In a discovery almost biblical in scope, scientists from the University of Utah have been able to make blind mice see again, says a paper published yesterday in the journal Nature Medicine.

Mice afflicted with both macular degeneration and diabetic retinopathy -- two of the most common age-related forms of blindness in humans -- were cured when researchers turned on a natural protein brake in their bodies that stopped the haywire blood vessel growth causing their eye ailments.

Dr. Dean Li, a professor of medicine at the Salt Lake City school and the senior study author, says most forms of degenerative blindness are caused by erratic blood vessel growth on the retina of the eye.

Li says macular degeneration, which gradually destroys central vision, and diabetic retinopathy, which can bring on total blindness, are both fundamentally blood vessel diseases.

"There's too many blood vessels and the blood vessels are leaky."

Until now, however, most researchers have concentrated on finding and targeting the substances in the body that cause the erratic blood vessel growth in the first place, Li says.

"All this paper is saying is that not only is there an accelerator in your car, there's actually a brake in your car."

In this case, Li says, the brake is a protein known by the sci-fi sounding name of Robo4.A01

Using a naturally produced enzyme known as Slit, Li's team reactivated the Robo4 brake, which had been overwhelmed by the uncontrolled vessel growth.

Keith Gordon, head of research with the Canadian National Institute for the Blind, said the research was "exciting" and could be a potent new addition to the drugs now used to treat macular degeneration.