Thyroid disorders are the leading cause of GP visits for adults’ ophthalmologic complaints in North America. Most people with Graves’ disease will experience eye problems, but other thyroid conditions can also present with ocular symptoms. Hashimoto’s disease can cause eye symptoms in a significant minority of patients, as can thyroid cancer. Eye trouble is often the first warning sign of thyroid disorder.

These cases can be frustrating for both physician and patient, as treating the underlying thyroid problem can aggravate preexisting eye symptoms. It’s not uncommon for individuals to have mild ocular symptoms while their thyroid is overactive, only to have them worsen after treatment with radioiodine.

Graves’ ophthalmopathy may resolve after thyroid treatment, but often there are mild vision impairments or cosmetic issues that remain to be dealt with — or lived with.

Upper eyelid retraction

This condition threatens the cornea with dessication or scarring. It’s usually prevented with lubricant gels and artificial tears such as hypromellose. It’s not an inflammatory condition and shouldn’t be treated as such.

Eyelids may not close fully at night (lagophthalmos). In severe cases, a partial or complete tarsorrhaphy (stitching together of the eyelids) may be required. Upper eyelid retraction can be surgically corrected by releasing Müller’s muscle on the inner surface of the eyelid, causing it to lower by 1-2 mm. Surgery is best postponed until the disease has stabilized for at least 6-12 months.

Proptosis

Proptosis can be well managed by removing either the orbital floor (into the maxillary sinus) or the medial wall (into the ethmoid sinus), or both. Steroids are typically given before surgery to achieve orbital decompression.

Diplopia

Mild double vision is quite common in the upgaze position, less so in side gaze, and rarest in forward or downgaze. Strabismus surgery is only offered for forward or downgaze diplopia.

Acute complications

The most dreaded complication is compressive optic neuropathy, which can cause permanent vision loss. It’s normally due to strangulation of the optic nerve by massively enlarged extraocular muscles. External beam radiotherapy is a safe and effective treatment, though high-dose corticosteroids are often employed first, to reduce intraorbital compression.

The big picture

Recent research has driven home one message — the link to smoking is very, very strong. The best thing patients can do for themselves is to quit. The worst thing they can do is smoke while taking radioiodine for overactive thyroid.