Abstract
OBJECTIVE: To analyse retinal and choroidal microvascular alterations in patients with thyroid-associated ophthalmopathy (TAO) and hyperthyroidism without signs of TAO using swept-source optical coherence tomography angiography (SS-OCTA) and to investigate the potential reasons for ocular microvascular changes in patients with TAO. METHODS: Thirty patients with active TAO (group A), thirty patients with hyperthyroidism without signs of TAO (group B), and thirty healthy subjects (group C) were recruited. The images of macula and optic nerve head were obtained by SS-OCTA. Vessel density (VD) of superficial capillary plexus (SCP), deep capillary plexus, radial peripapillary capillary and choriocapillaris (CC), choroidal vascularity index, foveal avascular zone area, macular thickness, macular ganglion cell complex thickness, choroidal thickness (CT), and retinal nerve fibre layer thickness were measured. RESULTS: Group A had significantly higher VD of SCP than group C (all p < 0.05), and group B had significantly lower VD of SCP than group C (all p < 0.05). The VD of CC was significantly lower in group A than in groups B and C (p < 0.05). CT was significantly thicker in groups A and B than in group C (all p < 0.05). Multivariable regression analysis showed that the free triiodothyronine was significantly negatively correlated with the VD of SCP in the parafoveal regions in groups B and C (p < 0.05) and proptosis was significantly positively correlated with the VD of SCP in groups A and B (all p < 0.05). CONCLUSION: We noted a difference in the VD of SCP and CC between patients with TAO and patients with hyperthyroidism without signs of TAO. These relative differences in ocular microvasculature indicated that local (orbital) and systemic (thyroid-related) factors may both play a role in disease presentation and progression, with orbital factors having a greater impact.