Diagnostic Value of Ocular Hemodynamics and Choroidal Thickness in Unilateral Sudden Sensorineural Hearing Loss: Non-Invasive Biomarkers of Systemic Microvascular Disease

Background/Objectives: Although vascular mechanisms are increasingly implicated in the etiology of sudden sensorineural hearing loss (SSNHL), the inability to directly visualize the labyrinthine artery remains a diagnostic obstacle. Sharing embryological and physiological parallels with the inner ear, the eye represents an accessible surrogate organ capable of reflecting systemic microvascular status. This study aimed to evaluate the diagnostic value of ocular hemodynamic and structural parameters in patients with acute unilateral idiopathic SSNHL. Methods: This prospective, comparative, cross-sectional study enrolled 30 patients with acute unilateral idiopathic SSNHL and 25 age and sex matched healthy controls. Three groups were defined: the affected eye, the contralateral eye, and the control eye. Retrobulbar hemodynamics (PSV, EDV, RI, PI) were assessed by color Doppler imaging; peripapillary choroidal thickness, RNFL, GCC+, and macular thickness by swept-source OCT; and macular microvascular perfusion by OCT angiography. Results: End diastolic velocity in the posterior ciliary arteries was significantly reduced in both patient eye groups relative to controls (p < 0.001), while RI and PI were significantly elevated (p = 0.001 and p = 0.004, respectively). Comparable hemodynamic impairment was observed in the ophthalmic artery. Peripapillary choroidal thickness was bilaterally reduced in the inferior and temporal quadrants in both patient groups (p = 0.003 and p = 0.010). No significant difference was detected between affected and contralateral eyes in any parameter. RNFL, GC+, and macular thickness remained comparable across all groups. Conclusions: The bilateral symmetry of hemodynamic impairment and choroidal thinning suggests that SSNHL arises against a background of systemic microvascular disease. The combined use of OCT and color Doppler ultrasonography holds clinical potential as a non-invasive biomarker panel for defining the vascular phenotype of the condition.