If you're experiencing problems with your eyeballs that you suspect are AS related you def. want to see an opthamologist... and pref. one who has experience with the fun things that go along with auto-immune disorders. They have the medical training to deal with issues that an optometrist won't have.
Otherwise, for run of the mill getting glasses, contacts or checking your prescription an optometrist is fine.

Here's me keeping me fingers crossed for you that you're not experiencing AS eyeball issues...


http://en.allexperts.com/q/Ophthalmology-Optometry-979/difference-optomotrist-opthalmologist.htm

"Traveler, there is no road, you make your path as you walk." - Antonio Machado