Protrusion of one or both eyeballs; can be congenital and familial, or due to pathology, such as a retro-orbital tumor (usually unilateral) or thyroid disease (usually bilateral). Syn: proptosis.
Exophthalmos is a medical condition that is usually linked with some other type of illness. Exophthalmos is characterized by bulging or protruding eyeballs. In most cases, both eyeballs are affected, but in some circumstances, only one eyeball is affected. If only one eyeball is affected, the condition is called proptosis.
Exophthalmos is most commonly associated with thyroid problems. The thyroid is a gland that controls the body’s metabolism. It is located in the neck and controls the rate at which the body uses its energy.
Exophthalmos occurs when tissue builds up in the eyeball socket. This causes the eyeball to be pushed forward and protrude to the front of the socket. The eyelids are then forced apart, exposing more of the eye’s white area. Patients suffering from this condition appear to be constantly staring.
Exophthalmos occurs in 30% of the patients suffering from orbital tumor. However, pain, diplopia, swelling, tearing and blurred vision are much more common presenting complaints. Since most optic nerve gliomas occur in the first two decades of life, loss of vision in children with or without optic atrophy suggests optic nerve glioma, particularly if some degree of exophthalmos exists. In a child, the presence of a retrobulbar mass with ecchymosis of the lids and subconjunctival hemorrhage associated with exophthalmos suggests a malignant tumor, particularly medulloblastoma. Mucormycosis should be considered in a diabetic patient suffering from a rapidly advancing exophthalmos with loss of vision and impaired motility. Always ask the patient if he hears a swishing sound. Such a symptom suggests a carotid-cavernous sinus fistula which may also be associated with pulsations of the globe. The more subtle cases with pulsation may only be observed when looking at the fundus with a direct ophthalmoscope. The bruit is best heard with a bell stethoscope.
Orbital tumors and some endocrine disorders can cause exophthalmos without impairment of motility. Benign orbital masses frequently cause only minor limitation of local rotation, usually in the field of action where the mass is located. Although the two conditions usually occur together, in some cases of endocrine disease ophthalmoplegia may occur before frank exophthalmos appears. Forced duction tests are usually positive in endocrine disease. However, some limitation may be experienced – and the test is less than specific – if considerable orbital edema or inflammation from other causes exists. Endocrine ophthalmoplegia usually manifests as limitation of upgaze, from restriction of the inferior rectus and inferior oblique in the area of Lockwood’s ligament
Vision Loss: Visual acuity loss can occur with exophthalmos from any cause; however, a retrobulbar tumor, particularly in the muscle cone, is the first consideration in the case of slowly progressive exophthalmos associated with loss of acuity. If the acuity can be restored by plus lenses and if increasing hyperopia is suggested, a retrobulbar tumor that is causing a flattening of the posterior surface of the eye should be considered. This is not pathognomonic of a retrobulbar tumor, since it can be seen also in posterior scleritis or with mild subretinal edema from other causes displacing the retina anteriorly.
In cases of endocrine exophthalmos, loss of vision is usually minimal and is frequently variable, suggesting some problem with the corneal epithelium secondary to exposure or to disturbance in the tear film from dryness or decreased blinking. In some cases, when exophthalmos progression is rapid and accompanied by considerable chemosis and inflammation, the loss of vision can be profound and may be caused by optic nerve involvement.
In some cases of thyroid disease, there is more pronounced swelling of the muscles in the posterior orbit with minimal signs of exophthalmos. A loss of vision then becomes hard to ascribe to thyroid disease until one sees a CT scan of the posterior orbit showing muscle compression of the optic nerve.
Bulging, or protruding, eyeballs are the most obvious and noticeable symptom of exophthalmos.
In thyroid conditions, such as Grave’s disease, bulging eyes occur as a result of the swelling of tissues in the eyeballs, and an increase in the number of cells in the eye. This pushes the eyes forward, making them protrude from their sockets (orbits).
As the eye sockets are made of rigid bone, they are unable to expand in order to accommodate the protruding eyeballs. The bulging eyeball forces the eyelid apart, causing you to take on a `wide-eyed’, staring expression. In exophthalmos, most of the whites of the eyes are exposed.
If you have exophthalmos, you may have limited eye movement. This is because the muscles in your eyes are weakened making it difficult to move your eyes. Muscle weakness can also result in the eyes turning inwards (amblyopia), or it can cause double vision (diplopia).
Painful, dry, and itchy eyes are also common symptoms that are associated with exophthalmos.
Causes and Risk factors:
Exophthalmos refers to abnormal protrusion of the eye. Some forms are associated with pulsations of the globe. Exophthalmos is a sign of orbital tumor but can also be caused by other conditions such as thyroid disease, orbital varix, arteriovenous fistula, collagen vascular disease, infections, pseudotumor, prolapse of cranial contents into the orbit and congenital cranial orbital defects.
Thyroid problems are the most common cause of exophthalmos. In particular, Grave’s disease – an autoimmune disease that causes the thyroid gland to produce an excess amount of thyroid hormone (hyperthyroidism) – is often associated with exophthalmos.
In exophthalmos, an increase in the amount of white cells (lymphocytes) in the eye, plus the inflammation and swelling that occurs as a result of an excess amount of thyroid hormone, results in the eyeballs being forced forward out of the eye sockets (orbits).
Exophthalmos does not always occur at the same time that thyroid gland problems, such as hyperthyroidism, or hypothyroidism, occur. It may occur months or, sometimes, years afterwards. However, sometimes, exophthalmos can occur before thyroid problems develop.
Simple Inspections: This is the first step in any physical diagnosis. The most common cause of lid swelling is a chalazion. The most intense rubor (redness) occurs with orbital cellulitis. Orbital and lid inflammation and minimal exophthalmos may occur after trauma to a dermoid tumor that has caused extrusion of its contents. Inflammation can also accompany rapidly growing tumors such as rhabdomyosarcoma in children.
Lid retraction can occur without exophthalmos in thyroid disease and give the eye the exaggerated appearance of exophthalmos. The observer must be careful in calling it lid retraction. A small ptosis in the other eye may give the appearance that the other, normal, lid is retracted. The patient complains about the cosmetic appearance of the eye that bothers him the most when in reality the problem may be in the other eye. True lid retraction usually leaves a small amount of sclera showing above the superior limbus or less commonly below. Dilation of vessels over the lateral rectus muscle not extending to the limbus is highly suggestive of endocrine exophthalmos.
Hertel instrument: It measures the relationship between the lateral orbital rim and the anterior cornea surface. This instrument allows the examiner to reproduce the same pupillary distance from exam to exam. It also allows the examiner to keep the same parallax view for observation of the corneal surface by lining up two lines in its mirrors.
Ninety-five percent of the population measures 19 mm or less from the lateral orbital rim to the tip of the cornea and most of the rest are in the 16 to 18 mm range. A difference of up to 2 mm can be considered normal. A slight degree of exophthalmos of about 1 to 2 mm may occur in a total third nerve palsy.
In cases of bilateral exophthalmos, particularly if there is no fever or chemosis or ecchymosis, a thyroid profile is the most valuable test. Orbital MRI may also be done. However, Graves’ disease may be present with normal thyroid function tests. Testing for thyrotropin receptor antibody and peroxidase antibodies should be done in these cases. Other endocrine studies may be necessary once hyperthyroidism has been excluded. In cases of unilateral exophthalmos, ultrasonography and plain films of the orbits and sinuses may be helpful, but a CT scan of the brain and sinuses is the most valuable diagnostic aid. Carotid angiography will need to be done to diagnose an arteriovenous fistula.
In order to help confirm exophthalmos, you may have a blood test, or a thyroid function test, to check whether your thyroid gland is functioning properly.
The ophthalmologist may also carry out some tests to check your ability to move your eyes, and to measure the degree of eyeball protrusion using an instrument called an exophthalmometer. If you have exophthalmos, you will be able to look upwards without moving your eyebrows.
Assessment of exophthalmos:
- History – specifically ask about the above symptoms. The rate and duration of onset should be noted. Transient visual loss may signify optic nerve compromise and warrants a more rapid referral. Explore other systems – could this be a manifestation of systemic disease?
- Examination: the proptosis – periorbital changes can be assessed in a well-lit rooms. With regards to the proptosis
- What is the direction of the proptosis? Look down at the patient from above and behind, so that you are looking at their eyebrows and the nose below.
- Observe the proptosed eye: is it displaced forward or to the side? Intra-conal lesions tend to push the globe directly forwards whereas extra-conal lesions push it to one side.
- How severe is it? This can be formerly assessed using a Hertel exophthalmometer which uses a system of small mirrors to visualize the corneal apices against a scale. Although less accurate, one can also measure these using a clear plastic rule by placing it at the lateral canthus (where the upper and lower lids meet) and holding it parallel to the patient’s nose. A difference of 2mm between the two eyes is significant.
- Examination: the orbit – look for lid swelling, engorged conjunctival and episcleral vessels and lagophthalmos/incomplete lid closure. Palpate the orbit for any tenderness or masses and examine the regional lymph nodes. If you suspect a high-flow lesion, listen to the globe over the closed eyelid with a stethoscope.
- Examination: the optic nerve – check for optic nerve function (visual acuity, check for RAPD, dyschromatopsia, assess brightness sensitivity and do a confrontational visual field test).
If you are diagnosed with exophthalmos, your ophthalmologist will want to examine your eyes on a regular basis. This is because exophthalmos is a progressive disease and your symptoms will worsen over time.
If you have exophthalmos, the treatment that your ophthalmologist will recommended for you will depend on what is causing the symptom.
Thyroid problems: If you have exophthalmos which is caused by a thyroid problem, treatment to improve the functioning of your thyroid gland may be recommended. The aim of this treatment will be to return your thyroid hormone levels to normal.
After treatment has been started, the appearance of your eyes and any distortion to your vision will hopefully be restored to normal. However, in some cases of exophthalmos, such as those that are caused by Grave’s disease, thyroid treatment may not help to improve bulging eyes and, sometimes, changes to your vision and the appearance of your eyes may be long-term or permanent.
Therefore, it is important that you seek medical advice as soon as you notice exophthalmos, so that treatment can be started immediately.
Surgery: Surgery may be required if you have exophthalmos that is caused by a problem with the connection between the arteries and veins in your eyes.
In very severe cases of exophthalmos, surgery may also be required to remove the bony floors of your eye sockets. This procedure is known as surgical orbital decompression. It allows the build up of any excess material, such as the white cells (lymphocytes) that are pushing your eyeballs forward, to move down into the space below. This space is known as the maxillary sinus (antrum).
Other treatments: As well as surgery and thyroid treatments, there are a number of other treatments that can be used to help improve the symptoms of exophthalmos.
Eye drops and eyeshades: For dry eyes, lubrication of the cornea (the transparent tissue that covers the front of your eyeball) using eye drops will help keep your eyeballs moist. If your eyes are painful and sensitive to light (photophobia), wearing eyeshades may help.
Corticosteroids: In severe cases of exophthalmos, where your eyes are particularly painful and inflamed, corticosteroids may be recommended. Corticosteroids are a type of medication that is often used to reduce swelling and inflammation.
Therefore, if you are prescribed a course of corticosteroids, it should help to improve your symptoms by reducing the inflammation in your eyes.
Treating a tumour: If you have a tumour behind your eye, your ophthalmologist will discuss with you the possibility of removing it. Depending on the type of tumour that you have, chemotherapy, radiation therapy, surgery, or a combination of these, are all possible treatment options.
Medicine and medications:
Ocular lubricants: Keep adequate moisture in eye and prevent dryness.
Artificial tears (Celluvisc, Murine, Refresh, Tears Naturale).
DISCLAIMER: This information should not substitute for seeking responsible, professional medical care.