Graves’ eye disease is present in about 25-50% of Graves disease patients. Medically speaking, we call it Graves’ Orbitopathy or Ophthalmopathy.

Eye disease in Graves patients usually develops concurrently with symptoms of hyperthyroidism. However, eye disease may precede or develop after the symptoms of hyperthyroidism.

Symptoms of Graves’ Eye Disease

Usual Symptoms of Graves’ Eye Disease:

The most common symptom of Graves eye disease is bulging of eyes, for which we use the term proptosis or exophthalmos. Usually, bulging of eyes occurs in both eyes symmetrically. Sometimes, the bulging may be more pronounced on one side than the other, in which case you should have an ultrasound, CT scan or MRI scan of the orbits to exclude any tumor behind the eye.

Often, there is a feeling of irritation as if there is a foreign body in the eyes, which leads to excessive tearing. Also, there may be redness of the eyes. In addition, there may be blurry vision and sensitivity to light due to corneal ulceration. Some patients may feel pressure behind the eyes.

Unusual Symptoms of Graves’ Eye Disease

Occasionally, there may be severe pain, which is an emergency for which you should call your physician immediately or go to the Emergency Room at a hospital.

Sometimes, you may start to see double, usually in the upward gaze, but double vision can be in any direction. Initially, double vision is intermittent, but later it can be present all the time. Rarely, Graves’ orbitopathy can lead to decreased vision and even blindness if left untreated.

How Does Graves’ Orbitopathy Develop?

Let me first give you a brief overview of the anatomy of the orbit.

Anatomy of the Orbit

The Orbit is the bony structure or the socket in which the eyeball is located. It is shaped like a pyramid with its base forwards and apex backwards. Behind the eyeball, there is a space, filled with fat, blood vessels, nerves, connective tissues and six muscles of eye movements. These muscles are known as extra-ocular muscles. Their function is to move the eye in different directions. In addition, there is another muscle known as levator palpebrae superioris, which elevates the upper eyelid.

Graves’ Eye Disease Is An Autoimmune Process

Graves eye disease is an autoimmune process in which your immune cells – lymphocytes – start to attack your own eyes.  These lymphocytes attack a type of cells called fibroblast, which are present in the fatty tissue behind the eyeball as well in the extra-ocular muscles. Once fibroblasts get activated, they start to express an otherwise hidden antigen, which is recognized by the lymphocytes as foreign. Subsequently, lymphocytes mount an immune response, leading to inflammation and swelling of the soft tissues behind the eyeball.

Development Of Symptoms Of Graves’ Orbitopathy

Bulging Eyes

The orbit is a bony structure. Therefore, it cannot expand. Thus, the net result of pressure from the increased, swollen, inflamed soft tissues behind the eyeball is to push the eyeball forward, causing the clinical features of bulging of the eyes. Medically speaking, it is proptosis or exophthalmos.

Double Vision

At the same time, swollen, extra-ocular muscles do not function properly, resulting in double vision.

Chronic activation of fibroblasts can eventually lead to scarring of the extra-ocular muscles, and levator palpebrae superioris muscle. Scarred, extra-ocular muscles become stiff and can lead to permanent strabismus, resulting is permanent double vision.

Scarred, levator palpebrae superioris muscle can lead to permanently retracted upper eyelid, causing cosmetic disfigurement.

Reddened Eyes

Moreover, swollen, soft tissues compress on the venous return, which contributes to swelling and congestion of the conjunctiva, which causes reddened eyes.

Dry, Sensitive Eyes With Excessive Tearing

As eyes are pushed forward, they cannot close completely, which causes the cornea to dry up. That’s why eyes feel dry, irritated and sensitive to light. As a reflex, there is excessive tearing. Exposure of the eyes can lead to ulceration of the cornea. Consequently, you may develop intense eye pain. In severe cases, it can seriously damage the cornea, leading to blindness.

Optic Neuropathy

In severe cases of Graves’ Orbitopathy, crowding of the swollen extra-ocular muscles at the apex of the orbit can compress the optic nerve and damage it. This leads to optic neuropathy. Loss of color vision is the earliest sign of optic neuropathy. Other features include decreased eyesight, blind spots in the field of vision or concentric narrowing of the field of vision.

Why Do Some Patients Develop Graves’ Orbitopathy?

In Graves’ disease, lymphocytes mount an attack on TSH receptors in the thyroid gland. As a result, there is production of stimulating antibodies. Then, these antibodies command the thyroid cells to produce increased amounts of thyroid hormone.

As it turns out, TSH receptors are also present on the fibroblasts in the ocular fatty tissue and the extra-ocular muscles.¹ Therefore, lymphocytes in patients with Graves’ disease chase TSH receptors and end up mounting attacks on the fatty tissue present in the orbit of susceptible individuals.

For the same reason, Graves’ Orbitopathy often worsens after patients with Graves’ hyperthyroidism receive radio-active iodine, because radioactive iodine destroys the thyroid cells. Subsequently, TSH receptor protein gets released in your circulation, and reaches the eyeball and further enhances the attack by the lymphocytes.

The same mechanism explains worsening of Graves’ Orbitopathy after thyroid surgery.

Treatment Of Graves’ Eye Disease

Graves’ orbitopathy should be treated by an experienced endocrinologist and an experienced ophthalmologist.

Aim of Treatment Of Graves’ Orbitopathy

1. Relief of symptoms
2. Prevent corneal damage
3. Recognize and treat emergencies such as optic neuropathy, severe proptosis and eye pain.
4. Corrective and Cosmetic surgery if and when needed.

 Treatment Of Mild Graves Eye Disease

Most cases of Graves’ orbitopathy are mild and improve spontaneously. These patients require simple measures such as artificial tears, glasses to protect eyes from dust and dark glasses if there is light sensitivity. In addition, taping the eyelids closed at night is also helpful.

Treatment Of Moderate to Severe Graves Eye Disease

In moderate to severe cases of Graves’ eye disease, oral prednisone can reduce the inflammation. However, it usually requires rather prolonged courses of prednisone, which can cause serious side-effects, such as osteoporosis, increased risk of infections, elevation in blood glucose, etc.

Sometimes radiation is helpful with or without prednisone to treat optic neuropathy.

Surgery For Graves’ Eye Disease

Some patients require surgery for their orbitopathy. Three types of surgery are available:

1. Decompression surgery. One or more walls of the orbit are removed to relieve intra-orbital pressure. The main indication for decompression surgery is optic neuropathy. Other reasons include severe bulging of eyes, severe orbital pain, and intolerable side-effects from prednisone.
2. Strabismus surgery to improve/correct double vision.
3. Eyelid surgery to improve/correct the retracted eyelids and also for cosmetic reasons.

When To Consider Surgery For Graves’ Eye Disease

The timing and decision to operate varies from case to case. Graves’ orbitopathy usually worsens in the first six months or so. Then, it may improve or become stable. Therefore, in general, wait unless vision is threatened.

As a general rule of thumb, surgery should be deferred until the patient has achieved a normal thyroid hormone level. The only exception to this rule is severe orbitopathy and threatened vision, in which case decompression surgery must be done immediately to relieve the intra-orbital pressure and save the eye.

In Summary

Graves’ Eye Disease affects most but not all patients with Graves’ Disease. Its symptoms are usually mild, but in some patients Graves’ Orbitopathy may lead to serious eye symptoms. Even your vision may be in jeopardy. Radioactive iodine and thyroid surgery may aggravate underlying Graves Eye Disease. In general, symptoms of Graves’ Orbitopathy subside with time. However, some patients require surgery on their eyes to save vision or for cosmetic reasons. Therefore, find an experienced endocrinologist and a Graves Eye Disease specialist if you have Graves Eye Disease.

References:

1. Williams GR. Extrathyroidal expression of TSH receptor. Ann Endocrinol (Paris). 2011 Apr;72(2):68-73.