Disclosed is a use of an ester prodrug of an active drug useful in treating a disease or condition affecting the back of the eye in the manufacture of a medicament for the treatment or prevention of retinitis pigmentosa, proliferative vitreal retinopathy, age-related macular degeneration, diabetic retinopathy, diabetic macular edema, retinal detachment, retinal tear, uveitus, or cytomegalovirus retinitis, wherein the medicament is formulated for sustained-delivery of the active drug to a posterior part of an eye of a mammal by subconjunctival or periocular administration, wherein the prodrug is contained in a polymeric microparticle system designed to enhance the sustained-delivery of said ester prodrug of an active drug, wherein said polymeric microparticle system is a poly(lactide co-glycolide) microsphere suspension, and wherein the ester prodrug of the active drug is not tazarotene or another retinoid. Also disclosed is a composition comprising the microspheres and a method for making microspheres.
