Orbital cellulitis is inflammation of the tissues surrounding the eye. It most commonly refers to an acute spread of infection into the eye socket from either the adjacent sinuses or through the bloodstream. When it affects the rear of the eye, it is known as retro-orbital cellulitis. Common signs and symptoms of orbital cellulitis include pain with eye movement, sudden vision loss, bulging of the infected eye, and limited eye movement. The treatment involves antibiotics to clear the infection, and sometimes surgical drainage to drain abscesses if present.