Strengthening=stronger; Standard use=as intended. You may have astigmatism - in any case, see your optician if the glasses are inadequate. If you are short-sighted: There is actually such a thing as over-sharp vision so no need to go for that - there is some evidence that short-sightedness sometimes worsens faster if the eyes are not needing to work on focussing. Also, there is some evidence that hard contact lenses help to hold back deterioration of the same. All of this with the case-by-case proviso.