Question about RAPD and Optic Neuritis

I have a question related to RAPD (relative afferent pupillary defect) being present on examination in the affected eye with Optic Neuritis. The question is a RAPD a clinical sign of demyelination. Any answers or links to answers would be highly appreciated. Thanks.

Any explanation about RAPD is very complicated but I hope this will help http://www.richmondeye.com/apd.asp

George