What differentiates preseptal cellulitis from postseptal cellulitis?

• A. Superficial versus deep to the septum of the eye
• B. Infectious versus non-infectious origin
• C. Viral versus bacterial infection severity
• D. Requires imaging versus physical examination only

Answer: (A)

Preseptal cellulitis and postseptal cellulitis are differentiated primarily by their anatomical locations relative to the orbital septum, which is a thin layer of tissue that separates the eyelid tissues from the deeper structures of the orbit. Preseptal cellulitis occurs in the tissues anterior to the orbital septum, affecting the eyelids and surrounding areas, while postseptal cellulitis, also known as orbital cellulitis, involves the tissues posterior to the orbital septum, which includes the contents of the orbit as well as the ocular muscles and fat.

This distinction is crucial because postseptal cellulitis is typically associated with more severe complications, including the potential for vision loss and intracranial spread of infection, which necessitates more aggressive treatment. The management of these conditions differs as well, with postseptal cellulitis often requiring imaging studies, hospital admission, and intravenous antibiotics, whereas preseptal cellulitis can frequently be managed on an outpatient basis with oral antibiotics.

Understanding this anatomical separation helps guide clinicians in both diagnosis and treatment, emphasizing the importance of correct identification of these conditions based on their location in relation to the orbital septum.