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An important clinical trial, sponsored by the National Eye Institute(NEI), a part of the National Institutes of Health (NIH), has provideddoctors with improved prognostic indicators and treatment options forretinopathy of prematurity (ROP), a blinding disease that affectspremature, low birthweight infants. ROP spurs the growth of abnormalblood vessels in the back of the eye. These vessels leak fluid and bloodand scar the nerve tissue inside the eye, increasing the risk of retinaldetachment and severe vision loss in infants.
Because it follows an unpredictable course, ROP presents doctors withdifficult treatment decisions. In many infants the disease spontaneouslyregresses and spares vision. However, in some infants ROP progresses,resulting in serious visual impairment. Although current therapy canstem its progression, many infants are still blinded by the disease. Dueto a lack of clinical criteria to predict which patients will ultimatelydevelop severe vision loss from ROP, ophthalmologists were forcedpreviously to defer treatment until it was clearly indicated.Unfortunately, as it turns out, delaying therapy can leave infants whomight benefit more from early treatment with poor visual outcomes.
The Early Treatment for Retinopathy of Prematurity (ETROP) studyresults, published in the December issue of the Archives ofOphthalmology, demonstrated that premature infants, who are at thehighest risk for developing vision loss from ROP, will retain bettervision when therapy is administered in the early stage of the disease.This treatment approach was found to be better than waiting until ROPhas reached the traditional treatment threshold. Just as importantly,the study also established the value of an improved risk assessmentmodel to more accurately identify those infants who are at the highestrisk for developing severe vision loss from ROP.
“Premature, low birthweight infants face a host of medicalcomplications with lifelong consequences. The results of this studyallow us to improve treatment for ROP and, hopefully, the quality oflife for children who most need sight-saving therapy,” said Paul A.Sieving, M.D., Ph.D., director of the NEI.
“This is a great step forward in research to treat blinding eyediseases,” said NIH Director Elias Zerhouni, M.D. “The NIH will continueto look for new ways to treat and even prevent ROP, which is one of theleading causes of severe vision loss in infants and young children.”
Each year ROP affects an estimated 14,00016,000 premature, lowbirthweight infants in the United States and thousands more worldwide,making it a leading cause of vision loss in children. Of these cases,approximately 1500 infants will develop severe ROP that requirestreatment. Despite available treatment, about 400600 infants withROP still become legally blind each year. Researchers have identifiedbirthweight of 2.75 pounds (1250 grams) or less as a major risk factorfor developing ROP.
The previous standard treatment threshold for ROP hinged on thedisease having progressed enough that the risk of retinal detachmentapproached 50 percent. As part of the ETROP study, a new computerizedrisk model, developed by NEI-supported researchers, was used to identifyhigh-risk infants early in the disease. The risk model assessedbirthweight, ethnicity, being a single or multiple birth baby,gestational age, ophthalmic exam findings, and whether the infant hadbeen born in a hospital that participated in the study. “This new riskassessment model proved invaluable in the early detection of infants whohave a high risk of blindness and may require treatment. It also allowedus to better identify and monitor those patients who are less likely torequire treatment,” said Robert J. Hardy, Ph.D., the University of TexasSchool of Public Health at Houston researcher who led the efforts todevelop this improved risk model.
Once identified, the infants were then assigned randomly either totreatment at the standard threshold (50 percent chance of retinaldetachment) or to early treatment. Researchers found that earlytreatment significantly reduced the likelihood of poor vision from 19.5to 14.5 percent at about one year of age. Early treatment alsoconsiderably reduced the likelihood of structural damage to the eye from15.6 to 9.1 percent.
Current treatments for ROP involve laser therapy or cryotherapy.Laser therapy uses heat from light energy while cryotherapy usesfreezing temperatures to retard blood vessel growth. A consequence ofthese treatments, known clinically as blood vessel ablation, is apartial loss of peripheral or side vision. Nonetheless, treatment isvaluable in preserving the most important part of our sightthesharp, central vision we need to read, see faces or perform detailedtasks that require hand-eye coordination.
“It is crucial that infants with high-risk ROP be identified earlyand be given timely treatment,” said the chair of the study WilliamGood, M.D., of the Smith-Kettlewell Eye Research Institute in SanFrancisco. “Early treatment could save infants from a lifetime of visualimpairment. The results also clearly indicate that for certain subgroupsof eyes, watchful waiting and not immediate treatment is the bestapproach.”
The study will continue to follow these infants until age six toensure that the benefits of early treatment persist into childhood.”Because visual acuity continues to develop during infancy and earlychildhood, the long-term effect of early treatment on visual developmentis not yet fully known. We expect that the significant benefits tovision found in this study will persist into childhood, but we have tobe sure,” Dr. Good said.
The study was conducted at 26 participating centers in the U.S. A list of study centers is attached.
The National Eye Institute (NEI) conducts and supports researchthat leads to sight-saving treatments and plays a key role in reducingvisual impairment and blindness. The NEI is part of the NationalInstitutes of Health (NIH), an agency of the U.S. Department of Healthand Human Services.
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- Early Treatment For Retinopathy Of Prematurity Cooperative Group. Revised Indications for The Treatment of Retinopathy of Prematurity: Results of The Early Treatment for Retinopathy of Prematurity Randomized Trial. Arch Ophthalmol. 2003 Dec. PubMed