A review published in Ophthalmology, the journal of the American Academy of Ophthalmology is set to change the way the world looks at glaucoma, which is known as the ‘sneak thief of sight’. The researchers consider glaucoma as a neurologic disorder [such as Alzheimer’s and Parkinson’s] that results in brain cells to degenerate and die; and not just an eye disease.
Glaucoma is the most common cause of irreversible blindness worldwide. The prevailing theory hitherto was that in glaucoma patients, vision damage was caused by abnormally high pressure inside the eye, known as intraocular pressure [IOP].
As a result, lowering IOP was the only goal of those who developed surgical techniques and medications to treat glaucoma. Today, a patient’s IOP is no longer the only measurement an ophthalmologist uses to diagnose glaucoma, although it is still a key part of deciding how to care for the patient, as tracking changes in IOP over time informs the doctor whether the treatment plan is working.
However, vision loss continues in some glaucoma patients despite successful lowering of IOP through surgery or medication. Also, some patients find it difficult to use eye drops prescribed by their physicians. These significant shortcomings spurred researchers to look beyond IOP as a cause of glaucoma and focus of treatment.
The new research paradigm focuses on the damage that occurs in a type of nerve cell called retinal ganglion cells [RGCs], which are vital to the ability to see. These cells connect the eye to the brain through the optic nerve.
RGC- targeted glaucoma treatments now in clinical trials include: medications injected into the eye that deliver survival and growth factors to RGCs; medications known to be useful for stroke and Alzheimer’s, such as cytidine-5-diphosphocholine; and electrical stimulation of RGCs, delivered via tiny electrodes implanted in contact lenses or other external devices. Human trials of stem cell therapies are in the planning stages informs Jeffrey L Goldberg, M.D., Ph.D., assistant professor of ophthalmology at the Bascom Palmer Eye Institute and Interdisciplinary Stem Cell Institute, who leads the review.
“As researchers turn their attention to the mechanisms that cause retinal ganglion cells to degenerate and die, they are discovering ways to protect, enhance and even regenerate these vital cells,” said Dr. Goldberg. “Understanding how to prevent damage and improve healthy function in these neurons may ultimately lead to sight-saving treatments for glaucoma and other degenerative eye diseases,”
If this neurologically-based research succeeds, future glaucoma treatments may not only prevent glaucoma from stealing patients’ eyesight, but may actually restore vision. Scientists also hope that their in-depth exploration of RGCs will help them determine what factors, such as genetics, make some people more vulnerable to glaucoma.