Ophthalmologymiddle twist
A 34-year-old woman has had a gritty, watering right eye since walking home through a dust storm yesterday afternoon. It hurts most when she blinks. She has never worn contact lenses and nothing like this has happened before. Corrected acuity is 6/6 in each eye and the left eye is white and comfortable. Corneal sensation is equal in the two eyes and there are no vesicles on the face or nose. Under cobalt blue light, several fine vertical lines in the upper half of the right cornea take up the dye; the cornea is otherwise clear and the anterior chamber is quiet. Which one of the following best accounts for the pattern of staining?