Glaucoma device developed at Duke

A doctor gains an advantage over an aggressive disease that afflicts 6 million

For eight years Sandra Naylor went to one eye doctor after another, but none could explain why, exactly, her vision was blurry.

It wasn't until she was referred to Dr. Sanjay Asrani, a Duke University glaucoma specialist, that Naylor learned she had an unusual form of glaucoma -- one that could cause her suddenly to lose part of her eyesight.

Not so long ago, Asrani wouldn't have been able to diagnose her, either.

But now, because of his curiosity and the skills of a colleague, he has a one-of-a-kind instrument that can catch an aggressive type of glaucoma that affects an estimated 6 million people worldwide and is on the rise.

So far Asrani has studied the instrument's capabilities on 63 patients. His results, published recently in the Archives of Ophthalmology, a peer-reviewed medical journal, have glaucoma experts excited.

"It has tremendous potential," said Dr. Andrew Iwach, executive director of the Glaucoma Center in San Francisco. "Anything that can lead to early detection can be a huge asset."

Studies show that early detection of glaucoma is the key to preventing vision loss. The disease is caused by a build-up of fluid. As a result, the pressure inside the eye increases and can irreparably damage the optic nerve.

Ophthalmologists rely on eye exams and diagnostic instruments to stop glaucoma. But what works reasonably well with most types of the disease isn't much help with narrow-angle glaucoma, Naylor's condition. Narrow-angle glaucoma can lead to sudden blockages and painful attacks. It accounts for about 10 percent of all types of glaucoma, but is three times as likely to lead to blindness.

To prevent an attack, most instruments offer clues at best, said Tom Brunner, a biomedical engineer and the chief executive of the Glaucoma Research Foundation, a San Francisco nonprofit.

"You can't examine the angle," Brunner said. "The optics of the eye won't let you see in there."

Asrani's instrument changes that. Five years ago, he went to Joseph Izatt, a Duke engineering professor and frequent collaborator, with the problem: how to see inside the eye, where the iris meets the cornea. Izatt led him to a graduate student, and the two spent the next three years adapting new and existing technology to meet their needs. By 2006, they had come up with an instrument that, similar to a video camera, produces detailed, digital black-and-white images of that part of the eye.

A Duke spinoff

So far, Asrani is the only doctor to use the instrument, which the Food and Drug Administration has not yet approved. A smaller, portable version is under development at Bioptigen, a Research Triangle Park company that commercializes medical diagnostic devices invented in Izatt's laboratory. Izatt is a co-founder of the company, which is a spin-off of Duke University. If the instrument receives FDA approval, the technology could come to market in about two years.

It could also be used to detect other eye problems, such as cysts, and guide eye surgeons in the operating room. But for now, preventing vision loss in people predisposed to narrow-angle glaucoma is its primary purpose.

"If you catch it early enough, the patient doesn't get a glaucoma attack," Asrani said.

Naylor, a retired court reporter who lives in Raleigh, said the ophthalmologists she saw could never agree on what was wrong with her eyes. A specialist in Mississippi recommended glaucoma surgery in March 2007. Two months later, another in California advised against the surgery.

After examining Naylor's eyes, Asrani urged her to have laser surgery in both eyes to prevent a glaucoma attack. The surgery will create tiny openings in her irises from which built-up fluid can drain.

Asrani was able to make the diagnosis because his instrument made the inside of Naylor's eyes visible in wide slices nearly a quarter-inch deep.

Magnified on the computer screen, the image of one of Naylor's eyes showed her iris, the colored ring around the pupil, and the cornea, the protective, transparent cover of the eye.

The cornea and the iris usually meet in an angle open enough that the two won't touch. But in Naylor's case, the angle was so narrow, parts of the iris were sticking to the cornea. Asrani pointed to these areas and explained that they could lead to a blockage and trigger an attack.

Looking at the screen and comparing images of her eye to those of a normal eye, Naylor could see what was causing her troubles.

"Now it's clear," she said.