I was discharged about a year ago due to optic neuritis and was given an Re-3p reenlistment code. My vision has since returned to normal and I was wondering if it's at all possible for me to reenlist. If it is possible to reenlist, would I be able to have Intelligence as my MOS once again or would my discharge exclude me from doing so? Any information at all would be helpful.

if the neuritis is something that can return, I believe you will not be able to return.
If it was something that was treatable and there is very little likelihood of it returning, then you can go through the enlistment process again and this time they will have to submit a bumed waiver for the medical condition.
They can actually prescreen this prior to you going to meps again.