Optic Nerve Thickness Assessed by Ocular Ultrasonography in Obstructive Sleep Apnea: Association with Disease...

Obstructive sleep apnea (OSA) has been associated with various ocular complications, yet ultrasonographic evaluation of optic nerve thickness and its relationship with nocturnal hypoxemia remains poorly understood. This study aimed to evaluate optic nerve thickness and globe dimensions using ocular ultrasonography in patients with different OSA severities and to investigate their associations with polysomnographic parameters.

In this prospective observational study, 108 participants (30 controls, 24 mild OSA, 20 moderate OSA, and 34 severe OSA) underwent overnight polysomnography and ocular ultrasonography. Right and left optic nerve thicknesses, globe transverse diameters, and anteroposterior diameters were measured.

Globe transverse and anteroposterior diameters did not differ according to OSA severity (all p > .05). In contrast, right and left optic nerve thickness progressively decreased with increasing OSA severity (p = .026 and p = .025, respectively). T90 was inversely correlated with right (r = -0.304, p = .001) and left (r = -0.294, p = .002) optic nerve thickness. In multivariable regression analyses adjusted for age and BMI, both AHI (right: β = -0.222, p = .030; left: β = -0.213, p = .039) and T90 (right: β = -0.236, p = .016; left: β = -0.286, p = .004) remained independently associated with optic nerve thickness.

Optic nerve thickness progressively decreased with increasing OSA severity, whereas globe dimensions remained unaffected. Cumulative nocturnal hypoxemia, reflected by prolonged T90, was independently associated with reduced optic nerve thickness in both eyes, suggesting that chronic nocturnal hypoxemia may contribute to optic nerve structural alterations in patients with OSA.