What is the primary source of infection in orbital cellulitis?

The primary source of infection in orbital cellulitis is often a sinus infection. This condition typically arises when bacteria from the sinuses, particularly the ethmoid or maxillary sinuses, spread to the orbit, which is the bony cavity that contains the eye. The close anatomical relationship between the sinuses and the orbit allows for this transmission of pathogens, leading to inflammation and infection of the orbital tissues.

In many cases, patients may exhibit symptoms of sinusitis before developing orbital cellulitis. While eye injuries, ear infections, and skin infections can contribute to infections in different contexts, they are less common pathways for the development of orbital cellulitis compared to the direct spread of infection from the sinuses.