Are you patching the eye based on your eye doctor's recommendation? If so, trust that he knows what he is doing. It WILL be blurry when you patch it because the vision in the lazy eye never developed. Your brain tuned out the affected eye because it cannot process two separate images at the same time. So the brain automatically tunes the vision in the worse eye out. So until your brain begins to pay attention to your bad eye, it will be blurry.

Generally, amblyopia must be caught and treated at a much younger age than 17 in order to be the most affective. That's not to say that you won't have some success with patching the good eye now, but the success rate goes down the older you are. It is generally crucial to catch it at a very young age, before the age or 6 or 7 usually, before the brain has totally tuned out the lazy eye and it can be re-trained. The older the patient is, the more damage is done and the harder it is to get results. Its not totally impossible to have success at your age, but understand that patching now is not a 100% guarantee that it is going to correct the problem.

If you are just patching your eye on your own and you are currently not under the care of an eye doctor, I would not proceed with self-treatment until you've been to your eye doctor. Amblyopia can be caused by a strong uncorrected refractive error, it can be caused by strabismus, or it can be some of each. Strabismus is a misalignment of the eyes and it will cause the brain to ignore one eye. Strabismus can be surgically corrected to even out the pull of the muscles in the eye to keep them straight. If strabismus is what caused your amblyopia, then patching your good eye won't do a whole lot for you, because your eyes are not focusing evenly on objects to begin with.