There are two antiviral agents that are commercially available for use in ocular herpes infections, idoxuridine, and vidarabine (Ara-A). In topical usage, these medications are similar in their effectiveness and toxicity; however, vidarabine is systemically active for treatment of deep ocular disease. Trifluorothymidine, which is still an experimental drug, has been shown in double-blind clinical trials to be the most potent antiviral drug for ocular use. These three antiviral drugs, however, are not truly selective in their action and interfere with normal cellular functions as well as virus synthesis. Several new drugs have been reported that are selective and are only effective in herpes virus infected cells; the most active of these compounds appears to be acycloguanosine.