Another rare cause of exophthalmos is glaucoma that occurs in early childhood.
From the orlandosentinel.com
The most common cause of true exophthalmos is Graves'disease.
From the orlandosentinel.com
More examples
Protrusion of the eyeball from the socket
Exophthalmos (also called exophthalmia or proptosis) is a bulging of the eye anteriorly out of the orbit. Exophthalmos can be either bilateral (as is often seen in Graves' disease) or unilateral (as is often seen in an orbital tumor). ...