Blind World

Doctor's eye implant may combat blindness.

April 11, 2002.

By Curtis Tate, Kentucky Kernel
University Wire.

Lexington, Ky.

University of Kentucky researchers are testing a combination of drug and laser therapies to treat eye diseases that strike AIDS patients, diabetics and the elderly, often causing loss of vision.

Jayakrishna Ambati, a retina surgeon in the UK Opthalmology Department, is testing these treatments on patients suffering from macular degeneration, the leading cause of blindness among the elderly.

"It is a public epidemic," Ambati said. Macular degeneration affects the back part of the eye, or retina, which is comparable to film in a camera, he said.

In macular degeneration, blood vessels under the retina swell, causing distorted vision. These vessels can potentially leak blood into the central part of the eye, leading to partial blindness.

Ambati said the cause of macular degeneration is not known. It cannot be stopped, but treatments may slow its progression.

"It was not previously thought of this way, but the research is convincing," he said.

The treatment involves inserting into the eyes of patients a small implant containing an anti-inflammatory drug, which reduces swelling in the affected blood vessels. A laser therapy is then employed to seal leaking blood vessels.

However, Ambati said only the laser component of this treatment is FDA-approved; the drug treatment is not. He said approval might come in two to three years, "if things go as planned."

Paul Ashton, president and CEO of Control Delivery Systems in Boston, spent five years in UK's Opthalmology and Pharmacy programs researching these treatments.

Ashton developed Vitrasert, a drug-releasing eye implant used to treat CMV retinitis, an AIDS-related viral infection. The virus causes bleeding similar to macular degeneration and can cause blindness in late-stage AIDS patients.

Ashton said the drug injections available prior to Vitrasert were not very effective for treatment of CMV retinitis.

"The drugs either typically didn't work or had serious side effects," he said.

Because the Vitrasert implant is placed into the eye, it uses 20,000 times less of the same drug. This makes it safer and less likely to cause side effects, he said.

Ashton said he is conducting clinical trials using similar implants and a different drug to treat diabetic macular edemas. More than half of all diabetics will develop the condition.

Though more than 25 universities are participating in the trials, Ashton said the research "stems from work originally done at UK."

The therapy is in its final development stages, Ashton said. But he said FDA approval could take awhile.

"Drug testing takes a long time," he said.

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