Thyroid Eye Diseases

Thyroid eye disease (TED), or thyroid-associated ophthalmopathy (TAO), is an autoimmune disorder in which the immune system erroneously attacks the thyroid gland, the orbital tissues and occasionally the skin, especially over the shin region. It occurs most commonly in young females, yet severe cases tend to occur in older males. It is mostly commonly associated with Graves’ disease (resulting in hyperthyroidism), but can also be associated with Hashimoto’s thyroiditis (hypothyroidism), carcinoma of the thyroid gland or irradiation exposure. Abnormal antibodies may be found in the blood and may directly or indirectly cause inflammation of the soft tissue around the eyes including extraocular eye muscles, fat and other connective tissues. The inflamed and swollen soft tissues including the muscles, fat, eyelid soft tissue and the lacrimal gland may result in the following symptoms: 

• Changes in the appearance of the eyes (usually a ‘staring look’ because of eyes bulging forward, i.e. proptosis and lid retraction)
• Swelling or feeling of fullness in the upper eyelids, i.e. eyelid puffiness
• Lid retraction
• Redness of the lids and eyes
• Pain inside or behind the eye, which may exacerbate on eye movement
• Difficulty in moving the eyes
• Blurred or double vision
• Gritty feeling in the eyes
• Dry or watery eyes 

These conditions can happen in one or both eyes, and can be asymmetrical in severity.

TED is mainly a clinical diagnosis. A comprehensive eye examination is required to confirm the diagnosis and evaluate the severity of TED. It includes, but not limited to, visual acuity, colour vision, intraocular pressure, eyelid parameter measurements, proptosis measurement, ocular motility testing, optic nerve function examination, dilated fundus examination. Sometimes photographs are taken for clinical reference and monitoring of disease. Additional investigations such as formal visual field testing, optical coherence tomography, Hess chart, CT or MRI of the orbital area and blood tests may be performed to help ophthalmologists in making a diagnosis and evaluating the severity of the condition.

Possible Complications 
Thyroid eye disease, if left untreated, can cause serious sight-threatening complications (which can be up to 3% to 5% of all patients with TED), such as corneal exposure complications like corneal ulcer, optic nerve compression, glaucoma, etc. Therefore, it is important for patients diagnosed with thyroid disorder to have regular eye examinations so that proper treatment can be given at early stage when necessary. Many a time, even non-sight threatening complications may cause significant physical and psychological burden to the patient. Double vision may affect the daily activities of the patient, alteration of outlook may pose psychological stress to a patient and may result in social withdrawal in some patients.

Irrespective of the underlying causes, treating the dysthyroidism by an endocrinologist, physician or family physician is very important. Thyroid dysfunction is known to be a risk factor for development and progression of TED. Cessation of smoking is essential as smoking is known to increase the risk of developing and progression of TED, and reduce the treatment efficacy of all kinds in TED. 

In TED patients, mild symptoms such as dry eyes can be relieved by liberal use of artificial tears or lubricating eye gel. Cool compress and sleeping at an incline head up position may reduce eyelid swelling. Glasses with prisms may sometimes help in double vision. Selenium may help reduce the severity and progression of disease in patients with mild TED. 

For sight-threatening TED due to dysthyroid optic neuropathy, intravenous pulse steroid may salvage vision, though a proportion may ultimately need urgent surgical decompression to prevent permanent visual loss. For active moderate to severe TED, a course of intravenous pulse steroid, usually of 12 weeks duration, may help control the clinical activity score. Some patients may also benefit from orbital irradiation therapy. There are recently some evidence in the use of systemic immunosuppressants or targeted therapy in selected patients with severe TED. The doctor will help decide which treatment or combination of treatments suits individual patients with TED. 

Chronic changes in the appearance of the eyes or eyelids, or double vision, may also require rehabilitative surgery to restore function and appearance as much as possible. This may include rehabilitative orbital decompression, squint surgery or eyelid surgery. Again, the doctor will help decide the type and timing of the surgery that is most suitable for individual patients with TED.