Purpose:
Obstructive sleep apnea (OSA) alters cerebral vascular reactivity, possibly mediated via hypercapnea. While OSA has been associated with anterior ischemic optic neuropathy, glaucoma, and raised intracranial pressure (ICP), the potentially detrimental effects upon optic nerve and retinal microvasculature health have not been comprehensively addressed. We evaluated optic nerve and retinal vasculature appearance prospectively in patients undergoing routine, diagnostic polysomnography (dPSG).
Methods:
Non-mydriatic fundus photography of patients undergoing overnight polysomnography was performed. Demographics and BMI were documented. A prospective questionnaire exploring medical/ocular history, increased ICP symptoms, headache, and sleepiness (including HIT6 & Berlin questionnaire) was administered. Fundus photographs were assessed for abnormalities. Fractal dimension and lacunarity (ImageJ/FracLac) of the retinal vascular tree were determined. Apnea-hypopnea index (AHI) and hypoxic burden were the primary polysomnography measures. OSA was defined as AHI>15
Results:
Of 180 patients undergoing dPSG, fundus photographs were performed on 155 patients (exclusions: 20 refusals, 3 unable to give consent, 2 known hydrocephalus). Demographics: mean age 58 years, 84M 71F, 59% Caucasian, 35% African-American. 23 patients had severe OSA (AHI>20, hypoxic burden>10%), and 63 moderate/mild OSA. The remaining 69 patients with other sleep diagnoses became the control population. 239 photographs were taken from the155 patients before, during and after a night of sleep. There was no difference between OSA and non-OSA patients with respect to age, sex, ethnicity and headache phenotype (p<0.05). OSA patients had a significantly greater BMI (34 versus 30;p=0.02). No patients had symptoms of increased ICP. No evidence of disc edema or vascular changes were observed in any patients (95%CI:0-4.5%). There was no association between vascular fractal measures and indices of OSA.
Conclusions:
There was no evidence of retinal vascular changes or optic disc edema to suggest subclinical increased ICP in our OSA population, even in those with severe OSA. Routine clinical fundoscopic screening of OSA patients appears unwarranted.
Keywords: neuro-ophthalmology: optic nerve • retina • imaging/image analysis: clinical