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What Causes Shingles?

Shingles is produced by the varicella-zoster virus, the same virus that causes chickenpox.

After an initial outbreak of chickenpox (often during childhood), the virus remains inactive within the nerve cells of the central nervous system. But in some people, the varicella-zoster virus will reactivate at another time in their lives.

When this happens, the virus travels down long nerve fibers and infects some part of the body, producing a:

  • blistering rash (shingles),
  • fever,
  • painful inflammations of the affected nerve fibers, and
  • a general feeling of sluggishness.

Risk Factors

Although shingles can occur in anyone exposed to the varicella-zoster virus, research has established two general risk factors for the disease:

  1. advanced age, and
  2. a weakened immune system.

Studies show that people over age 80 have a five times greater chance of having shingles than adults between the ages of 20 and 40.

Unlike herpes simplex I, the varicella-zoster virus does not usually flare up more than once in adults with normally functioning immune systems.


Find an Ophthalmologist


Varicella-zoster virus may travel to the head and neck, perhaps involving an eye, part of the nose, cheek, and forehead. In about 40 percent of those with shingles in these areas, the virus infects the cornea.


Doctors will often prescribe oral anti-viral treatment to reduce the risk of the virus infecting cells deep within the tissue, which could inflame and scar the cornea. The disease may also cause decreased corneal sensitivity, meaning that foreign matter, such as eyelashes, in the eye are not felt as keenly. For many, this decreased sensitivity will be permanent.

Follow-Up Eye Exam

Be aware that corneal problems may arise months after the shingles are gone. For this reason, it is important that people who have had facial shingles schedule follow-up eye examinations.