<prompt> Ganciclovir is preferred over acyclovir in the following condition:Herpes simplex keratitisHerpes zosterChickenpoxCytomegalovirus retinitis in AIDS patients  <response>: Ganciclovir is the drug of choice for CMV infections. Acyclovir is highly effective against Herpes simplex and Varicella zoster chicken pox and herpes zoster but it has very little activity against CMV. 