The destructive effects of herpetic ocular involvement involve both th
e cytotoxic effects of the viral particles directly and a variety of i
mmunological mechanisms that are activated even after the acute stage
of infectious disease has passed. These so-called noninfectious immune
reactions represent a host response to rid the body of an antigen tha
t can never be completely eradicated. Herpes simplex virus (HSV) prese
nts in several ways, including infectious epithelial keratitis and ker
atouveitis, and as several conditions that have a proposed immunologic
al basis. In managing herpetic conditions, one should always consider
these immune-based phenomena, as erroneous treatment directed only tow
ard the virus can result in progressive injury to the eye. The clinica
l and experimental support for the immune response accompanying HSV ke
ratitis is well established. These changes are classified on the basis
of the structures involved. First, a low-grade immune response can be
associated with epithelial basement membrane changes in epithelial tr
ophic ulcers. Second, the stroma can involve several types of reaction
s, including stromal interstitial keratitis, Wessely immune rings, lim
bitis, and disciform keratitis. Third, an immunological basis is belie
ved to be responsible for the endotheliitis that can accompany herpeti
c disease. Clearly, there are other forms of herpetic involvement that
are, in part, immune-based, such as herpetic iridocyclitis, but this
chapter is limited to those involving the cornea.