Evaluation of retinal vascular structure via optic coherence tomography angiography in obstructive sleep apnea

Evaluation of the retinal vascular structure with optic coherence tomography angiography (OCT-A) in patients with obstructive sleep apnea (OSA).

A total of 47 severe (Group 1), 30 moderate (Group 2), and 25 mild (Group 3) OSA patients and 51 healthy volunteers (Group 4) were included. Total, parafoveal, perifoveal superficial (SCP), and deep capillary plexus (DCP) vascular densities, foveal avascular zone (FAZ) and blood flow of choriocapillaris and outer retina were evaluated. Results were examined comparatively, and their correlation with hypoxia parameters (minSpO₂, meanSpO₂, T90%) in polysomnography was investigated.

There was no difference in terms of age and gender (p = 0.155, p = 0.313, respectively). No difference was detected between the groups in terms of SCP and DCP (p > 0.005 for all parameters). FAZ were 0.28 ± 0.28, 0.26 ± 0.08, 0.25 ± 0.09, and 0.28 ± 0.98 mm² for Group 1-4, respectively (p = 0.880). For Group 1-4; blood flow areas of outer retinal layer were 8.38 ± 4.5 (4.5-17.1), 8.18 ± 1.9 (5-16.8), 8.62 ± 2.1 (5.5-17.2), 8.44 ± 3.2 (5.1-17.5) mm² and blood flow areas of choriocapillaris were 19.96 ± 1.4 (17.6-31.2), 19.98 ± 0.8 (18.5-21.6), 19.98 ± 1.1 (17.7-22.2), 19.97 ± 1.1 (18.1-23.2) mm², respectively (p = 0.622, 0.558, respectively). Total, parafoveal and perifoveal DCP densities were correlated with meanSpO₂ (ρ = 0.269, 261, and 0.277, respectively); total and perifoveal DCP densities were correlated with meanSpO₂ (r = 0.028, 0.042, respectively). No correlation was detected between T90% and any OCT-A parameters.

After considering confounding factors, no significant difference was observed in the retinochoroidal circulation between the study group and healthy volunteers, or across different stages of OSA. The weak to moderate correlation between hypoxia parameters and DCP density may suggest that the microvascular structure could be impacted in the early stages.