Low Vision Therapy

Understanding Low Vision Therapy
There are unfortunate circumstances where the visual apparatus of a patient is damaged beyond the point where vision cannot be restored to normal. This is a condition called low vision. Low vision patients might actually have quite useful vision and might be able to carry out most of the activities of daily living, such as shopping, reading and even driving. However, they often can enjoy these tasks more with certain aids, i.e., Low Vision Aids. There are two ways in which vision might be reduced, specifically, loss of the visual field and loss of central acuity (or clarity).

Visual Field Loss
There are certain diseases such as glaucoma, and retinitis pigmentosa that specifically cause losses of peripheral vision prior to causing loss of central acuity. To imagine what life for these patients might be like, try this simple experiment. Roll up two pieces of paper into two tubes and look through them, placing one tube over each eye. See how difficult it is to maneuver around a room; imagine trying to cross a street with this impediment! This is loss of the entire peripheral field. Other pathologic states cause losses of only portions of the peripheral fields. This problem occurs most often after brain injury, surgery, stroke, or from the presence of a tumor. It is possible to lose sight of everything above the area that you are inspecting, as if you were wearing a hat with a very wide brim, or to lose sight of everything to the left of the area you are inspecting so that you only see the right halves of things. It is possible to lose everything on the left side when looking with the left eye and everything on the right side when looking with the right eye, as if you were wearing horse-blinders! Life with these defects is terribly frustrating for many patients, but there are things a ophthalmologist/low vision specialist can offer. First, the Ophthalmologist would map out the area of deficient vision using a visual field test. Then, glasses with prism (lenses that bend light without otherwise focusing it) so that the portions of the patient 's world that is being missed can be brought into view. This can save a patient from constantly turning their head and reduce their chances (and alleviate their fear) of bumping into a passerby or walking into an oncoming car. The most important thing a patient can do is come to his ophthalmologist/low vision specialist as early as possible in the course of his eye disease so that they can benefit the most from the many aids available.

Acuity Loss
Certain diseases, such a diabetic retinopathy or age-related macular degeneration often decrease central acuity before reducing peripheral vision. To imagine what this might be like, hold your hand over what you are reading and look directly at your hand while trying to read with your peripheral vision. You will realize that the clarity of peripheral vision is much less than that of central vision and will probably become quickly frustrated. However, there is a great deal that an ophthalmologist/low vision specialist can offer the many patients suffering loss of central acuity. First, the clinician would evaluate the patient and determine the patient's visual acuity. Then, they would discuss at length with the patient what visual tasks the patient needs or wants to do most. There are really only six types of tasks, i.e., viewing at short, intermediate or long distances, where each may be performed for either a short or extended time period. Depending upon the degree of disability, and the nature of the task, the ophthalmologist would offer both optical- and non-optical devices and aids that will help make the visual experience more enjoyable and useful. These include large-print reading materials, magnifiers of all different styles, advice on reading hygiene (including lighting, body position, and duration of task), audio-devices (such as books on tape), filters that reduce glare, etc. The Ophthalmologist would also counsel the patient and refer the patient to support groups, or even orientation- and mobility-therapists. As with all vision problems, the best results are achieved when the problem is diagnosed and treated early in the course of the disease. Once a patient is told they cannot or will not see 20/20 in either eye, they should seek the aid of an ophthalmologist specializing in low vision, even if their vision is not far from perfect. Everyone has a right to enjoy their eyes and to make the most of whatever they have!