Causes of childhood low vision and blindness in New Zealand.

IMPORTANCE: This is the first national study on childhood visual impairment in a developed nation, New Zealand; describing prevalence, aetiology and preventable causes of low vision and blindness in children.

BACKGROUND: Causes of childhood blindness varies between regions. This study aimed to present region-specific data on epidemiology of childhood blindness affecting a developed nation, New Zealand.

DESIGN: Retrospective data analysis PARTICIPANTS: All children enrolled with the Blind and Low Vision Education Network (BLENNZ) with best corrected visual acuity =<6/18, or binocular visual field <10 degrees.

METHODS: 1000 out of 1321 children with visual impairment enrolled with BLENNZ were included. The principal cause of visual loss was determined, and the severity of visual loss categorized as low vision, or blindness according to the WHO criteria.

MAIN OUTCOME MEASURES: Main outcome measures were degree of visual impairment, aetiology of visual impairment and treatment modalities for visual rehabilitation.

RESULTS: The calculated prevalence of childhood blindness and low vision was 0.05% and 0.06%. Principle causes of blindness were: cortical visual impairment (31.5%), optic nerve atrophy (16.5%) and optic nerve hypoplasia (9.0%). The main preventable causes of blindness were neonatal trauma/asphyxia (31.5%), retinopathy of prematurity (18.2%) and non-accidental injury (10.3%).

CONCLUSIONS AND RELEVANCE: This is the first national report on prevalence of childhood low vision and blindness in New Zealand. The prevalence and leading causes of low vision and blindness found in this study were comparable to other developed nations; however, preventable causes of low vision and blindness appeared unique to New Zealand.