Bulging eyes (also called exophthalmos or proptosis) are usually a symptom of an underlying medical problem, not a disease by themselves.

Main medical causes

  • Thyroid eye disease / Graves’ disease
    • This is the most common cause in adults.
* It happens when the immune system attacks tissues and muscles around the eyes in people with thyroid problems (usually an overactive thyroid, or hyperthyroidism). Swelling and extra tissue behind the eye push the eyeball forward, making it look “bulgy.”
  • Hyperthyroidism (overactive thyroid), with or without Graves’
    • The thyroid gland in the neck makes too much hormone, speeding up many body functions.
* Eye changes can include bulging, irritation, redness, and double vision when the tissues behind the eye become inflamed.
  • Infections around or behind the eye (orbital cellulitis, periorbital cellulitis)
    • A serious infection in the tissues around the eye socket can cause swelling that pushes the eye forward.
* This often comes with pain, redness, fever, and sometimes trouble moving the eye, and it needs urgent medical care.
  • Tumors or growths in the eye socket (orbit)
    • Benign or cancerous masses can take up space behind the eye and push it outward.
* These may include lymphomas, neuroblastoma, rhabdomyosarcoma, or other orbital tumors in adults or children.
  • Bleeding or injury behind the eye
    • Trauma to the face or head can cause bleeding in the orbit (behind the eye), leading to sudden bulging of one eye.
* Sudden bulging after an injury is treated as an emergency because it can rapidly damage vision.
  • Blood vessel problems / vascular issues
    • Abnormal clusters of blood vessels (hemangiomas) or problems with veins and arteries around the eye can cause gradual or sudden protrusion.
  • Glaucoma and other less common causes
    • Severe or congenital glaucoma can enlarge the eye and make it appear more prominent, sometimes resembling bulging.
* Rare inflammatory conditions in the orbit (sometimes called orbital pseudotumor) and other systemic diseases like sarcoidosis can also cause proptosis.

When it’s an emergency

  • Sudden bulging of one eye , especially with pain, vision changes, double vision, or after an injury, is considered a medical emergency and needs immediate assessment in an emergency department or urgent eye clinic.
  • Bulging that comes on more slowly, with symptoms like weight loss, tremor, or feeling very hot, may point toward thyroid disease and still needs prompt medical evaluation.

How doctors figure out the cause

  • History and exam : A clinician will ask when the bulging started, whether it’s one or both eyes, and check for pain, double vision, redness, or systemic symptoms (like weight changes, fevers, or thyroid symptoms).
  • Blood tests : Often include thyroid function tests to look for hyperthyroidism or Graves’ disease.
  • Imaging : CT or MRI scans of the orbits help detect tumors, infections, bleeding, or inflammatory diseases behind the eye.
  • Specialist referral : Many people are seen by both an eye specialist (ophthalmologist) and, if needed, an endocrinologist or oncologist, depending on the suspected cause.

Treatment overview

The treatment always focuses on the underlying cause , not just the appearance:

  • For thyroid eye disease / Graves’ : thyroid hormone–controlling medicines, sometimes steroids, newer immune‑modulating drugs, radiation, or surgery to relieve pressure behind the eye.
  • For infections : urgent antibiotics (often through a vein) and sometimes surgery to drain infected pockets.
  • For tumors or bleeding : surgery, radiation, chemotherapy, or other cancer‑specific treatments when needed.
  • For glaucoma : eye‑pressure–lowering drops, medications, or surgery to protect the optic nerve.

Supportive care (lubricating eye drops, ointments, taping lids shut at night in severe cases) helps protect the cornea from drying and damage when the eyelids can’t fully close.

A quick example

Imagine someone whose eyes have slowly started to look more “staring” over several months, along with weight loss, feeling very hot, and a racing heart. An exam shows both eyes bulging and difficulty moving them fully. This pattern would strongly suggest thyroid eye disease related to hyperthyroidism, and the doctor would confirm it with thyroid blood tests and imaging of the orbits.

Important: If you or someone you know notices new or worsening bulging of one or both eyes—especially if it is sudden, painful, or associated with vision changes—seek in‑person medical care urgently. Online information is not a substitute for an examination and imaging by a professional.

Information gathered from public forums or data available on the internet and portrayed here.