Cross-sectional study on childhood cerebral visual impairment in New Zealand

PURPOSE To determine the prevalence, etiology, and avoidable causes of childhood cerebral visual impairment (CVI) in New Zealand. METHODS The clinical and educational records of blind and low vision children enrolled in the Blind and Low Vision Education Network, New Zealand (BLENNZ), a national referral center, were retrospectively analyzed. The WHO Program for Prevention of Blindness (WHO/PBL) Eye Examination Record for Children with Blindness and Low Vision was used to record data from children <= 16 years of age diagnosed with CVI and visual acuity <= 6/18 enrolled with BLENNZ. Data analyzed included demographics, etiology, visual acuity, visual fields, educational setting, and rehabilitation plan. RESULTS A total of 182 children (blind, 143; low vision, 39) were included. The calculated prevalence of childhood CVI in New Zealand was 0.02%. Of these, only 21% required low vision aids. Principle causes of CVI blindness were perinatal hypoxia/asphyxia (25%), nonaccidental injury (7%), and prematurity (7%). Approximately 50% of all cases of CVI blindness were potentially avoidable; of these, 52% were caused by perinatal hypoxia and 14% by nonaccidental injury. CONCLUSIONS The conservative calculated prevalence of CVI, responsible for 30% of all childhood blindness in New Zealand, was 0.02%. The most common cause of CVI blindness in New Zealand, perinatal asphyxia, is also an avoidable cause.