Impaired blood flow of optic nerve head in patients with severe obstructive sleep apnea/hypopnea syndrome

This study prospectively analysed the difference in the blood flow of the optic nerve head (ONH) between patients with obstructive sleep apnea/hypopnea syndrome (OSA) and control subjects by laser speckle flowgraphy (LSFG), and determined the correlations between LSFG variables and the severity of OSA. A total of 100 participants consecutively underwent full-night polysomnography, ophthalmologic examinations, and LSFG measurements. The LSFG parameters were summarised as the mean blur rate in all areas of the ONH (MA), in the big vessel area of ONH (MV), and in the tissue area of ONH (MT). When the control (17 subjects) and patients with mild/moderate OSA (42 patients) were grouped together and compared with patients with severe OSA (41 patients), the MA, MV, and MT were decreased significantly in patients with severe OSA compared with control subjects and patients with mild/moderate OSA (p < 0.0001, p = 0.0001, and p = 0.0034, respectively). Negative correlations were identified between the apnea-hypopnea index and MA (ρ = -0.244, p = 0.0016), between AHI and MV (ρ = -0.263, p = 0.0006), and between AHI and MT (ρ = -0.198, p = 0.0105). Positive correlations were identified between the lowest saturation of oxygen (LSaO₂) and MA (ρ = 0.332, p < 0.0001), between LSaO₂ and MV (ρ = 0.354, p < 0.0001), and between LSaO₂ and MT (ρ = 0.227, p = 0.0035). Our study demonstrated that OSA could have a negative impact on the microcirculation of the optic nerve head, including MA, MV, and MT measurements. Furthermore, the decreased blood flow of the optic nerve head obviously correlated with the severity of OSA.