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Overview
Graves’ ophthalmopathy (GO) is a condition that
primarily affects the extraocular muscles, the
muscles that rotate the eyeball up, down, and to
the sides. It is closely associated with Graves’
disease, an autoimmune
disorder that causes the thyroid to produce excess
thyroid hormone (hyperthyroidism). Graves’
ophthalmopathy is also known as thyroid eye
disease or thyroid-associated ophthalmopathy. In
GO, an unknown antigen (substance that triggers an
immune response) activates lymphocytes (a type of
white blood cell), which infiltrate extraocular
muscle tissue and other orbital tissues, producing
inflammation and causing the tissues to swell. The
swollen eye muscles force the eyeball to bulge out
of the bony orbit (i.e., eye socket).
GO and Graves’ disease are two separate conditions
that run independent courses. GO may occur long
before, at the same time as, or long after thyroid
disease is diagnosed and treated. Although most
patients with Graves’ disease have Graves’
ophthalmopathy, about 10% of patients with GO have
normal thyroid function.
Progression of the disease usually stops on its
own within a 2-year period and it rarely recurs.
Mild symptoms may completely self-resolve, but
treatment may be necessary to restore eyelid
function, improve appearance, and correct vision.
Incidence and Prevalence
Graves' disease occurs in less than 1/4 of 1% of
the U.S. population. About 3,000,000 patients in
the United States and Europe have the condition
and there are 37,000 new cases per year in the
United States. Up to 80% of patients with Graves’
disease develop eye symptoms. Graves’
ophthalmopathy is more prevalent in Caucasian
women between the ages of 30 and 50.
Risk Factors
Smokers are more likely than nonsmokers to develop
Graves’ disease and GO and are more likely to
develop more severe symptoms of eye disease.
Symptoms
Symptoms of GO vary. Redness and irritation in the
eyes is common, but inflammation that causes
permanent or serious vision damage occurs in less
than 1% of cases.
Other ocular symptoms include:
-
Double vision
-
Eye dryness
-
Eye muscle weakness
-
Excessive tearing
-
Exophthalmos proptosis (protrusion of the eyes)
-
Increased intraocular pressure
-
Irritation
-
Light sensitivity
-
Swelling of the eyelids
-
Upper and lower eyelid retraction
Patients may have difficulty closing their eyes
completely, which can lead to irritation, dryness,
and corneal abrasions. Vision is affected in
severe cases.
Eye muscle swelling can increase pressure within
the eye as well as compress the optic nerve.
Because of the increased pressure, GO patients
carry a risk for
glaucoma.
The eye muscles may become impaired to the point
where they are unable to freely move the eye in
all directions, leading to double vision (diplopia).
In rare instances, swelling may compress the optic
nerve in one or both eyes, leading to optic
neuropathy and possibly vision loss.
Diagnosis
Diagnosis is based on clinical signs and symptoms,
as well as tests to determine the extent and
severity of the disease. Patients exhibiting
symptoms of GO are examined and assessed for
Graves’ disease with a thyroid function test. The
eye disease is treated by an ophthalmologist.
After a comprehensive eye examination, the eye
care practitioner may also check for exophthalmos
proptosis (forward displacement of the eye), which
leads to incomplete lid closure, exposure of the
cornea while blinking or sleeping, and irritation.
A CT scan or ultrasound is performed to determine
if the muscles around the eye are swollen and to
detect fibrosis (hardening of muscle tissue).
Fibrotic tissue can permanently reduce some degree
of range of eye movement.
The specialist measures how far the eye protrudes
with an exophthalmometer, a small instrument that
resembles a ruler. The patient faces the doctor
and the exophthalmometer is positioned to measure
how far the eye protrudes beyond the rim of the
eye socket. This measurement helps assess the
degree of tissue swelling and muscle enlargement
behind the eye.
Treatment
Treatment of Graves’ ophthalmopathy is aimed at
relieving symptoms, which usually results in
decreased intraocular pressure (IOP) and reduced
risk for glaucoma and possible blindness.
Patients with GO who have hyperthyroidism are
treated with antithyroid drugs, radioactive iodine
(may carry a slight risk for making eye symptoms
worse), or surgery to reduce the production of
thyroid hormone. The selection of a particular
modality depends on the patient’s age and
preference, and the severity of the illness. Eye
symptoms may improve, but sometimes GO continues
to progress.
Ointments or artificial tears and cool compresses
can relieve dryness and irritation. If the eyelids
cannot completely close, the eyes may be taped
shut at night to help the patient sleep and to
avoid dryness. Sleeping with the head of the bed
elevated can alleviate swelling. Wearing
sunglasses protects the eyes from sun and wind and
prism sunglasses can help correct double vision (diplopia).
Medications
Nonsteroidal antiinflammatory drugs (e.g.,
ibuprofen) and oral corticosteroids (e.g.,
prednisone) are used to reduce inflammation and
swelling. Corticosteroids also suppress the immune
system, which can slow or stop the progression of
the autoimmune response that is causing the
symptoms of GO.
Chronic treatment with oral corticosteroids can
produce a number of side effects, however,
including the following:
-
Behavioral changes (extreme mood swings)
-
Decreased carbohydrate tolerance
-
Impaired wound healing
-
Muscle wasting
-
Peptic ulcer
Increased intraocular pressure is common with
chronic corticosteroid treatment, so the effects
of this medication must be closely monitored when
it is used to treat GO.
Cessation of smoking may reduce symptoms and
enhance treatment.
Surgery
A surgical procedure called orbital decompression
may be performed when:
-
proptosis has led to corneal exposure and risk
for corneal ulceration;
-
there is severe orbital discomfort; or
-
there is compression of the optic nerve.
This involves removing bone tissue from the eye
socket to create more space for the eye and
enlarged muscle tissue. Surgery also may be
performed on the eye muscles to realign the eyes
and correct double vision in the straight-ahead
gaze. The patient may continue to have double
vision in other directions (left, right, up,
down). Oculoplastic surgery (link) may be
performed on the eyelids to enable the eyes to
close completely and to minimize protrusion of the
eyes.
Surgeries are performed in the following order and
never at the same time:
1.
Orbital decompression
2.
Eye muscles
3.
Eyelid repair
A waiting period follows each procedure. If the
problem is alleviated, further surgical treatment
may be unnecessary.
Prevention
There is no known way of preventing Graves’
disease or Graves’ ophthalmopathy. Not smoking may
decrease the incidence. |
