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
Most common adverse effect on eye in contraceptive usage is: 
Select and explain. 
A. Colour blindness, B. Ring scotoma, C. Optic neuritis, D. Nystagmus
C: Optic neuritis
Answer: C: Optic neuritis 
Explanation: Ans. Optic neuritis