Retrospective investigation of improvements in functional vision for adolescent students with cerebral vision impairments in a specialist residential school and college setting

Cerebral and/or cortical vision impairment (CVI) is the leading cause of childhood vision impairment in the Global North. Previous studies have demonstrated that the functional vision of children with CVI can develop over time, but evidence for the effectiveness of interventions is still in its infancy. In this study, we retrospectively reviewed student records from a specialist residential school and college in the United Kingdom that had implemented an evidence-based approach to assessment and intervention for adolescent students with CVI called the CVI Range. The outcome of CVI Range assessments were recorded annually over a 5-year period, and potential predictor variables such as measures of visual acuity and presence of conditions such as cerebral palsy and seizure disorders were recorded as part of standard practice within the service. A total of 73 annual assessments were analysed from a total of 24 students between the ages of 9 and 25 years old. We used a mixed model for repeated measures approach to reveal a significant fixed effect of time on functional vision that equated to a linear increase of 0.78, 95% CI [0.60, 0.97] in CVI Range Rating 2 for each year of participation on the programme. The mixed effects models also revealed significant interindividual differences in functional vision, which could be partly explained by a significant negative effect of acuity and by a joint positive effect of nystagmus and time, but not by age. These findings demonstrated that significant improvements in functional vision are still possible for students with CVI long after the accepted sensitive period of neuroplasticity in the visual cortex. Further studies incorporating research designs appropriate for evaluating complex interventions are required to determine which individual and contextual characteristics are valid and reliable predictors of improvements in functional vision for young people with CVI.