What You Need To Know About Thyroid Eye Disease

Putting the Ease in Thyroid Eye Disease: Diagnosis and Management

With millions Americans suffering from some form of thyroid disease in the United States, odds are you have seen a patient with thyroid issues in your office this past week. In fact, researchers agree that as high as ten percent of the population may possess a thyroid disorder, although many have yet to be diagnosed.^1,2,14 What does this mean for us as optometrists? It means we need to look for signs of thyroid disease’s cousin, thyroid eye disease, and manage them appropriately.

Remind me, what is thyroid eye disease again?

Thyroid eye disease (TED) is an inflammatory response of the eye and its surrounding structures. It is typically associated with an autoimmune condition of the thyroid gland. While this can occur with a normal functioning (euthryoid) or underactive thyroid (Hashimoto’s disease), the majority of TED cases coexist with an overactive thyroid gland (Graves’ disease). For this reason thyroid eye disease is often found under the aliases of Graves’ eye disease or Graves’ ophthalmopathy.

Approximately 50% of those affected by Graves’ disease have some form of ocular involvement.^2,13 Although Graves’ disease and Graves’ eye disease are often comorbid, they stem independently. Both diseases present more commonly in females, but affect males more severely.⁹ Numerous research studies suggest that the immune system’s antibodies attack a shared antigen of the thyroid gland and the ocular orbital contents, inducing many of the inflammatory effects in TED.^3-5,13 Note that thyroid eye disease ordinarily presents with both an active inflammatory phase that can last a few months to several years, as well as an inactive phase.⁸ The signs and symptoms mentioned here are characteristic of the active phase or residual effects of the active phase.

Right, so how exactly will this affect my patients’ eyes?

Patients with Graves’ disease can present with a variety of signs and symptoms. These are most commonly mild to moderate but can range to very severe.

Very often Grave’s disease sufferers are identified by the hallmark signs of exophthalmos and a staring appearance. In fact, Grave’s disease is the most common cause of bilateral exophthalmos in adults.¹¹ These signs occur because as the extraocular muscles and orbital connective tissue become inflamed and enlarged, the increased volume within the orbit causes the globe to become proptotic. Intensifying this appearance, these patients frequently display retraction of their upper eyelid (Dalrymple’s sign), and lid lag in downward gaze (von Graefe’s sign).⁵ It is common for them to also experience lagophthalmos and swelling of the eyelids.

While the cause of this upper lid retraction and lid lag is not fully understood, these issues contribute to other challenges for TED patients: dry eye syndrome and exposure keratopathy. Without proper lid function, this population presents with the classic symptoms of itchiness, soreness, tearing, and foreign body sensation. A defenseless cornea also leaves these patients more prone to photophobia, punctate epithelial erosions, and corneal ulcers.

On the more severe end of the spectrum of signs and symptoms of Graves’ ophthalmopathy, patients may exhibit diplopia or restricted eye movements secondary to muscle inflammation and fibrosis. The extraocular muscle most commonly affected is the inferior rectus followed by the medial rectus. The involved inferior rectus causes a hypotropia with restricted elevation while an inflamed medial rectus generates an esotropia with restricted abduction of the involved eye.⁶ The strabismus and motility constraints are often bilateral but not always symmetric.¹³

In rare but critical circumstances, thyroid eye disease may cause compressive optic neuropathy. This occurs from orbital congestion at the apex due to extraocular muscle inflammation. Signs include but are not limited to loss of visual acuity, relative afferent pupillary defect, decreased color vision, and central scotoma and arcuate defects apparent on visual field testing. The optic nerves are often edematous but may also display pallor.^7,13 Compressive optic neuropathy has potential to cause permanent vision loss and is an ocular emergency!

Okay, so how do we manage these patients?

In most cases, symptoms from Graves’ eye disease can be treated successfully in our offices. However, do not hesitate to refer to another physician (such as a neurologist or ophthalmologist) if it is deemed necessary or if you are uncomfortable with managing any aspect of a case.

Dry eye and exposure keratopathy resulting from Grave’s eye disease require the same treatment that they would in any circumstance. The standard is to initially recommend liberal use of artificial tears throughout the day and lubricant ophthalmic ointment at night to combat the effects of incomplete lid closure while sleeping. TED sufferers frequently advance to a prescription dry eye therapy such as topical cyclosporine or ophthalmic steroids.⁸ In extreme cases, patients may benefit from using a patch or taping their eyelids shut while sleeping. Realize these patients are at an increased risk for corneal ulcers. Treat these aggressively should one unfortunately arise. If corneal effects are very distressing to the patient, consider eyelid retraction repair or blepharoplasty.

Encourage TED sufferers to wear sunglasses. Not only does this help to alleviate their photophobia, but aids with their increased need for UV protection as well. With improper lid function, these patients have more corneal and overall globe exposure to harmful ultraviolet rays.

If your patient is experiencing diplopia, consider prescribing prism in their spectacle lenses before suggesting surgical options if no compressive optic neuropathy is noted. Given that the diplopia often resolves with steroid therapy or when the active phase of thyroid eye disease subsides, Fresnel prisms and temporary monocular occlusion are also viable options. Strabismus surgery should only be performed after the active phase of the disease process has resolved and residual signs and symptoms have been stable for a few months.⁸

If compressive optic neuropathy is present, consider surgery regardless of whether or not an active phase of Graves’ ophthalmology exists. First line treatment for compressive optic neuropathy is orbital decompression surgery. If strabismus or blepharoplasty surgeries are being considered, they should only be performed after orbital decompression. If a patient is not a surgical candidate, other options include aggressive intravenous or oral steroid therapy and radiation. You may choose to refer the patient for the initiation for steroid treatment, but realize patients are most commonly initiated on a high dose intravenous glucocorticoid regimen followed by an oral steroid taper.^3,13 Proptosis, diplopia, and lid swelling also have the potential to improve throughout the course of steroid therapy.

If you are confident in imaging study interpretation, it benefits you to order a computed tomography (CT) or magnetic resonance imaging scan (MRI) of the orbits. A CT is more habitually ordered, but both scans are useful in viewing pathological changes in TED. Both of these technologies aid in the diagnosis of enlarged extraocular muscles and orbital fat infiltration. If the intraorbital fat increases enough to compress the optic nerve, the nerve appears straightened in an axial scan.⁹ The images also assist in identifying exophthalmos and the efficacy of medical or surgical treatment over time. While you may choose to refer your patient to another physician for further testing or monitoring, it is imperative for us to know the scope of the testing at hand.

Is there anything else I should look for?

Avoid making the grave mistake of misdiagnosing a patient in these pressing circumstances.

Possible differential diagnosis for TED include but are not limited to metastatic disease, intraorbital tumor, orbital pseudotumor, orbital cellulitis, ocular myositis, orbital lymphoma, orbital abscess, sinusitis, carotid cavernous fistula, optic nerve sheath meningioma, orbital hemorrhage, sarcoid granuloma, and a multitude of other inflammatory diseases.^10,11

Be wary of diagnosing thyroid eye disease if patients present with recent onset high fever. CT and MRI scans are particularly useful in identifying sinus disease and tumors versus signs of thyroid orbitopathy.

Got anything else for me?

Encourage your patients to support an overall healthy lifestyle and maintain continued management with their endocrinologist or primary care physician. It is paramount to discuss smoking cessation with patients who are smokers given that the risk of ocular inflammation greatly increases with smoking.^12,13 Routine blood work should be performed to ensure their thyroid hormone levels are balanced. Be aware that thyroid disease sufferers are at an increased risk of being diagnosed with other autoimmune conditions as well.¹⁴ Also note that many thyroid disease sufferers have undergone radioactive iodine treatment or a thyroidectomy. Thus a number of patients with both Graves’ and Hashimoto’s diseases alike may be taking supplemental thyroid hormone in the form of Synthroid (levothyroxine).

Thyroid eye disease patients are best managed with a synergistic approach amongst all physicians involved in their care. It is important for us as optometrists to recognize our role as a member on a larger medical team. Lines of communication should remain open between the patient’s optometrist, primary care physician, endocrinologist, ophthalmologist, and/or neurologist. This is imperative for creating a successful treatment plan and maintaining the patient’s optimum health.

References

Bensenor IM, et al. “Hypothyroidism in the Elderly: Diagnosis and Management.” Clinical Interventions of Aging, U.S. National Library of Medicine, Apr 2012.
Stone MB, Wallace RB. Prevalence and Consequences of Thyroid Dysfunction. Washington, DC: National Academies Press (US); 2003.
Stan M N, et al. “The Evaluation and Treatment of Graves’ Ophthalmopathy.” Medical Clinics of North America, Feb 2012.
Lehmann GM, et all. “Immune Mechanisms in Thyroid Eye Disease.” Thyroid, U.S. National Library of Medicine, Sep 2008.
SE Feldon, L Levin. “Graves’ Ophthalmopathy: V. Aetiology of Upper Eyelid Retraction in Graves’ Ophthalmopathy.” British Journal of Ophthalmology, U.S. National Library of Medicine, Aug 1990.
Wright KW, Spiegel PH. Pediatric Ophthalmology and Strabismus. New York, NY: Springer-Verlag New York; 2003.
Miller NR, Subramanian PS, and Patel VR. Walsh and Hoyt’s Clinical Neuro-Ophthalmology: The Essentials, Third Edition. Philadelphia, PA: Wolters Kluwer Health/Lippincott Williams & Wilkins; 2016.
Liaboe CA, et al. “Thyroid Eye Disease: A Summary of Information for Patients.” EyeRounds.org., University of Iowa Department of Ophthalmology and Visual Sciences, 1 Sept. 2016. Web, 24 Feb. 2018.
Kahaly GJ. “Imaging in Thyroid-Associated Orbitopathy.” European Journal of Endocrinology, U.S. National Library of Medicine, Aug 2001.
Daubner D, et al. “Diagnosis and Differential Diagnosis of Graves’ Orbitopathy in MRI.” Radiologe. Jun 2012;52(6):550-9. doi: 10.1007/s00117-012-2330-3.
Boddu N, et al. “Not All Orbitopathy Is Graves’: Discussion of Cases and Review of Literature.” Frontiers in Endocrinology, U.S. National Library of Medicine, 31 July 2017.
Stan MN, Bahn RS. “Risk factors for Development or Deterioration of Graves’ Ophthalmopathy.” Thyroid, U.S. National Library of Medicine, July 2010.
Bartalena L, Tanda ML. “Graves’ Ophthalmopathy.” New England Journal of Medicine, 5 Mar. 2009.
Boelaert K, et al. “Prevalence and Relative Risk of Other Autoimmune Diseases in Subjects with Autoimmune Thyroid Disease.” The American Journal of Medicine. Feb 2010;123(2): 183.e1–183.e9. doi: 10.1016/j.amjmed.2009.06.030.