Thyroid Eye Disease (Thyroid Ophthalmopathy)

Thyroid Eye Disease

Thyroid Eye Disease

General Overview:

Thyroid Eye Disease (also called TED or thyroid ophthalmopathy or thyroid orbitopathy) is a disease condition of the eye, wherein the ocular muscles and fatty tissue behind the eyes get inflamed. This may lead to forward displacement or bulging of the eye (proptosis). The eyes and the eyelids turn red and become swollen. In some cases, there occurs stiffening and swelling of the eye & ocular tissues which tend to move the eyes in such a way, that the eyes are no longer in line with each other, which may lead to diplopia (double vision). Very rarely, TED can produce blindness, as a result of pressure on the optic nerve at the back of the eye or lead to corneal ulcer formation in front of the eye.

Thyroid Orbitopathy is an autoimmune disorder. When the immune system of the body attacks the eye causing inflammation, TED results. TED is mainly found to occur in persons with an over-active thyroid gland (hyperthyroidism) due to Grave’s disease, however it may even be found in people with an under-active (hypothyroidism) or a normally functioning thyroid gland. Grave’s disease is one of the most important factors/causes responsible for producing. Hence, TED is also termed as “Grave’s Orbitopathy”.

TED may lead to multiple problems of the eye. These problems are such as swelling and redness, decreased vision, diplopia (double vision), bulging eyes (proptosis) and eyelid retraction (superior displacement of the upper eyelid).

Eye problems will generally take place and often change in severity or type in the initial period of 6 months to 2 years. Once stabilized, it is not usual for the eyes to change again. Some patients are left with permanent changes in the eye. Whereas, in the rest, the eye returns to normal.

Predisposing factors:

  • TED is generally associated with generalized (systemic) hyperthyroidism or Grave’s disease. Grave’s disease is an autoimmune process. By autoimmune disease, it is meant that it is a process by which the body sees some part of itself as being foreign and reacts to in much in the same manner as it would to a bacteria or a virus.
  • In case of Grave’s disease, the body sees its own thyroid gland as being foreign and produces antibodies, which attack the thyroid gland. This often leads to damage & the over-activity of the thyroid gland.
  • In case of TED, the different antibodies which are produced, attack the ocular muscles which are concerned with eye and eyelid movement. Though the thyroid gland and the eye may be under influence of attack by the same immune system, both of these conditions remain independent of one another. The antibodies attacking the eye may produce inflammation and swelling of the muscles and fat around the eye, which further leads to forward displacement of the eye, retraction of the eyelids and double vision.
  • Smoking is also said to be one of the important factors responsible for causing TED.

Clinical Presentation:

The most common symptoms which patients present with are as follows:

Ø  A feeling of grittiness, burning, irritation in the eyes

Ø  Change in the appearance of the eyes (staring or bulging eyes)

Ø  Sensitivity to light

Ø  Dry or watery eyes (teary eyes)

Ø  Redness of the eyes and eyelids

Ø  Swelling of the upper and lower eyelids

Ø  Pain in or behind the eye, especially when looking up, sideways or down

Ø  Double vision or blurring of vision

Ø  Difficulty in moving the eyes

How is TED diagnosed?

Diagnosis can be made by simply examining of the eyes.

If  there is pre-existing thyroid gland problem, then some tests are mandated.

  •  Blood tests:

Thyroid Function Tests (TFTs) are required to back up the diagnosis. These tests help in determining whether the thyroid gland is functioning well by measuring its hormones (chemical messengers) ie. T3,T4 and TSH in the bloodstream. More specialized blood tests can be performed to measure the presence of the various antibodies in the bloodstream.

  • Scans:

Thyroid uptake scans are performed occasionally to assess the functioning of thyroid gland. If swelling in the orbit is suspected, MRI can be performed which will help to assess the tissues that have been most affected (for instance, the thickening of the extra-ocular muscles).

  •  Other tests:

For assessment of general sight including peripheral vision and the ability to see colours, tests such as vision tesing, colour vision testing, visual fields, exophthalmometry, eye pressure readings, eyelid measurement etc may be carried out. Eye movement test can be carried out to assess which muscles have been affected and to diagnose any limitation of ocular motility.

Treatment:

  • Artificial tear drops may be helpful in mild cases, where the eyes feel gritty with lots of watering and sensitivity to bright light.
  • Selenium supplements are useful in cases of mild TED.
  • Surgery may be helpful in such cases. In more acute and vision threatening cases, surgery combined with other treatments like intra-venous steroids and radiotherapy are carried out.
  • Rehabilitative surgery may involve:

Eye muscle & Squint surgery – for treating double vision

Eyelid surgery – for improving the appearance of the eyelids

Orbital Decompression surgery’ – to create more space behind the eyes when there is pressure on the optic nerve or when there is lot of protrusion of the eyeballs (proptosis). Orbitotomy & Orbital Decompression Surgery are performed for improving a person’s cosmetic appearance, as well as for functionally rehabilitating the patient.

  • Other treatments such as prisms attached to spectacles in order to improve double vision and high dose steroids may be beneficial.

Prevention:

  • Give up smoking.
  • Avoid fluctuations in thyroid levels.