What are ghost vessels in the cornea indicative of?

Ghost vessels in the cornea are indicative of previous keratitis. These vessels are actually remnants of neovascularization that can occur in response to inflammation, particularly following conditions like keratitis, where the cornea becomes inflamed, and new blood vessels grow to supply nutrients to the affected area. Once the keratitis resolves, these blood vessels may regress, leaving behind faint, ghostly markings or "ghost vessels" as they become less prominent.

This phenomenon is important in understanding the history of corneal health in a patient. It signifies that there has been a previous inflammatory response and that the cornea underwent changes to cope with that condition. In contrast, the other options do not accurately reflect the significance of ghost vessels: recent ocular surgery would typically lead to acute changes rather than the long-term appearance of ghost vessels, normal blood flow would not create such markings, and allergic reactions typically do not result in the formation of ghost vessels in the cornea. Hence, the presence of ghost vessels strongly suggests the prior existence of keratitis.