Rapid recovery from cortical visual impairment in a pediatric patient following vision training: A case study
Background. Cortical visual impairment (CVI) is a severe loss of visual function caused by damage to the visual cortex or its afferents, usually as a consequence of stroke or hypoxic insult. It is one of the leading causes of vision loss in children.
Objective. Several studies have demonstrated limited vision restoration in adult CVI patients who trained on well-controlled psychophysical tasks involving complex motion stimuli. Given the greater potential for plasticity in the young brain, we hypothesized that similar vision training would be more effective in young patients.
Methods. To test this hypothesis, we conducted a proof-of-principle study in one young CVI patient (age 18), to test the training speed, efficacy and generalizability of vision rehabilitation using complex motion stimuli. The patient trained at home and in the laboratory, on a psychophysical task that required discrimination of motion stimuli presented in the blind field. Visual function was assessed before and after training, using perimetric measures, as well as a battery of psychophysical tests.
Results. The patient showed rapid improvements on the training task, with performance going from chance to 80% correct over the span of 11 sessions. With further training, improved vision was found for untrained stimuli and for perimetric measures of visual sensitivity. Some, but not all, of these performance gains were retained upon retesting after one year.
Conclusion. These results suggest that existing vision rehabilitation programs can be highly effective in pediatric patients. Validation with a large sample size is critical, and future work should also focus on improving the usability and accessibility of these programs for young patients.