Premature birth carries the risk of multiple disabilities, including retinopathy of prematurity, or ROP. ROP affects the retina, the part of the eye that detects light before it is transformed in the brain to an image. ROP babies have poor vision, and in many cases, go blind.
In a study to be published online and in the March issue of Investigative Ophthalmology and Visual Science, Dr. Joseph Garcia, assistant professor of internal medicine at UT Southwestern, and colleagues, have identified a protein in mice called HIF-2a, which is important in retina formation. Controlling this protein, which is also found in humans, may help doctors treat or even prevent ROP before it happens.
Dr. Garcia examined the eyes of mice genetically engineered to lack the HIF-2a gene. These mice could not make HIF-2a protein and had multiple visual defects associated with blindness. They were blind by 1 month of age.
"These mice initially behaved as if they were blind," Dr. Garcia said. "And indeed, when we examined them, we found they had severe retinopathy."
Physiological studes using light, conducted by Dr. David Birch, collaborating scientist from the Retina Foundation of the Southwest and adjunct professor of ophthalmology at UT Southwestern, determined how their eyes were failing. Additional investigation of the mice lacking HIF-2a revealed extensive malformation of the blood vessels in their eyes, leading to ischemia, or reduced blood flow.
HIF-2a belongs to a class of proteins called transcription factors, which turn specific genes in the cell nucleus on in response to signals from the environment. Genes activated by HIF-2a create proteins that help the cell respond to noxious stimuli.