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 epithelial keratitis. It works by inhibiting viral DNA synthesis, thereby preventing the replication of the virus. Vidarabine Monohydrate is formulated in ophthalmic ointments for topical application, allowing direct delivery to infected tissues. Due to its limited solubility and stability, it has largely been replaced by more effective and convenient antivirals like acyclovir. However, it remains historically significant as one of the first antiviral drugs developed for clinical use. It has also been studied for activity against varicella-zoster virus (VZV) and certain DNA viruses, with applications in research settings for understanding viral replication mechanisms.