Thyroid Eye Disease and Exophthalmos

Introduction to Exophthalmos

The American College of Radiology states that thyroid eye disease is the most common cause of exophthalmos, but other etiologies such as orbital tumors, inflammatory conditions, vascular abnormalities, and infections must be considered in the differential diagnosis 1, 2
Bilateral exophthalmos is most commonly due to thyroid eye disease, while unilateral exophthalmos raises suspicion for orbital mass lesions 1

The American College of Radiology recommends considering thyroid eye disease as the most common cause of bilateral exophthalmos 1
Characterized by tendon-sparing enlargement of extraocular muscles, thyroid eye disease often presents with lid retraction, restrictive strabismus, and orbital congestion 2, 3
The American Academy of Ophthalmology notes that thyroid eye disease can occur in hyperthyroid, hypothyroid, or euthyroid states 2

The American College of Radiology suggests that lymphoma, IgG4-related disease, and carotid-cavernous fistula should be considered in the differential diagnosis of exophthalmos 1
Vascular studies such as CTA, MRA, or DSA are recommended when vascular abnormalities are suspected 1

The American Academy of Ophthalmology recommends assessing for eyelid retraction, lid lag, and restrictive strabismus in patients with exophthalmos 2
Evaluating for signs of optic neuropathy, including visual acuity, color vision, visual fields, and pupillary exam, is crucial in patients with exophthalmos 2, 3
The American College of Radiology suggests that:

The American Academy of Ophthalmology notes that myasthenia gravis should be considered in patients with thyroid eye disease who have atypical ocular motility findings 3
Systematically evaluating patients with exophthalmos and utilizing appropriate imaging studies can help identify the underlying cause and prevent vision-threatening complications, as recommended by the American College of Radiology 1
The American College of Radiology recommends CT scan as the best way to demonstrate thyroid ophthalmopathy, particularly when evaluating extraocular muscle involvement and when considering orbital decompression surgery 1
Physical examination is the initial step in diagnosis and includes measurement of exophthalmos using an exophthalmometer, assessment for eyelid retraction and lid lag, evaluation of extraocular muscle function and restriction, and observation for fixation duress (brow elevation and eyelid retraction on attempted ocular elevation) 3
Imaging helps differentiate thyroid ophthalmopathy from other orbital inflammatory conditions and masses, and:
Clinical findings may include: