Patients who have glaucoma or Retinitis Pigmentosa almost always lose much of their peripheral vision (being able to see out of the corner of the eyes to the sides while looking straight ahead). We use our peripheral vision for mobility and to find things. Limited peripheral vision can cause people to bump and collide into things while walking as well as tripping.
A way to think about limited peripheral vision is to imagine looking through a tube. The vision within the tube might be very good but the only way someone can see objects in their path when walking is to move their head left, down, right, up and center to cover all fields of vision. This action is conceptually simple but actually is a bit of a challenge to learn. It is unnatural for us to have to look in every direction when we walk.
Scanning is the technique we teach people who have limited peripheral vision better negotiate their environment. This technique involves practicing to learn to move someone’s head systematically to enable them to see items.
We teach patients an exercise, using a paper and pencil, to help them learn how to scan effectively. Our occupational therapist creates a sheet with many different letters printed at random on the page. The low vision patient now has to find all same letters (“A” for example) and circle them. Another way to practice is to have a friend or family member scatter items on a table or bed and have the low vision patient scan all directions to locate them all. To make it this exercise even more challenging, we scatter items on the floor in random places over several rooms.
These scanning techniques should be practiced repeatedly until they become more natural. When scanning is mastered, the risk of bumping into things and tripping is significantly reduced.
Thank you to Susan Gelfman, one of our occupational therapists, for this article.