A clinical trial sponsored by the National Eye Institute (NEI), part of the National Institutes of Health (NIH), has provided doctors with improved prognostic indicators and treatment options for retinopathy of prematurity (ROP), a blinding disease that affects premature, low-birthweight infants.
Each year ROP affects an estimated 14,000-16,000 infants 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. Despite available treatment, about 400-600 infants with ROP still become legally blind each year. Researchers have identified birthweight of 2.75 pounds (1250 grams) or less as a major risk factor for developing ROP.
ROP spurs the growth of abnormal blood vessels in the back of the eye. These vessels leak fluid and blood and scar the nerve tissue inside the eye, increasing the risk of retinal detachment and severe vision loss in infants. Because it follows an unpredictable course, ROP presents doctors with difficult treatment decisions. In many infants the disease spontaneously regresses and spares vision.
However in some infants ROP progresses, resulting in serious visual impairment. Although appropriately timed laser therapy may stem its progression, many infants still are blinded by the disease. New information about the timing of laser treatment may improve visual outcomes for some of these high-risk infants.
The Early Treatment for Retinopathy of Prematurity (ETROP) study results, published in the December issue of Archives of Ophthalmology , demonstrated that premature infants, who are at the highest risk for developing vision loss from ROP, retained better vision when therapy is administered in an earlier stage of the disease. This treatment approach was found to be better than waiting until ROP has reached the traditional treatment threshold.
Just as importantly, the study also established 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 ROP.
"As the regional referral center for ROP-related retinal detachments, we see many unfortunate children with vision loss from ROP despite appropriate treatment," said Emory Eye Center pediatric ophthalmologist Amy Hutchinson, who while on the faculty at Medical University of South Carolina in Charleston participated in the ETROP study. "We are hopeful that these new treatment recommendations will result in fewer retinal detachments and better vision and quality of life for these high-risk babies."
As part of the ETROP study, a new computerized risk model, developed by NEI-supported researchers, was used to identify high-risk infants in the disease's early stage. The risk model incorporated birth weight, ethnicity, single-or multiple-birth babies, gestational age, ophthalmic exam findings, and whether the infant had been born in a hospital that participated in the study.
Once identified, the infants were assigned randomly either to treatment at the standard threshold (50 percent chance of retinal detachment) or to early treatment. Researchers found that early treatment significantly reduced the likelihood of poor vision from 19.5 to 14.5 percent at about 1 year of age. Early treatment also considerably reduced the likelihood of structural damage to the eye from 15.6 to 9.1 percent.
Current treatments for ROP involve laser therapy or cryotherapy. Laser therapy uses heat from light energy while cryotherapy uses freezing temperatures to retard blood vessel growth. A consequence of these treatments, known clinically as blood vessel ablation, is a partial loss of peripheral or side vision. Nonetheless, treatment is valuable in preserving the most important part of sight: the sharp, central vision needed to read, see faces or perform detailed tasks that require hand-eye coordination.
"Premature, low-birthweight infants face a host of medical complications with lifelong consequences," said Paul Sieving, director of the NEI. "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."