There is case histories published of Ulcerative Colitis (UC) patients having optic disc edema, optic neuritis, retinal vein occlusion, optic neuropathy, and other vision disorders including blindness. See PubMed
and search on "Ulcerative Colitis vision".
Any correlation with vision correction surgery would be peripherial at best, but you may want to forego Epi-Lasik, Lasik, or All-Laser Lasik which require the use of a microkeratome that dramatically increases the intraocular pressure (IOP) during surgery. It seems very unlikely that the short-term IOP spike would cause problems, but in the event of a compromised optic nerve it seems prudent to avoid the extra pressure.
I do not see where UC is listed or proven to be a contraindication for Lasik, Epi-Lasik, LASEK, or PRK in the medical literature, however a common treatment for UC is 5-aminosalicylic acid.
One known side effect of 5-aminosalicylic acid is vision fluctuation and tissue dehydration. If you are using 5-aminosalicylic acid during evaluation for vision correction surgery, surgery, or recovery, there is a possibility (albiet apparently a low probability) that there may be an unpredictable result.
As always, notify your doctor of all medications you currently take and/or that you may likely require during the period immediately before, during, and after surgery.