Review Question - QID 212556

A 3-year-old boy is brought to the pediatrician by his mother for "irritated eyes." The mother states that 2 days ago she noticed that the patient kept rubbing his eyes. Yesterday, his eyes appeared slightly red. Then this morning he woke up crying because he couldn’t open his eyes. The patient has atopic dermatitis and uses topical triamcinolone as needed. He had surgery for eustachian tube dysfunction 6 months ago. The patient’s temperature is 101.3°F (38.5°C), blood pressure is 102/60 mmHg, and pulse is 110/min. On physical exam, extraocular eye movements are intact and the pupils are equal and reactive to light. Figure A shows the patient’s eyes as they appear grossly. Which of the following is the most likely cause of the patient’s symptoms?