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
A child presents with sudden loss of vision with painful ocular movements. The eye is white and there are no obvious signs on ophthalmoscopy. The most likely diagnosis is - 
Select and explain. 
A. Optic nerve glioma, B. Retrobulbar neuritis, C. Craniopharyngioma, D. Papillitis
B: Retrobulbar neuritis
Answer: B: Retrobulbar neuritis 
Explanation: Information in this question are :-


Sudden loss of vision
Painful ocular movement
Normal fundus on ophthalmoscopy


All are seen in retrobulbar neuritis and last two features are more characteristics of retrobulbar neuritis and differentiate it from papillitis.

Papillitis vs retrobulbar neuritis

Papillitis and retrobulbar neuritis have almost same clinical features except :

i) Painful ocular movement is more common in retrobulbar neuritis than papillis
ii) Fundus is normal in retrobulbar neuritis while papillitis has characteristic fundus abnormalities.