What Is Unilateral Exophthalmos?

Common Causes

The likely cause depends on how quickly the bulging developed and what other symptoms are present. Acute unilateral proptosis raises concern for infection, bleeding, or vascular problems. Slow, progressive proptosis more often suggests a tumor or chronic inflammatory disease.

• Thyroid eye disease, which can be unilateral in some patients
• Orbital cellulitis or other infection
• Orbital tumor or mass
• Vascular causes such as carotid-cavernous fistula or orbital varix
• Bleeding behind the eye after trauma or surgery

Warning Signs That Need Urgent Care

Seek urgent care if unilateral bulging is associated with pain, fever, reduced vision, or double vision. Trouble moving the eye, a swollen eyelid, or a sudden onset are also red flags. These findings can indicate orbital cellulitis, hemorrhage, or vascular emergencies. Any signs of optic nerve compression, such as decreased color vision or a rapidly worsening visual field, require emergency evaluation.

How It Is Evaluated

Evaluation includes a full eye exam, checking vision, eye movements, pupil responses, and the cornea for dryness or ulcer risk. Clinicians may measure proptosis using exophthalmometry and compare both eyes. Imaging such as computed tomography or magnetic resonance imaging of the orbits is commonly used to identify infection, mass, or bleeding. Thyroid testing may be ordered when thyroid eye disease is suspected.

Treatment and Next Steps

Treatment depends on the cause and may involve antibiotics for infection, steroids or immune therapy for inflammation, or surgery for tumors, decompression, or bleeding. Lubrication is often used to protect the cornea if the eyelids cannot close fully. Some conditions require urgent multidisciplinary care with ophthalmology, otolaryngology, neurology, or endocrinology. Do not delay care if symptoms are new, worsening, or associated with vision changes.