Well, looks like your eyes are not in good conditions. And generally speaking, our eyes would not be blurry if we use our cellphones properly. I suspect that your problem is due to long time using of iphone, because our eyes need time to rest and while we are using it, our eyes blink less and become dry, which could generate blurry vision. If the problem does not go away after you stopped using it, you probably have some other problems and you should see a doctor.
Yes, your eyes will get blurry vision after using the iphone for a long time. The shining screen will stimulate your eye nerves which will make your eyes get tired easily. If you don't have the rest for a while, you may get the tiredness easily. If you do this often, your eyes may get short sighted problems.
Well, generally speaking, it is normal to have blurry vision, if you look at iphone screen for a long time. First, you should know that if you look at iphone screen for a long time, it will just make your eyes focus on the small point too long. And then that can just make your eyes be stressed, leading to eye strain. There are long term effects of eye strains. For example, it can put stress on the eye muscles and the facial and scalp muscles, causing pain and headache. And what is worse, it can lead to making your vision become worse, leading to blurry eyes.