by Dan Roberts
Retinal diseases are not, in themselves, painful. Prolonged ultra-close viewing, however, is often practiced by people with visual impairment. That can cause headaches of the type reported by some members of our low vision community. Generally referred to as eye strain, such discomfort may be caused by stress on the large medial rectus muscles that control the side-to-side movement of our eyeballs.
When those muscles are relaxed, both eyes are gazing straight ahead into the distance, something that doesn’t work when trying to clearly view a near object or text. As an object draws near, our eyes gradually converge to keep us from experiencing diplopia (seeing double). The closer the object, the more our eyes converge, until they either cross or simply give up when the object gets within about 5 inches of our noses. Test this by holding up your index finger and trying to stay focused on it as you move it toward your face.
The medial rectus muscles are attached to the exterior sides of the eyeballs. If those muscles are strained, we can acquire a headache as a warning that we’re overdoing it. The most obvious solution is to avoid the necessity of ultra-close viewing by maximizing lighting and by magnifying or enlarging the task at hand. A visually impaired person, though, sometimes needs to use ultra-close viewing under less than optimum conditions. So what other accommodations can help to avoid the discomfort?
1. Use corrective lenses adjusted to your best focal distance for a specific task.
2. Close one eye to eliminate the need for convergence.
3. Keep the task in the center of your gaze, which allows your eyeballs’ exterior muscles to relax.
4. Strive for the best balance between focus and convergence. By way of explanation, focusing is done by each eyeball individually using its own internal muscles and does not involve the exterior muscles. Convergence, on the other hand, requires the exterior muscles, and a headache can occur when they are overworked.
The best distance is a point at which the least convergence is required and the best focus is achieved. To help avoid a headache, maximize the distance between your eyes and the task, even if you have to sacrifice a little focus.
Headaches seem to be most common in early disease states in which both eyes still retain some functional vision. If that describes you, and you are experiencing headaches, consider the above suggestions. At the same time, think about your posture and your head position — both of which can cause pain if improper. If these suggestions do not offer relief, consult your general physician. You should not have to live with discomfort that might be easily alleviated.