Insight into preemies’ blindness

About 5 percent of premature babies suffer vision losses, including blindness, due to a condition known as retinopathy of prematurity. The damage occurs when excessive growth of blood vessels and other tissue pulls the newborn’s retinas away from the walls of their eyes. Now, researchers have linked the condition to low concentrations of a substance called insulin-like growth factor 1 (IGF-1).

Previous research established that IGF-1 concentrations are higher in full-term babies than in preemies, says Lois E. H. Smith of Harvard Medical School in Boston. She and her colleagues also knew that IGF-1 is crucial for the survival of cells that make up blood vessels. So, they looked at the effect of various concentration of IGF-1 and found that the concentrations associated with premature birth aren’t high enough to ensure survival of blood vessel cells in laboratory cultures.

To see if these lab results reflect a link between IGF-1 and retinopathy, Smith and her colleagues at the Queen Silvia Children’s Hospital in Göteborg, Sweden, measured IGF-1 concentrations in the blood of 41 infants born 5 to 12 weeks premature. In babies of the same gestational age, those with the lower IGF-1 concentrations were more likely to develop retinopathy.

“Measurement of this growth factor might help researchers predict which premature infants are most at risk of developing the disease,” Smith says. “Ultimately, replacing IGF-1 might allow doctors to prevent this tragic complication.”

“This is potentially a good way to treat a serious problem of thousands and thousands of infants,” said Ross Clark of the University of Auckland in New Zealand. He noted that IGF-1 might have beneficial side effects since it’s involved in the normal growth of the lungs and gut, which often remain underdeveloped in preemies.

Enticing as IGF-1 treatment sounds, Clark cautions that preemies are so small that it may be hard to monitor the growth factor’s concentration in blood. Says Clark: “Treating premature infants with drugs raises serious concerns.”