A disease of viral keratitis in one eye may be transmitted to the other eye. When the body’s immunity is low, the cornea’s defenses are reduced, and viruses attacking the cornea may cause viral keratitis. The main pathogen that causes viral keratitis is the herpes simplex virus. Viral keratitis is usually contagious, and when one eye is infected with viral keratitis, the other eye may become infected by contact with the virus through the use of a towel, rubbing the eye with the hand, and so on. Therefore, it is important to treat viral keratitis in one eye and pay attention to personal hygiene to avoid infecting the healthy cornea.