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Early Treatment of Blinding Eye Disease in Infants Can Prevent Severe Vision Loss

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Duke Health News 919-660-1306

DURHAM, N.C. -- In a new study, eye researchers at locations
throughout the U.S., including Duke University Eye Center, have
demonstrated that premature infants at highest risk for severe
vision loss caused by retinopathy of prematurity (ROP) retain
better vision when treatment is administered at an earlier
stage of severe disease rather than at the previously accepted
threshold for treatment. By using an improved risk assessment
tool to more accurately identify which premature infants were
most likely to develop severe vision loss from the disease,
researchers were able to target treatment for babies who needed
it and avoid treating those whose cases may resolve on their
own.

ROP is a potentially blinding eye disease that affects
premature, low birth weight infants. The disease is among the
most common causes of vision loss in childhood and can lead to
lifelong vision impairment and blindness. ROP spurs the growth
of abnormal blood vessels, which leak fluid and blood in the
back of the eye leading to retinal scarring and increasing the
risk of retinal detachment. Retinal detachment is the main
cause of visual impairment and blindness in ROP.

"For years, many of us who screen and treat premature
infants with ROP have suspected that earlier laser treatment
for the more aggressive cases of the disease might improve the
visual outcomes of some of these very tiny infants," said
Sharon Freedman, M.D., a pediatric ophthalmologist at the Duke
Eye Center and lead investigator at this site. "These study
results suggest that we can feel more comfortable that we're
providing timely treatment in high risk cases and feel
justified in watchful waiting of those babies with ROP who are
not at high risk for severe visual loss."

The findings of the Early Treatment for Retinopathy of
Prematurity (ETROP) study appear in the December 2003 issue of
the Archives of
Ophthalmology
.

Treatments for ROP include laser therapy, which uses heat
from light energy, or cryotherapy, which uses freezing
temperatures, to retard the growth of blood vessels in the eye.
One consequence of these treatments, called blood vessel
ablation, is a partial loss of peripheral or side vision.
However, treatment is valuable to preserve the most important
part of the visual field -- the sharp, central vision needed to
read, see faces or perform detailed tasks that require hand-eye
coordination, the researchers said.

A total of 401 infants were enrolled at 26 study locations
throughout the U.S. Once identified, the infants were assigned
randomly either to treatment at the standard threshold or to
early treatment. The standard treatment threshold for ROP
depends on the disease having progressed enough that the risk
of retinal detachment approaches 50 percent.

Researchers found that early treatment significantly reduced
the likelihood of poor vision from 19.5 percent 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 percent to 9.1 percent.

As part of the ETROP study, the researchers used a new
computerized risk model to identify high-risk infants at
earlier stages of the disease. The risk model assessed birth
weight, ethnicity, being a single or multiple birth baby,
gestational age, ophthalmic exam findings and whether the
infant had been born in a hospital that participated in the
study.

Because the course of ROP is often unpredictable, treatment
decisions can be difficult for physicians to make, said
Freedman. In many cases ROP regresses spontaneously, sparing an
infant's vision. In other cases, however, ROP progresses and
results in serious visual impairment. Although current therapy
can stem its progression, many infants are still blinded by the
disease. Due to a lack of clinical criteria that can accurately
predict which patients will ultimately develop severe vision
loss from ROP, ophthalmologists have been forced to defer
treatment until treatment was clearly indicated. Delaying
therapy, however, can leave infants who might benefit from
early treatment with poor visual outcomes, said Freedman.

ROP affects approximately 14,000 to 16,000 infants annually
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 ROP severe enough to
require treatment. Despite available treatments, about 400 to
600 infants with ROP still become legally blind each year.
Infants with birth weights of 2.75 pounds (1,250 grams) or less
are at major risk for developing ROP, the researchers say.

The ETROP study will continue to follow these infants until
age 6 to ensure that the benefits of early treatment persist
into childhood, said Freedman. "By following the babies who
received treatment through the study until they reach 6 years
of age, we'll be better able to judge the longer term
beneficial effect of the treatment. Alternatively, we'll also
be able to see if there have been any detrimental effects," she
added.

The study was funded by the National Eye Institute (NEI) of
the National Institutes of Health. The NEI conducts and
supports research that leads to sight-saving treatments and
plays a key role in reducing visual impairment and blindness.
The NEI is part of the National Institutes of Health (NIH), an
agency of the U.S. Department of Health and Human Services.

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