As a 38 year old with "computer glasses" (my eye doctor, a woman about my age, graciously avoided calling them "reading glasses"), I would say it could be normal... can you focus on anything at all when it happens? Close or far?
If it happened to me I'd get my eyes checked. Dunno that it is related to AS or anything.
Jen, 42, happy partner of James and Moma to Evan, 14, & Lucy, 12.5 (Crohn's dx @ age 3; on Remicade since April 2010.) I take piroxicam, Flexeril, & Nucynta ER nightly. 3 anti-TNFs didn't pan out for me.
"Science is the father of knowledge, but opinion breeds ignorance." -- Hippocrates