Image of the Week: Thin Film on the Cornea of an Elderly Woman

An 85-year-old woman is admitted to the hospital for management of chronic obstructive pulmonary disease. She is treated with bronchodilators, oral glucocorticoids, antibiotics, and noninvasive ventilation for 7 days. A novel thin white film appears on the patient's cornea. It does not slough with swabbing; the patient is otherwise asymptomatic.

Which of the following histories is most consistent with these findings? ...