This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: All India exam, Subject name: Ophthalmology
Most common cause of rubeosis iridis is 
Select and explain. 
A. Vitreous hemorrhage, B. CRVO, C. CRAO, D. Diabetes mellitus
D: Diabetes mellitus
Answer: D: Diabetes mellitus 
Explanation: Rubeosis iridis is a condition in which new blood vessels form on the anterior surface of the iris. It occurs in diabetics of long standing and in thrombosis of the retinal vein.