Clinical and demographic associations with optic nerve hypoplasia in New Zealand

To identify the clinical features of optic nerve hypoplasia (ONH) and prevalence within a population of New Zealand children with severe visual impairment.

Retrospective review of medical records of children with severe visual impairment registered with Blind and Low Vision Educational Network New Zealand.

Of 1500 children with severe visual impairment, 94 (6.3%) exhibited ONH, and 91 (97%) cases were bilateral. Of these 94 cases, 52 (55%) were males and ethnicities were European Caucasian (52%), Maori (40%), Pasifika (6%) and other (2%). Most children with ONH had poor vision, with 60% having ≤ 6/60 Snellen visual acuity equivalent. The median maternal age was 20.0 years old with 52% ≤ 20 years. There was a statistically significant over-representation of Maori ethnicity (40%) and young maternal age with age less than 20 years old (44%) in our cohort compared to the general population (14.6% and 7.4%, respectively; p<0.0001). Half had hypopituitarism, while neuroimaging abnormalities were detected in 60% cases. Cerebral neuroradiographic abnormalities were found to be associated with higher rate of developmental delay (OR 9.764 95% CI 3.246 to 29.373).

This is the first major study of visual impairment in New Zealand children, and it demonstrates that ONH is an important cause of severe visual disability; with an over-representation of Maori children and younger maternal age.