Ischemic optic neuropathy (ION) is damage to the optic nerve caused by ischemia and hypoxia of the optic nerve due to an impairment of the blood supply to the optic nerve from the arteries. Obstructive Sleep Apnea Hypoventilation Syndrome (OSAHS) is a sleep-breathing disorder characterized by recurrent upper airway obstruction and apnea during sleep, leading to recurrent intermittent hypoxemia with fragmented sleep and daytime sleepiness. Due to the lack of accurate methods to evaluate blood flow, the correlation between the two is unclear and uncertain. The study will enroll 80 patients from the First Affiliated Hospital of Nanjing Medical University and categorize them into mild, moderate, and severe OSA groups according to their apnea-hypopnea index (AHI). Participants will undergo a baseline evaluation, including polysomnography (PSG) and ophthalmologic examinations such as optic nerve and macular blood flow OCT, visual acuity, refraction, intraocular pressure, and visual fields. Eligible patients will be treated with CPAP for 3 months, after which their PSG and ophthalmologic examination-related results will be re-evaluated to assess treatment efficacy.