 | William L. Park, OD, FAAO is in private practice in Wichita, KS. He works exclusively with patients referred for low vision evaluation, low vision rehabilitation and neurological vision loss. He is a past Director of Low Vision Services, Lions Research & Rehabilitation Center, Wilmer Eye Institute-Johns Hopkins University. Dr. Park can be reached at William L. Park, OD, LLC, www.parklowvision.com, 610 N. Main, Suite 201, Wichita, KS 67203, (316) 440-1690 or drpark@parklowvision.com. |
Vision
2011-01-01 10:18:00
Cortical visual impairment
Question: My four-year-old son has been diagnosed with possible cortical visual impairment. I am at a loss as to whom I should see for guidance.
Answer: For medical purposes, cortical visual impairment (CVI) may be defined as visual impairment in both eyes caused by damage to the occipital lobes and/or to a specific visual pathway. CVI is almost invariably associated with an inefficient, disturbed visual process due to widespread brain disturbance. For educational concerns, CVI is a neurological disorder, which results in unique visual responses to people, printed materials and the environment. CVI is one of the most frequent causes of visual impairment in children of developed countries.
CVI can be congenital or acquired and may also exist with optic nerve disease, or retinopathy of prematurity. A few causes of CVI are asphyxia, cytomegalovirus, premature birth, metabolic and seizure disorder, hydrocephalus, brain bleeds, periventricular leukomalacia, shaken baby syndrome and exposure to toxins and drugs. Most children with CVI improve in functional behaviors, with the poorest prognosis for recovery in children with periventricular leukomalacia and children who suffer shaken baby syndrome that present with retinal bleeding.
The objective of working with children with CVI is to help them create visual memory and to use their remaining functional vision. Children with CVI usually have some level of vision that can improve over time. However, this requires a team of health care professionals with very specific backgrounds to ensure that your son has maximum potential to meet the goals necessary to improve his learning process. This team would include, but not be limited to; vision rehabilitation practitioner, psychologist, pediatric occupational therapist, teacher of the visually impaired and patient coordinator.
Common characteristics include aspects such as non-purposeful gaze, light gazing behavior and difficulty with novelty and/or complexity (too much auditory, visual or tactile information). There is a preference for the colors red and yellow. Ninety percent of children affected by CVI have visual field deficits that may have an impact on mobility. It is also common to have an atypical or absent response to visual threats of objects in their visual space. The child will, however, tend to bring the object close to block out irrelevant background.
Atypical motor behavior will result in a child looking at a person or object and then looking away from the person or object as they reach for that object. Ocular and ocular motor issues need to be evaluated so that maximum correction is provided for any of these problems.
The computer is an excellent tool to use with children who have CVI. It provides high contrast, two dimensions and fills the child’s visual field to eliminate the effects of figure-ground. There are excellent computer programs for children that are simple and educational that use bright colors, eliminating visual clutter and providing movement. Simple and consistent teaching approaches are optimal to the overall goal of improving visual function.
This is just a brief answer to address areas of concern and the necessity for interdisciplinary rehabilitation for your son.
