UM School of Medicine doctors took part in national study published in Archives of Ophthalmology
Premature infants at risk for losing their vision may benefit from earlier laser therapy to treat retinopathy of prematurity (ROP), a blinding disease that affects premature, low birth weight babies. Researchers at the University of Maryland School of Medicine took part in a national clinical trial that has shown promising results for infants who were treated earlier.
"ROP is one of the most common causes of vision loss in children and can lead to lifelong vision impairment and blindness," says Ira Gewolb, M.D., professor of pediatrics at the University of Maryland School of Medicine and a neonatologist at the University of Maryland Medical Center. "The results of this new study show that beginning treatment sooner may improve the lives of thousands of children."
The clinical trial, called the Early Treatment for Retinopathy of Prematurity (ETROP) study, showed that early treatment significantly reduced the likelihood of poor vision from 19.5 percent to 14.5 percent at about one year of age. Early treatment also reduced the likelihood of structural damage to the eye from 15.6 percent to 9.1 percent.
According to Scott Steidl, M.D., an associate professor of ophthalmology at the University of Maryland School of Medicine and director of the Retina Service at the University of Maryland Medical Center, "ROP can progress quickly. The ETROP study shows that even a few days can make a difference."
The National Eye Institute (NEI), a part of the National Institutes of Health, sponsored the ETROP trial, which involved more than 400 children at 26 medical centers including the University of Maryland Hospital for Children. Archives of Ophthalmology published the results in the December 2003 issue.
"Premature, low birth weight babies face a host of medical complications with lifelong consequences. The results of this study allow us to improve the treatment of ROP and, hopefully, the quality of life for children who most need sight-saving therapy," says Paul A. Sieving, M.D., Ph.D., director of the NEI.
Each year ROP affects an estimated 14,00016,000 premature, low birth weight infants in the United States and thousands more worldwide. Of these cases, approximately 1,500 infants in the U.S. will develop severe ROP that requires treatment. Despite available treatment, about 400-600 infants with ROP still become legally blind each year.
Researchers identified birth weight of 2.75 pounds (1250 grams) or less as a major risk factor for developing ROP. These children are usually born before 31 weeks of gestation, while a full-term pregnancy runs 38-42 weeks. The smaller the baby, the greater the chance the child will develop ROP, which usually occurs in both eyes.
Infants' eyes develop rapidly during the last 12 weeks of pregnancy. When infants are born prematurely, normal blood vessel growth in the eye may stop. ROP occurs when abnormal blood vessels grow and spread throughout the retina, the tissue that lines the back of the eye. These abnormal blood vessels are fragile and can leak, scarring the retina and pulling it out of position. This causes a retinal detachment, the main cause of visual impairment and blindness in ROP.
Current treatments for ROP involve laser therapy or cryotherapy. Laser therapy uses heat from light energy while cryotherapy uses freezing temperatures to retard abnormal blood vessel growth. These treatments can lead to a partial loss of peripheral or side vision; however, they preserve the most important part of our sight, the sharp, central vision we need for straight-ahead activities such as reading, driving or seeing faces.
In many infants, ROP spontaneously regresses and their vision is unaffected. However, in other cases, ROP progresses, leading to serious visual impairment. Until the ETROP study, babies received laser or cryotherapy when they reached "threshold" ROP, a point at which without therapy about 50 percent would be expected to develop detached retinas. However, follow-up of infants who received laser or cryotherapy at that threshold showed that while retinal detachment could be prevented in many cases, visual acuity was often still poor. Preliminary data suggested that earlier treatment might be beneficial and provided the impetus for the national study.
"The results of the ETROP study also give us a new model to assess which infants are at higher risk for developing severe vision loss. By identifying these patients sooner, we can treat them sooner," explains Dr. Gewolb. "The new risk assessment model also allows us to identify children where watchful waiting and delaying treatment may be the best approach. So we now have a new standard to evaluate when the earlier invention would be most beneficial."
The researchers will follow these infants until age six to ensure that the benefits of early treatment continue through childhood.
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