Overview

Thyroid eye disease or TED, (also known as Graves' eye disease) is an autoimmune disease. It is a complex inflammatory disorder of the orbit. The prevalence of TED is approximately 50% amongst Graves’ disease patients in the Caucasian population. The annual incidence is 16.0 in 100,000 for females and 2.9 in 100,000 for males in the US population. TED is most common in people with hyperthyroidism due to Graves’ disease and rarely occurs in euthyroid or hypothyroidism cases. It happens when you have a hyperactive immune system. This can damage the thyroid gland as well as other parts of the body, including the eyes.^1,2,3

What is thyroid eye disease?

The tissues around your eyes can be affected by certain types of thyroid diseases, causing inflammation, swelling, and pain. This is called thyroid eye disease (TED/Graves’ eye disease). Most cases are mild, but severe cases may involve eye muscles and eyelids, preventing your eyes from moving and closing properly. This can lead to a variety of problems for your eyes.⁴

 Symptoms of thyroid eye disease³

• A feeling of coarseness in your eyes (like “sand in your eyes”) and sensitivity to light
• Pain behind your eyes or while moving your eyes
• Your eyes will look red due to the swelling/irritation of the thin coating (Conjunctiva) that covers the white part of the eye
• Dry eyes
• Extra tearing of the eyes
• Puffiness around the eye (Periorbital edema)
• Forward bulging of your eyes (Proptosis)
• Strabismus leads to the visualisation of the double image of one object (Double vision)/diplopia
• Difficulty in closing your eyelids (Lagophthalmos)

Thyroid eye disease illustration. Various clinical manifestations found in moderate to severe thyroid eye disease are shown in this illustration

Original figure with Cleveland Clinic Foundation copyright 2015⁷

Complications of thyroid eye disease

Thyroid-related eye disorders constitute a wide clinical spectrum ranging from minor ocular (eye) discomfort, lid retraction difficulty, lid lag, and ocular injection to sight-threatening eyeball protrusion and optic nerve compression. These disorders most frequently occur in hyperthyroidism cases. However, in 10% of cases, typical eye signs have also been reported in euthyroid and hypothyroid states.⁵

Optic neuropathy/ Dysthyroid optic neuropathy (DON) is the most dreaded manifestation of thyroid eye disease (TED). The European Group on Graves Orbitopathy (EUGOGO) classifies the severity of TED as mild, moderate-severe, or sight-threatening. Approximately every 5 in 100 patients with TED progress to sight-threatening optic neuropathy.⁶ If you have decreased visual acuity (VA), impaired color vision, visual field defects during clinical evaluation, as well as optic disk swelling/pallor and relative afferent pupillary defect (RAPD) during ophthalmological examination, then it’s indicative of DON.⁷

Corneal ulcer- One of the most serious complications of Graves’ ophthalmopathy which requires an ophthalmological emergency due to its deadly consequences. It leads to a decrease in vision and, in the worst-case scenario, even blindness and loss of the eye. Emergency treatment is mandatory to restore the anatomical integrity of the eyeball, to salvage useful vision, and to minimize complications as much as possible.⁸

Vision loss- When your immune cells mistakenly attack the fat and fibroblast tissues around the eyes, it leads to eye irritation, bulging eyes, swelling, retracted eyelids, light sensitivity, and vision problems. In rare cases, permanent loss of vision takes place due to TED. Swollen tissue around your eye will press the optic nerve and cause blindness gradually.⁹

FAQs

Risk factors⁹

• Mostly prevalent in 30-50yrs old 
• It is 5 times more common in women than men
• Smokers are more likely to develop TED than non-smokers
• Radioactive iodine therapy is undertaken as the treatment for thyroid cancer but TED is left untreated
• About 1 in 3 people with Graves’s disease develop TED

What is visual acuity(VA)?

The goal of the visual acuity test is to determine the clarity or sharpness of vision. Visual acuity testing examines your ability to distinguish different optotypes (recognizable letters or symbols) at a standard distance by Snellen’s chart. ¹⁰

What is’ relative afferent pupillary defect (RAPD)’?

When you have healthy eyes, the reaction of the pupils in both eyes is linked. To be precise, when a bright light is directed in one of your eyes it leads to an equal constriction of pupils of both eyes. In this case, The ‘swinging light test’ is used to detect RAPD. It engages in detecting differences between the two eyes in how they respond to a light shone in one eye at a time. ¹¹

When to see a doctor³

• The outer surface of your eyeball is prone to injury
• If your eyelids cannot close fully 
• If you have difficulty in seeing colors
• If a portion of your field of vision is gone

Summary

Early detection and on-time management are essential to treat TED cases effectively. It requires a multi-speciality involvement. Thyroid disorder cases are primarily treated by physicians and endocrinologists. If you are already a thyroid patient you should undergo regular eye checkups. Long-term sustenance of euthyroid status is the foremost criterion for the prevention of TED. 

Appropriate control of smoking and nicotine addiction is necessary with the involvement of psychiatrists, de-addiction clinics, anonymous support groups, counselling, and patient deterrence. The sight-threatening disease and cosmetic disfigurement are also a source of anxiety for the patients. Psychosocial issues should be dealt with by trained professionals