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| Division of Occupational Therapy - OT Connect Neurological Visual Impairment
Neurological Visual Impairment (NVI), (also referred to as Cortical Visual Impairment or Cortical Blindness) is a disorder that commonly occurs in children, which results in mild to severe loss of functional vision (Huo et al., 1999). In these children the eye and its structures are normal, but the brain is unable to process the visual information it is receiving (Morgan, 2002). When given a standard eye exam, the person with NVI typically shows normal eye function and normal visual reflexes. The problem is not in the eyes or in the visual tract, but rather in the brain structures the eyes send information to. For this reason NVI cannot be corrected by with glasses or with eye surgery. Causes of NVI include CNS malformations, neurological disorders, metabolic and neurodegenerative disorders, drugs and poisons, both accidental and non-accidental trauma, and perinatal hypoxic-ischemia (Hoyt, 2002; Afshari et al., 2001). Common Symptoms/Course of Disease
(Brodsky et al., 2002; Baker-Noble, 1997; Afshari et al., 2001; Dutton et al., 1996) NVI is highly variable, in some cases resolving in childhood. The cause of the disorder, the severity of the injury, and the type of injury will all influence the prognosis. A better prognosis is correlated to younger age of diagnosis (Huo et al., 1999). It is believed that this may be due to the pliability of the younger child’s brain (TSBVI, 1984). Most children show an improvement in vision with the most dramatic recoveries occurring within six months of injury (Huo et al., 1999). Although most children diagnosed with NVI experience some improvements, 90% remain with some visual deficits that require additional services to help them function in daily life (Huo et al., 1999). Age of onset: NVI can be caused at any time throughout the life span but is common due to trauma or infection before, during, or shortly after birth (Brodsky et al., 2002). Sex bias: None reported Cultural bias: The incidence of NVI in infants has dramatically increased within the past ten years to become the leading cause of visual impairment in children in developed countries (Huo et al., 1999). This increase is due to medical advancements in prenatal and perinatal care that are keeping children who have experienced trauma at birth or early in life alive. Current Medical Treatment: One hundred percent of the children diagnosed with NVI also have another impairment or disability (Baker-Nobles, 1997). Some of these related disorders include cerebral palsy, mental retardation, learning impairments, impaired motor function, seizures, hearing loss, periventricular leucomalacia, and other neurological disorders (Afshari et al., 2001; Huo et al., 1998; Dutton et al., 1996; Hoyt & Good, 2001). Treating the visual impairment in the presence of the additional deficits is a complex task. Seizures and medications associated with the secondary deficits may interfere with visual functioning (Huo et al., 1999). This condition, while limiting, is not life threatening, and for this reason is often overlooked until the child is medically stable and in an educational environment. Occupational Therapy Involvement The goal of occupational therapy is to help the individual learn to use their residual vision effectively. Research has shown that the best way to help these people accomplish this task is by altering their everyday environments. One of the most important first strategies is to reduce visual clutter, making it easier to visually find important features (Afshari et al., 2001; Baker-Noble, 1997). Contrasting colors can be used to mark or label items or environmental features like closets and drawers. Bright colors and two-dimensional forms are easier for the person with NVI to see because color perception is often a strength for these people. Three-dimensional objects may be difficult for some people to process, and contrast colors can be used as drawer liners and placemats to help the individual locate clothing, utensils and other important three dimensional objects. Textures can be used to help draw attention to objects using the unimpaired sense of touch. When the child feels something of interest, they can then be prompted to look at it and build multi-sensory associations (Baker-Noble, 1997). Using other intact sensory systems allows the child to compensate for impairments and may help in interpreting visually information for them. Sensory enrichment and a variety of visual stimulation activities are encouraged for children with NVI in order to stimulate the visual areas of the brain to hopefully improve visual functioning (TSBVI, 2003). As the children reach school age they will may special assistance and accommodations. In adolescents and adults with NVI the treatment focus is on adapting environments to support safe independent opportunities for participation in personal care, work, and leisure tasks. References
How OT Makes a Difference: Evidence-Based Practice There is much research literature about the sue and effectiveness of occupational therapy in improving function in persons with low vision. The population of persons with NVI is diverse, and research specific to this population in any field is limited because of this. the following paper provides a case study and an overview of NVI in children. Baker-Nobles L, Rutherford A. (1995) Understanding cortical visual impairment in children. American Journal of Occupational Therapy, 49(9):899-903. This article presents a review of the literature and a case study on a child with cortical visual impairment. The literature review covers the diagnosis, etiology, prevalence, prognosis, and a comparison of the differences between children with cortical visual impairment and those with ocular impairment. The case study presents occupational therapy intervention strategies specific to cortical visual impairment and results of treatment. Children are often referred to the Assistive Technology clinic at West Virginia University for assessment for potential assistive technology tools to help them participate in the classroom environment. Jon, a 10 year old with severe spastic cerebral palsy came to clinic to evaluate switch access for computer use. During assessment Jon looked away from people in the room, and even with many prompts to look at the computer, turned his head away. He had little success with either the touch screen or the head mouse for computer input. Because Jon did not ever use his eyes to help him with any task, including eating, the occupational therapist asked if his eyes had been tested. Jon's father said that they had been tested and he had "perfect vision" he was just too lazy to try and use it. Following further questioning, it was clarified that the ophthalmologist reported that Jon's eyes and visual tracts were intact, but the family was not aware of the brain's role in vision. When the occupational therapist investigated further, it seemed that Jon was looking at things, but he was looking out of the corner of his eyes, using his peripheral vision. When the computer was placed to his left, in-line with his peripheral line of sight Jon's accuracy with switch access improved by 50%. Later, when the Track IR head mouse was positioned near the outside edge of his left eyebrow (rather than in the center of his forehead) Jon was able to use an on-screen keyboard and effectively indicate needs on a scanning array with 95% accuracy. Jon was able to then use this equipment in school, and was, for the first time making progress in reading and other academic subjects. The family later reported that the computer access opened up his world, but even more important to them was an understanding of Jon's vision and ways to help him in his everyday life. They had been able to follow-up with the occupational therapists suggestion and gotten much additional information about NVI, and had arranged for Jon to have a vision specialist as a consultant to the school team.
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