This review discusses the roles and interactions of prostaglandins and other possible chemical mediators in cystoid macular edema. Prostaglandins have been studied as a potential causative factor of cystoid macular edema following cataract/intraocular lens surgery. The authors' hypothesis and data with regard to the mechanisms of postoperative cystoid macular edema and other inflammatory conditions are presented. The effects of nonsteroidal anti-inflammatory drugs, which are antagonists of prostaglandin biosynthesis, on postoperative inflammatory conditions including cystoid macular edema are also reviewed. Lastly, a mechanism for the induction of cystoid macular edema by anti-glaucoma eyedrops, including prostaglandin analogs is proposed. The results from two clinical trials recently conducted by the authors suggest that the preservative rather than the active ingredient is the causative factor.