Memantine in the Glaucoma Treatment
By: Nina Mondoc, M.D.
Principal Investigator: Robert Ritch, MD
Co-investigator : Celso Tello, MD
Research Coordinator: Nina Mondoc, MD
Patients with certain types of glaucoma are at risk of progression - worsening of the disease and despite good control of the pressure in their eyes some patients' glaucoma would continue to progress - worsen. It has been suggested that the sight of patients with glaucoma may be protected in another way.
A compound called memantine (taken orally as tablets) may be able to delay sight loss in patients with glaucoma. This study is to show whether memantine is safe and effective in protecting nerve cells in the eye from damage that leads to sight loss in glaucoma patients. From the outset we stress that throughout the study, in addition to taking the study medication, glaucoma would be managed according to normal clinical practice.
How does memantine work?
Memantine appears to protect the nerve cells against glutamate, a messenger chemical released in excess amounts by cells damaged by certain neurological disorders. When glutamate binds to N-methyl-D-aspartate (NMDA) receptors, this attachment permits calcium to flow freely into the cell. Sustained elevation of glutamate leads to chronic overexposure to calcium, which in turn leads to cell degeneration. Memantine may prevent this destructive sequence by filling the NMDA receptor sites, by binding to the receptor molecule for glutamate on the cell surface. Without glutamate, calcium cannot enter the nerve cell. Therefore, the nerve cells are protected from too much calcium, which can be toxic to the cell. Memantine is able to accomplish this without interfering with the normal function of the cell. This ability to protect the cell from calcium and still allow normal cell function gives memantine an advantage . So, it would seem that memantine may block the chain reaction of events that leads to cell death.
Approximately 1050 patients with Open Angle Glaucoma were enrolled at 50 centers, on daily doses of placebo, 10 mg and 20 mg Memantine. They are followed every 3 months for 5 years, except the patients that showed progression , and who exit the study after 4 years.
Our center is the largest in the USA and the second in the world.
We hope this study will show whether memantine is safe and effective in protecting nerve cells in the eye from damage that leads to sight loss in glaucoma patients. If this is so, we may be able to preserve the RGC, the optic nerve, and one of our most important senses: sight.