Just because it doesn't 'itch' doesn't mean you're not allergic!!!!!!
Not all allergies have itching as one of their symptoms.
I'm allergic to No7 eyeliner - I get watery eyes, and it stings - No itching, but I'm still allergic.
My point is, you may be allergic to it. Try another brand and see how you get on with that. If you still have 'blurry' eyes, then it may just be down to your application technique.