Abstract
CVI (cortical or cerebral visual impairment) refers to bilateral reduction in vision function due to damage to the visual cortex and/or the posterior visual pathways in the absence of ocular pathology. CVI is the most common cause of bilateral severe visual impairment in children in the developed world. The causes include hypoxic–ischemic brain damage, head injury (such as shaken baby syndrome), infection, hydrocephalus and metabolic disorders. CVI occurs commonly in premature infants and is often accompanied by cerebral palsy, quadraplegia, seizure disorders and developmental delay. Assessment of vision function in children with CVI is a challenge. Preferential looking methods and sweep VEP methods can be used sucessfully and in our population of children with CVI show an enormous range of values of visual acuity (20/50 to 20/800 VEP grating acuity) and contrast sensitivity (1.3 to 25% Michelsen contrast). Large discrepancies often occur between behavioral and VEP measures of function (often a factor of 10 or more). Longitudinal follow-up of 39 children with CVI over 6.5 years on average demonstrated significant improvement in about 50% of the patients and showed that early VEP measures can predict later behavioral vision function. Improvement in vision function occurred over a surprisingly long time (into the teens).
Meeting abstract presented at VSS 2013