Abstract:AIM: To investigate the potential of optical coherence tomography angiography (OCTA) for detecting subclinical microvascular damage, possibly before ocular complications develop, in treatment-naive Cushing’s disease (CD) patients. METHODS: This retrospective cross-sectional study included 48 newly diagnosed, treatment-naive CD patients and 48 healthy controls. Ophthalmological examinations, including best-corrected visual acuity, intraocular pressure, optical coherence tomography (OCT), and OCTA were conducted. Retinal and choroidal vessel density (VD) parameters were assessed in the macular and peripapillary regions. Correlations between VD and systemic hormone levels were analyzed. RESULTS: Age (47.3±13.3y vs 43.4±15.8y; P=0.053) and gender distribution (CD: 35 females, 13 males; controls: 34 females, 14 males; P=1.000) did not significantly differ. Patient group exhibited significant reductions in radial peripapillary capillary (RPC; P<0.05) and choriocapillaris (CC) VD across all quadrants (P<0.05) compared to controls. Nasal deep capillary plexus (DCP) VD was also significantly decreased (P=0.035). Subfoveal choroidal thickness (SFCT; P=0.459) did not differ significantly, but nasal choroidal thickness (CT) at 1500 µm (P<0.040) and 3000 µm (P<0.031) was markedly increased. Notably, hormonal correlations revealed associations between ACTH and temporal CC VD (r=0.367, P=0.009), plasma cortisol and superior RPC VD (r=0.303, P=0.034), and urinary free cortisol with superior, and nasal RPC (r=-0.404, P=0.004, r=-0.317, P=0.027) and nasal DCP VD (r=-0.287, P=0.045). CONCLUSION: High endogenous cortisol levels in CD patients primarily affect the peripapillary region and the nasal part of the macula. VD changes occur before pachyvessel formation, choroidal thickening, and the development of pachychoroid spectrum disorder.