Eye structure, muscles help brain manage eye functions

ST. LOUIS — Understanding how eye movement is controlled may help ophthalmologists better diagnose and treat disorders such as strabismus, an animal study suggests.

Researchers at Washington University in St. Louis School of Medicine conducted two sets of tests in primates. In the first test, the primates tracked a moving target by moving only their eyes; in the second, the bodies or heads of the primates rotated while the eyes remained fixed. In both sets, the researchers electrically measured the activity of oculomotor neurons as well as the vertical, horizontal and torsional eye movements.

The neurons “changed their firing activity” when head and body movement were involved, indicating the brain’s involvement in control of vestibule-ocular reflex, according to a press release from the university describing the study’s finding. In the test in which only the eyes moved, those same nerves did not “significantly change their firing patterns,” indicating that some of the guidance for eye movement comes directly from the eye itself, the release said.

“It appears that the motor plant of the eye is equipped to solve the problem on its own, and then whenever you need to step in and override that process, the brain has a way to take over,” said one of the study’s authors, Dora Angelaki, PhD, in the press release. Understanding how that ability is naturally engineered into the motor plant of the eye will have implications for clinical applications because “every time a surgeon manipulates the muscles around the eye it might interfere with these abilities,” she said.