This lens is to be used over your best distance prescription, which should meet saftey standards, never by itself.
Guidelines for lens choice:
To Fit Lens:
1) Pull bands to concave side of lens.
2) Put arms of frame through bands.
For metals frames slide band over nosepiece on opposite side.
3) Pull nasal band tight to secure.
Loosen nasal band and remove carefully
If shot group opens up: Are you really concentrating on the front sight? Or it may be time to try another lens.