(RxWiki News) When most people think of glaucoma, they think "eye disease." However, doctors are rethinking that categorization, instead suggesting the disorder may be brain-related.
The disease, which can lead to blindness, instead appears to be a neurologic disorder that causes nerve cells in the brain to deteriorate and die, much like Parkinson's disease.
Dr. Jeffrey L Goldberg, an assistant professor of ophthalmology at the Bascom Palmer Eye Institute and Interdisciplinary Stem Cell Institute, noted that as attention has been turned toward the mechanisms that cause the retinal cells to degenerate and die, new methods are being discovered to protect and even regenerate these cells.
He said that understanding how to prevent damage and improve healthy function can lead to treatments that can save the sight of patients with glaucoma and other degenerative eye diseases.
Doctors have long relied upon measuring intraocular pressure, or the pressure inside the eye, in treating glaucoma. A prevailing theory had suggested that abnormally high pressure caused vision loss in patients with glaucoma.
Today, that measurement is still used to determine a patient's care, but it is no longer the sole measurement used to determine whether treatments are working.
Researchers note that doctors began looking beyond eye pressure measurements when surgery and medication designed to lower the pressure did not aid all patients.
Dr. Goldberg and his colleagues wrote that this prompted a shift in studying glaucoma. Investigators are now instead examining damage that occurs in a type of nerve cell called retinal ganglion cells (RGCs), which are integral to the ability to see. The cells connect the eye to the brain through the optic nerve.
Numerous glaucoma treatments have entered clinical trials as a result of this line of thinking, including drugs injected into the eye to increase survival and growth factors to RGCs. Electrical stimulation of RGCs through electrodes in contact lenses are being examined in another clinical trial, and stem cell therapy trials are currently being planned in humans. Some of these treatments could possibly not only maintain sight, but also reverse previous vision loss.
"There is no doubt that glaucoma is a degenerative neurologic disease with primary manifestation in the eye," said Dr. Christopher Quinn, an optometrist with Omni Eye Associates.
"The question for researchers is to determine the primary site of the pathology. Is there something in the eye that triggers the neurologic degeneration or is the origin on the degenerative process in the brain? In either case, treatments directed at preventing degeneration of the retinal ganglion cells hold promise for the millions of patients who have glaucoma and may represent a paradigm shift over current treatments which work to lower eye pressure alone."
The research was recently published in Ophthalmology, the journal of the American Academy of Ophthalmology.