Specifically -
Do magnifiers help with astigmatism?
^ It depends.
Magnifiers that offer a focus/diopter adjustment can
potentially help for shooters with astigmatism. However, it's not a guarantee.
As with the degree of visual aberration/artifacts seen through the RDS, direct, whether the shooter ends up seeing a perfectly resolved dot or suffers with continued distortion of that dot when that variable diopter magnifier is used has a lot to do with that unique shooter's eye pathology.
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Overall / General thread -
Why green? -
The simple answer -via vision science (this is actually my bread and butter
)as we understand it today- is that the cone cells (the type we use to see in higher light levels [i.e. photopic vision]) in our eyes are more sensitive to colors in the green frequency than any other.
This is why many shooters actually prefer not just only a green powered "dot" for their "RDS," but also the same for the fiber-optic insert for iron sights and the tritium vial for night-sights.
While the science is the science, there's more that comes into play in terms of each of our subjective preferences where it comes to the sights on our firearms.
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The LASER -
In terms of the the visible laser, quality modern green visible lasers are viable for even outdoor use at typical CQB distances, according to SMEs in the optics/laser/lights sector, like John "Chappy" Chapman, who consults for the likes of Steiner, Surefire, etc. -
Note that the Alliance PD Training Facility's shoothouse is an open-air structure (certain portions do see coverage with a catwalk, albeit of open metal grating).
That said, it's definitely way more visible, indoors!