Retinal nerve fibre layer measurements are reduced in patients with obstructive sleep apnoea syndrome

To determine the retinal nerve fibre layer (RNFL) thickness in patients with obstructive sleep apnoea syndrome (OSAS) in order to investigate the possibility of detecting early signs of glaucoma in this population.

A total of 66 consecutive patients admitted for polysomnographic evaluation of suspected OSAS. Patients underwent an overnight sleep study in an effort to diagnose and determine the severity of OSAS. Patients who had the disease were classified as having mild and severe OSAS, while patients who did not have the disease were classified as controls. All patients received physical, neurological, and ophthalmological evaluation including visual acuity, slit-lamp examination, Goldmann applanation tonometry, gonioscopy with a three mirror contact lens, and fundus examination. After these examinations, patients with glaucoma and patients who had ophthalmological and/or systemic disease known to affect RNFL thickness were excluded from the study. The RNFL thickness was assessed with a scanning laser polarimeter (Nerve Fiber Analyzer GDx, Laser Diagnostic Technologies Inc., San Diego, CA, USA).

A total of 34 patients with obstructive sleep apnoea (19 mild, 15 severe) and 20 age-matched controls were included in the study. The thickness of RNFL was reduced in patients with OSAS compared to controls. The decrease in RNFL was found to be correlated with the severity of sleep apnoea (r=0.78, P=0.01).

The sleep apnoea syndrome is correlated with a proportional decrease in the RNFL. Decreased ocular perfusion related to hypoxia and vasospasm associated with OSAS may cause RNFL thinning, which may precede clinically detectable glaucoma.