By comparing a group of 32 elderly people with healthy vision to 44 patients with a clinical diagnosis of glaucoma, researchers found that they were able to identify glaucoma by interpreting maps of people's eye movements while they watched a TV show or a movie. The study — "What's on TV? Detecting age-related neurodegenerative eye disease using eye movement scanpaths"— appears in Frontiers in Aging Neuroscience, an open-access academic publisher and research network.
"Your eye movements are one of the fastest movements that your body makes," said David Crabb, the study's lead author and a professor at City University of London. "By tracking eye movements for just a few minutes, we end up with a picture that looks like a bunch of dots connected by lines. And within that picture, we've been able to find a signature, a fingerprint really, for how someone uses their eyes."
What sort of programming did subjects watch? The 2006 British film "History Boys" and "Dad's Army," a popular BBC sitcom from the 1970s, Crabb said.
Glaucoma is not curable, and vision lost cannot be regained, but medication and surgery can halt further vision loss, according to the Glaucoma Research Foundation.
As it turns out, Crabb explained, people with glaucoma use their eyes differently than people with healthy vision, often in a way that compensates for vision and effects their peripheral vision first. It's these subtle compensatory movements, unraveled using computer models, that allow researchers to determine whether someone is suffering from a disease like glaucoma.
Both of the groups studied also underwent standard vision examinations, and disease severity was measured for the group with clinical glaucoma diagnoses, according to researchers.
"You get thousands of these data points after only a few minutes," Crabb said, "and if you look at those points with the human eye it looks like a huge mess."
Researchers suspected there might be patterns in the "mess," but they couldn't be sure until computer programs normally used in biomathematics allowed them to "untangle the patterns in the scramble."
"It was quite thrilling," Crabb noted.
Glaucoma is irreversible, and what makes it particularly dangerous, according to the study, is that vision loss can occur subtly at first. As the disease worsens, the eye's ability to compensate erodes, leading to noticeable sight loss and, in some cases, blindness. Crabb said tracking people's eye movements by having them watch a film could improve early detection and monitoring of glaucoma; he noted that patients frequently complain about having to go into a clinic for periodic testing.
The Glaucoma Research Foundation estimates that more than 2.2 million Americans have glaucoma, but only about half know they have the condition.
"Technology that identifies where someone is looking has improved dramatically in the last five years," Crabb said. "This technology is very much being driven by people developing phones and tablets, and we think it's going to be more affordable and accurate over time, and you might be able to do your eye testing at home at some point."
The study was funded by the U.K. charity Fight for Sight.