Ganciclovir is primarily used in the treatment of cytomegalovirus (CMV) infections, particularly in immunocompromised patients such as those with HIV/AIDS or organ transplant recipients. It is effective in managing CMV retinitis, a serious eye infection that can lead to blindness if left untreated. Additionally, ganciclovir is utilized as a preventive measure to reduce the risk of CMV disease in transplant patients. It is also employed in the treatment of other herpesvirus infections, including herpes simplex virus (HSV) and Epstein-Barr virus (EBV), in specific clinical scenarios. The drug is available in various forms, including intravenous, oral, and ocular implants, to cater to different medical needs.