You're changing the focus like a depth of field on a camera your eyes zoom in and out depending on how much you relax or tense your muscles. After a while the words can take on a an unusal clarity and crispness that is hard to describe because you've learnt to focus on the words in a different manner.
What you're experiencing right now is the adjustments to discovering what's optimal for you. Nothing wrong with the process we were originally taught to use our eyes differently for reading. It's like looking at 3d pictures (stereograms). At first it seems impossible to get into focus then with some practice and in a relatively short period of time you can get them like a snap. If you don't view them for a while the muscles of the eye need to be trained again for a short while till you get to that snap stage again.
Alex
