Proptosis Causes and Evaluation

Proptosis and Bulging Eyes

Woman with eye pain. Eric Audras

Proptosis, also known as exophthalmos, is a bulging of one or both of the eyes. While some people naturally have eyes that seem to bulge due to variations in our anatomy, others can develop the condition. If a person suddenly develops proptosis, it is considered serious. Sudden onsets of proptosis should always be evaluated by an eye doctor.

What Causes Proptosis?

One of the most common causes of bilateral (both eyes) bulging eyes is a thyroid condition referred to as Graves Disease.

In Graves disease, swelling, fibrosis and scarring may occur within the eye muscles surrounding the eye. This crowds the bony orbit where the eye sits, causing the eyes to bulge forward.

When a person develops unilateral (one eye) proptosis, medical testing is recommended quickly as this can be a sign of a serious medical condition. Unilateral proptosis can result from a sinus infection that has spread into the orbit creating an abscess. Unilateral proptosis can also be caused by trauma, inflammation, arterio-venus malformations, orbital tumors and cancer. 

Evaluating Proptosis

When proptosis is mild, a doctor may measure the degree of bulging with a ruler or an exophthalmometer. If measurements are outside of normal ranges, more testing may be recommended. Tests may include an MRI, blood work, ultrasound or even a biopsy.

Is Proptosis Serious?

Proptosis can impact the eyes in several different ways.

First, because the bulging orbit may elevate the pressure behind the eye, pressure inside the eye may increase. The pressure inside of the eye is known as intraocular pressure. When intraocular pressure increases, risk for developing glaucoma also increases.

When proptosis occurs, the eyelids may not be able to close completely during normal blinking or sleeping, causing the cornea to dry out significantly.

This dryness is not only uncomfortable, but scarring can also occur which could lead to permanent vision loss. Artificial tears or gels should be inserted several times per day to alleviate discomfort and protect the cornea from severely drying out. Patches may also be worn at night while sleeping to keep the eyes moist. In severe cases, eye movement may even be affected, causing double vision.

Treating proptosis is centered around finding the underlying cause. In the case of thyroid disease, medications may be all that is needed to reduce the proptosis. In extreme cases, surgery may be needed.