Thyroid Eye Disease
 

A patient with bilateral thyroid eye disease with upper lid retraction and exophthalmos. There are also bilateral periorbital oedema. 1 1 Right unilateral thyroid eye  disease causing severe  restriction of the inferior rectus  and upgaze.Note the lid lag on  down-gaze.

Thyroid eye disease is one of the commonest cases in the final MRCOphth, it is important that you know it well. It can be presented as a spot diagnosis, orbital examination or ocular motility examination. Spot diagnosis  The patient has bilateral (unilateral) exophthalmos with lid retractions. There are also periorbital swellings.  The diagnosis is thyroid eye disease.  Look at the neck for thyroid enlargement or thyroidectomy scar (this may be hidden by necklace).   Orbital examination The patient has bilateral (unilateral) exophthalmos (do not forget to examine the patient from the side and  above). Exophthalmometer shows reading of _____mm for the right eye and ______mm for the left eye.  Also mention if the proptosis is axial or non-axial. In thyroid eye disease with severe restriction of the inferior  rectus, the globe may deviate inferiorly in the primary position. Note: Do not forget other causes of proptosis  if the problem appears to be unilateral. Mention that you like to: examine the ocular motility looking for upgaze restriction and lid lag examine the optic nerve function (visual acuity, afferent pupillary reaction, colour vision, fundoscopy  and visual field) examine the patient's thyroid status. Ocular motility examination. This patient has bilateral (unilateral) exophthalmos. There is restriction of upgaze in both eyes (this may be  asymmetrical or only affect one eye). The eyes show lid lag on down-gaze. As in orbital examination, mention that you like to check the function of the optic nerve and thyroid status. .

Questions:

1. The following is the CT scan of a patient with right proptosis. What does the scan show?
 

Answer The scan shows enlargement of the lateral rectus  without involvement of the tendon. The features  are characteristic of thyroid eye disease.

2. What is the thyroid status in a patient with thyroid eye disease?

Answer
In the majority of cases (about 80%), hyperthyroidism is present. However, its presence is not necessary for the diagnosis of thyroid eye disease because the patient can be euthryoid and sometimes hypothyroid.

3. What are the triad of Grave's disease?

Answer
The triad are eye signs, thyroid acropachy and pre-tibial myxoedema.

4. How would you manage a patient with a right upper lid retraction and an unilateral downward displacement of the globe?

Answer
Before undertaking any surgery, it is important to make sure that the disease is inactive (this may take 6 months to 2 years). Regular clinical and orthoptic assessment are necessary to document the disease progress. Any diplopia is treated with prism during the active period.
Once the condition is stable, surgical condition should first be given to muscle surgery as this may reduce the upper lid retraction. The cause of the downward displacement is invariably caused by a tight inferior rectus and the treatment of choice is inferior rectus recession on an adjustable suture. Any residual retraction can be treated with recession of the Muller's muscle.

5. Would you be concerned about a patient who complains of sore throat while receiving medical treatment for hyperthryoidism?

Answer
Yes. This is because the use of carbimazole or propyluracil are associated with agranulocytosis which can be potential life-threatening by causing opportunistic infection and septicaemia. However, a patient who develops agranulocytosis on carbimazole may not develop the same problem with propyluracil and vice versa. 

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