The following is a slit lamp photograph of a 60 year old woman with complaints of chronic foreign body sensation. Which of the following is the least likely cause of her condition?

Correct Answer: Neurotrophic keratitis

The photograph shows peripheral corneal thinning secondary to dry eye. This can be caused by keratitis sicca, poor blink secondary to Bell’s Palsy, or systemic collagen vascular disease, such as rheumatoid arthritis. Neurotrophic keratitis can cause corneal thinning, but would usually not be associated with chronic foreign body sensation.