Used primarily as an antiviral agent, especially in the treatment of herpes simplex virus (HSV) infections affecting the eye, such as acute keratoconjunctivitis and recurrent superficial keratitis. It has also been employed in the management of severe HSV encephalitis, although its use is limited due to poor solubility and the availability of more effective alternatives like acyclovir. Vidarabine works by inhibiting viral DNA synthesis, thereby preventing the replication of the virus. It was historically administered as an ophthalmic ointment for localized eye infections and, in some cases, given intravenously for systemic or central nervous system infections. Its application has declined over time but remains of interest in specific antiviral research and in settings where other antivirals are not available.