Posted on 17 Comments

AR-15 Red Dot Sights and Astigmatism

Why Your Red Dot Looks Blurry and What to Do About It

When you look through a red dot sight, do you see a crisp, clearly-defined reticle, or something completely different?

If you see a blurred dot that looks more like a star or a comma, or if you see multiple dots instead of one, you could have a defective optic or you may have a red dot astigmatism.

 

Common Ways Astigmatism Affects a Red Dot Reticle
Common Ways Astigmatism Affects a Red Dot Reticle

What is an astigmatism?

According to the American Academy of Ophthalmology, an astigmatism is an imperfection in the curvature of your cornea (the eye’s lens) that causes blurred or distorted vision. This isn’t just a problem for people with poor eyesight – you can have good overall vision and still have a mild astigmatism. In fact, LASIK surgery can create irregularities in the curvature of the cornea as well.

Comparison of a normal eye and the one with astigmatism

You may not even realize you even have an astigmatism until you first look through a red dot sight.

 

US Army Service Manual AR 15 Ebook

 

Diagnosing a Red Dot Astigmatism vs a Defective Red Dot

Diagnosing Astigmatism vs Red Dot Sight

Of course, if your experience with a red dot has these kind of results, you’ll first want to confirm that it is indeed your eyes, and not a defective optic. There are a few different ways to do this:

  1. Turn on the optic, cover the front lens and take a picture of the dot. Does it appear the same way in the picture as it does when you look through the sight? A properly focused picture will show what the dot really looks like.
  2. Look at the dot through your backup iron sights. Is it still blurry and fuzzy?

 

Blurry Red Dot on Astigmatism

When you look at the dot through your rear peep sight, it reduces the amount of light your eyes are taking in, allowing you to see the dot’s actual shape.

  1. While looking through the sight, line the dot up with an object, and then rotate the optic either clockwise or counterclockwise without moving the dot off target. If the issue is with the optic, the distorted image will move with the optic.

Once you have ruled out a faulty optic as the culprit, you should see an optometrist to find out more information on what is wrong with your vision and what you can do to correct it. If you already have vision issues, you can most likely get an updated prescription that corrects the astigmatism.

 

Working with What You Have

Red Dot Sight for Astigmatism

If you’ve bought red dot, there are a few things to try to see if it can work for you, despite your newly discovered vision issues. An astigmatism causes light to refract to multiple focal points in your eye, so reducing the amount of light going into your eye from the red dot minimizes the blurring effect.

You can:

  • Use a lower brightness setting.
  • Look “through” the dot and focus on the target instead of looking “at” the dot.
  • Use your peep sight and red dot at the same time.
  • Get corrective lenses for shooting.
  • Wear polarized sunglasses.

 

If these tactics don’t work, you might wonder if you might have to just forego optics entirely. Fortunately, that isn’t necessary, and there are a few alternatives available for you to choose from:

Red Dot Sight with a larger MOA

  • A red dot with a larger MOA may be easier to see and have less distortion than a smaller MOA dot. This won’t eliminate the blur, but it may lessen the effect you experience while shooting. If you plan to try out this option, you will want to look for something with a reticle at least 4 MOA or larger.
Holographic Red Dot Sight
  • A holographic sight bounces light off of a holographic grate to project light onto the lens. This acts like a polarizing filter, reducing the amount of light your eye is exposed to. Shooters with astigmatisms report a reduced amount of distortion when using holographic sights.

Prismatic Red Dot Sight

  • A prismatic sight uses a lens and etched glass to produce its reticle, and functions more like a traditional rifle scope than a red dot. Many people with astigmatisms report fewer difficulties with these kinds of sights. They are offered in various magnification levels, but one with no magnification could be an ideal red dot replacement for a shooter with an astigmatism.

 

Having an astigmatism will not prevent you from enjoying electronic optics, but it may reduce which styles of optic will meet your needs.

If you have already bought a red dot sight, try out the tips mentioned above and see if it’s worth your while to keep.

Coping with Astigmatism

If not, or if you haven’t already made a purchase, go down to your local gun shop and ask to see what the reticles look like for red dot sights of different MOAs, holographic sights, and prismatic sights. Doing this will help you quickly determine which sights will work for you right out of the box before spending your hard-earned money.

One Last Tip

If there’s anyone that knows the AR-15 platform, it’s the US military. As a special offer for our readers, you can get the Official US Army Manual for AR-15/M4/M16 right now – for free. Click here to snag a copy.

17 thoughts on “AR-15 Red Dot Sights and Astigmatism

  1. As a member of the rapidly increasing “old guys” demographic, I care less about tacticool and spray and pray as I once did. Some days, three holes touching in a paper 100 yds away is just as exciting as a huge pile of empty brass. This series addresses everyday issues and concerns that should benefit almost everyone that would invest the time to read them. I thank you for taking the time and doing the research for these articles, although they should really be titled as lessons. Good job!

  2. Hi Mark,

    We really appreciate your feedback. We work hard to put together an article like this to help AR-15 users understand the current issues, to give ideas and to provide suggestions. We’re glad you liked the article.

  3. Why does my red dot sight move around when shooting my M4?

    1. If you mean you cant get it zeroed, make sure your sight is mounted correctly, if its on a picatinny type rail system, make sure it is pushed forward against the rail when tightening it down. This will stop any movement caused by recoil. Other than that check your shooting position, you can have an improper or inconsistent cheek weld etc. Worse case, you may have a faulty optic that won’t hold a zero.

  4. Good article, with a good explanation of what astigmatism does. Although I’m corrected with either glasses or contacts, as good as it can be, I still notice a slight imperfection in the dot. I’ve found that staying in the low dot intensity settings works best

  5. Very informative article and having an astigmatism in my left eye for better than 40+ years (now 70 years old) it is something I never considered.

    Until recently (last 10 years) never invested much time in AR platforms and red dot scopes. Hog hunting with my sons in Texas twice a year has taught me otherwise. Being a traditional wooden stock guy has been my norm. Change over to semiauto in “evil” black has been a challenge for me in NYS, land of the Safe Act. Over the last 5 years I HAVE BUILT 5 AR-15’s (1 ea 5.56 and 4 ea 6.5G) and one AR-10 (7mm08) and left all of them in Texas. Easier than TSA inspection while flying and not NYS registered.

    With all this being said, I noticed the red dot blurr phenomena as I progressed with my red dot scopes and finally said enough is enough and went to night vision and thermal on AR’s in question. Up until this article came to my attention I had found a solution in other scope technology however never understood why it was happening with red dot’s.

    Thanks for the enlightenment and the article itself. As we say, “Good to Know!”

    1. Bear in mind that astigmatism is only going to have that affect if uncorrected with lenses. If your prescription is up to date it is possible that other problems such as cataracts are causing aberrations that lenses cannot correct.

  6. Having this very issue I have found green dots to be the way to go, they don’t tend to bleed like the red dots do

  7. First of All Thanks for such a great article. It is very helpful for a beginner like me. I just wanna ask that for turkey hunting, what should be the size of reticle? Is 4 MOA red dot reticle is good or not? Need your expert opinion.

    1. Thanks for taking a timeout to read our articles. Whichever one you like better at 40yds. A lot of guys use the 4 with great results but then some thought 8 might be too large and still after trying it out they had no issues with it. Was nowhere near as large as they thought it would be. It really boils down to personal preference, in my opinion, a 4MOA is about perfect.

  8. As someone with mild astigmatism,i dont see any of these except the smear towards the top at extreme angles looking down(i have to look at the ground for the smear to go upwards)
    I dont understand why people worry about what the dot looks like if its not multiples or a 1 moa it shouldnt matter on a handgun.

    1. Valid point, most people who are using a rd on a pistol aren’t “bullseye” shooters anyway, an rd that doesn’t look perfectly round isn’t going to be an issue. Even (most) competition pistol shooters aren’t shooting for minimum moa/groups, it’s all about speed.

  9. Hi Mark,
    Thank you for your excellent and very informative article on astigmatism. One thing I noticed is that the blurring effect is mitigated by the use of green dots. My optician said that green is less disturbing than red. What do you think?

    1. I have an astigmatism and own both red and green dot sights, the green is definitely better then the red. There is also a gold dot on the market now that is supposed to be great for people with color issues but not sure how it would work with an astigmatism.

  10. Hello, I just had a 4 hour carbine class for my new Ar-15 and after the 1 hour range time, the instructor could not get my red dot accurate. It was high, it was low, it was to the left, etc…. Can you recommend someone or someplace that can zero in my scope as i do not know how and I can watch YouTube videos all day however I want a professional to do this and would like to learn how for the future. Thanks, Tom 602-614-93198

    1. If the instructor had issues getting your red dot to hit where it should it could be a faulty optic, bad or loose mount, or possibly even a bad rail. Start with trying the optic on a different rifle and go from there.

  11. I had ( kinda ) the same problem ! my red dot looked like a ‘broken plate’… I thought it was bad, until I tried 3 of ’em on my AR’s and they all looked the same !!!

    My eyeball doctor said that I was growing a cataract, and that he hadn’t mentioned it because it wasn’t serious enough ( yet ) to worry about… I had the standard ‘lens’ replacement surgery and now my red dot looks just peachy… The only problem I have is when my 2 MOA dot covers up my 1 MOA target !!!

Leave a Reply

Your email address will not be published. Required fields are marked *