Dr. Whitaker’s intervention prescribes training in three specific activities. The first—reaching for and grasping objects—is covered by one or more hour-long sessions with an occupational therapist.
“Both the speed and accuracy of the grasp is negatively affected by loss of binocular vision,” Dr. Whitaker said. "For example, they will grab for something and not get it on the first try, or they will be pouring coffee or tea and miss the cup."
Rice learned to remedy this by wrapping one hand around the cup while she pours with the other hand. Adding the nonvisual signal (from the sense of touch) helps the brain judge the distance and location more accurately, Dr. Whitaker said.
Adults who lose vision in one eye also have more collisions when walking, especially on the side where they lost the vision. That’s where sessions with an orientation and mobility specialist can help.
“The emphasis is on helping people to judge distances by using monocular clues, such as something called motion parallax. If you’ve ever seen a cat moving its head or eyes side to side before it jumps, that’s motion parallax,” Dr. Whitaker said.
“You can train a person to do this by using more side-to-side head movements.” Rice said that, to avoid bumping into people in crowded stores, for example, she’s learning to stop and check her right side before she moves.
The final part of the intervention is learning new techniques for driving safely with vision in only one eye. “The loss of depth perception means that people have a hard time judging their vehicle’s distance from another car, or whether their car can fit into a parking space,” Dr. Whitaker said.
“We can train people to turn their head more toward the non-seeing eye, and some driving instructors may recommend special interior or exterior mirrors that can help improve field of vision as well.”