Bilateral proptosis describes the outward bulging of both eyeballs from their sockets. This condition is not a disease in itself but rather a physical manifestation of an underlying medical issue affecting the tissues behind or around the eyes. Recognizing this symptom is an important first step, as it often signals a need for medical evaluation to identify and address the root cause.
Understanding Bilateral Proptosis
Bilateral proptosis presents as a noticeable protrusion of both eyeballs, giving a “wide-eyed” or “startled” appearance. The white part of the eye, typically less visible, may become more apparent above or below the iris. This displacement can sometimes make it difficult to fully close the eyelids, potentially leading to increased exposure of the eye surface.
Individuals may experience eye irritation, a gritty sensation, or excessive dryness due to inadequate lubrication of the cornea. Blurred vision or double vision (diplopia) can also occur, along with pain or discomfort in the eyes. Redness and swelling of the eyelids or surrounding tissues may also be observed.
Common Underlying Causes
Thyroid Eye Disease (TED), also known as Graves’ ophthalmopathy, is the most frequent cause of bilateral proptosis in adults. This autoimmune disorder is often associated with hyperthyroidism, where the immune system mistakenly attacks tissues around the eyes, leading to inflammation and swelling of orbital fat and muscles. TED accounts for nearly 90% of bilateral proptosis cases.
Orbital tumors can also result in bilateral proptosis by occupying space within the eye sockets. These can include various types of growths, such as meningiomas or lymphomas, or even metastatic disease spreading from other parts of the body. In children, bilateral proptosis might be caused by conditions like neuroblastoma or leukemia.
Inflammatory conditions, such as idiopathic orbital inflammation or sarcoidosis, can also cause bilateral proptosis. These conditions involve immune system responses that lead to inflammation and swelling of orbital tissues. Orbital cellulitis, a bacterial infection, is a common cause of proptosis, particularly in children.
Vascular abnormalities can also contribute to bilateral proptosis. Conditions like carotid-cavernous fistulas, which involve abnormal connections between arteries and veins, can lead to increased blood flow and pressure within the orbit.
Diagnostic Process
Diagnosing bilateral proptosis begins with a comprehensive clinical examination by a healthcare professional. This involves assessing the overall appearance of the eyes and face, checking for symmetry, and evaluating eye and eyelid movement. A specialized instrument called an exophthalmometer is used to accurately measure the degree of eyeball protrusion; a protrusion of more than 2 millimeters indicates proptosis.
Imaging studies are usually performed to visualize the structures within and around the orbits and to identify any abnormalities. Computed tomography (CT) scans are frequently used, while magnetic resonance imaging (MRI) scans may be ordered for more detailed visualization, especially if conditions affecting the optic nerve or brain are suspected. These scans can help detect tumors, inflammation, or other structural changes.
Blood tests play a significant role in identifying underlying systemic conditions. Tests for thyroid function, including levels of Thyroid Stimulating Hormone (TSH), T3, and T4, along with thyroid auto-antibodies, are routinely conducted to confirm or rule out Thyroid Eye Disease. Other blood tests, such as those for C-reactive protein, may be ordered to check for signs of inflammation. In some instances, if an infection or a specific type of growth is suspected, a biopsy of the affected orbital tissue might be necessary.
Management and Treatment
The management of bilateral proptosis focuses primarily on addressing the specific underlying cause. For individuals with Thyroid Eye Disease, treatment involves controlling thyroid hormone levels through medications, radioactive iodine therapy, or thyroid surgery. A newer medication, teprotumumab, has been approved specifically for treating Thyroid Eye Disease in adults, showing significant improvement in proptosis.
Symptomatic relief is also provided. Lubricating eye drops, gels, and ointments are often prescribed to combat dryness and irritation. Elevating the head during sleep can also help reduce swelling around the eyes. For inflammatory causes, corticosteroids or other immunosuppressants may be administered to reduce inflammation.
Surgical interventions are considered for severe cases, especially when vision is threatened or when other treatments are insufficient. Orbital decompression surgery can create more space within the eye socket, allowing the eyeballs to recede. Eyelid surgery may be performed to correct eyelid retraction or improve eyelid closure. In cases of orbital tumors, surgical removal of the growth is necessary. Radiation therapy may also be used in specific situations, such as for active thyroid eye disease or certain types of tumors.