“Visual crowding” is a condition that prevents some people from seeing beyond the clutter –– or recognizing people’s faces, objects or single letters inside big words. It’s a common problem among people with lazy eye, patients with traumatic brain injuries, and those of us who need reading glasses.
Until now, it was believed that visual crowding was caused by a problem in the peripheral vision.
But in a new study published in Nature’s Scientific Reports, Prof. Uri Polat, Maria Lev and Dr. Oren Yehezkel of Tel Aviv University‘s Goldschleger Eye Research Institute have found that visual crowding can be traced to a different area in the eye –– the fovea.
The fovea is the sharp vision center in the retina. The way it is linked to the brain’s processor appears to have a strong influence on visual crowding.
“Current theories strongly stress that visual crowding does not exist in the fovea, that it’s a phenomenon that exists only in peripheral visual fields,” said Polat. “But our study points to another part of the eye altogether — the fovea — and contributes to a unified model for how the brain integrates visual information.”
The Tel Aviv University researchers showed that visual crowding can be linked from the retina to the brain’s processing speed. This makes them suspect that using novel training methods focused on the fovea could help people overcome their limitations and let them ditch the reading glasses altogether.
A visible difference
Polat says that vision is dynamic and it has the ability to adapt quickly to new things, yet it still takes a certain amount of time for the brain to process what it is seeing — whether news headlines streaming on the television screen, or an abundance of traffic signs along a fast-moving highway.
All of these are hard for anyone to read, but given enough time to see these fast-moving objects, usually a person with healthy vision can “get” the gist of the information.
But people with slower brain processing speeds — from poor perceptive development, or as a symptom of age — may not be able to “get” any of the signs or headlines. When Polat retrained the brain and the foveal part of the eye, he could measure improved vision in his test subjects.
He said: “Training adults to reduce foveal crowding leads to improved vision. A similar training we conducted two years ago allowed adults to eliminate their use of reading glasses altogether, using a technology provided by the GlassesOff company.
“Other patients who had lost sharp vision for whatever reason were also able to benefit from the same training and improve their processing speed and visual capabilities,” said Polat.
PhD candidate Lev conducted the study as part of her doctoral thesis and reported working with one young person who had visual impairment from foveal crowding. This condition prevented the subject from getting his driver’s license. But after undergoing training exercises that targeted working on the foveal rather than peripheral vision, he was able to overcome the problem.
“He finally managed to learn to read properly and found his way forward,” said Lev. “I’m proud to say that today he is not only eligible for a driver’s license, he’s also been able to earn his master’s degree.”
The team is now investigating just how their findings can be translated to new clinical studies and applications.