ORBITS
LEARN / ANATOMY
ORBITAL/OCULAR INFECTION
Most common etiology of orbital infection is direct spread of infection from the paranasal sinuses, especially bacterial rhinosinusitis involving the ethmoid air cells. Other etiologies include trauma, foreign body, odontogenic infection.
CELLULITIS
Preseptal cellulitis
Involves anterior periorbital STs of the eyelids, superficial to the orbital septum.
Trauma is #1 cause, also insect bites
Staph, step & H flu
Generally mild and much more common than orbital cellulitis.
Sx: eyelid swelling and erythema.
SQ fat stranding and swelling of the eyelids and face but normal orbital fat.
Often managed by oral Abx
Orbital cellulitis
Post septal cellulitis is extranconal &/or intraconal; involves the mm and fat deep to the orbital septum.
Sinusitis is MCC; can be 2/2 foreign bodies and penetrating trauma.
Polymicrobial, including anaerobes
Risk of complications such as abscess and intracranial spread via valveless opthalmic veins.
Sx: eyelid swelling, erythema, PAINFUL opthalmoplegia, chemosis and/or proptosis.
Orbital fat stranding, sometimes w extraocular mm edema, proptosis or an intraconal or extraconal phlegmon.
abx and complications may require surgical intervention
SUBPERIOSTEAL ABSCESS
Suppurative collection involving the bony orbit under its periosteum.
It can arise associated with or independent of orbital cellulitis.
Convex rim-enhancing collection tracking along the bone surface, most commonly the medial orbital wall in the setting of ethmoid sinusitis.
ORBITAL ABSCESS
Abscess located w/n the ST of the orbit 2/2 consolidation of orbital cellulitis or rupture of subperiosteal abscess
Focal rim-enhancing collection
OCULAR TRAUMA
Globe rupture or open-globe injury is usually diagnosed on clinical examination but CT can be helpful in unclear cases or to exclude orbital foreign bodies.
Imaging
Flat tire sign: wall contour irregularity and decreased globe volume, change in anterior chamber depth, intraocular foreign body or intraocular gas.
Increased depth of the anterior chamber suggests posterior segment rupture, while decreased depth suggests anterior segment rupture (corneal perforation)
Nonacute mimics include
Globe outpouching: coloboma, staphyloma
Pthisis bulbi (atrophic and calcified globe)
Focal ocular calcifications (optic nerve dfusen, senile scleral plaques)
Scleral bands or intraocular gas/air placed to treat retinal detachment