If the outermost layer of the cornea, called the epithelium, is damaged from trauma of any type, i.e. getting a foreign body in your eye such as piece of metal, a poke in the eye from a branch or a finger or even from a dirty or damaged contact lens, it is possible for bacteria, viruses or fungi to penetrate the cornea and cause an infection which is called a Keratitis. Keratitis can cause a painful inflammation with a discharge, which if not treated quickly and appropriately, can lead to corneal erosion, corneal ulceration and corneal scarring that can result in a loss of corneal transparency and require a corneal transplant in order to restore vision.
Herpes Zoster Keratitis (Shingles)
Herpes Zoster Keratitis is actually caused by the same virus that causes chicken pox, called Varicella-Zoster Virus. It is entirely possible that after having chicken pox as a child, the Varicella-Zoster Virus remains in the nerve cells of your body in an inactive state. The virus can reactivate later in life and travel through the nerves in your body causing a painful blistering rash. If the Varicella-Zoster Virus travels to your head or neck it can affect the eye and cause a corneal infection.
Ocular Herpes and Herpes Keratitis
Ocular Herpes or Herpes of the eye is caused by the Herpes Simplex Virus and is the most common causes of corneal blindness in the United States today. Up to 50% of people who have a single Herpes Simplex viral infection of the eye will experience a flare up or recurrence. The virus often leads to irreversible scarring of the cornea.