Effect of obstructive sleep apnoea syndrome and continuous positive airway pressure treatment on choroidal structure

Objectives To evaluate the effect of obstructive sleep apnoea syndrome (OSAS) and continuous positive airway pressure (CPAP) therapy on choroidal structural changes and choroidal vascularity index (CVI) in patients with OSAS. Methods Choroidal structural changes in patients with OSAS immediately after diagnosis and 12 months after CPAP treatment were evaluated and compared with healthy controls. The choroidal images on enhanced depth imaging optical coherence tomography (EDI-OCT) were binarized into luminal area (LA) and stromal area (SA) using the ImageJ software. CVI was calculated as the ratio of LA to total choroid area (TCA). The correlations between the results of polysomnography (PSG) and choroidal parameters were evaluated. Results A total of 48 eyes of 48 patients (22 patients with OSAS, and 26 controls) were included. The mean age of the patients was 47.21 +/- 8.82 (range, 30-63) years. The mean CVI values were 68.10 +/- 1.80% in the OSAS group before CPAP therapy, and 69.22 +/- 1.40% in the control group (p < 0.05). After 12 months of regular CPAP therapy, the mean CVI value increased significantly to 69.15 +/- 1.77%, and SA decreased significantly from 0.51 +/- 0.07 mm(2) to 0.48 +/- 0.07 mm(2) in the OSAS group (p < 0.05). No statistically significant correlation was found between the results of PSG and choroidal structural parameters. Conclusion According to our results, OSAS was associated with increased stromal oedema in the choroid, which improved after 12 months of regular CPAP therapy. CVI can be an important parameter for the follow-up of patients with OSAS.