The facial  coronal CT slice shows a ‘tear drop’ sign. There is herniation of the infra orbital fat and inferior rectus into the maxillary sinus.

Orbital blow-out fracture is due to sudden increase in the intra ocular pressure causing fracture of the orbital floor. On the facial view x-rays /CT, it can be seen as

1. Tear drop sign as above.
2. Eyebrow sign – air from maxillary sinus rising superiorly within the orbital cavity.
3. There may be associated fluid within the maxillary sinus.

Reference: Grainger & Allison’s Diagnostic Radiology Essentials.