You step up to the firing line, weapon in prime condition, match grade ammo . . .

Range  safety called for eyes and ears and you recheck your hearing protection and slip on your safety glasses.  You sight down the targeting pips aligning your eye with the target, let out your breath and slowly squeeze the trigger.

And then the math catches up with you.  Those glasses on your face are there for protection.  They're a convex shape, right?  What happens if the light that passes through that lense is refracted off by as little as .005 degrees.  That's 5 one-thousandths of a degree.  That's not too bad is it?

I guess not. 
At a target 50 meters away that's only 4 millimeters off (about 1/6th of an inch.)
At 100 meters it's only 8.7 millimeters (about 1/3rd of an inch.)
At 300 meters that's only 26 millimeters (or about 1 inch.)
Are you beginning to see how the guy down the line with the spiffy SunBuster shooting glasses with the ShotReader™ lenses is able to put together a much tighter shot pattern?

It's because he's sighting in on the target, not a distorted image of the target.

SunBuster sponsored shooters, in real competitions routinely outshoot their competitors.   Don't you think it's time to wear what the pros wear?