Rosamond Gianutsos, Ph.D., F.A.A.O.

Cognitive Rehabilitation Services

Sunnyside, NY

To appear in Family Articles for Traumatic Brain Injury, Communication Skill Builders, Tucson, AZ, 1994

Have you ever gone to the eye doctor and been surprised at how much your vision had changed... something that you only realized when you tried on the new glasses and saw how much you'd been missing? Well, significant injuries to the brain, including strokes, can also affect the visual processing system and unfortunately, many survivors are similarly unaware of these changes. Worse still, these visual problems affect most aspects of functioning -- reading, balance, safety, awareness, ability to concentrate and driving. All too frequently, these visual problems are assumed to be cognitive in nature. The good news is that many of these problems can be managed, if not remedied. Two kinds of visual difficulty are of special concern after brain injury.

The first difficulty is with the coordinated use of both eyes, or "binocularity." Many brain injury survivors report double vision early in their recovery; others suffer binocular problems without realizing it. Furthermore, many doctors still believe in a "conservative" approach, which is to "treat" double vision by patching one eye or by doing nothing -- waiting for it "to get better on its own." Unfortunately, the visual system may adjust by suppressing the use of one of the eyes -- a phenomenon some optometrists call "neurological inhibition." In other words, left untreated, the vision may get worse. Both patching and suppression make the individual function as a one-eyed person. One-eyed people have to compensate for the lack of a sense of three-dimensional space. People who grow up this way manage fairly well, but people who lose binocular vision after an injury can have problems with balance, walking, and estimating distances in driving and sports activities. While reading, the letters may become blurred or jump around, especially when tired. Concentration is a struggle and it is easy to lose one's place. People in certain lines of work (e.g., mechanic, welder, surgeon, sculptor) are particularly disabled because these work activities depend on the coordinated use of both eyes.

Without careful diagnosis, these symptoms are misinterpreted as attentional and behavioral problems. Without proper treatment the binocularity problems remain, or get worse and the overall situation may deteriorate further.

Sometimes treatments for other effects of brain injury impede the binocularity system. For example, many medicines for muscle spasticity, behavior management, depression and seizure prevention cause the small muscles in the eye to relax or be inefficient. This, in turn, affects the coordination of the two eyes (binocularity) as well as the ability to adjust the focus of vision to different distances ("accommodation"). For example, in the classroom accommodation is needed to look back and forth from one's notes to the teacher and the board.

If the treatment can't be changed, you may need an optometrist's help to manage the visual side effects.

The second major problem area caused by brain injuries involves gaps in the visual "fields." More often than not, a person with visual field losses is unaware of the problem. Just as people with hearing losses sometimes feel that others are mumbling, people with visual field losses may feel that the world has changed, e.g., why are they making clocks that way? People without brain injuries, who think they are seeing everything, may be shocked to learn that they too have gaps in their vision. Known as "physiological blind spots" these gaps are caused by the lack of sensory receptors where the nerve leaves the eye to carry visual information to the brain. You have one in each eye, about the size of a fist at arm's length. Close one eye and try to locate yours. Is it on the inside or the outside? In each eye it is located a little to the outside and slightly down from where you are looking. If -- like most people -- you don't feel this blindness, try the demonstration below.

Notice: Although the letter disappears, the paper does not. This phenomenon is known as the completion effect. The brain fills in gaps in the visual field with predictable patterns or surfaces.

People with gaps in the visual fields caused by brain injury, therefore, may have a double disability: the loss of vision and the loss of awareness. Normally, the nervous system tends to fill in the background and to lose the figure. So if such a person were to attempt to drive (not recommended!), they might see the road, but not a pedestrian or child running into the street.

Brain injury can cause different patterns of loss, including blind spots and tunnel vision. However, most common is a pattern called "homonymous hemianopia" in which corresponding halves of the fields are lost in each eye. For instance, in left homonymous hemianopia the blindness affects the left side of each eye. The blindness may be absolute (complete) or relative (reduced sensitivity).

It is not easy to test for visual field losses, especially if there are cognitive problems caused by the brain injury. And since people are often unaware of the loss, it is quite possible that the losses will remain undiagnosed. Fortunately, new computerized methods have been developed to check for visual field impairment. Because these techniques offer immediate feedback, they can be used to build awareness and to lay a foundation for treatment.

The first step is knowing what you are dealing with. A thorough visual system examination is important for at least three reasons: (1) visual system problems are fairly common after brain injury, (2) awareness is frequently affected, and (3) treatment is often simple, straightforward and relatively inexpensive. Sometimes a rigorous visual screening is done by rehabilitation personnel, followed up by a coordinated referral to an optometrist who is experienced and interested in rehabilitation. The screening examination should include a lot more than checking of acuities --as optometrists say, "20/20 is not enough." The exam should cover both near and distant vision, coordination of the two eyes and visual field mapping.

If there is any question whatsoever, seek a complete vision examination from an eye doctor. If you have an eye doctor who knows you well, you could return to this doctor for re-evaluation. If you need to find an eye doctor, bear in mind that, as in most fields, specialties exist and not all eye doctors can serve the specialized needs of the brain injury survivor. How does one find an eye doctor? Is it better to go to an ophthalmologist (medical doctor specializing in vision) or an optometrist?

Optometry and Ophthalmology are overlapping, but not identical, professions. Ophthalmology is a medical specialty that addresses the medical conditions e.g., infections, detached retinas, cataracts, glaucoma, etc., which can affect the eye's functioning. Optometry is a specialty that emphasizes vision as a processing system interacting with environmental demands. Optometrists are eye doctors who have spent 4 years in Optometry school following college. They have passed internships, residencies and licensure. Optometrists are legally required to diagnose medical eye conditions requiring ophthalmologic attention and to make appropriate referrals. The most logical vision specialist for the brain injury survivor, therefore, is an optometrist who will detect medical conditions but will also diagnose and treat problems with the functioning of the visual system.

Rehabilitative Optometry, sometimes called Neuro-optometry, is a developing specialty of Optometry that concerns itself with the particular problems and needs of people who are undergoing rehabilitation for problems caused by an injury to the brain including strokes. Generally, you should look for an eye doctor who specializes in Rehabilitative Optometry or another rehabilitation-oriented specialty in Optometry, such as: Low Vision, Behavioral, and Developmental Optometry.

The rehabilitative optometric examination includes many of the aspects of a traditional optometric examination; however, certain issues are addressed in much greater detail, and most issues are addressed at a pace and in a manner that the individual can deal with. The experience of the rehabilitative optometrist enables a more accurate diagnosis and an appropriate treatment plan. A careful examination will require at least two hours and may be scheduled in more than one session.

At times optometric treatment is as simple as getting a different pair of glasses; while at other times it may involve a series of vision therapy sessions as well as special lenses. Once again, because of cognitive problems, brain injury survivors may need extra structure and help to follow through on the recommended exercise program and to use the prescribed lenses consistently. For this reason optometric vision therapy may be conducted by occupational therapists in rehabilitation facilities under the guidance of an optometrist.

American Academy of Optometry (4330 East-West Highway - Suite 1117, Bethesda, MD 20814-4408)

American Optometric Association (243 N. Lindbergh Blvd., St. Louis, MO 63141)

College of Optometrists in Vision Development (PO Box 285, Chula Vista, CA 92012)

Neuro-optometric Rehabilitation Association (PO Box 1408, Guilford, CT 06437)