Alterations in retrobulbar haemodynamics in thyroid eye disease

Abstract

Purpose: To study the orbital perfusion parameters of ophthalmic artery (OA) and central retinal artery (CRA) in inactive TED and the changes following surgical decompression.

Methods: Non-randomised clinical trial. 24 inactive moderate-to-severe TED orbits of 24 euthyroid cases underwent surgical decompression and examined again at 3 months. The peak systolic velocity (PSV), end-diastolic velocity (EDV), and resistivity index (RI) of OA and CRA were evaluated using colour doppler imaging and normative database was established using 18 healthy controls.

Results: The mean age was 39.38 ± 12.56 years and male: female ratio was 1: 1.18. Intraocular pressure was higher, and CRA-PSV, CRA-RI, OA-PSV, and OA-EDV were lower in TED in comparison to heathy orbits. The CRA-PSV, CRA-EDV, OA-PSV, and OA-EDV negatively correlated with proptosis and duration of thyroid disease. The area under curve of OA-PSV (95% CI:0.964-1.000, p < 0.001) and OA-EDV (95% CI:0.699-0.905, p < 0.001) helped in differentiating TED orbits from HC, and in predicting the severity of disease. Post decompression, CRA-PSV, CRA-EDV, OA-PSV, and OA-EDV improved, with decrease in CRA-RI and OA-RI in both lipogenic and MO.

Conclusions: The orbital perfusion is reduced in inactive TED. The changes in OA flow velocities can help in differentiating inactive TED from healthy orbits and progression of TED. Sequential orbital CDI of OA and CRA can serve as an objective tool for case selection and monitoring response to surgical decompression.

Fig. 1. ROC comparing doppler parameter changes.

A Between TED orbits and healthy controls. Maximum AUROC is observed for OA-PSV, followed by OA-EDV, and minimum for CRA-EDV. B Between mild and moderate-to-severe TED orbits. Maximum AUROC is observed for OA-EDV, followed by OA-PSV, and minimum for CRA-RI. C Between ‘high Barret index’ and ‘low Barret index’ orbits. Maximum AUROC is observed for OA-EDV, followed by OA-PSV, and minimum for OA-RI. CRA Central retinal artery, EDV End diastolic velocity, OA Ophthalmic artery, PSV Peak systolic velocity, RI Resistivity index.

Fig. 2. CDI showing gate placement and velocity waveform.

A–D Moderate-to-severe inactive TED with Type – 1 orbitopathy. A CRA showing PSV = 7.7 cm/s, EDV = 2.9 cm/s, RI = 0.62 at enrolment, which improved to B CRA with PSV = 13.2 cm/s, EDV = 4.1 cm/s, RI = 0.69 post decompression. C OA at enrolment showing PSV = 13.5 cm/s, EDV = 3.7 cm/s, RI = 0.73 which improved post surgery to D OA showing PSV = 20.3 cm/s, EDV = 5.2 cm/s, RI = 0.74. E–H Moderate-to-severe inactive TED with Type – 2 orbitopathy. E CRA showing PSV = 5.65 cm/s, EDV = 1.23 cm/s, RI = 0.78 at enrolment, which improved to F CRA flow with PSV = 10.3 cm/s, EDV = 3.9 cm/s, RI = 0.62 post decompression. G OA at enrolment showing PSV = 9.8 cm/s, EDV = 1.9 cm/s, RI = 0.81 which improved to H OA showing PSV = 15.6 cm/s, EDV = 7.6 cm/s, RI = 0.51. I–L: Fellow orbit with moderate-to-severe inactive TED and Type – 2 orbitopathy. I CRA showing PSV = 16.3 cm/s, EDV = 5.0 cm/s, RI = 0.69 at enrolment, which decreased to J CRA flow with PSV = 12.7 cm/s, EDV = 3.4 cm/s, RI = 0.73 at three months follow-up. K OA at enrolment showing PSV = 20.1 cm/s, EDV = 8.3 cm/s, RI = 0.59 which worsened to L OA showing PSV = 16.5 cm/s, EDV = 5.9 cm/s, RI = 0.64.