1. tumor
a) intraorbital tumor:may be due to mass effect from tumor or to compromised venous drainage from the orbit
● optic sheath neuroma
● lymphoma
● optic sheath meningioma
● orbital involvement with multiple myeloma
● orbital invasion by invasive pituitary neuroendocrine tumor
● in peds: metastatic neuroblastoma
● in peds: Langerhans cell histiocytosis as part of Hand-Schüller-Christian (triad: DI, exophthalmos and lytic bone lesions (particularly of the cranium)) b) due to hyperostosis from a sphenoid ridge meningioma
2. Graves’ disease (hyperthyroidism + exophthalmos)): even though the exophthalmos is usually bilateral with this (80%), thyroid disease is still the most common cause of unilateral proptosis
3. enlargement of periorbital fat
4. infection: orbital cellulitis (usually has concomitant sinusitis)
5. inflammatory: orbital pseudotumor. Usually unilateral
6. hemorrhage
a) traumatic
b) spontaneous
7. 3rd nerve palsy: can cause up to 3 mm proptosis from the relaxation of the rectus muscles
8. cavernous sinus occlusion (may affect both eyes)
a) cavernous sinus thrombosis
b) cavernous sinus tumor obstructing venous outflow
9. pseudo-exophthalmos
a) congenital macrophthalmos (bull’seye)
b) lid retraction:e.g.in Graves’disease
c) coronal craniosynostosis can cause a “relative” proptosis