Blind World

Retinopathy of prematurity:
New hope to save prem babies' sight.

October 26, 2002.

Herald Sun(Melbourne).

AS PREMATURE babies fight for life, another battle is raging behind their tiny eyelids: an eye disease that blinds up to 2000 of these infants a year in the US.

Now scientists are exploring two promising new ways to save prem babies' sight: strictly maintaining their oxygen levels at a constant but slightly lower level than usual. This apparently slashed blindness at one major hospital. It gives the smallest babies an eye-important growth hormone they lack. Preventing the blinding disease -- called retinopathy of prematurity, or ROP -- is a major goal because once it hits there's no sure way to save vision. Today's best treatment, laser therapy, decreases the chance of blindness by only a quarter, and many babies who don't go blind still will never see well enough as adults to drive.

The smaller the prem baby, the bigger the risk of ROP. So with doctors saving more and more of the 40,000 prem babies born every year, new ways to battle the disease are crucial.

"It's devastating," Harvard Medical School's Dr Lois Smith says. She describes watching prem babies survive only to lose their sight. Smith, who discovered the growth-hormone connection, calls today's ROP treatment "medieval . . . but we just do what we can."

Very premature babies don't have properly formed blood vessels in the retina, the eye's innermost layer. Sudden exposure to oxygen as doctors try to save the babies is believed to cut off blood vessel formation. Blood-starved retinal tissue then sends out an urgent call for help that results in sudden growth of abnormal blood vessels, eventually causing vision-blocking retina scars and even detachment.

To cut off that abnormal growth, doctors use a laser to destroy part of the retina emitting the distress call. That destroys some working eye tissue in hopes of saving the rest, but it can't restore lost sight.

Preventing ROP would be far better. So hospitals strive for moderate oxygen levels and hope for the best.

Now two experiments point to possible new solutions:

CEDARS-Sinai Medical Centre in Los Angeles set prem baby oxygen levels about 10 per cent lower than normal for a healthy person.

The hospital's incidence of severe ROP dropped from 12.5 per cent in 1997 to a mere 3.7 per cent last year, without harming survival or increasing brain damage.

OXYGEN isn't the only player. Harvard's Smith discovered that another growth hormone called IGF-1 also is crucial. She studied 80 prem babies and found those with ROP had the lowest IGF-1 levels. Next year she hopes to begin testing to determine if giving premature infants doses of IGF-1 right after birth can protect them. Both experiments are generating cautious excitement.

For now, there's little advice to offer anxious parents except to be sure their prem baby is treated in a neonatal intensive care unit and is checked for ROP four to six weeks after birth, experts say.

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