Herpetic Corneal Dendrite as seen with special staining and lighting . Repeated episodes of herpetic keratitis may eventually lead to corneal scarring requiring cornea t ransplant surgery to improve vision .
Humans are the only natural host of the herpes simplex virus.
The Herpes simplex Type I virus , causes the familiar 'cold store ' or ' fever blister ' on the lips . However , the same virus can repeatedly infect the cornea . While some patients with herpes simplex keratitis will describe a history of recurrent fever blisters , not all patients who develop herpes simplex keratitis will report such a history . The herpes simplex Type I virus will lie dormant in the nerve root of the trigeminal nerve at the base of the brain , being held in check by the body's immune defenses . When the body's immune system becomes weakened , for whatever reason , the virus can travel down the length of the trigeminal nerve to the nerve endings in the cornea , releasing infectious virus particles.