Study: Sleep apnea associated with retinal nerve fiber layer

In a small study, sleep apnea syndrome was correlated with a proportional decrease in the retinal nerve fiber layer. A decrease in ocular perfusion related to hypoxia and vasospasm associated with sleep apnea may cause retinal nerve fiber layer thinning and may precede clinically detectable glaucoma, the study authors noted.

S.H. Kargi, MD, and colleagues at Karaelmas University in Turkey evaluated 66 patients admitted for polysomnographic evaluation of suspected obstructive sleep apnea syndrome. Patients underwent an overnight sleep study to determine the severity of the sleep apnea. Patients were divided into three groups: those with mild sleep apnea, those with severe sleep apnea and those without sleep apnea. All patients underwent an ophthalmic exam that included visual acuity, slit-lamp examination, Goldmann applanation tonometry, gonioscopy and fundus exam.

Patients diagnosed with glaucoma or who had systemic diseases known to affect retinal nerve fiber layer thickness were excluded, leaving 34 patients in the study.

Of the 34 patients, 19 were diagnosed with mild sleep apnea and 15 with severe sleep apnea. Results were compared with 20 subjects without sleep apnea.

In patients with sleep apnea, retinal nerve fiber layer thickness was reduced when compared with subjects who did not have sleep apnea. The decrease in retinal fiber thickness was correlated with the severity of sleep apnea (P = .01).

The study is published in the May issue of Eye.