Prof Michele Rucci with study equipment.

Researchers from Rochester University in New York have discovered that small eye movements we’re not even aware of, can have a large effect on our visual acuity (VA).

Previously, it was assumed a person’s VA was primarily determined by the optics of their eye and the anatomy of the retina, but this new research, published in Nature Communications, may lead to improved treatments and therapies for vision impairments, said Professor Michele Rucci and Janis Intoy, a neuroscience graduate student from Boston University working in Prof Rucci’s lab.

“Humans are normally not aware that their eyes are always in motion, even when attempting to maintain a steady gaze on a point,” said Intoy. These gaze shifts, known as fixational eye movements, were once thought to be inconsequential because they are so small. But they are large on a microscopic level, relative to the size of cells in the retina, and shift an image across many receptors, which is critical to visual system processes and to help us reconstruct scenes, she said.

“We found that achieving 20/20 vision is not only the outcome of good optics and a healthy retina but also fine motor control, to a level that eludes awareness… a factor that is presently not monitored at all,” said Prof Rucci.