What is proptosis?
Proptosis, also called exophthalmos or bulging eyes, is a condition in which one or both eyes protrude forward from the eye socket beyond their normal position. When the eye bulges outward, more of the white of the eye becomes visible, and the eye may take on a wide, staring appearance.
The eye socket is a rigid bony structure with a fixed amount of space. When anything inside that space grows, swells, or expands, including inflamed tissue, a cyst, a tumor, or excess fat, the eye has nowhere to go but forward. Proptosis is always a symptom of an underlying condition, so identifying and treating the underlying cause is the first and most important step in managing it.
What causes proptosis?
The most common cause of bulging eyes in adults is thyroid eye disease (TED), an autoimmune condition most often associated with Graves' disease, in which the body's immune system attacks the tissue and muscles behind the eye. This causes swelling and expansion of the orbital contents that pushes the eye forward. Thyroid eye disease can affect one or both eyes.
Other causes of proptosis include:
- Orbital tumors, both benign and malignant, that grow behind the eye and displace it forward
- Orbital cellulitis, a bacterial infection of the tissue surrounding the eye that causes rapid swelling
- Orbital inflammatory disease, a non-infectious inflammation of the orbital tissues
- Bleeding behind the eye resulting from trauma or injury
- Cysts within the orbit
- Cancers that have spread to the orbit from elsewhere in the body
In children, orbital cellulitis is the most common cause of a rapidly bulging eye. Slower-developing bulging in children is more likely to be caused by a tumor or cyst.
What are the symptoms of proptosis?
The most noticeable sign of proptosis is the forward displacement of one or both eyes. Additional symptoms vary depending on the underlying cause and the degree of eye bulging and can include:
- Increased visibility of the white of the eye, particularly below the iris
- Difficulty fully closing the eye, especially during sleep
- Dry, irritated, or gritty eyes due to increased corneal exposure
- Redness or swelling of the eye or eyelids
- Double vision
- Decreased or blurred vision
- Pain or pressure around the eye
- Sensitivity to light
Symptoms that develop rapidly, over hours or days, warrant prompt evaluation, as they may indicate an infection or bleeding behind the eye that requires urgent treatment.
How is proptosis diagnosed?
Diagnosis begins with a thorough evaluation by an oculofacial plastic surgeon. During this appointment, your surgeon will:
- Review your symptoms, how quickly they developed, and any relevant medical history, including thyroid conditions or prior cancer diagnosis
- Measure the degree of eye protrusion
- Assess vision, eye movement, and the health of the cornea and surrounding structures
- Examine the eyelids and evaluate how fully they close over the eye
Imaging studies are an important part of evaluating the cause of proptosis. This typically includes a CT scan, which provides detailed images of the bony orbit and helps identify the size and location of any mass, fluid collection, or structrual abnormality. An MRI scan provides more detailed images of the soft tissue structures within the orbit, including the muscles, fat, and optic nerve.
Blood tests to evaluate thyroid function are typically ordered when thyroid eye disease is suspected. If a tumor or cyst is identified, a biopsy may be needed to determine its nature.
How is proptosis treated?
Treatment depends entirely on what is causing the eye to bulge. The goal in every case is to address the underlying condition, protect the eye's surface from dryness and damage, and preserve vision.
Eye lubrication and protection is part of almost every treatment plan for proptosis. When the eye cannot close fully, the cornea is exposed to air and at risk for drying, irritation, and damage. Lubricating eye drops and ointments help protect the corneal surface while the underlying condition is being treated. In severe cases, a temporary procedure to partially close the eyelid may be used to protect the eye until more definitive treatment can be completed.
Thyroid eye disease is managed in coordination with an endocrinologist to address the underlying thyroid condition. For mild cases, lubricating drops and close monitoring are often sufficient. Moderate to severe cases may be treated with corticosteroids to reduce orbital inflammation, targeted biologic medications, or orbital decompression surgery.
Orbital decompression surgery is a procedure in which bone and fat are carefully removed from the orbit to create more space and allow the eye to move back into a more natural position. It is used most commonly for thyroid eye disease and is recommended when the degree of eye bulging is significant, when vision is at risk from compression of the optic nerve, or when the eye cannot close adequately. Orbital decompression may also improve the cosmetic appearance of the eyes.
Orbital tumors that are causing the eye to bulge may require surgical removal, radiation, or other treatments depending on the type and nature of the tumor.
Whether the cause is thyroid disease, an orbital mass, inflammation, or another condition, an accurate diagnosis is the first step toward the right treatment. The oculofacial plastic surgeons at The Iowa Clinic provide personalized treatment to evaluate and treat the full range of conditions that cause proptosis. Call 515.875.9480 to schedule an appointment.