Thyroid Eye Disease

From EyeWiki


Thyroid Eye Disease (TED) consists of a variety of ocular manifestations which are related to systemic thyroid dysfunction. It is a condition that should be assessed by both the primary care physician and the ophthalmologist.[1]

Disease Entity

Thyroid Eye Disease (TED)

Disease

Thyroid Eye Disease (also known as Graves' ophthalmopathy, thyroid-associated ophthalmopathy, thyrotoxic exophthalmos, dysthyroid ophthalmopathy, and several other terms) is orbitopathy associated with thyroid dysfunction. The cause of thyroid eye disease is unknown.  Thyroid eye disease is typically associated with Graves hyperthyroidism but can also occur with immune-induced hypothyroidism or in the absence of thyroid dysfunction. The course of ophthalmic changes associated with thyroid eye disease does not necessarily correlate with thyroid function.  Bartley et al in a 1996 epidemiologic study of patients with thyroid eye disease determined an incidence rate for women was 16 cases per 100,000 population per year and an incidence rate of 3 cases per 100,000 population per year.  The peak incidence rates occurred in a bimodal distribution in the age groups 40-44 years and 60-64 years in women and 45-49 years and 65-69 years in men.  

Etiology

Etiology of thyroid eye disease is unknown.

Risk Factors

Thyroid Dysfunction, Family history of Thyroid Eye Disease. Smoking is associated with severe thyroid eye disease. 

General Pathology

Mixed inflammatory infiltrate restricted to the extraocular muscles. 

Pathophysiology

The pathogenesis of TED is a complex immunological process involving the TSH-receptor, fibroblasts, adipocytes, and a cytokine mediated immunologic response. Orbital fibroblasts are a key component in modulating the orbital inflammatory process.  Up-regulation and production of gylcosaminoglycans and adipogenisis play a major role in orbital pathology.  


Diagnosis

Eyelid retraction with association with any of the follow: biochemical thyroid dysfunction, exophthalmos, optic neuropathy, or extraocular muscle involvement. If eyelid retraction is absent, biochemical dysfunction associated with exophthalmos, optic nerve dysfunction, or extraocular muscle involvement. 

History

  • History of Thyroid Disease: date of onset of thyroid disease, treatment (oral medication, radioactive iodine ablation, surgery)
  • History of ophthalmic disease and treatment: date of onset, signs, symptoms, treatment (conservative/supportive treatment, medical therapy, eyelid surgery, eye muscle surgery, orbital decompression)
  • Family history of thyroid disease, thyroid eye disease.
  • Family history of autoimmune disease.

Physical examination

Visual acuity, pupil exam, extraocular movement, slit-lamp exam, fundus exam, eyelid measurements ( retraction, lid lag, lagophthalmos, Von Graefe's sign ), exophthalmometry, color vision, visual field, resistance to retropulsion 

Signs

Soft tissue swelling and erythema, eyelid retraction, lid lag, Von Graefe's sign, chemosis, exposure keratopathy, proptosis, optic nerve swelling, choroidal folds, restrictive myopathy

Symptoms

Pain, photophobia, lacrimation, foreign body sensation, diplopia.

Clinical diagnosis

Eyelid retraction with association with any of the follow: biochemical thyroid dysfunction, exophthalmos, optic neuropathy, or extraocular muscle involvement. If eyelid retraction is absent, biochemical dysfunction associated with exophthalmos, optic nerve dysfunction, or extraocular muscle involvement.

If only orbital signs are present, the patient should be monitored for future development of thyroid dysfunction and other orbital disease.

Diagnostic procedures

Ultrasound

shows bilateral, asymmetric enlargement of the extraocular muscles. The muscle belly's are typically enlarged and the tendon insertions are spared.

CT Scan

Proptosis of globe, increased lucency of fat, multiple enlarged extraocular muscles (inferior and medial rectus most commonly involved) , and possible enlarged superior ophthalmic vein.

MRI

Enlarged extraocular muscles with homogenous signal isointense to normal muscle on T1- weighted images ( slightly hyperintense on T2 weighted images ). Contrast with gadolinium administration reveals marked enhancement.

Laboratory test

TSH, T4, Thyroid Stimulating Immunoglobulin 

Differential diagnosis

Idiopathic Orbital Inflammation, Orbital neoplasm, sarcoidosis, vasculitis, orbital cellulitis, carotid-cavernous fistula

Management

TED is usually self-limiting process and generally requires supportive care

General treatment

Most patients with thyroid eye disease only require supportive care. Ocular lubrication, sunglasses, cool compresses, salt-restricted diet, and elevation of the head of the bed help with minor orbital inflammation and congestion. Establishing an euthyroid state is important.

Medical therapy

Acute active phase of thyroid eye disease is usually controlled with oral corticosteroids for 4-6 weeks. IV steroids may be considered in severe cases ( liver function tests should be monitored ). Orbital radiation is effective in treating compressive optic neuropathy and is often combined with oral steroids. Radiation therapy should be avoided in patients with vasculitic disease or diabetes. 

Medical follow up

Long term side-effects of steroid use must be discussed with the patient and patients undergoing intravenous treatment of steroids must have liver function tests. 

Surgery

Approximately 20% of patients with thyroid eye disease undergo surgery. Surgery generally proceeds in a specific order - orbital surgery, eye muscle surgery, and eyelid surgery.  Orbital decompression is effective in treating optic neuropathy and excessive proptosis. Eye muscle surgery is generally performed for intractable diplopia in primary gaze or reading position 6-8 weeks after orbital decompression.  Eyelid surgery is performed subsequently to decrease ocular exposure and enhance cosmesis. 

Surgical follow up

Patients are routinely followed up at 1 day, 1 week, 1 month , 2 months, 3 months, 6 months, 9 months and 1 year. 

Complications

Complications of thyroid eye disease are loss of vision, double vision, and exposure keratopathy. 

Prognosis

Thyroid eye disease is a generally self-limited process last 1-2 years in most people. It may last longer in smokers. After the active phase, a cicatricial phase develops. Reactivation of disease occurs in approximately 5-10% of people.  

Additional Resources

References

  1. Phelps, Paul O., and Kenya Williams. "Thyroid eye disease for the primary care physician." Disease-a-Month 60.6 (2014): 292-298.
  1. Durairaj VD. Clinical Perspectives of Thyroid Eye Disease. The American journal of Medicine. 2006;119: 1027-1028
  2. BahnRS.UnderstandingtheimmunologyofGraves’ophthalmopathy.Isit an autoimmune disease? Endocrinol Metab Clin. 2000;29:287-296.
  3. Bartley GB, Fatourechi V, Kadrmas EF, et al. Chronology of Graves’ ophthalmopathy in an incidence cohort. Am J Ophthalmol. 1996;121:426- 434.
  4. Bartley GB, Fatourechi V, Kadrmas EF, et al. Clinical features of Graves’ ophthalmopathy in an incidence cohort. Am J Ophthalmol. 1996;121:284-290.
  5. Bartley GB, Fatourechi V, Kadrmas EF, et al. The incidence of Graves’ ophthalmopathy in Olmsted County, Minnesota. Am J Ophthalmol. 1995;120:511-517.
  6. Bartley GB, Gorman CA. Diagnostic criteria for Graves’ ophthalmop- athy. Am J Ophthalmol. 1995;119:792-795.