I'm sorry to hear the eyedoctor found optic neuritis. It's good he's calling your neuro -- sounds like you'll likely move from "clinically isolated syndrome" to "having MS". It's good it's been caught early and it sounds like your doctor is eager to get you started on meds, a good thing.
In a post you mentioned concern about the cost. If you have prescription drug coverage with your health insurance, it'll likely pay for the drug as it does for other prescriptions, and you'd only be subject to the standard co-pay. If you don't have prescription drug coverage, or inadequate coverage, the companies that manufacture these drugs have programs that might help. You and your doctor would need to contact them to find out how to apply. If those options don't work, come back and ask, as some of us know about other programs that you might be eligible for. Be sure to share your concerns with your doctor, too, as she might be able to offer some suggestions to be sure you get covered, too.