My eyes sometimes starts to blur....i have new glasses for a couple of months now.sometimes i read or knit fine...at other times i have to strain.

Few things: Could be cataracts, or since it is fluctuating, dry eyes. Try some artificial tears and see if that helps clear things up the next time you experience the problem.

Review: Was the problem developing when you were examined and got your glasses, or is it new? Have you been screened for diabetes (which causes blurring).? Do you have a new medication? Did you get a tint on the glasses that requires more light on you reading tasks? You need to see either your personal physician or your ophthalmologist for review. Good luck.