This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Ophthalmology
All of the following may be used to differentiate Central Retinal Venous Occlusion (CRVO) from Ocular Ischemic Syndrome due to, except: 
Select and explain. 
A. Dilated Retinal Vein, B. Touous Retinal Vein, C. Retinal Aery Pressure, D. Ophthalmodynamometry
A: Dilated Retinal Vein
Answer: A: Dilated Retinal Vein 
Explanation: Central Retinal Vein Occlusion and Ocular Ischemic Syndrome due to carotid aery stenosis are both associated with Dilated Retinal veins and hence this feature cannot be used to distinguish these conditions. Ref: Ophthalmology By Yanoff, 3rd Edition, Page 625; Ocular Therapeutics Handbook: A Clinical Manual, 2nd Edition, Page 86