Risk Factors for Fellow Eye Involvement in Patients with Nonarteritic Anterior Ischemic Optic Neuropathy.

INTRODUCTION: To investigate the possible risk factors for fellow eye involvement in patients with nonarteritic anterior ischemic optic neuropathy (NAION). METHODS: A total of 113 patients with unilateral NAION attack were included and divided into two groups according to whether fellow eye involvement was present over a mean follow-up period of 2.70 years (P25-P75: 0.77-3.54 years). General characteristics (including age, sex, diabetes, hypertension, hyperlipidemia and obstructive sleep apnea syndrome) and ocular characteristics (including initial best corrected visual acuity, initial visual field damage of the first eye and the presence/absence of a crowded disc) were analyzed and compared between the two groups. Cox regression was used to assess the risk factors for fellow eye involvement. RESULTS: During the follow-up period, 40 patients developed fellow eye involvement. The initial best corrected visual acuity (P = 0.048) and mean deviation (MD) of the visual field (VF) (P = 0.039) of the first eye in patients with fellow eye involvement were worse than those in patients without it. Diabetes (HR = 3.06, 95% CI: 1. 50, 6.26, P = 0.002) and increased VF damage (moderate vs. mild, HR = 2.92, 95% CI: 1.03, 8.25, P = 0.043; severe vs. mild, HR = 5.01, 95% CI: 1.65, 15.20, P = 0.004) were associated with a significantly increased risk of fellow eye involvement. In 57 patients with apnea hypopnea index (AHI) data for further study, an AHI score≥ 23.2 was also found to be a risk factor (HR = 3.36, 95% CI: 1.17, 9.69, P = 0.025). CONCLUSION: Diabetes, severer initial VF damage, and more severe obstructive sleep apnea syndrome (OSAS) were risk factors for fellow eye involvement in NAION. For patients with these risk factors, more intensive follow-ups might be warranted.