Serving the growing population of adults with brain injury and related visual impairments provides our field with unprecedented challenges, but also new opportunities for growth, professional expansion, and collaboration with professionals from a wide range of rehabilitative services. Whether they are returning service members from the wars in Iraq and Afghanistan; adults injured in motor vehicle accidents, falls, or other trauma; or survivors of stroke or other brain injury, these presenting patients are forcing us to rethink some of our rehabilitation strategies and adapt our methods to meet their complex needs. Rehabilitation training, particularly traditional methods of teaching the special skills needed by people who are visually impaired (that is, who are blind or have low vision), often relies on the use of cognitive processes such as attention, memory, and auditory processing. Although each brain injury is unique and multifaceted in its effect on rehabilitation learning, the performance of these skills may be the most challenging to a person with a brain injury (Lew, 2005). Nevertheless, a growing body of research and collaborative teamwork with other professionals treating brain injury give us many tools for working with an individual with such an injury. The future is exciting for those of us who work in blind or vision rehabilitation, and we all have a chance to make a positive impact on a substantial population.
CALLING ALL SERVICE PROVIDERS
Medical treatment is improving the rate of survival among those wounded by war or trauma, but survivors often live with multiple disabilities, including traumatic brain injuries (TBIs) that can result in vision loss. As the number of individuals with brain injury-related vision loss increases, all levels of vision rehabilitation service providers will need to be involved in working with this population, especially as returning service members with brain injuries and vision issues who are served at military treatment centers and the network of Department of Veterans Affairs (VA) facilities will begin dispersing into their home communities. Veterans are not the only group of individuals with brain injuries and related visual impairments that will soon be overwhelming health care. Adults in the general population are living longer, but with age-related health conditions that may affect the brain or vision. The chance of having a stroke approximately doubles for each decade of life after age 55. Heart or artery disease, diabetes, obesity, and hypertension are more common with age and are major risk factors for stroke, which can damage the brain and vision (American Heart Association, 2010). Not only are individuals living longer, but the number of individuals living into old age is rapidly increasing as well. In the United States and around the world, the aging of populations is unprecedented, pervasive, and enduring, and this growing cohort of elderly individuals will require more rehabilitative and health services than ever before (United Nations Department of Economic and Social Affairs, 2002). According to a United Nations report (2002), persons 65 years or older numbered about 39.6 million in 2009, and they represented 12.9% of the U.S. population (about one in every eight Americans). By 2030, there will be about 72.1 million older persons (that is, 19% of the U.S. population-more than twice the number in 2000). The sheer number of the people reaching ages associated with increased health risks suggests there will be ubiquitous opportunities to interact with and serve a population with brain injury and vision impairment (Administration on Aging, 2010; Ghusn, Stevens, & Atassi, 1998).
DEFINING TBI AND ABI
Brain injury is receiving more press and research attention as "the signature wound of the war[s]" in Iraq and Afghanistan (Oakie, 2005), but terms involving brain injury are often used imprecisely or are misunderstood in popular literature. Individuals may confuse the terms acquired brain injury (ABI) and TBI, and brain injury may be confused with dementia, learning disabilities, or attention deficit disorder (Hibbard, 2007; Grandinette, 2006). ABI is an injury to the brain that is not hereditary, congenital, degenerative, or caused by birth trauma. It is a broad term used to indicate that a person has experienced a brain injury after childhood, but does not include degenerative disorders such as Alzheimer's, Parkinson's, or Huntington's disease. ABI does include brain damage as a result of TBI, stroke, metabolic disturbance, infection, hypoxia, substance abuse, blood loss, electrical injuries, or the like (see Box 1). TBI, therefore, is just one type of acquired brain injury.
TBI, as the name implies, involves trauma to the brain. The leading causes of TBI are falls (35.2%), motor vehicle or traffic accidents (17.3%); struck by/against events (16.5%); and assaults (10%) (Faul, Xu, Wald, & Coronado, 2010; Brain Injury Association of America, BIAA, 2010). About 75% of TBIs that occur each year are concussions or other forms of mild TBI (Champion, Holcomb, & Young, 2009). An increasing number of incidences of TBI are due to blasts or explosions that occur during warfare or terrorist attacks (Lew, 2005).
Currently there are at least 5.3 million Americans living with disabilities because of TBIs, and, in the next year, an average of 1.4 million Americans will sustain TBIs (BIAA, 2010). These numbers do not include the incidence or prevalence of ABIs, which tend to occur with anoxia or stroke. Another 360,000 men and women are estimated to have incurred TBI in the conflicts in Iraq and Afghanistan (Fischer, 2009). Service members are surviving TBI with eye injuries in unprecedented numbers and surviving longer as compared with soldiers of earlier conflicts due to improved battlefield medicine, body and vehicle armor, and transportation, and advances in emergency and rehabilitative medicine (Goodrich, Kirby, Cockerham, Ingalla, & Lew, 2007; Lew, 2005). As those actively serving the military achieve veteran status and as these veterans grow older, they are likely to access community health services, as well as VA medical resources (Ghusn, Stevens, & Atassi, 1998), which will have an effect on all levels of care in adult vision rehabilitation.
Box 1. Causes of acquired brain injury Causes of acquired brain injury can include, but are not limited to: * Airway obstruction * Near-drowning, throat swelling, choking, strangulation, crush injuries to the chest * Electrical shock or lightening strike * Trauma to the head or neck or both * Traumatic brain injury with or without skull fracture, blood loss from open wounds, artery impingement from forceful impact, or shock * Vascular disruption * Heart attack, stroke, arteriovenous malformation (AVM), aneurysm, intracranial surgery * Infectious disease, intracranial tumors, metabolic disorders * Meningitis, certain venereal diseases, AIDS, insect-carried diseases, brain tumors, hypo- or hyperglycemia, hepatic encephalopathy, uremic encephalopathy, seizure disorders * Toxic exposure * Illegal drug use, alcohol abuse, lead or carbon monoxide poisoning, toxic chemicals, chemotherapy (in rare cases) (Fischer, 2009; National Institute of Neurological Disorders and Stroke, 2002.)
The visual consequences of TBI are a popular topic of discussion and research within our profession. Civilian cases have presented with changes in visual acuity, reduced visual fields, and impaired oculomotor function (Schlageter, Gray, Hall, Shaw, & Sammet, 1993). Blast-related TBI, in both military and civilian populations, is an emerging area of study. Current research suggests that the visual consequences of blast-related TBI include open-globe injuries; blunt trauma without penetration of the eyeball (closed-globe injuries); compromised visual acuity, visual fields and binocular function; and other more subtle effects (Cockerham et al., 2009; Taber, Warden, & Hurley, 2006). Damage to the brain and visual structures in primary TBI can come from cerebral contusions and diffuse axonal injury. Contusions are bruising on the brain's surface due to impact, whether focal (as under a fracture at the site of impact) or diffuse (as when the whole head decelerates--such as when a football player's head hits the ground or a passenger in a motor vehicle accident hits the windshield) (McLatchie & Jennett, 1994). Diffuse axonal injury refers to widespread stretching or tearing of the tail-like axons of neural cells in cortical or subcortical areas of the brain. Secondary brain damage results from three main mechanisms: raised intracranial pressure, hypoxia, and intracranial infection. The mechanism of injury can be important in predicting what kinds of deficits and damage may be present (Biehl, Valdez, Hermady, Steidl, & Burke, 1999).
Blasts are rife in the current conflict and in terror events at home and abroad. Blasts damage brain and visual structures through a number of mechanisms. Primary blast injury is caused by the blast wave itself, and the sudden pressure changes can cause sheafing, turbulence, and cavitation within and around the eye. Secondary blast injuries are caused when flying objects including dirt, rocks, and shrapnel create penetrating and focal damage. Blasts can also create rapid deceleration injuries when a body in motion impacts a stationary object. As such, blasts create complex, multifaceted injuries with elements of both focal and diffuse contusions and diffuse axonal injury to the brain, nerves and visual pathways within those structures. (Defense and Veterans Brain Injury Center, 2009; Stapczynski, 1982).
Mechanisms of injury that affect the visual system are myriad with TBI. Injury to or compression of the optic nerves can cause vision loss. Diffuse brain injury limits the processing of vision and impairment to the cranial nerves may limit eye and ocular adnexa (eyelid and orbit) innervations. Damage to the afferent visual pathway, from the retina to visual centers in the brain, can result in severe blindness, loss of central and/or peripheral visual fields, various types of hemianopia or homonymous field defects, and loss or changes in visual acuity (Cockerham et al., 2009). The tear, film, and blink reflexes of the eye may be disrupted, leading to dry eye and loss of acuity. Trauma can lead to the development of retinal detachment or clouding of the lens, as well as issues with arterial blood flow that can cause loss of acuity, loss of sight and visual field, and diplopia or double vision (Weichel, Coyler, Bautista, Bower, & French, 2009).
The efferent visual pathways include both voluntary and involuntary functions affecting the muscles within and surrounding the eye. These include the iris; ciliary body; parasympathetic nerves to the eye socket that cause the pupil to become small and cause the lens to focus for near work; and cranial nerves, which control oculormotor movements such as tracking, convergence, or divergence. Damage to these structures can cause diplopia, convergence, accommodative insufficiency, and referred headache pain from the greater occipital nerve. Fixation instability and inability to maintain binocular fusion will result in intermittent diplopia and blur (Cockerham et al., 2009).
Visual disorders after ABIs such as stroke are also very common and are often under treated. Central vision and oculomotor disorders occur in 20%-40% of neurological rehabilitation center patients, yet few receive systematic treatment (Zihl, 1989). Rowe's study (2009) cites that a substantial proportion (92%) of patients referred with suspected visual difficulty had visual impairment. One-fifth of patients referred had perceptual consequences from their stroke relating to inattention and cortical visual processing impairment (Rowe, 2009). Commonly cited visual disturbances after strokes include visual field loss, blurry vision, double vision, and moving images. Strokes can cause whole sections of the visual field to appear missing, particularly for those with hemianopia--not being able to see to the left or right from the center of the field of vision in each eye. If hemianopia occurs in both eyes, it is referred to as homonymous hemianopia. Other patterns of field loss include quadrantinopia (loss of one quarter of the field), central field loss, and scattered scotomas. When stroke affects the areas of the brain that process visual information, it can cause "visual neglect" (that is, the lack of awareness of one half of the body or space), as well as difficulties with judging depth and movement.
Other visual problems that may occur as a result of stroke include eye muscle and nerve problems, which can result in double vision and moving images as well as other effects, such as sensitivity to light. As with TBI, there may be a slowed blink rate, or there may be incomplete eye closure with a partial blink that will cause a part of the cornea to dry and become damaged, interfering with clarity of vision. In addition, visual and visual-cognitive disorders can negatively impact nearly all aspects of a patient's vision--from balance and spatial orientation to color recognition.
Visual symptoms and disabilities after a brain injury are high, but sometimes underdiagnosed, particularly if the TBI is mild or if the patient lives in a locality with fewer available rehabilitative services (Lew, 2005; BIAA, 2007). Stelmack and colleagues found that 76% of patients with polytrauma and 75% of patients with a TBI reported visual symptoms at a VA clinic. Problems were reported with reading (50%-60%) and there were accommodative disorders (30%-47%) (Stelmack, Frith, Van Koevering, Rinne, & Stelmack, 2009). People who experience TBI report poorer physical and emotional health as compared to those with other disabilities and those without disabilities. Individuals with brain injuries who live with residual disability often fail when they attempt to return to active military duty, productive work, previous social roles, familial responsibilities, and preinjury lifestyles. People with TBI are 66% more likely to receive welfare or disability payments and are four times more likely to attempt suicide than people without disabilities. Although not thoroughly documented in the literature, the statistics are even higher for people with visual disturbances related to brain injuries (Silver, Kramer, Greenwald, & Weissman, 2001). This population of civilians and veterans are stretching the resources of the field of blindness and vision rehabilitation as never before as they seek medical and community services. Collaboration and cooperation among professionals is required if we are to meet the needs of and provide the services so richly deserved by this population.
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This article does not represent the opinions of the Department of Veterans Affairs, Department of Defense, Defense and Veterans Brain Injury Center, or the U.S. Government.
Cyndy Iskow, Ph.D., COMS, CBIS, blind and vision rehabilitation outpatient specialist, Polytrauma BROS, Office 1B-141A, Richmond VA Medical Center, 1201 Broad Rock Boulevard, Stop 171, Richmond, VA 23249; e-mail: