I hadn't looked through a red dot sight in many years and recently decided a few of my firearms needed them because of my aging eyes. So when Midway USA had a recent sale on one of them I ordered a couple. When they arrived I immediately opened one to try it out. To my surprise I didn't see one red dot but several in a cluster. Then other times I would see a lopsided dot, more like a elongated teardrop shape.
So think it was a battery issue, I tried a new one. No luck, same issues. So I call the manufacturer and the first think he asked me was how old I was after telling him about the issue. He then laughed and said you probably have an astigmatism. So he asked that I try a simple test to determine if that was the cause of my multiple dots. All I needed to do was take a photo of the sight with it on using my cell phone or other digital camera. If I say a single dot in the photo, it was an astigmatism. The photo reveal a single clear image of a dot. This is one of the issues why the military specifies a holographic sight instead of a red dot.
He advised that because of the way the sight projects the dot on the glass it reveals the astigmatism. A holograph red dot sight does not reveal the astigmatism because of the projection of the red of green dot. He said I could switch to a holograph sight or seek medical help. When I went to my optometrist she seemed a little perplexed at the issue and did not believe it until she tried it and saw the cluster of dots also. So she is now seeking out an optometrist who specializes in such issues for me because she has never experienced this and my testing showed a very minor astigmatism, normally not needing correction. My current prescription glasses only two months old would not correct the issue.
Below is just one of many articles I found online about the issue.
https://www.at3tactical.com/blogs/news/ar-15-red-dot-sights-and-astigmatism
David Reiss - NRA Life Member & PSC Range Member Retired Police Firearms Instructor/Armorer
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