A 9-year-old boy is brought to the emergency department for evaluation of right eye pain of several hours duration. His mother states, “He’s been fighting something all week. He's been blowing his nose non-stop; I think he had a fever too.” He has no significant past medical history. Temperature is 38.5°C (101.3°F), pulse
is 106/min, respirations are 18/min, and blood pressure
is 112/84 mmHg. Physical examination reveals tenderness to palpation over the right orbit with associated right eyelid swelling with erythema. The patient reports significant pain with extraocular eye movement. Which of the following is the most likely diagnosis?