Corneal Abrasion and Corneal Ulcer

A corneal abrasion is a scratch through the corneal epithelium. A corneal ulcer is an infected, excavating defect in the corneal stroma. Both present with a red, painful, watering, light-sensitive eye and a patient who is convinced something is still in it. One heals in a day or two with no consequence at all. The other can destroy vision in the same period. That is the entire clinical problem of this lesson: the presentations overlap, the outcomes do not. The discriminating features are learnable and largely nursing-accessible. A simple abrasion has a clear cornea around the defect. An ulcer has a white or grey infiltrate — an opacity in the corneal tissue itself — and may have hypopyon, a layer of white cells in the anterior chamber. An abrasion improves steadily; an ulcer worsens. An abrasion in a non-contact-lens wearer after a fingernail scratch is low risk; the same symptoms in someone who slept in their contact lenses is infectious keratitis until proven otherwise. Contact lenses are the thread running through the whole topic. They are the dominant modifiable risk...