Which finding is uncommon in pre-septal cellulitis compared to orbital cellulitis?

Proptosis, which refers to the protrusion of the eye, is more commonly associated with orbital cellulitis due to the involvement of the orbital tissues and increased pressure within the orbit. In orbital cellulitis, the inflammation and infection can lead to swelling that pushes the eye forward, resulting in proptosis. On the other hand, pre-septal cellulitis affects only the eyelids and anterior portion of the orbit and typically does not involve the deeper orbital tissues. Therefore, the presence of proptosis is considered an uncommon finding in pre-septal cellulitis.

In contrast, redness and tenderness of the eyelids, fever, and swelling of the conjunctiva can occur in both conditions, but they are more indicative of the inflammatory response to infection in pre-septal cellulitis. Fever might be present as a systemic response to the infection and is not exclusive to either type of cellulitis. Similarly, conjunctival swelling can occur due to the inflammatory process that affects the eyelid and surrounding areas in pre-septal cellulitis. Thus, while redness, fever, and conjunctival swelling can appear in both conditions, proptosis distinctly differentiates orbital cellulitis from pre-septal cellulitis.