Alzheimer's drug works on glaucoma

The Yomiuri Shimbun

A medicine designed for treating Alzheimer's patients has been found to work for treating glaucoma, according to a research group at Tokyo Medical and Dental University.

The finding may lead to preventing the loss of eyesight due to glaucoma. The report was to be carried in the online edition of U.S. magazine The Journal of Clinical Investigation on Friday.

Glaucoma is a disease of the optic nerve that gradually reduces vision and is the primary cause of eyesight loss in Japan. About 4 million people are said to suffer from the disease in the country.

There are two types of glaucoma. One is caused when intraocular pressure increases, and the other occurs even when intraocular pressure is normal. The latter type accounts for 70 percent of Japanese glaucoma cases.

The study group led by Prof. Koichi Tanaka focused its attention on the observation that the optic nerve of mice were damaged when glutamic acid--a type of amino acid that transmits light information to the optic nerve--accumulated on their retinas. Normal mouse eyes have a function that removes excessive glutamic acid. When the researchers suppressed the function, the mice suffered glaucoma.

The scientists administered a shot once a day of Memantin, an Alzheimer's drug approved in the United States and Europe, for a week and compared the results against mice with glaucoma that did not receive the shots.

The mice with glaucoma that did not receive the shots lost 20 percent of their optic nerve cells, while the mice that received shots lost only 3 percent.

The cause for the second type, or normal tension glaucoma, is still unknown, but doctors usually prescribe eye-drops that lower intraocular pressure.