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Victoria Tilney McDonough, BrainLine (page 2 of 3) Page 2 of 3
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.
BrainLine: What other techniques and compensatory strategies do you use?
Dr. Goodrich: 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.
BrainLine: What professionals help a person learn these strategies and compensations?
Dr. Goodrich: 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.”
BrainLine: When does a brain injury result in blindness?
Dr. Goodrich: 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.
BrainLine: Are vision problems after blast injuries different from, say, vision problems after a car crash or sports injury?
Dr. Goodrich: 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.
BrainLine
Gregory L. Goodrich, PhD,
Dr. Goodrich received his PhD in Experimental Psychology in 1974 from Washington State University.
His career with the US Department of Veterans Affairs began in 1974 and he is currently supervisory research psychologist (Psychology Service) assigned to the Western Blind Rehabilitation Center.
He also services as the program coordinator for the Optometric Research Fellowship Program at the VA in Palo Alto.
Dr. Goodrich has been an active member of the Association for Education and Rehabilitation of the Blind and Visually Impaired serving as its president, and past president. He currently serves as a member of the research advisory committee of Lighthouse International and a member of the national program advisory committee of the American Foundation for the Blind.
Dr. Goodrich is also a research consultant to Neuro Vision Technology Systems. His primary areas of research are low vision reading and mobility and outcome studies. Most recently his research has focused on the treatment of polytrauma veterans with visual loss returning from operations in Iraq and Afghanistan.
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Comments [5]
It should be noted that in many TBI patients with symptomatic epilepsy, the treatment is anterior temporal lobectomy. As the optic nerve travels through the temporal lobe (Myer's loop) it is often damaged by the surgery, resulting in permanent quadrantopsia.
Thank you for highlighting this issue. Thanks to hearing an expert in the field at a Brain Injury Assoc. caregivers conference, I was able to obtain vision therapy from a qualified optometrist for my husband who has global eschemia from hypoxia. The results so far are subtle but encouraging.
Thank you for sharing this article. I was wondering why there was not more discussion on the cognitive/perceptual deficits that are related to TBI?
Bravo for this article on vision issues after TBI. I have struggled with this since sustaining mTBI in 1994 (and 1998). But I have found that my best compensatory strategy has been my sense that part of the difficulty I encounter in the community is TBI related and the other part is the lack of knowledge on the part of the general public of the role played by environmental issues. I thought I could no longer read, until I learned that I could read pages that were "ragged right" (not fully justified). I advocated with BI organizations to make their print material more TBI-friendly. And I ask the state office of legislative services to print proposed legislation for me in a ragged right fashion. Although I can find science on what TBI does to vision, and what vision impairments contribute to reading difficulties, I cannot find the authoritative statement that puts them together (if I could, I could effect more change). Accommodating print colors, styles, line widths (and other practices of good design for print material) goes a long way to reduce the "I can'ts" that come with vision problems (aagh - filling out forms). Please do not ignore advocacy and civil rights issues when it comes to helping people learn to accommodate the impairments that come with vision disturbances following TBI! I wish that some group would come up with guidelines for print (and web) material to make the most readable materials for people with TBI vision impairments (and just for folks who are plain getting older). The CDC has been the BEST in this area; but unfortunately some organizations serving TBI populations need to develop awareness and make changes! I am glad vision issues have been brought out of the darkness. In vision, as well as other TBI-affected impairments to resuming life as best we can, self-advocacy and a good healthy sense of the American with Disabilities Act goes a VERY LONG WAY. And for those folks who participate in surveys about disabilities: speak up when a survey asks about vision impairments that are solely eye-ball related. Explain vision issues you experience so that future survey questions can be broadened (Surveys usually imply problems are with dimness; my problem is with glare!) Education and advocacy may not provide a "cure," but getting accommodations sure goes a long way in helping us see the light!
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Is there a reason monocular diplopia is not mentioned anywhere (double vision in a single eye--irrespective of binocular focus or visual neglect issues)? That is my problem since TBI, as well as issues (perhaps related) with high contrast "vibration" especially with type (black on white page) or stripes.
Jul 27th, 2011 6:46pm