Well, according to your description, you like looking into those stuff very much. So, as a matter of fact, if you keep focusing on those things for quite a long time, you are likely to suffer from a blurred vision or dizzy feelings, or an eye strain. Anyway, do not ever go to extremes. Of course it is true, because you would blink less and assimilate some harmful lights, which could do some damage to your eyes.
Yes, it is true that if you look at optical illusions often, it may hurt your vision which will cause your vision at blurry state. You should not do this often. The illusions will cause the light resource not to lad on the right position of your corneal. If it does for a long time, your eyes may not see things clearly and cause the blurry state.