- The orbital septum defines the boundary between the orbital cavity and the skin covering the eye and orbit.
- Orbital cellulitis = post-septal cellulitis. The preferred term is “orbital cellulitis.”
- Preseptal cellulitis = peri-orbital cellulitis. The preferred term is “preseptal cellulitis.”
Orbital cellulitis is a much more serious infection due to the limited space of expansion within the confining skull bones.
Etiology: the bacteria are sinus bacteria – M cat, H flu, S pneumo. H flu is not that common anymore – untypeable H flu can still be seen.
Complications of preseptal cellulitis: extension into orbital cellulitis, cavernous sinus thrombosis, extension into frontal sinus and frontal lobe.