Shingles is a disease that affects older people who had chicken pox when they were children. Chicken pox is caused by the herpes zoster virus. Even when the disease has run its course, the virus isn't eliminated but only goes dormant. Later, when the person's immune system might be less strong than it was in their youth, the virus might be activated and shingles occurs. The one good thing about shingles is that it's not contagious. The first signs that shingles is developing are shooting pains or tingling. Itching might accompany these sensations as well. They usually happen on one side of the body and the intensity of the pain can vary. Many people, however, find the pain of shingles excruciating. Even after the blisters subside, the pain can linger for years. This is called post-herpetic neuralgia. Blisters then appear along the line of the nerves and can last from one day to two weeks. Sufferers who get the blisters in the face must take special care, for the disease can damage their hearing or their vision. People whose eyes are affected by shingles can develop a sensitivity to light or have blurred vision. They can also feel that they have something in the eye. In worst cases, shingles can lead to scarring of the eye, glaucoma or even blindness. As of now, shingles has no cure. People can receive vaccinations that may help prevent shingles from forming. The vaccine seems to be about 51 percent effective in reducing the incidence of shingles. Medications are also available to treat the pain of the disease. To treat intense pain, the patient might be given nerve blocks or corticosteroids, though corticosteroids carry the risk of the rash spreading. The vaccination is only taken once and there's no upper age limit. Doctors recommend that people be vaccinated when they're 60 years old or older, as the older a person is the more adversely the disease affects him or her.