hi everybody, i am nearsighted wearing prescription lenses at present. the grade(of the lenses) are pretty high, around -550 each eye. i shoot with both eyes open , but close the left for plates and targets starting at 25 meters upwards. my question to you guys is what do you mean by having the prescription lenses ground for the sights? do i change to a higher and lower grade? thanks and i hope somebody can further elaborate on this. i can shoot comfortably, but my eye speed is slow and i am very finicky sights-wise; i use a thinner front sight for added light.