What single factor differentiates preseptal cellulitis from orbital cellulitis?

• A. Fever
• B. Pain with eye movement
• C. Visual changes
• D. AMS

Answer: (B)

The key idea is whether the orbit itself is involved. Pain with eye movement indicates inflammation inside the orbit that affects the extraocular muscles, which is characteristic of orbital cellulitis. Preseptal cellulitis is limited to the eyelid and periorbital tissues anterior to the orbital septum, so eye movements are typically not painful. That makes painful eye movements the best single sign to distinguish orbital involvement from preseptal disease.

Fever can occur in both conditions, and visual changes or AMS are more variable and less specific. In orbital cellulitis you also often see restricted extraocular movements, proptosis, or decreased visual acuity, reflecting the deeper orbital involvement. In preseptal cellulitis those findings are absent and vision remains normal with full ocular motility.