Evaluation of retinal vascular parameters in bipolar disorder using optical coherence tomography angiography

Background: This study aimed to characterize retinal microvascular and morphological alterations in BD patients using optical coherence tomography (OCT) and optical coherence tomography angiography (OCTA), correlating findings with clinical variables and exploring potential biomarkers. Methods: Forty-four euthymic bipolar disorder patients and forty-four healthy controls were enrolled in the study. Only the right eye was examined in all subjects. Structural OCT and OCTA scans with signal strength ≥7were included. Group comparisons were initially performed using MANCOVA, followed by ANCOVA for individual variables, controlling for age and sex. Correlations between OCT/OCTA parameters and clinical variables were also assessed. Results: Our findings indicated that significant differences in VD were observed between BD patients and HCs across the superficial, deep, and choriocapillaris layer quadrants (t:−3.483, p = 0.00; t:-3.359, p = 0.00; t:4.908, p = 0.00; t:2.890, p = 0.000; t:3.797, p = 0.00; t:-2.391, p = 0.01, respectively). RNFL thickness was found to be higher in the HCs for both the superior and inferior quadrants (t:-2.079, p = 0.04; t:-2.099, p = 0.03). ANCOVA revealed that parameters such as VD in the superficial central, deep central, and deep superior layers were significantly lower in the BD group compared to the control group (p < 0.001). The correlation analysis revealed several correlations between VD, RNFL and various clinical variables. Conclusions: BD is associated not only with retinal neuronal degeneration, such as RNFL changes, but also with vascular dysfunction, as indicated by parameters like VD in our study. The diagnostic value of OCTA underscores its potential as a valuable tool for monitoring and diagnosing BD.