OCTA-based evaluation of retinal microvascular and structural changes in patients with obstructive sleep apnea-hypopnea syndrome before and after treatment.

PURPOSE: This study aimed to investigate whether retinal microvascular and microstructural parameters vary according to the severity of obstructive sleep apnea-hypopnea syndrome (OSAS) and to assess changes before and after continuous positive airway pressure (CPAP) therapy using optical coherence tomography angiography (OCTA).

METHODS: A total of 60 healthy controls (60 eyes) and 97 OSAS patients (97 eyes) were recruited from the Departments of Otolaryngology and Pulmonology at The Affiliated People's Hospital of Ningbo University. Based on apnea-hypopnea index (AHI), OSAS patients were categorized into four groups: mild (n = 20, 20 eyes), moderate (n = 38, 38 eyes), severe (n = 19, 19 eyes), and extremely severe (n = 20, 20 eyes). Additionally, data from 26 eyes of 26 OSAS patients undergoing CPAP therapy were included. We assessed parameters including AHI, mean SpO2 (MSpO2), lowest SpO2 (LSpO2), baseline SpO2 (BSpO2), body mass index (BMI), systolic blood pressure (SBP), diastolic blood pressure (DBP), intraocular pressure (IOP), axial length (AL), and OCTA imaging. Statistical analyses were conducted using SPSS 29.0.

RESULTS: OSAS patients exhibited significantly higher BMI, SBP and DBP compared to controls(P < 0.05). OCTA findings indicated that, in comparison to controls, OSAS patients had a significantly larger foveal avascular zone (FAZ) area, increased FAZ perimeter and a reduced FAZ circularity index, along with decreased average retinal nerve fiber layer (RNFL) thickness, inner limiting membrane-retinal pigment epithelium (ILM-RPE) thickness, mean and minimum ganglion cell layer-inner plexiform layer (GCL-IPL) thickness, as well as lower central perfusion density(P-C), full perfusion density(P-F), and central linear vessel density(V-C) (all P < 0.05). Among the four OSAS severity groups, significant differences were observed in SBP, DBP, AL, AHI, MSpO2, LSpO2, BSpO2, average RNFL thickness, ILM-RPE thickness, mean and minimum GCL-IPL thickness, FAZ area, FAZ perimeter and all retinal related vascular parameters (P < 0.05). The FAZ area and perimeter were positively correlated with AHI (P < 0.05), while other retinal structural and vascular parameters showed negatively correlations with AHI (P < 0.05). Following CPAP therapy, we observed a significant reduction in both FAZ area and perimeter across all enrolled patients, along with improvements in retinal structural and vascular parameters. Notably, among the retinal vascular parameters, only P-C showed a significant increase across all three severity groups (moderate, severe, and very severe) of OSAS (all P < 0.05).

CONCLUSION: OSAS is associated with progressive retinal microvascular impairment accompanied by neuroretinal structural thinning. CPAP therapy can improve retinal vascular parameters together with accompanying structural changes, suggesting that retinal imaging may serve as a sensitive tool for evaluating retinal involvement and monitoring the efficacy of CPAP treatment in this population.