Living better with poor vision

Taking a brisk walk is tough to do when you can’t see well. Still, some people with limited vision clip along quite well, and researchers at Johns Hopkins are trying to understand why some with poor vision fare better than others and which of their lessons can be passed along.

The Johns Hopkins studies are part of the Salisbury Eye Evaluation Project (SEE) begun in 1993, when scientists at Johns Hopkins began gathering the vision and health data of roughly 3,000 elderly residents of Salisbury, MD. In the past, research has focused on common problems such as reading, face recognition, and sharpness of vision, measurements that can be taken from seated subjects.

But within the last five to 10 years, technology has improved the ability to measure vision in motion (through virtual environments, portable eye trackers, and faster computers), enabling SEE researchers to concentrate on a relatively new area: the effect that limited peripheral vision has on movement.

What the studies make clear is that vision alone does not determine how well one navigates a trail. In the studies those who were able to walk most quickly and efficiently used both external and internal cues to guide their walks. In other words, they were better able to create a mental map of the environment to augment their sense of where they were.

Lessons to share 

People can learn to compensate for poor peripheral vision by using nonvisual cues such as sounds, muscle responses, and body systems that let them know where they are in space. Those with compromised vision can learn to draw on internal maps of where they are, lessening dependence on visual cues. For instance, when you enter a room through one door, observing a chair on the right and a lamp on the left, and then enter the next time by another door, you can rotate the room in your mind, reorienting yourself to the new entrance.

Visual aids are available as well. In addition to the traditional white cane, there are now sonar devices that provide audible cues about what’s in the immediate environment. Image enhancers like the Low Vision Enhancement System developed by Johns Hopkins and NASA can enlarge images of surroundings. And at key locations like public restrooms in a number of cities in the United States and other countries, Talking Signs are now in use, transmitting voice messages about their location to small handheld boxes.

Perhaps the best news from the SEE studies is that with training and aids, poor vision doesn’t have to mean the end of travel, exercise, or independence.

(Source: Johns Hopkins: July 2009)