Zovirax ophthalmic ointment is used for the treatment of herpes simplex virus infections of the eye. Aciclovir (the active ingredient in Zovirax ophthalmic ointment) belongs to a group of medicines called "anti-virals". Zovirax ophthalmic ointment works by stopping the production of the herpes simplex virus. Zovirax ophthalmic ointment does not get rid of the virus from your body. Zovirax ophthalmic ointment is only suitable for use in the eye.