NEI awards $2.8 million grant to Wright State psychologist for eye research

Scott N J Watamaniuk, PhD (Image courtesy of Wright State University)

The National Institute of Health’s National Eye Institute has awarded a $2.8 million grant to Scott N J Watamaniuk, PhD, a psychology professor at Wright State University, to research how the brain coordinates the movements of the two eyes.

According to a Wright State University news release, the study has potential implications for those who have strabismus.¹

In the release, Watamaniuk said a theory proposed by Ewald Hering in 1868 maintains that the brain sends a single command that moves the eyes. From the ophthalmologist’s perspective, while it is believed that the brain controls the movement of each eye simultaneously, if one eye is moving correctly but the other is not, the signal from the brain is working and there must be another issue with the other eye.

The university noted that mild cases of strabismus are treated by putting a patch over the eye that is functioning correctly to tone up the muscles of the misaligned eye so that it works properly. For some patients this corrects the problem, but for others that slight deviation gets progressively worse over time. In more severe cases surgery is used as a corrective measure.

Watamaniuk pointed out that with a prevailing theory that the signals from the brain to both eyes are the same, it is believed that muscles controlling the eye are imbalanced.

“Surgical treatment of strabismus involves snipping muscle fibers to weaken them,” he said in the news release. “Unfortunately, while initially successful, in 40 percent of these operations the eye goes back to where it was within six to 12 months.”

Surgeons frequently perform the procedure on children before the age of 6 to allow the visual part of the brain to develop properly, according to the news release. Should the procedure be performed too late, stereopsis will not develop normally.

“There are about a million of these surgeries a year. So, that means for 400,000 of them, it won’t work,” Watamaniuk said in the news release.

The issue led to talks between Watamaniuk and a pediatric ophthalmologist colleague of his from the Smith-Kettlewell Eye Research Institute, an independent, nonprofit research institute known for its research on vision, eye diseases and sensory rehabilitation engineering.

There was a competing theory to Hering’s position, put forth in 1867 by Hermann von Helmholtz that stated the movement of each eye was controlled by the brain independently. In these instances, strabismus likely isn’t caused by a defect of the eye.

Watamaniuk pointed out in the news release that most people measure eye movements based on following an object on a screen, which doesn’t have any depth information.

“Our experiment, which was published in 2021, had people follow a real object set up on a track that moved back and forth directly in line with the middle of the subject’s eyes and while the movement of both eyes was recorded,” he said in the news release.

The researchers noted that the same movement would then be recorded while one eye was covered with an infrared pass filter. It was noted that participants in the study could not see through the filter, but the eye trackers, using infrared light, could still track the eyes and record what they were doing.

Watamaniuk pointed out that when researchers did that, the covered eye did not move as it should, or at least did not move as it had been moving, and clearly did not move the way that Hering’s theory said it should.

“The covered eye was behind in time by up to two seconds,” he said in the university’s news release. “Its movements were not syncing. You cannot have one signal from the brain coming to both eyes and have a two-second delay.”

According to the news release, the information raises several questions that Watamaniuk said in the news release he hopes to answer through additional research. If he can prove he is right about disproving Hering’s theory, it will be important to detail why the surgery is effective in 60% of strabismus patients and what can be done for the others.

Watamaniuk said that for those patients for which surgery is successful, the problem of strabismus may occur in the brain stem where things happen somewhat reflexively. There are centers there that are responsible for controlling eye movements, but they do not get a lot of feedback from higher centers in the brain.

Researchers noted the prefrontal lobe of the brain controls eye movement and is responsible for higher-level functions and will take in data from the way the eye functions.

“The brain stem doesn’t care if you have done something to the eye, like correcting alignment through surgery. It just executes the command,” Watamaniuk explained in the university’s news release. “The prefrontal lobe gets used to certain data.”

Watamaniuk explained that if it is used to feedback from the eye that says it works a certain way, it will try and “correct” the eyes’ alignment after surgery.

“One question we are trying to answer is what type of diagnostics can we come up with to tell in which part of the brain the problem exists,” he concluded in the release.

Reference:

1. Erica Harrah. Wright State psychologist receives $2.8 million grant for eye research. Wright State University. Published August 22, 2023.