Glaucoma advanced imaging technology
Casey Researchers Take New Look at Glaucoma Using Advanced Imaging Technology
Called the “silent thief of sight,” glaucoma often has no warning signs or symptoms in its early stages. Because most people are unaware of the damage that first occurs to the peripheral or side vision, you may not be diagnosed with this common eye disease until it affects your central vision. By then, eyesight may be irreparably harmed.
However, a team of researchers at OHSU Casey Eye Institute are opening the curtain on this stealthy disease that can be a challenge to identify and follow over time. Using groundbreaking optical imaging techniques, the scientists are studying the eye’s blood flow to improve early detection and better understand how glaucoma develops. This technology, a high-speed version of optical coherence tomography (OCT), was pioneered by David Huang, M.D., Ph.D., Weeks Professor of Ophthalmic Research and professor of ophthalmology and biomedical engineering at OHSU. A novel feature is its ability to provide non-invasive, three-dimensional imaging of vascular tissues in the eye, said Dr. Huang, principal investigator of the NIH-funded “Functional & Structural OCT for Glaucoma” research grant at Casey.
Glaucoma is a group of diseases that damages the optic nerve in the back of the eye, which sends visual signals to the brain. “It is the second leading cause of blindness in the United States and the top cause of irreversible vision loss,” notes glaucoma specialist John Morrison, M.D., Kenneth C. Swan Professor of Ophthalmology and principal investigator of the clinical study at Casey.
With the most common type, open-angle glaucoma, injury to the optic nerve occurs slowly, causing progressive but gradual vision loss. It is often linked to increased eye pressure caused by a build-up of fluid in the front of the eye that does not drain properly. Treatment for open-angle glaucoma generally requires medication to lower the pressure inside the eye, but laser treatment, and in some cases, surgery may also be used.
Today, glaucoma is detected and monitored using a variety of methods, such as eye pressure checks, visual field tests and an eye examination to see if there are changes or injury to your optic nerve. But all have some limitations and may not pick up on the disease in its early stages or be applicable for every patient. “For example, although elevated eye pressure is a risk factor for glaucoma, many patients with the disease are actually in the normal range,” notes Dr. Huang. Imaging with standard OCT and other diagnostic tools are also used to visualize the optic nerve, but are unable to detect subtle changes over time.
The high-speed OCT at Casey not only produces more finely detailed images of the optic nerve, it can carefully measure and store them for future comparison. “That allows us to identify subtle changes more easily, such as whether a patient under treatment is stable,” notes Dr. Morrison.
The Casey researchers are venturing into new territory by using the investigational technology to study the relationship between blood flow in the eye and its effect on the optic nerve. According to Dr. Huang, evidence suggesting a connection between altered blood flow in the body and the development of glaucoma deserves further exploration. For example, high blood pressure, diabetes and other conditions causing poor blood circulation are considered risk factors for glaucoma. Low blood pressure at night may also worsen the disease. “A number of glaucoma patients who don’t have high eye pressure may have poor blood flow to the optic nerve,” says Dr. Morrison.
The ability to measure blood flow and changes in the optic nerve will provide crucial information that may help better predict a patient’s risk of progression and lead to new glaucoma treatments directed at improving blood circulation in the eye. “This experimental OCT provides us with more than a snap shot of the eye. It adds another layer of sensitivity and gives us insight into the mechanisms that may contribute to glaucoma,” says Dr. Morrison.
Are you at risk for glaucoma?
Anyone can develop glaucoma. Some people are at higher risk than others. They include the following:
- African Americans over age 40
- Everyone over age 60, especially Mexican Americans
- People with a family history of glaucoma
If you are at higher risk, make sure you get a comprehensive dilated eye exam every 1 to 2 years and encourage family members to do so as well. This exam may help save your sight because when glaucoma is detected early, it usually can be controlled through medications or surgery.
For additional information about glaucoma, visit www.nei.nih.gov/glaucoma .