Optic disc parameters and associations with early life exposures in over 3000 12-year-old children: findings from the ALSPAC cohort

Objectives
We aimed to investigate the distribution of small optic discs and large cup-to-disc ratio in children and to examine associations with maternal and environmental factors.

Methods
Retinal photographs were graded from over 3000 12-year-olds in the Avon Longitudinal Study of Parents and Children. Regression models examined associations between disc parameters and maternal and early-life exposures.

Results
Mean cup-to-disc area ratio (CDAR) for 3288 children was 0.21 (95%CI 0.20,0.21). Discs with CDAR > 0.3 were present in 11%. The odds of CDAR > 0.3 were increased nearly three-fold in underweight children (adjusted odds ratio (aOR) 2.9 (1.1, 7.3) p = 0.03) and 28-fold in severely premature ( < 28 weeks) children (paOR 28 95%CI 4.6,172, p < 0.001) with nearly one in four children affected. Mean cup-to-fovea/disc diameter (CF/DD) for 3327 children was 2.48 (95%CI 2.47,2.50). Small discs (CF/DD > 3) were present in 6% of which a third were bilateral. The odds of a small disc were increased in the offspring of mothers who smoked in pregnancy (aOR 1.7 (1.0,2.8) p = 0.04) and more than doubled in children born with a small head circumference (aOR 2.5 (1.4,4.5) p < 0.001).

Conclusions
Small optic discs and high cup-to-disc ratio are more frequent than usually supposed at age 12. The odds of CDAR > 0.3 are increased by severe prematurity and pathologically low child BMI. The odds of a small disc are increased by maternal smoking and small head circumference. Optimisation of risk factors in pregnancy and delivery and early childhood nutrition may play an important role in ophthalmic neurodevelopment and thus have a lifelong impact on ocular health.