<prompt> The most common cause of Macular edema isSecondary glaucomaCataract surgeryRetinitis pigmentosaUveitis  <response>: Macular edema refers to the collection of fluid in the outer plexiformHenles layer and an inner nuclear layer of the retina, centered around the foveola.EtiologyIt is associated with a number of disorders. A few common causes are as follows:1. As postoperative complication following cataract extraction and penetrating keratoplasty.2. Retinal vascular disorders e.g., diabetic retinopathy and central retinal vein occlusion.3. Intraocular inflammations e.g., pars planitis, posterior uveitis, Behcet disease.4. As a side-effect of drugs e.g., following use of adrenaline eyedrops, especially for aphakic glaucoma.5. Retinal dystrophies e.g., retinitis pigmentosa.Ref: Khurana; 4th edition; Pg.No. 273 