Premature infants at high risk for losing their vision experience better outcomes when therapy is administered earlier, a finding that contradicts long-held treatment protocols for the most fragile of babies. The findings, gathered in part at Golisano Children’s Hospital at Strong, appear in the Dec. 9 issue of Archives of Ophthalmology.
Retinopathy of prematurity – commonly known as ROP - is a potentially blinding eye disease primarily affecting premature infants weighing less than 2 pounds, 12 ounces. The disease spurs the growth of abnormal blood vessels in the eye, vessels that leak fluid and blood, and scar the nerve tissue inside the eye. This increases the risk of retinal detachment and severe vision loss in these infants, most born more than two months prematurely.
“Each year, ROP affects between 14,000 and 16,000 premature infants in the United States, making it a leading cause of vision loss in children,” says Dale Phelps, M.D., the Golisano Children’s Hospital neonatologist who led the study locally. “An infant’s prematurity is directly linked to the chances of developing the disease.”
Until now, infants at risk for severe ROP were not treated until specialists determined that their risk of retinal detachment was at least 50 percent. As part of this study, however, a new, computerized risk model was used to identify high-risk infants early in the disease.
The risk model assessed birth weight, ethnicity, being a single- or multiple-birth baby, gestational age, eye-exam findings, and whether the infant was born in a participating hospital. “These findings will help us preserve vision for many infants throughout the country,” Phelps says. “Now we know that earlier treatment is helpful and safe. We also learned better criteria about which cases of ROP should be treated earlier with laser.”
During the study, infants who had retinopathy of prematurity were assigned randomly to have one eye treated at the standard threshold - 50 percent chance of retinal detachment – and the other to early treatment, the new way of thinking. 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 in the eye from 15.6 to 9.1 percent.
In addition to redefining the criteria for when ROP treatment should begin, the study establishes the value of an improved risk assessment model to more accurately identify those infants who are at the highest risk for developing severe vision loss from retinopathy of prematurity. “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.
Infants involved in the study, which concluded this year, will be followed until age 6 to ensure that the benefits of early treatment persist into childhood. Golisano Children’s Hospital was one of 26 centers in the United States participating in the study; Phelps helped organize and run it.
Retinopathy of prematurity became prevalent in the 1940s and 1950s with the introduction of oxygen-rich incubators for premature infants. During this time, the disease was the leading cause of blindness in U.S. children. In 1954, scientists funded by the National Institutes of Health determined that the high levels of oxygen routinely given to premature infants at that time were an important risk factor, and that reducing oxygen levels decreased the incidence of retinopathy of prematurity. With newer technology and methods to monitor the oxygen levels of infants, oxygen use as a risk factor for the disease has diminished in importance.
In the 1970s, advances in neonatal care enabled the survival of smaller babies, and retinopathy of prematurity again emerged as an important public health problem. In 1988, scientists funded by the National Eye Institute discovered that briefly freezing a portion of the surface of the eye can protect many premature infants against blindness from the disease. The procedure, called cryotherapy, stops the growth of abnormal blood vessels. The more recent of laser surgery replaces cryotherapy, but accomplishes the same goal.
This newest study is the latest good news in the fight to save premature infants’ eyesight. “This is a great step forward in research to treat blinding eye diseases,” says Elias Zerhouni, M.D., of the National Institutes of Health.
The National Eye Institute conducts and supports research that leads to sight-saving treatments and plays a key role in reducing visual impairment and blindness. It is part of the National Institutes of Health, an agency of the U.S. Department of Health and Human Services. Faculty members from Golisano Children’s Hospital at Strong have worked collaboratively with these organizations on several important studies regarding retinopathy of prematurity.