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Bulging Eyes

Medically referred to as exophthalmos, protruding or bulging eyes could be a sign of Graves' ophthalmopathy. This story provides information on the contributing factors for this condition.
Dr. Sumaiya Khan
The terms 'exophthalmos' or 'proptosis' refer to the condition of bulging eyes. This eye condition could be unilateral or bilateral, which means that it could affect one or both the eyes. The onset of this condition may be sudden or slow.
The extent of the protrusion of the eyeball can be measured with the help of an exophthalmometer. If the degree of forward displacement of the eye is high, other diagnostic tests would be conducted.
Complete or partial dislocation of the eye from the orbit is also possible due to the swelling of surrounding tissue, which in turn might result from trauma. In severe cases, where the eyelids fail to close during sleep, the affected individual could experience corneal dryness, and might be at a risk of developing corneal damage.

Contributing Factors

Graves' Disease
Protruding eyes is often a symptom of Graves' ophthalmopathy, which could occur in individuals affected by Graves' disease. Graves' disease is an autoimmune condition which is characterized by the excessive production of thyroid hormones by the thyroid gland.
The symptoms of Graves' disease include hand tremors, weight loss, enlargement of the thyroid gland, increased heat sensitivity, palpitations, anxiety, etc. Basically, this condition occurs when the immune system attacks the thyroid gland, as it mistakes the gland to be a foreign body.
Autoantibodies to the TSH-receptor activate that TSH-receptor, thereby stimulating the synthesis and increased secretion of thyroid hormone. In case of Graves' ophthalmopathy, the autoantibodies that are present in the blood target the fibroblasts in the eye muscles, which can differentiate into fat cells.
Fat cells and muscles expand and become inflamed, while veins get compressed and are unable to drain fluid. This gives rise to edema and protrusion of the eyes.
Thus, in case of Graves' disease, the displacement of the eye is due to abnormal connective tissue deposition in the orbit and around the extraocular muscles. These changes can be observed with the help of a CT or an MRI scan.
Other Causes
Although Graves' disease is by far the most common cause of protruding eyes, other conditions could also cause the eyeballs to bulge. Diseases that affect the eyes directly or indirectly could lead to the protrusion of the eyes. Cancer or tumors could be the contributing factors for unilateral bulging of eyes.
Eye cancer is relatively rare, with retinoblastoma being the most common type of eye cancer. The second most common type of cancer is melanoma. Glaucoma is a serious disorder which is characterized by an increase in the pressure inside the eyeball. This could lead to enlargement and protrusion of eyes outside the socket.
Eye infections, or hemorrhage/bleeding behind the eye (due to traumatic head injury) can lead to bulging of the eyeball. An orbital fracture could also lead to this condition. This is a medical emergency, and medical assistance must be sought immediately. Other relatively rare conditions that can lead to exophthalmos include:
Leukemia
Eye problems like orbital cellulitis
Meningioma
Dacryoadenitis
Mucormycosis
Duane syndrome
Carotid cavernous fistula
Hemangioma
High altitude cerebral edema
Exophthalmos should be taken seriously, as the process that is causing the displacement of the eye may also compress the optic nerve or ophthalmic artery. This could eventually lead to partial or complete blindness, which could even be permanent. Thus, medical assistance must be sought to treat this eye condition and its underlying cause at the earliest.
Disclaimer: The information provided in this story is solely for educating the reader. It is not intended to be a substitute for the advice of a medical expert.