to better identify and monitor those patients who are less likely to require treatment,” Hardy said.
ROP causes abnormal growth of blood vessels into the retina and nerve tissue in the back of the eye, which can lead to retinal scarring or detachment and blindness. Treatment involves either laser therapy or cryotherapy (freezing) to stop blood vessel growth.
Previous NEI-funded research showed that delaying treatment raises the risk of blindness in high-risk babies. But because most ROP patients get better without treatment, and clinical criteria to identify high risk infants early were lacking, there was a strong incentive to wait and watch, avoiding unnecessary surgery in vulnerable babies. Standard practice was to wait to treat until the disease progressed to where the risk of retinal detachment approached 50 percent.
In the present study, 401 high-risk infants identified by the risk assessment program were assigned randomly either to standard treatment or to earlier treatment. Researchers found that early treatment significantly reduced the likelihood of poor vision from 19.5 to 14.5 percent at about one year of age. Early treatment also considerably reduced the likelihood of structural damage to the eye from 15.6 to 9.1 percent.
Results were published in the December issue of Archives of Ophthalmology, a journal of the American Medical Association. A companion article in the journal reported on the risk analysis model developed by Hardy and Tung.
Their risk assessment model takes into account birth weight, gestational age, ethnicity, being a single or multiple-birth baby, ophthalmic exam findings and whether the infant had been born in the hospital participating in the study.
Study chair William Good, M.D., of the Smith-Kettlewell Eye Research Institute in San Francisco presented study results and new clinical guidelines for treatment at the annual meeting of the American Academy of Ophthalmology in November.
Each year ROP affects an estimated 14,000-16,000 premature, low-birth-weight infants (2.75 pounds or less) in the United States and thousands more worldwide, making it a leading cause of vision loss in children. Of these cases, approximately 1,500 infants will develop severe ROP that requires treatment and about 400-600 infants with ROP still become legally blind each year.
The NEI has funded a second phase study that will follow the ETROP infants until age 6 to ensure that the benefits of early treatment persist into childhood.
— By Scott Merville, Public Affairs