Diagnosis
Grave’s ophthalmopathy
Discussion
Differential Diagnosis:
This patient presents with possible Grave's ophthalmopathy, also know as thyroid ophthalmopathy. Other diseases in the differential diagnoses include conditions that cause orbital congestion (orbital tumors, orbital infections like orbital cellulitis), other causes of orbital inflammation (orbital pseudotumor - now called idiopathic orbital inflammation, Wegener's granulomatosis, orbital myositis).
Definition:
Grave's ophthalmopathy occurs secondary to an autoimmune process which leads to changes in orbital content (mainly extraocular muscles and orbital fat). The process is thought to be an antibody-mediated reaction against the thyroid stimulating hormone (TSH) receptor, although specific immunoglobulins are found in only 50% of patients via blood tests. T-cell lymphocytes also migrate to the orbit where they are stimulated to initiate an immune response. This causes infiltration and enlargement of the extraocular muscles (with sparing of the muscle tendons), and orbital congestion (which accounts for most of the clinical findings in Grave's ophthalmopathy). Patients with thyroid ophthalmopathy do not always have active thyroid disease.
Examination:
Symptoms may include upper and lower eyelid retraction, dry eyes, double vision, eye muscle weakness, excessive tearing, and eye irritation. Exam findings may show exophthalmos or proptosis (forward movement of the globe), lagophthalmos (inability to close eyes), strabismus (misalignment of eyes), swelling of the eyelids, corneal dryness, chemosis of the conjunctiva, increased intraocular pressure, and, in extreme cases, congestion of the optic nerve by the swollen orbital structures and vision loss.
Work up of Grave’s ophthalmopathy includes a non-contrast orbital CT which will often show bilateral extraocular muscle (EOM) enlargement with sparing of tendons. Other work-up can include TSH, and free T3, T4 levels.
Treatment:
Treatment of Grave’s ophthalmopathy is independent of systemic disease. Treatment depends on signs and sxs and severity of disease. Artificial tears can be used for corneal exposure. Eyelid surgery can be considered for severe lid retraction. High dose glucocorticoids are used for severe orbital congestion and optic neuropathy. Steroid-sparring agents and additional immunomodulators are also used (cyclosporine, azathioprine). Sometimes, surgical decompression of the orbit is needed to prevent severe exophthalmos and optic nerve compression. If patients develop diplopia secondary to muscle enlargement and fibrosis, prisms and then strabismus surgery are offered after the inflammatory response is controlled. Eyelid surgery is offered in patients that have severe exposure due to a fibrotic levator muscle. Most cases of grave’s ophthalmopathy stabilize within 8-36 months.
