Natural history and visual outcome of nonarteritic anterior ischemic optic neuropathy in Southern Taiwan: a pilot study.

Purpose: To investigate the natural course, visual outcome, and risk factors for visual loss after nonarteritic anterior ischemic optic neuropathy (NAION) attack in Chinese patients from a tertiary medical center in Southern Taiwan.

Methods: This is a longitudinal observational study that included sixty NAION patients, who were seen in our neuro-ophthalmology clinic from 2007 to 2016. Records of their ophthalmic history, medical history, best-corrected visual acuity (BCVA), visual field (VF) testing, and optical coherence tomography (OCT) were obtained for analysis.

Results: When the first visit was within two weeks after NAION onset, 62% of patients had BCVA of less than 0.1 (logMAR BCVA ≥ 1) and 38% had at least moderate-severe depression (VF grade ≥ 3) on VF on the initial visit. VA stabilized at three months after onset and was predictive of VA at 12 months. Diabetes mellitus was a risk factor associated with VA worsening. Sixty-one percent of patients had BCVA of less than 0.1 at 12 months after onset. VF remained relatively unchanged during the disease, with 41% eyes having VF grade ≥ 3 at 12 months after onset. On OCT, all quadrants of retinal nerve fiber layer thickened initially, returned to the level of the fellow eye at one month, and continued thinning up to 12 months slowly.

Conclusion: In Southern Taiwan, a higher proportion of Chinese patients (over half) presented with severe visual loss during the first two weeks of NAION attack and at 12 months after the onset of NAION as compared to the findings previously reported in Caucasians. Understanding the natural course of NAION in Chinese patients may provide insights toward a possible therapeutic window for NAION treatments in this group of patients.