Vision Issues After Brain Injury

BrainLine sat down with Dr. Gregory Goodrich to talk about the problems with vision that can arise after a traumatic brain injury. Dr. Goodrich is the supervisory research psychologist assigned to the VA Western Blind Rehabilitation Center in Palo Alto, California. He also serves as the program coordinator for the Optometric Research Fellowship Program at the VA hospital in Palo Alto.

How common is it to have vision problems after traumatic brain injury (TBI)?

For TBI in general, the literature says 20-40 percent of people with brain injury experience related vision disorders; however, the exact prevalence is not known. ^{1, 2}

In the military population — although we don’t have a definitive statistic — we have found in mild TBIs that troops exposed to one or more blasts can have trouble with their eyes coordinating with one another, what we call “oculomotor or binocular dysfunction.”

In moderate to severe TBI, about one third of the troops tested have some sort of visual impairment, which can include visual acuity and field loss, binocular dysfunction, and spatial perceptual deficits.

Complete visual examinations are now a required part of testing for brain injury in all four VA polytrauma centers, which will help with data collection since, until this mandate was passed, comprehensive visual examinations were not an integral part of interdisciplinary protocols for brain injury. The hope is that in the future this comprehensive test will be part of any evaluation of someone with a TBI whether civilian or military.

What are the tests for visual problems like currently?

To date, if a person has a traumatic brain injury, he is not given a full visual examination. What is administered most often is a basic test called the Confrontation Visual Field Test, or CVFT. Basically, it consists of a doctor standing at arm’s length away from the patient, wiggling his fingers in different areas of the person’s visual field, and saying, “Can you see this?” This is a good, quick-and-dirty test, but unfortunately, it often misses significant visual problems.

Comprehensive visual examinations include the types of examinations you would receive normally for annual ophthalmological and optometric examinations. They look at eye health, refractive errors, visual fields, contrast sensitivity, and so on. What is unique about these comprehensive examinations is that they include examinations for occult injury, binocular function, and other specialized testing which goes beyond what is normally provided. In short, they are designed to detect vision disorders which are not commonly seen by clinicians and which require specialized testing to uncover.

Again, we hope that soon a complete visual examination will be a requirement of an interdisciplinary evaluation of someone with a TBI — civilian or military.

What are the most common kinds of visual problems?

The two big categories are visual acuity loss and visual field loss.

Let’s start with visual acuity loss. If a person wears prescription glasses and takes them off, he will have a loss of acuity — or clarity. With brain injury, people can have a relatively small visual acuity loss or significant loss.

Visual acuity loss results from damage to the eye, the nerve fibers that carry signals from the retina in the eye to the brain, or to the visual cortex. This loss can sometimes be effectively treated with glasses, magnifiers, or electronic reading aids such as closed-circuit televisions. How much the loss impacts an individual’s life depends on the degree of the loss. Needing a small amount of magnification is in some ways similar to those of us who need bifocals. A need for more optical magnification than that can require different devices and training.

Visual field loss is a bit more complicated. Think of your visual field as a pie. Visual field loss is categorized by which part of the pie is affected.

• If you have hemianopsia, half of your pie — or visual field, either vertically or horizontally — is gone; you cannot see it.
• If you have quadranopsia, a quarter of your visual field is lost.
• If you have homonymous hemianopsia, the same quarter or half is lost in both eyes.
• If you have bitemporal hemianopsia, you are missing the outer half (or inner half) of both the right and left visual field.

Hemianopsia and quadranopsia are the most common types of visual field losses; but going back to the pie analogy, other types of field losses include loss around the edges of the pie or loss from the middle going outward. And, of course, there can be differing combinations depending upon the individual injury.

Visual field loss is caused by damage to the nerve fibers that carry the visual signal from the eyes to the visual cortex and/or connect operations between different parts of the brain.

Are these vision problems temporary or permanent?

Just like people, all brain injuries are unique, and that includes the process of recovery; so it is difficult to generalize. After a brain injury, once the person is medically stable, we will start visual rehabilitation. If the visual problems resolve, great; if not, we have a head start by starting that early. Vision is integrated into other problems that can occur post-TBI like muscular imbalance and vestibular problems (dizziness, imbalance, vertigo, etc.)

Can people with brain injury suffer from both kinds of vision loss?

Yes, people with TBI can suffer from both visual field loss and visual acuity loss. After all, 40-50 percent of the brain is involved in vision; so if a person’s brain is damaged in a specific location or several locations, there is a high probability that his vision will be affected in some way.

If someone has hemianopsia can they learn how to compensate for that, or “see” it?

Broadly speaking, there are two kinds of visual field losses — those with neglect and those without neglect, and this is a huge oversimplification but perhaps useful to begin understanding field loss.

Let’s take your example of the woman who has hemianopsia, and she can’t see the left side of her world. If she has hemianopsia with neglect, she doesn’t even know that the left side of her world exists. It’s just not there. She has no awareness of its existence. She might look in the mirror and only comb the right side of her hair, or apply mascara only to the right eye. She doesn’t know she is ignoring her left side because she has no awareness that it exists. Because of her complete lack of awareness, it would be challenging, but possible, to teach a person like this compensatory strategies.

If she has hemianopsia without neglect — if she has retained an awareness of the lost side of her vision — she can learn compensatory strategies to “search into” that side of her world. Such strategies include scanning, moving the head from side to side, and re-teaching her eyes to move and look into the missing areas.

What other techniques and compensatory strategies do you use?

In rehab, there are various techniques we can use to help people with visual problems after TBI. For someone with visual acuity loss, we teach them the importance of better lighting, the use of magnification, and strategies or assistive technologies to make reading or using the computer easier. Prescription glasses or contacts may also help.

For people with visual field loss, we give them specific strategies to scan their environment, based on where their hemianopsia is located.

For example, if a man has lost the bottom half of his visual field, he is at greater risk of falling off a curb, tripping over a threshold, or falling over a skateboard left in the driveway. So we will teach more efficient scanning processes — ways for him to scan the ground, to move his eyes and head down and around to prevent falling and tripping.

For some people — and this is ideal, of course — problems like hemianopsia after TBI resolve themselves. For others, it doesn’t, and learning scanning processes and other strategies can take a short time or weeks before a person reaches his maximum level of independence.

The length of time for learning compensatory strategies depends on a person’s cognitive level post-injury. For someone with TBI who has more cognitive impairment, has perceptual deficiencies, and has less awareness, the rehab will be harder. This person may be able to see the skateboard in the driveway, but he may not be able to connect seeing it to the fact that he needs to walk around it.

What professionals help a person learn these strategies and compensations?

You might think I’d answer with just ophthalmologists and neurologists, but I want to emphasize the importance of interdisciplinary rehabilitation for people with brain injury. An interdisciplinary team can include nurses, physical therapists, occupational therapists, speech-language pathologists, physical medicine and rehab physicians, neurologists, neuropsychologists, audiologists, ophthalmologists, and so on. And each one of these professionals may play a part in rehabilitating vision.

Let me give you an example of how an interdisciplinary team worked with one of our patients. Among other issues resulting from his brain injury, the patient had a left hemianopsia with neglect; he was unaware that the left side of his world existed. He was mostly confined to bed. His nurses, who spent the most consistent time with him, noticed that the way his bed was positioned precluded him from being able to see who was coming into his room, which made him more agitated and less confident. So they suggested to the team that they move his bed so that the door was by his right side, enabling him to greet staff or visitors. As he got stronger and more confident, the nurses, in continued collaboration with the interdisciplinary team, then did the opposite. They moved his bed so that the door was by his left field of vision, the half that was lost. By doing this, he had to work on scanning — moving his head and eyes beyond his right visual field — and also learning to listen for audio cues.

Especially because each brain injury is unique, an interdisciplinary team is a matter of “more heads are better than one.”

When does a brain injury result in blindness?

Blindness can come from a penetrating injury like a gun shot or a non-penetrating injury like a blast in combat. It can also be a result of an injury to the back of the head — like from a fall — that destroys or damages an area that coordinates signals between the brain and the eyes. In this case, the eyes could be perfectly normal, but the function in the brain allowing the eyes and brain to communicate would be damaged and no longer work. Our experience with troops returning from the current wars suggests that total blindness is less common than other visual losses; perhaps occurring in 2-4 percent of all cases.

Are vision problems after blast injuries different from vision problems after a car crash or sports injury?

So far we think that blast injuries and injuries from a car crash or a sports injury produce similar visual problems. However, we lack a good understanding of how exactly a blast causes brain injury. Blasts cause injury not just by the brain banging around in the head; but they also add torsional forces. (Picture a plastic ruler being twisted between both hands, each hand twisting it in the opposite direction. The ruler would be in a state of torsion.) The brain being twisted in this way may cause shearing, which is basically the stretching and tearing of the tiny nerve cells that comprise the brain and/or the blood vessels which provide nourishment to the nerves.

But all we can say now, based on the evidence we have, is that the visual consequences from blast and non-blast brain injuries appear very similar. Until we clearly understand how blast injury occurs, we should be cautious in interpreting our findings.

How do visual deficits influence quality of life?

Having visual deficits after a brain injury can definitely interfere with a person’s quality of life. Visual problems often go hand-in-hand with cognitive or physical problems and also with psychological problems like depression. If a person cannot see well, he may isolate himself because he doesn’t want to be out in the world bumping into people or losing his way. He may have a fear of crowds or may feel embarrassed that he can’t read the expressions on his friends’ faces. This social isolation can be devastating and can then lead to depression, anxiety, and substance abuse.

What advice would you give someone after a TBI who is experiencing visual problems?

I would say if following a brain injury the person has any visual symptoms at all — even a little blurriness or fuzziness, eyes that fatigue easily, difficulty reading, or frequent bumping into things on one side more than the other — he should get a comprehensive eye examination by an ophthalmologist or optometrist. A comprehensive test would include testing the visual field and acuity, contrast sensitivity, and binocular vision. Make sure to find out if the symptoms are related to the visual system or something else … that is, are the symptoms a result of the brain injury or is it a simple need for a new pair of glasses? Try to find an optometrist or ophthalmologist who has experience working with people with brain injury. And keep persisting until you get the help you need.

Footnotes
¹ Gianutsos, R. (1991). Computerized screening: Visual field deficits after brain injury. Journal of Behavioral Optometry, 2(6), 143-150.
² Kerkoff, G. (2000). Neurovisual rehabilitation: recent developments and future directions. Journal of Neurology, Neurosurgery, and Pscyhiatry, 68, 691-706.

Gregory Goodrich, PhD
BrainLine sat down with Dr. Gregory Goodrich to talk about the problems with vision that can arise after a traumatic brain injury. Dr. Goodrich began his career with the U.S. Department of Veterans Affairs (VA) in 1974 and is currently supervisory research psychologist (Psychology Service) assigned to the Western Blind Rehabilitation Center in Palo Alto, California. He also serves as the program coordinator for the Optometric Research Fellowship Program at the VA hospital in Palo Alto. His primary areas of research are low-vision reading and mobility. Most recently, his research has focused on the treatment of polytrauma veterans with visual loss returning from Iraq and Afghanistan.

The opinions expressed are those of Dr. Goodrich and not those of the Department of Veterans Affairs.