Johns Hopkins reports on new drugs for fighting glaucoma.
Physicians have recently confirmed through large clinical studies that lowering intraocular pressure (IOP) is highly beneficial in reducing vision loss in people with glaucoma. Indeed, the lowering of IOP is the only FDA-approved approach for treating glaucoma. However, newer approaches to the treatment of glaucoma are being studied to supplement present therapy in order to reduce the progressive loss of vision in glaucoma even further.
Glaucoma researchers are investigating a number of ways to intervene in this process. Overall, their area of research is known as neuroprotection -- protecting the retinal ganglion cell from damage. Retinal ganglion cells are responsible for visual signaling from the eye to target areas in the brain, and their death is the hallmark of glaucoma. The hope of neuroprotection research is that this retinal ganglion cell loss can be slowed, or even stopped altogether.
A number of neuroprotection strategies are under investigation. Some use drugs originally developed for other conditions, such as multiple sclerosis. Some of the most promising are as follows:
- Memantine (Namenda). This drug is FDA-approved for treating Alzheimer’s disease. It is taken orally and appears to protect brain cells from the damaging effects of high levels of glutamate, an amino acid. A large study of memantine in more than 2,000 people with glaucoma is currently under way; the study is expected to end next year.
- Brimonidine (Alphagan). This medication is currently used in eye drop form to treat glaucoma by lowering IOP. In animal studies, oral and injected forms of bromonidine show promise as having a protective effect on the optic nerves and the retinal ganglion cells. In people, brimonidine is being tested and compared with another glaucoma drug, timolol (Timoptic) in 190 people with normal-tension glaucoma (people with IOP readings in the normal range whose glaucoma is worsening). The goal of the study is to see whether there is any difference between the two drugs in terms of visual field stability or deterioration. It is important to note that the use of brimonidine eye drops as a neuroprotectant has no definitive evidence in humans.
- Glatiramer (Copaxone). This drug, normally used to treat multiple sclerosis, may protect the optic nerve by triggering a mild autoimmune response. Glaucoma researchers theorize that the autoimmune response is one way the body protects itself from injury to nerve cells. By using glatiramer, researchers hope to boost the autoimmune response to the initial damage and prevent any additional damage.
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