Thyroid Eye Disease
Orbital Decompression for Thyroid Eye Disease (TED)
What is thyroid eye disease?
This condition characterized by a tendency for the eyes to be pushed forwards (so-called “proptosis”) and for the eyelids to open too far (lid retraction). It is often associated with red, irritable and watery eyes. Eye movements can also be reduced and this can cause double vision. In a few cases the optic nerve, carrying the visual signals back to the brain, can be compressed and this leads to a failing of eyesight.
The eye changes generally affect both eyes sides, but very rarely one side can be affected much more than the other. Although most people with TED have a history of an over- or an under active thyroid gland, this is not always the case and some people with characteristic eye disease never have an abnormal blood test.
Why do the changes occur in thyroid eye disease?
TED is an autoimmune condition where the body’ own immune system attacks the tissues of the thyroid gland and the eye socket. Inflammation of the tissues in the eye socket causes the signs of TED, but the reason for the inflammation (not infection) is not fully understood. Inflamed tissues around and behind the eye become swollen and congested causing proptosis and sore/red eyes can result from the eyelids not closing fully. Swelling of the eye muscles reduces their ability to contract and relax thereby affecting eye movements. If the muscles get very swollen, they can compress the optic nerve at the back of the eye socket causing the vision to drop,
What can I do to help prevent or improve the TED?
At present there are four factors known to affect the outcome for TED: Two of them (age and sex) are hard to change. The other two factors, which can be modified, are the thyroid gland activity (needs regular checking by blood tests) and smoking. In recent years it has become evident that smoking seriously worsens the outcome for TED and carries a significant risk of blindness. If you smoke, you should stop (or at least drastically reduce) this habit and please see your GP if you need help with this.
How can TED be treated?
Mild TED might require no treatment, or just some lubricant eye drops to reduce discomfort of the eyes. Most cases of TED are mild and self-limiting over a few years. Severe inflammation may need to be damped down, as it can otherwise lead to problems both during the inflamed phase and with scarring of tissues as the inflammation settles. The inflammation can be reduced by the use of powerful drugs, such as steroids, or by low doses of orbital radiotherapy (X-ray therapy). Orbital radiotherapy is similar to that used for treatment of tumours but, with TED, is used at a much lower dosage and so side effects are almost unknown. If the eyesight is impaired due to pressure on the optic nerve (so called “optic neuropathy”), it may be necessary to perform urgent orbital decompression to prevent permanent loss of vision. Orbital decompression involves removal of some bony walls of the orbit (they do not need to be replaced) to create more space for the inflamed orbital tissues, in most cases, relieving the pressure on the optic nerve and allowing a recovery of sight.
Squint surgery (surgery on the eye muscles) may be necessary to improve the double vision and lid surgery may be needed to improve the appearance or eyelid closure. Orbital decompression is also of value in improving the facial cosmetic appearance where there is significant proptosis, gross thickening of eyelid tissues or where there is a lot of “pressure” behind the eyes.
What is an orbital decompression?
This is where one to three of the four bony walls of the orbit are removed surgically, allowing considerable backward movement of the eyes in the eye-sockets. The surgery is performed under general anaesthetic and lasts about 2 to 3 hours. The incision is generally made at the outer angle of the eyelids and the scar rapidly fades into the natural creases. The surgery is a major procedure and the small size of the incision must not give the idea that this is a minor operation. It involves admission to hospital for at least one night. There is some bruising, swelling and relatively mild discomfort after surgery and it is necessary to take time off work, usually around 3-4 weeks. In some cases this time off can be quite long if double vision is troublesome.
If you are aspirin or any other drug to “thin the blood”, these drugs needs to be stopped for 3-4 weeks before surgery, however with agreement from your General Practitioner or Cardiologist. Likewise, anti-inflammatory drugs, such as Neurofen or Brufen, need to be avoided for 2 weeks prior to surgery and the dosage of anticoagulants (Warfarin) will need to be adjusted.
After surgery, both eyes will be firmly padded for about 6-12 hours and there may be a small drain in place on each side, to help prevent significant swelling and bruising. The dressing and the drains are normally removed the morning after surgery by the doctor and you can usually return home on the first or second postoperative day.
What are the risks and side effects with this surgery?
There are risks and side effects with a major procedure like orbital decompression: Most side effects are either temporary or can be treated by further medications or surgery. Some risks, although extremely rare, may be irreversible and lead to a permanent disability.
The most important risk is, perhaps, loss of eyesight: Although many orbital decompressions are done for patients with poor vision due to thyroid optic neuropathy, there is a risk of loss of some, or even all, vision with any surgery on the eye socket. The risk of vision loss is, however, extremely low probably less than 1-in-1000 for one eye and, therefore, less than 1-in-a-million for complete blindness in both eyes. There is also a risk of post-operative bleeding in the eye socket which could also affect the vision and may require surgical intervention.
Following an orbital decompression some patients will develop postoperative numbness of the cheeks and upper front teeth, because the nerve supplying the “feeling” is exposed during surgery. In most cases it will recover over some months, but in about 5% a partial or complete numbness will persist. This numbness does not affect facial appearance or movement. Some double vision (“diplopia”) is common immediately after surgery (due to increased swelling of the eye muscles) and typically settles over a few days or weeks. If persistent, we can often help by fitting a temporary (“stick-on”) prism to your glasses, or by occlusion of one spectacle lens (to blur out the image). If double vision persists long-term, squint surgery or special glasses may be necessary when the eye movements have settled (frequently by 6-12 months after decompression).
With TED there is often double vision present before surgery. It can, however, occur for the first time (or be worsened) after orbital decompression and it is most important to realise that diplopia has a major effect on life-style for example, the ability to drive and may prevent early return to work. Your preoperative preparations must take this risk into account.
Despite major reduction in proptosis with orbital decompression, any tendency to upper eyelid retraction tends to persist after surgery. This persistent retraction may require the use of lubricant eye drops or later eyelid surgery, which is typically performed as an outpatient under local anaesthesia.
Patients will, rarely, have problems with recurrent sinusitis (or sinus ache) after surgery although this typically settles over 6-12 months. The disruption of the facial sinuses during orbital decompression means that there is a risk of major sinus pain during air travel and such travel should probably be avoided, if possible, for about 2 weeks after orbital decompression. In some cases the sinus drainage may need surgical correction at a later date, particularly if it leads to an over-correction of the orbital decompression. There may be asymmetrical or over-correction of proptosis, with one eye set further back than the other, which may require further surgery.
Will I need medication after my surgery?
You will be asked to take some medications after surgery such as eye drops, antibiotics, steroids, or pain-killers.
What is the follow-up treatment?
All being well you will be discharged home the day after surgery and given a clinic appointment for one week after surgery.