Changes in Orbital Macrovascular and Intraocular Microvascular Blood Flow After Orbital Decompression Surgery in Patients With Thyroid Eye Disease

Thyroid-associated orbitopathy (TAO) is an autoimmune condition that can lead to increased orbital tissue volume, proptosis, elevated intraocular pressure, and impaired venous outflow. In the inactive phase of the disease, balanced orbital decompression (BOD) is commonly performed to relieve orbital pressure and improve both anatomical and functional outcomes.

While the clinical benefits of orbital decompression are well established, its effects on orbital blood flow and intraocular microcirculation have not been sufficiently investigated, particularly over time. This study is designed to prospectively evaluate the impact of BOD on orbital macrovascular structures and retinal-choroidal microvascular networks in patients with inactive TAO.

Patients undergoing BOD for severe proptosis will be evaluated before surgery and at multiple postoperative follow-up visits. Assessments include clinical ophthalmologic examinations, intraocular pressure measurements, and imaging-based evaluation of orbital and intraocular circulation. Orbital macrovascular parameters will be assessed using Doppler ultrasonography, while retinal and choroidal microcirculation will be analyzed using optical coherence tomography angiography (OCTA).

The study aims to characterize time-dependent vascular changes following surgery and to explore the relationship between macrovascular and microvascular responses. By providing longitudinal data, this study seeks to improve understanding of how orbital decompression influences ocular perfusion and vascular regulation, contributing to a more comprehensive evaluation of surgical outcomes in inactive TAO.

Inclusion criteria

• Adults aged 18 years or older
• Diagnosis of inactive thyroid-associated orbitopathy
• Presence of moderate-to-severe proptosis with indication for surgical orbital decompression
• Planned to undergo balanced orbital decompression surgery
• Ability to provide written informed consent
• Adequate image quality for OCTA and Doppler ultrasonography assessments

Exclusion criteria

• Active phase thyroid-associated orbitopathy
• Thyroid dysfunction or systemic condition contraindicating general anesthesia
• Proptosis due to causes other than TAO
• History of orbital radiotherapy
• Previous orbital or intraocular surgery
• Presence of retinal or choroidal pathology affecting vascular measurements
• History of systemic vasculitis or other vascular diseases
• Diabetes mellitus or systemic hypertension
• Use of systemic immunosuppressive therapy
• Age under 18 years