Update on non-radiologic ocular and orbital imaging in thyroid eye disease: a review

SignificanceThyroid eye disease (TED) involves inflammatory, vascular, and fibrotic remodeling of periocular tissues that is traditionally characterized by clinical activity scores and, at times, by conventional neuroimaging. Emerging noninvasive imaging modalities are poised to enhance clinical assessment by objectively quantifying inflammation, vascular alterations, fibrosis, and changes in tissue architecture. These tissue biomarkers have the potential to improve prediction of disease progression and therapeutic response beyond what can be inferred from clinical activity scores alone.AimThis review synthesizes established and emerging periocular nonionizing imaging techniques for TED, including ultrasound-based methods, optical coherence tomography (OCT), confocal microscopy (CM), and spatial frequency domain imaging (SFDI).ApproachPeer-reviewed studies evaluating human subjects with TED were reviewed to understand the technical aspects, advantages, limitations, and clinical relevance of each modality.ResultsUltrasound elastography and high-frequency ultrasonography enable assessment of tissue stiffness, thickness, and vascularity but are limited by operator dependence and penetration depth. OCT and OCT-angiography provide high-resolution evaluation of retinal, choroidal, and anterior segment structural and vascular changes associated with orbital congestion. Confocal microscopy identifies anatomical alterations that differentiate active from inactive disease. SFDI enables wide-field, noncontact quantification of periocular optical properties, with preliminary findings suggesting sensitivity to inflammatory edema.ConclusionsThis review summarizes current and emerging imaging modalities used to provide quantitative, high-resolution assessment of structural and functional tissue changes in TED.