Exophthalmos (Proptosis) • LITFL • FFS

Exophthalmos, also known as proptosis, is an abnormal protrusion of the eyeball. It may indicate serious underlying pathology, including:

Space-occupying lesions in the orbit or intracranial cavity
Thyroid eye disease (TED)

Regardless of the cause, proptosis can compromise visual function and threaten ocular integrity.

Note: Some literature uses “exophthalmos” specifically for thyroid-related cases, using “proptosis” for all other causes.

Epidemiology

In adults, Graves disease is the most common cause of unilateral or bilateral exophthalmos.

Pathology

Causes

Exophthalmos is broadly divided into:

1. Space-occupying lesions

Category	Examples
Tumours	Orbital neoplasms
Trauma	Orbital fractures, retro-orbital haematomas
Infection	Orbital cellulitis, retro-orbital abscess
Vascular lesions	Cavernous sinus thrombosis, carotid-cavernous fistula, AVMs, hemangiomas, lymphangiomas
Coagulopathy	Retro-orbital haematomas (e.g. in anticoagulated patients)

2. Endocrine

Condition	Mechanism
Graves disease	Autoimmune orbital inflammation affecting fat and extraocular muscles; impaired venous outflow (e.g. superior ophthalmic vein) can worsen engorgement

Complications

Complications may arise from either the underlying cause or the exophthalmos itself:

Optic nerve compression: Drying → corneal ulceration → secondary infection
Exposure keratopathy: May cause irreversible vision loss from ischaemia

Clinical Assessment

Key History

Recent trauma
Known thyroid disease
Coagulopathy or anticoagulant use (e.g. warfarin, DOACs)

Examination Findings

Protrusion of the globe may be obvious on inspection. A prominent feature is the visibility of the sclera above the cornea (which is normally hidden by the upper eye lid).

In more subtle cases, exophthalmos may be more apparent by observing the patient’s eye from the side or from above.

In general, a difference of > 2 mm between a person’s two eyes is considered abnormal.

Exophthalmos left eye — Exophthalmos as seen from the side of a patient’s face. Note that the sclera is clearly visible above the cornea, normally the upper lid covers the upper part of the cornea and the sclera is not seen in this region.

Examination Area	Purpose / Possible Findings
Conscious state and orientation	Altered mental state may suggest serious intracranial pathology
Vital signs	Fever may indicate infection (e.g. orbital cellulitis)
Visual acuity and pupillary reflexes	↓ Visual acuity, RAPD, or visual field deficits suggest compressive optic neuropathy
External inspection	Obvious globe protrusion; sclera visible above cornea
Side/profile view of eyes	Helps detect subtle proptosis
Chemosis and conjunctival vessel engorgement	Suggest orbital congestion from mass or venous obstruction
Eye movements (EOMs)	Pain on movement, diplopia, or ophthalmoplegia suggest muscle or nerve involvement
Fundoscopy	Look for optic disc swelling or pallor
Slit lamp exam	Assess for exposure keratopathy or corneal ulceration (if indicated)
Periorbital tissues	Swelling, erythema, or tenderness may indicate periorbital/orbital cellulitis
Cranial nerve exam	Involvement of CN III, IV, V1, or VI may indicate cavernous sinus pathology
Palpation and auscultation of the globe/orbit	Pulsations or bruit may indicate carotid-cavernous fistula
Thyroid signs	Tremor, lid lag, tachycardia, or goitre suggest thyrotoxicosis

Investigations

Bloods

FBC
CRP
U&Es, glucose
TFTs
Coagulation profile

Imaging

Modality	Use
B-scan ultrasound	For intraocular pathology when direct view obstructed (e.g. hyphema, cataract)
CT orbit with contrast	Good for orbital/intracranial masses, retro-orbital infection, vascular lesions, and Graves’ orbitopathy
MRI/MRA	Superior soft tissue detail and vascular lesion identification (e.g. cavernous sinus thrombosis)

Management

Directed at:

Underlying cause
Secondary ocular complications:
- Lubricating eye drops
- Eye protection
- Surgical orbital decompression if needed

Disposition

All patients with exophthalmos require Ophthalmology review
Further referral (e.g. ENT, Neurosurgery, Endocrinology) depending on cause

Appendix 1

thyroid ophthalmopathy — Abnormal protrusion of the globes bilaterally. Radiopaedia

Axial CT images and at a level of the lens. If the distance from the anterior margin of the globe to interzygomatic line exceeds 21 mm, it is compatible with proptosis. In the case above the distance from anterior margin of the globe to interzygomatic line is 23 mm (right) and 25 mm (left). The findings are compatible with ocular proptosis due to thyroid ophthalmopathy.

Appendix 2