In an effort to detect and prevent glaucoma-associated blindness, scientists say they’ve developed a test that can pick up glaucoma up to four years earlier than conventional methods. With more clinical trials being planned, researchers hope the diagnostic test will prevent, or at least slow down, vision loss associated with glaucoma worldwide.
"Glaucoma is one of the leading causes of irreversible blindness in the world, and in the early stages patients usually have no symptoms and are not aware they are developing permanent vision loss," said Michael Kalloniatis, Director of the University of New South Wales (UNSW) Center for Eye Health, and co-designer of the new visual test.
Commonly, glaucoma results when the eye’s fluid pressure builds up, which causes damage to the optic nerve that’s located at the back of the eye. The change usually happens gradually and without pain, so many people who have glaucoma symptoms may not be aware that their vision is at risk. As such, glaucoma often described as a disease that steals vision without warning. In the United States alone, the Glaucoma Research Foundation estimates over 3 million Americans have glaucoma.
"The cause of the disease is unknown and there is no cure, but its progression can be slowed with eye drops or surgery to lower pressure in the eye. So, early detection and early treatment is vital for prolonging sight," said Kalloniatis.
The new glaucoma test is a computerized system that analyzes a patient’s visual field. Patients are asked to look at many dots of light that vary in size and brightness. The inability to see certain dots indicates blind spots in the eye and a potential loss of peripheral vision, which is mainly affected by glaucoma.
Traditional methods to assess glaucoma risks often rely on physical measurements of the eye. This includes assessing the intraocular pressure, the optic nerve, and other exams of the eye itself. However, because glaucoma symptoms are gradual, these types of tests are not sensitive enough to pick up glaucoma before the condition worsens. Furthermore, because eye pressure may change throughout the day, these types of measurements can be unreliable.
Aside from the physical eye exams, doctors also use a visual field test (called the Visual Field Analyzer), but the researchers criticized this test for its limitations. "The current method of visual field testing, which uses just one dot size, is good but not ideal. Our test appears to be much more sensitive at detecting disease in an early stage. On average, we expect we will be able to detect glaucoma four years earlier than at present," said Kalloniatis.
In comparing the new visual test to standard methods in 13 patients, the team reported their test was superior at detecting vision loss. They are ramping up to include up to 30 more patients in the next clinical trial. In the meantime, Kalloniatis and co-author Siu Khuu, have patented their system in the US and the European Union.
"We hope our new approach will eventually be introduced around the world, and treatment can begin earlier to slow down vision loss in glaucoma," said Kalloniatis.
Additional source: University of New South Wales, Bel Mara Health