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Abstract
IDU has been found active in eradicating virus from tissue culture and appears virtually nontoxic in most tissue culture systems. However, conclusions from tissue culture studies can be drawn only with great caution if they are to be applied to in vivo work. More important, IDU is unquestionably active in the treatment of herpetic keratitis in rabbits and monkeys, and appears similarly effective in man. In vivo it is apparently nontoxic, and yet it appears specifically to eradicate virus from the cornea under some circumstances and to permit healing. This is in direct contrast to the damage than can be caused by the use of caustic agents such as iodine, after which there appears to be an extremely high incidence of metaherpetic keratitis.
Although antiviral agents are useful in the treatment of dendritic ulcers and superficial stromal disease, they are not useful in the treatment of irregular corneal defects in which no virus is present (metaherpetic disease), or in the treatment of disciform keratitis, bullous keratopathy, and iritis. These latter conditions appear to respond to corticosteroids in combination with antiviral agents, although the duration of therapy is unpredictable. When this combination of agents is used, antiviral agents should be given in the maximum tolerated dose until after the corticosteroids are stopped; they should not be gradually tapered, whereas the corticosteroids should be used in the minimum effective dose and should be decreased as soon as possible. Cytosine arabinoside is an antiviral agent that appears similar to IDU in its activity. Although CA is toxic under some circumstances, there is reason to believe that patients resistant to one agent will be susceptible to the other.