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What is 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 - and explain in detail?
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.