I have a vision problem after taking fanapt (iloperidone). is this a normal sife effect?

Yes: Blurred vision can occur in up to 3% of patients who use fanapt, (iloperidone) according to www.Drugs.Com. It would be best for you to see your eye md to make sure that you don't have a condition called "narrow angle glaucoma.".

There can be ocular: side effects with Fanapt. Per Drugs.Com >> Blurred vision & conjunctivitis may occur in 1 to 10% of people. Dry eye, blepharitis, eyelid edema, eye swelling, lenticular opacities, cataract, hyperemia (including conjunctival), nystagmus may occur in 0.1 to 1% of patients. REF:https://www.drugs.com/sfx/fanapt-side-effects.html