Led by Lois E.H. Smith, of Children's Hospital in Boston and Harvard Medical School, the scientists demonstrated that a well-known hormone, called growth hormone (GH), caused retinal neovascularization, an abnormal growth of new blood vessels that can destroy sight. Furthermore, they found that blocking GH1s actions decreased the amount of neovascularization. The findings are reported in the June 13 issue of Science.
The results suggest that new treatment approaches that inhibit GH1s secretion or action could prevent neovascularization-related blindness. The current treatment for neovascularization consists of destroying the affected part of the retina, the light-sensitive tissue that lines the back of the eye, with laser or extreme cold. This treatment is only partially effective, and it results in additional vision loss.
Retinal neovascularization afflicts people of all ages. Age-related macular degeneration affects over 13 million Americans, while diabetic retinopathy affects 5 million and is the leading cause of blindness in people aged 20 to 74. Smith says, 3Over a long enough period of time, virtually every diabetic patient is at risk for this disease.2 In addition, premature infants who weigh 2.75 pounds or less at birth are at risk of developing retinopathy of prematurity.
Retinal neovascularization occurs when the retina is deprived of oxygen. New blood vessels grow into the retina to increase the amount of oxygen. These blood vessels can cause scarring and bleeding, leading to a detached retina and blindness.
In addition to Smith, the paper1s authors are John J. Kopchick, Wen Chen, and Joanne Knapp of Ohio University; Fumi Kinose, Douglas Daley, and Eliot Foley of Children1s Hospital and Harvard Medical School; and Roy G. Smith and James M. Schaeffer of Merck Research Laboratories.
The research was funded, in part, by the V. Kann Rasmussen Foundation and the National Eye Institute.