Anatomic Considerations in Thyroid Eye Disease.

PURPOSE: To review and summarize the clinical findings in thyroid eye disease (TED) related to the unique anatomical structures of the eyelids and orbit.

METHODS: A PubMed search was performed searching for anatomical relationships between eyelid and orbital anatomy and the clinical findings of TED.

RESULTS: The major clinical findings associated with TED are varied. They typically involve both the eyelid and the orbit. In the eyelid, usual findings include upper eyelid retraction, contour abnormalities, eyelid edema, prolapsed orbital fat, conjunctival injection and chemosis, caruncular edema, and meibomian gland dysfunction. The exact causes of these changes remain a matter of controversy, but numerous hypotheses have been proposed, most with limited experimental support. In the orbit, inflammation and congestion characterize the acute active phase, with tissue expansion and fibrosis persisting into the chronic inactive phase. All of these findings result, at least in part, from the unique anatomy of the eyelids and orbit and their interaction with the immunologic processes underlying TED. Here we review these major characteristics of TED, with special reference to their anatomic relationships.

CONCLUSIONS: The major findings characterizing TED are related to unique anatomic features in the eyelid, including Müller muscle, the levator palpebrae superioris muscle, and suspensory ligaments of the conjunctiva. In the orbit, Graves-related remolding results from the special physiologic features of the extraocular muscles, the structure of the orbital walls and their relations to adjacent paranasal sinuses, and the reaction of orbital fat to immunologic challenges.