Structure-Function Analysis of Nonarteritic Anterior Ischemic Optic Neuropathy and Age-Related Differences in Outcome

Background: The optic nerve head is vulnerable to ischemia leading to anterior ischemic optic neuropathy (AION), the most common acute optic neuropathy in those older than 50 years of age. Methods: We performed a cross-sectional study of 55 nonarteritic anterior ischemic optic neuropathy (NAION) eyes in 34 patients to assess clinical outcome and perform structure-function correlations. Results: The peak age of NAION onset was between 50 and 55 years. Sixty-seven percent of patients presented with their first event between the ages of 40 and 60 years, and 32% presented at ≤50 years. Those with NAION onset at age ≤50 years did not have significantly better visual outcome per logMAR visual acuity, automated perimetric mean deviation (PMD) or optical coherence tomography (OCT) measurements. Kaplan-Meier survival curve and multivariate Cox proportional regression analysis showed that age >50 years at NAION onset was associated with greater risk of second eye involvement, with hazard ratio of 20. Older age at onset was significantly correlated with greater thinning of the ganglion cell complex (GCC) (P = 0.022) but not with logMAR visual acuity, PMD, or thinning of retinal nerve fiber layer (RNFL). Using area under receiver operating characteristic curve analyses, we found that thinning of RNFL and GCC was best able to predict visual outcome, and that mean RNFL thickness >65 m or macular GCC thickness >55 m significantly correlated with good visual field outcome. Conclusions: We showed that NAION onset at age >50 years had a greater risk of second eye involvement. Patients with OCT mean RNFL thickness >65 m and mean macular ganglion cell complex thickness >55 m had better visual outcomes.