TECHNOLOGY TO WATCH A BIOTECH CURE FOR A KIND OF BLINDNESS A drop of protein ''glue'' helps people with a rare, previously untreatable disorder regain the ability to read or drive a car.

(FORTUNE Magazine) – The human eye works much like a camera, with the light-absorbing retina that lines the interior wall serving as nature's instant photographic film. A pinhead-size point critical for sharp straight-ahead vision, called the macula (from the Latin for ''spot''), sits at the back of the eye, in the center of the retina.

As people age, shrinking can occur in the transparent, gelatinlike substance known as the vitreous humor, which fills most of the eye. If it contracts, it can tear away light-processing cells from the retina, creating a hole and lifting adjacent retinal tissue. Normally this merely limits peripheral vision. But if it takes place at the macula (see diagram), it blots out eyesight directly ahead. Onset can be quick and scary. One day last year, Lois ! H. Edwards of Little Neck, New York, was riding in a car with her husband, Barney. In a single, frightening moment, she lost most of her central vision: ''Suddenly, I couldn't make out the license plates of the cars in front of us, and I couldn't even see Barney's face -- just the outline of his head.'' Until recently, eye doctors could do nothing for people with macular holes. Edwards was lucky. Her ophthalmologist sent her to Bert M. Glaser, 42, an eye surgeon who directs the retina center at St. Joseph's Hospital in Towson, Maryland. Glaser began experiments on animals in the late 1980s to see if he could close macular holes with a natural protein that helps wounds heal. It's called transforming growth factor-beta2 -- TGF-beta2 for short. Glaser thought he could use it as a biological glue to fasten down the edges of macular holes, restoring vision. Celtrix Pharmaceuticals Inc., a small publicly held Silicon Valley biotech company, discovered TGF-beta2 and supplies him with it. Glaser and his colleagues have treated more than 200 people, with a 90% success rate. The operation consists of removing part of the vitreous humor and applying a drop of the growth factor with a hollow instrument called a cannula. It's the first use of a biotech product inside the eye. At the end of the operation, the surgeon introduces a bubble of air or gas into the eye to press the protein glue into place. Recovery is no lark: The patient has to remain facedown for four to six weeks while that bubble does its work. As with other invasive eye surgery, there is a risk of cataracts or infection. After having macular holes sealed in both eyes, Edwards developed cataracts -- but says having them removed was ''a piece of cake'' by comparison. Glaser is conducting a large study to see if the growth factor can help treat a much more widespread condition -- macular degeneration, in which cellular debris accumulates in the eyes. While macular holes affect perhaps 50,000 Americans a year, the National Eye Institute thinks macular degeneration is likely to become the No. 1 cause of deteriorating vision among the aging, affecting millions.