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Figure 34-5.  Cavernous hemangioma of the left orbit, which is causing proptosis.

orbit with proptosis, globe displacement, and eyelid swelling. The average age of presentation is 7 years. Prompt diagnosis with orbitotomy and biopsy is crucial, because overall mortality is 60% once the disease has extended to the orbital bones. Current treatment strategies with radiation and chemotherapy have lowered mortality rates to 5 to 10% for orbital rhabdomyosarcoma.

15.What is the most common benign orbital tumor in adults that causes unilateral proptosis?

The cavernous hemangioma (Fig. 34-5) is a slow-growing vascular tumor that is usually diagnosed in young adulthood to middle age. CT scanning usually shows a well-defined orbital mass within the ocular muscle cone. Visual acuity is often not affected. Treatment is observation or surgical excision.

16.What is the most common malignant orbital tumor in adults that causes unilateral proptosis?

Orbital lymphomas typically develop in the superior orbit with a slow onset and progression. These lesions may be associated with a subconjunctival “salmon-colored” mass in the fornix. CT scanning shows a poorly defined mass conforming to the shape of the orbital bones and globe without bony erosion. Diagnosis is made following orbital biopsy, and definitive treatment is radiation therapy. Orbital lymphoma can be associated with systemic lymphoma; therefore a medical consult and systemic evaluation are necessary for all patients.

17.Of the various orbital tumors causing proptosis, list those tumors that are encapsulated or appear well circumscribed on neuroimaging.

•Cavernous hemangioma

•Fibrohistiocytoma

•Hemangiopericytoma

•Schwannoma

•Neurofibroma

Bibliography

Dolman PJ, Glazer LC, Harris GJ, et al.: Mechanisms of visual loss in severe proptosis, Ophthal Plast Reconstr Surg 7:256–260, 1991.

Frueh BR, Garber F, Grill R, Musch DC: Positional effects on exophthalmometric readings in Graves’ eye disease, Arch Ophthalmol 103:1355–1356, 1985.

Frueh BR, Musch DC, Garber FW: Exophthalmometer readings in patients with Graves’ eye disease, Ophthalmic Surg 17:37–40, 1986.

Henderson JW: Orbital tumors, New York, 1994, Raven Press.

Hornblass A: Oculoplastic, orbital and reconstructive surgery, Baltimore, 1988, Williams & Wilkins.

McCord CD, Tannenbaum M, Nunery WR: Oculoplastic surgery, ed 3, New York, Lippincott, 1995, Williams & Wilkins. Rootman J: Diseases of the orbit, ed 2, Philadelphia, Lippincott, 2003, Williams & Wilkins.

Zimmerman RA, Bilaniuk LT, Yanoff M, et al.: Orbital magnetic resonance imaging, Am J Ophthalmol 100:312–317, 1985.

1.What is thyroid eye disease?

Thyroid eye disease (TED) is a chronic inflammatory disease of the orbits that occurs most often in patients with a systemic thyroid imbalance. Chronic inflammation results in scarring and dysfunction of the orbit. The course and severity are variable.

2.Who is at risk for thyroid eye disease?

TED occurs in a wide range of ages. It has been reported from 8 to 88 years of age, with the average age of onset in the forties. Females are affected three to six times more often than males. Children are rarely affected.

3.Is everyone with thyroid eye disease hyperthyroid?

Ninety percent of patients who develop TED have Graves’ hyperthyroidism, 3% have Hashimoto thyroiditis, 1% have primary hypothyroidism, and 6% are euthyroid. As many as one-third of patients do not develop clinical hyperthyroidism for more than 6 months after the onset of symptoms of TED. Thus, a significant number of patients who present with TED have not yet developed hyperthyroidism.

4.What causes thyroid eye disease?

We do not know. TED is an immune-mediated process with the primary target the orbital fibroblast. Many theories link the orbit and thyroid gland by a shared antigen, the thyroid-stimulating hormone receptor. Research continues to try to better understand TED.

5.Do environmental factors affect thyroid eye disease?

Smoking is the one environmental factor that has been shown to affect TED. Multiple studies have shown a higher incidence of smoking in patients with TED than in patients with Graves’ disease who do not have TED. Research suggests that smokers with TED have more severe disease and the disease lasts longer than in nonsmokers. The effects of secondhand smoke can only be speculated on.

6.Does thyroid eye disease improve when the systemic thyroid imbalance is treated?

Treatment of the systemic thyroid dysfunction has little predictable effect on the course of TED. Posttreatment hypothyroidism may worsen TED, especially if the hypothyroidism is profound. Also debated is whether radioactive iodine (RAI), surgery, and medical treatment have different effects on the course of TED. A large study suggested that treatment with radioactive iodine has a greater chance of causing progression of TED. The study also showed that giving systemic steroids during the treatment decreases and may eliminate this risk.

7.Should all patients who receive radioactive iodine be treated with systemic steroids?

Unless the patient has specific contraindications or until further studies show otherwise, we recommend that patients undergoing radioactive iodine treatment receive a course of systemic steroids. The dosage and length of treatment are controversial. The patients at the highest risk of worsening TED with RAI are smokers and patients with active disease.

8.What are the early signs of thyroid eye disease?

Many patients initially present with intermittent eyelid swelling along with nonspecific ocular irritation, redness, and swelling (Fig. 35-1). Because all of these symptoms are nonspecific, early-onset TED is infrequently diagnosed. The disease is not recognized until the appearance of more obvious clinical signs, such as eyelid retraction, eyelid lag, or early proptosis (Fig. 35-2). Suspecting TED in patients with the aforementioned nonspecific symptoms is important, especially if they have symptoms or history of a thyroid imbalance.

9.What studies need to be done in the workup for thyroid eye disease?

The most effective screening tool for systemic thyroid imbalance in patients with TED is the level of thyroid-stimulating hormone. An internist or endocrinologist can do further evaluation and workup.

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Figure 35-1.  Early thyroid eye disease with mild eyelid retraction of the left upper eyelid and the right lower eyelid.

Figure 35-2.  Thyroid eye disease with proptosis and eyelid retraction.

Patients require a complete ophthalmic exam. Special attention should be paid to visual function, including acuity, pupils, color vision, and, if indicated, visual fields. In particular, the ophthalmic exam should include noting eyelid position, evaluation of ocular motility with note of any diplopia, and checking for corneal exposure and proptosis.

10.Which patients require orbital imaging?

Not all patients with TED require orbital imaging. Indications for imaging include suspicion of optic nerve compression, evaluation for orbital decompression surgery and/or orbital irradiation, unclear diagnosis, and a need to rule out other orbital processes. We prefer a computed tomographic scan without contrast in patients with thyroid-related ophthalmopathy who require imaging.

11.What findings are present on orbital imaging?

The classic finding is enlargement of the rectus muscle belly with sparing of the tendon (Fig. 35-3). The inferior rectus is the most commonly involved muscle, followed by the medial rectus and the superior rectus. The lateral rectus is least likely to be involved.

12.Does everyone with proptosis have thyroid eye disease?

No. TED is the most common cause of both unilateral and bilateral proptosis in adults, but it is not the only cause. Patients with systemic thyroid disease may develop orbital tumors and nonthyroid orbital inflammation. TED is a bilateral disease, whereas most orbital tumors are unilateral. TED may present asymmetrically and appear unilateral, especially early in the disease. In rare cases, the disease may remain unilateral. If the entire clinical picture is not consistent with TED, orbital imaging is indicated.

13.How do the tissues of the orbit change in thyroid eye disease?

The extraocular muscles, eyelid muscles, and orbital fat are the main tissues affected in TED. When stimulated, orbital fibroblasts secrete glycosaminoglycans, cytokines, and chemoattractants. Orbital and eyelid swelling are common early in the disease. Late in the disease the inflammation resolves and the enlarged muscles are left fibrotic and scarred.

14.How long does the disease last?

Most patients go through a period of active inflammation causing their eyes and orbital tissues to change. This period lasts from 6 months to more than 2 years. In some patients the process may involve slow, mild changes over many months, whereas in others the process is more acute with rapid changes over weeks. Once the disease activity has quieted and the eyes are stable, reactivation is rare (5 to 10%). Careful examinations that note changes in motility, eyelid position, proptosis, and general inflammation help to determine disease activity.

284  OPHTHALMOLOGY SECRETS IN COLOR

A

B

Figure 35-3.  Axial A, and coronal B, computed tomographic scans showing enlargement of all four rectus muscles.

15.Is everyone who develops thyroid eye disease affected in the same way?

No. There is a wide variation from mild irritation and eyelid retraction that totally resolve to severe orbital infiltration with visual loss. Visual loss may result from optic nerve compression or corneal scarring due to corneal exposure. More severe disease involves older patients (average age of 52 years versus 36 years for milder disease) and has less of a gender difference (female-to-male ratio of 1.5:1 in severe disease versus 8.6:1 in mild disease).

16.What can be done to treat thyroid eye disease?

Many patients do not require any treatment, but monitoring during the active phase of the disease is important. Ocular lubrication often relieves symptoms. Systemic steroids decrease inflammation. Because of their side effects, systemic steroids are best used as a temporizing measure until more definitive treatment is given. Cessation of steroids generally results in return of orbital inflammation. Orbital irradiation may decrease inflammation in the orbit. Surgical treatment is also an option.

17.When are systemic steroids used?

Systemic steroids are used to decrease orbital inflammation acutely, usually on a temporary basis until other treatment can be started. The most common indication is visual loss from optic nerve compression. Severe proptosis with resultant corneal exposure is a second indication. Both short-term and long-term side effects of steroids limit their usefulness as long-term treatment. High-dose pulsed steroids have been studied, looking for any long-term improvement in TED. The results have been inconclusive.

18.Is orbital irradiation standard treatment for thyroid eye disease?

The use of orbital radiation is controversial. A study published in 2001 from the Mayo Clinic concluded that orbital irradiation does not improve TED. Subsequent smaller studies have shown stabilization of disease progression compared to controls. Many oculoplastic specialists believe that orbital irradiation

CHAPTER 35  THYROID EYE DISEASE  285

has a role in the treatment of TED and that it stops progression of the disease but does not improve preexisting changes such as proptosis. Radiation may help stabilize ocular motility. How orbital radiation is used varies with the individual physician.

19.How does orbital irradiation affect thyroid eye disease?

The exact mechanism of action of irradiation in the orbit is unclear. Multiple theories of localized immunosuppression in the orbit have been postulated, but all remain unproven. Many patients have a definite decrease in orbital inflammation and edema after orbital irradiation. Irradiation seems to be most effective at stopping disease progression and less effective at reversing changes that have already occurred.

20.Does orbital irradiation work immediately?

No. It takes 2 to 4 weeks to see the initial effects of irradiation, and improvement may continue for 6 months. If steroids are stopped immediately after completion of irradiation, inflammation may recur rapidly.

21.Which patients are candidates for orbital irradiation?

Any patient with active TED is a candidate. The exception is patients with diabetes and vasculitic disease, as radiation may worsen their retinopathy. Early treatment, if effective, prevents the chronic orbital changes associated with TED. Later in the disease, irradiation can quiet the active disease and allows earlier and more effective surgical rehabilitation. Orbital irradiation has resulted in fewer patients with severe TED when used in select patients.

22.Which patients require surgery?

Surgery may be indicated on an emergent basis because of optic nerve compression or corneal exposure. More often, patients require nonemergent surgery because of severe disfiguring proptosis, double vision from restrictive myopathy, or eyelid retraction.

23.What kinds of surgery are done in patients with thyroid eye disease?

Surgery falls into three basic categories: orbital decompression, eye muscle surgery, and eyelid surgery. Surgery needs to be done in this order because earlier surgeries affect the results of later surgeries. Decompression should be done before eye muscle surgery. Decompression affects ocular motility and may alter muscle surgery. Likewise, muscle surgery should be completed before eyelid surgery is done.

24.What is orbital decompression?

Orbital decompressive surgery involves removal of bone and/or fat to allow the eye to settle back in the orbit. Bone is removed from the inferior and medial walls of the orbit to let the expanded orbital tissue move partially into the sinus space. Lateral wall decompression can also be done. Removal of orbital fat has a decompressive effect to a much lesser degree. The amount of decompression is related to the amount of fat removed.

25.Which patients require orbital decompression?

Patients with optic nerve compression require decompressive surgery to relieve pressure on the optic nerve. Patients with severe proptosis resulting in corneal exposure or disfigurement are also candidates for orbital decompressive surgery.

26.What is optic nerve compression?

Optic nerve compression involves squeezing of the optic nerve at the apex of the orbit. When the extraocular muscles swell in TED, there is relatively little space at the apex of the orbit; therefore enlargement of muscles exerts pressure on the nerve lying in the center of the muscles. Pressure decreases vision because the function of the optic nerve is affected. This loss of function can manifest as decreased vision, decreased color vision, or visual-field loss.

27.What are the complications of orbital decompression?

The most common complication is worsening of existing diplopia or new double vision. Patients with preexisting motility problems have a much higher risk of postoperative diplopia. Many patients have infraorbital hypesthesia postoperatively, but it usually improves with time. Risk of visual loss is small. Bleeding and infection, as with any surgery, must be considered.

28.When do patients require muscle surgery?

Patients with double vision in their functional field of vision require muscle surgery. Every effort must be made to ensure that the inflammation is quiet and the patient’s motility pattern is stable. Repeated stable measurements over months help to ensure that motility is stable.

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