This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Vitreous and retina, Subject name: Ophthalmology
[{'content': 'The most common cause of Macular edema is \nSelect and explain. \nA. Secondary glaucoma, B. Cataract surgery, C. Retinitis pigmentosa, D. Uveitis', 'role': 'user'}, {'content': "Answer: B \nExplanation: Macular edema refers to the collection of fluid in the outer plexiform(Henle's 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", 'role': 'assistant'}]