What is the most common cause of periorbital cellulitis?

Periorbital cellulitis is most commonly caused by the spread of infections from adjacent structures, with acute ethmoiditis being a frequent culprit. The ethmoid sinuses are located near the orbits, and when they become infected, the bacteria can easily extend into the surrounding tissues, leading to periorbital cellulitis. This condition typically presents with swelling and redness around the eyes, and it can result from either a direct bacterial infection or as a complication of sinusitis.

In many cases, the infection originates from the sinuses, making acute ethmoiditis a significant cause of periorbital cellulitis. Clinicians often evaluate sinus symptoms such as nasal congestion, rhinorrhea, and purulent nasal discharge in patients with this condition. Early identification and treatment are crucial to prevent complications, such as the spread of infection to the orbit and possible vision loss.

Other causes, such as viral infections, trauma, and specific bacterial infections like Staphylococcus, may contribute to periorbital swelling or infection, but they are less commonly the primary cause compared to acute ethmoiditis resulting from sinusitis.