Thyroid eye disease
More information
The thyroid gland, located in the neck, produces thyroid hormone which helps regulate our metabolism. It may occasionally produce too much thyroid hormone (hyperthyroidism or thyrotoxicosis) or too little (hypothyroidism or myxoedema). Imbalance in either direction can cause eye and vision problems. The precise cause of thyroid eye disease, which may be very variable in its manifestations, remains a mystery.
What are the symptoms of thyroid related eye problems?
A staring appearance and dry eyes are often the first symptoms. Early signs include swelling of the eyelids and tissues around the eye. The eyes can become red and the conjunctiva (the membrane overlying the white of the eye) may swell giving a “jelly-like” appearance above the lower eyelids. Swelling of the normal fat surrounding the eye and the eye muscles can push the eye forward creating a protrusion of the eye (proptosis or exophthalmos). The degree of protrusion is variable and may involve one or both eyes.
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| Severe proptosis in a patient with thyroid eye disease |
Swelling of the muscles which move the eyes may produce double vision. In severe cases, the clear covering of the eye (the cornea) may dry or even ulcerate, or the optic nerve may be compressed resulting in impairment of vision. Severe proptosis in a patient with thyroid eye disease
Can thyroid eye disease occur even if thyroid function tests are normal?
Protrusion and other symptoms and signs of thyroid eye disease may be present even when tests show a normal level of thyroid hormone in the blood. Most patients with eye symptoms, however, have abnormal blood levels of thyroid hormone.
How is thyroid eye disease treated?
Once an overactive thyroid gland is suspected, the thyroid function must be evaluated and appropriately treated by an endocrinologist (a doctor specializing in the investigation and management of disorders such as thyrotoxicosis and diabetes). The eye disease may continue to progress after the thyroid function has been treated. Any residual eye problems should be followed and, and, if necessary, treated by an ophthalmologist with expertise in this field.
Two phases of eye treatment should be considered. The first phase involves treating the active eye disease. The active period, which usually lasts two or more years, requires careful monitoring until stable. The second phase involves correcting unacceptable permanent changes which persist following stabilisation of the active phase.
Treatment during the active phase of the disease focuses on preserving sight. Medical treatment, such as artificial tears and ointments, steroids, anti-inflammatory drugs, steroid-sparing drugs e.g. azathioprine, orbital surgery, and possible radiation (X-ray treatment) of the orbit, may be required. In the second phase, treatment of permanent changes may require surgical correction of double vision, eye protrusion, eyelid retraction and “eyebags".
With rare exceptions surgery for thyroid eye disease is performed in the following sequence (although not every stage is required):
2. Eye muscle (strabismus) surgery
3. Eyelid repositioning surgery
What is an orbital decompression operation?
An orbital decompression operation is a surgical procedure undertaken to create more space in the orbit.
Strabismus surgery
Surgery to deal with double vision is only undertaken when the deviation of the eyes has remained stable for a period of 6 months. Whenever possible, temporary stick on prisms (Fresnel prisms) are fitted to glasses to overcome double vision until surgery is deemed appropriate. This surgery is performed by other colleagues who specialize in strabismus (squint) surgery.
Eyelid repositioning surgery
Upper and lower eyelid retraction may be treated by lengthening the tendons of the eyelid retractor muscles. This is usually performed under local anaesthesia for the upper eyelids. This allows greater accuracy to be achieved with regard to the final height and contour of the upper eyelids. Nevertheless it may be very difficult to achieve symmetry and to avoid a flaring of the outer aspect of the upper eyelids.
Complications of such surgery include an under or overcorrection of the degree of retraction requiring further surgery. Lower eyelid retraction may be treated by means of grafts taken from the hard palate (roof of the mouth) usually under general anaesthesia. Often eyelid retraction is not required in patients who have undergone an orbital decompression as the eyelid retraction often resolves following such surgery.
What are the risks of eyelid repositioning surgery?
The risks of eyelid repositioning surgery include infection, bleeding and reduced vision, but these complications occur very infrequently. A temporary inability to fully close the eye after surgery is not uncommon. Lubricant drops and ointments are frequently useful in this situation. It is also important to know that, although improvement of the lid height is usually achieved, perfect symmetry in the height and contour of the two eyelids and full eyelid movement is sometimes not achieved. More than one operation is occasionally required.
What happens after eyelid repositioning surgery?
You will be asked to clean the eyelids and repeat the application of antibiotic ointment to the eyelid wound 3 times a day for 2 weeks. The sutures used are usually dissolvable but can be removed after 2 weeks if necessary. Wearing make-up should be avoided for at least 2 weeks. Postoperative bruising and swelling usually takes 2-3 weeks to subside. The upper eyelid scar following a levator recession is hidden within the upper eyelid skin crease. Occasionally the surgery is performed on the inside of the eyelids leaving no visible scars.
Blepharoplasty
Severe eyelid swelling in thyroid eye disease may leave the eyelids with a very "baggy" appearance and with excess skin. Blepharoplasty involves the removal of excess skin and/or fat from the lids. This may improve the appearance of the lids but cannot restore normality. Upper eyelid surgery has to be conservative to avoid aggravating any dry eye symptoms.
Click here for more information on the Blepharoplasty procedure
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