OCT Angiography Drived Alterations in Thyroid-associated Orbitopathy (TAO)

January 7, 2026 updated by: Osijek University Hospital

Effect of Morphological Orbital Changes on the Retinal Vascular Layers in Patients With Thyroid-associated Orbiopathy

The aim of this observational study is to evaluate retinal microvascular alterations in patients with thyroid-associated orbitopathy (TAO) using optical coherence tomography angiography (OCTA). The specific objectives are:

  • To assess the impact of extraocular muscle (EOM) enlargement on vessel density in the superficial and deep retinal capillary plexuses in patients with TAO.
  • To determine the effect of increased orbital fat volume on superficial and deep retinal vessel density in TAO.
  • To evaluate the relationship between disease activity, as measured by the Clinical Activity Score (CAS), and retinal microvascular density in patients with TAO.

Study Overview

Status

Completed

Conditions

Detailed Description

After obtaining written informed consent and confirming eligibility, all patients with TAO and controls underwent a detailed medical history review and ophthalmologic examination. Collected clinical data included age and sex. For patients with TAO collected data also oncluded duration of Graves' hyperthyroidism (GH) and orbitopathy (GO), as well as serum levels of thyroid-stimulating hormone (TSH), triiodothyronine (T3), thyroxine (T4), thyrotropin receptor antibodies (TRAb), and anti-thyroid peroxidase antibodies (anti-TPO). For all participants a comprehensive ophthalmologic assessment was performed, which included evaluation of the periocular region, ocular motility, pupillary reflexes, best-corrected visual acuity (BCVA), slit-lamp biomicroscopy, intraocular pressure (IOP) measurement using Goldmann applanation tonometry in primary and upward gaze, exophthalmometry with a Hertel device, and dilated fundus examination.

Disease activity in patientss with TAO was assessed using the Clinical Activity Score (CAS), following the European Group on Graves' Orbitopathy (EUGOGO) guidelines.

MRI images of orbit in TAO patients acquired using 1.5T and 3T scanners (Siemens Magnetom Avanto Fit 124 and Magnetom Skyra, Siemens Healthcare, Germany) during TAO evaluation were reviewed manually by an experienced radiologist using the PACS imaging software (Sectra 126 IDS7, Version 24.1, Linköping, Sweden). Measurements were performed on T1- and T2-weighted images in both coronal and axial planes.The maximum diameter of each of the four rectus muscles (medial, lateral, superior, and inferior) was measured at its thickest midpoint. Horizontal diameters of the medial and lateral rectus muscles were obtained on axial images, while vertical diameters of the superior and inferior rectus muscles were measured on coronal sections.

Exophthalmos was determined as the perpendicular distance between the anterior surface of the cornea and the line connecting both lateral orbital rims on the slice where the globe and optic nerve were most clearly visualized. Orbital fat thickness was measured as the maximum distance from the lateral border of the medial rectus muscle to the medial orbital wall. Based on radiological characteristics, patients with TAO were classified into three subtypes: fat-predominant, muscle-predominant, and mixed type.

Optical coherence tomography angiography (OCTA) was performed in all paticipants (patients with TAO and controls) using the OptoVue XR Avanti device equipped with the split-spectrum amplitude-decorrelation angiography (SSADA) algorithm (software version 2014.2.0.90), with the Angio Retina 6×6 mm protocol. Retinal vessel density was analyzed at two vascular levels-the superficial capillary plexus and the deep capillary plexus. Following the instrument's standardized protocol, the macula was divided into nine regions: a central foveal zone, parafoveal ring, and perifoveal ring, each subdivided into superior, inferior, nasal, and temporal quadrants. The foveal avascular zone was also measured.

Study Type

Observational

Enrollment (Actual)

68

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • Croatia
      • Osijek, Croatia, 31000
        • University Hospital Osijek

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

Yes

Sampling Method

Non-Probability Sample

Study Population

Patients with TED followed at Department of Ophthalmology, University Hospital Osijek, Department of Ophthalmology, Croatia.

Description

Inclusion Criteria:

  • adult patients (≥18 years) of both sexes with a confirmed diagnosis of TAO treated at University Hospital Osijek.

Exclusion Criteria:

  • anterior segment pathology (e.g., central keratopathy),
  • primary open- or closed-angle glaucoma,
  • posterior segment disorders (e.g., diabetic retinopathy, age-related macular degeneration, retinal vascular occlusion),
  • previous ocular trauma or uveitis,
  • refractive errors exceeding ±6.0 Diopter sphere or ±3.0 Diopter cylinder
  • media opacities that compromised angio optical OCTA image quality,
  • contraindication for orbital MRI

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

Cohorts and Interventions

Group / Cohort
Patients with TAO
The study cohort consisted of patients diagnosed with TAO of varying activity and duration. All subjects were Caucasian without other significant ocular comorbidities that could confound retinal microvascular measurements. Patients with TAO were classified based on MRI characteristics into three subgroups: fat-predominant, muscle-predominant, and mixed type.
Control group
Participants without TAO or other significant ocular comorbidities were included. All subjects were Caucasian and were age- and gender-matched to the TAO patient group.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Retinal vessel density (VD)
Time Frame: Baseline
Vessel density reflects the proportion of perfused vasculature within a defined retinal area and serves as a quantitative marker of retinal microcirculation. VD was evaluated separately in the superficial capillary plexus and the deep capillary plexus across the whole image as well as within the foveal, parafoveal, and perifoveal regions. Changes in vessel density were used to characterize microvascular alterations associated with thyroid-associated orbitopathy compared to healthy patients and to explore their relationship with disease activity and orbital structural parameters in TAO patients.
Baseline

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Osijek University Hospital

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

December 9, 2024

Primary Completion (Actual)

June 15, 2025

Study Completion (Actual)

July 30, 2025

Study Registration Dates

First Submitted

December 22, 2025

First Submitted That Met QC Criteria

January 7, 2026

First Posted (Actual)

January 14, 2026

Study Record Updates

Last Update Posted (Actual)

January 14, 2026

Last Update Submitted That Met QC Criteria

January 7, 2026

Last Verified

December 1, 2025

More Information

Terms related to this study

Keywords

Other Study ID Numbers

  • R1-11 819/2024.

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

UNDECIDED

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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