- structural alterations in the bony orbit
- orbital fat atrophy
Specific causes include :
- orbital blowout fracture: most common
- silent sinus syndrome
- orbital metastasis: breast cancer orbital metastasis most commonly produces a desmoplastic response leading to retraction and considered one of the earliest signs of metastatic breast cancer
- maxillary sinus mucocele
- orbital varix: paradoxically causes posterior displacement of the globe when the varix empties
- Horner syndrome
It may or may not be associated with hypoglobus.
Exophthalmos (or proptosis) is the opposite, displacement of the globe anteriorly.