This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Neuro Ophthalmology, Subject name: Ophthalmology
Which of the following is a cause of sudden blindness in a quiet eye with normal media and fundus? 
Select and explain. 
A. Retrobulbar neuritis, B. Vitreous hemorrhage, C. Optic neuritis, D. Iridocyclitis
A: Retrobulbar neuritis
Answer: A: Retrobulbar neuritis 
Explanation: Retrobulbar neuritis: sudden blindness with normal media and fundus. In retrobulbar neuritis, disc edema is absent.