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Why are Prism Scopes Better for Astigmatism?

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When acquiring a proper sight picture with your optic, astigmatism can be one of the greatest hindrances. If you live with astigmatism, you’ve likely experienced the difficulties in finding an optic that works well. 

Astigmatism is a defect in the lens of one’s eye. It’s characterized by a deviation from the normal spherical shape of the eye lens. Because of this defect, the eye has multiple focal points for light to reflect off instead of just one.  

Though its effects are different for everyone, for some, it can change how you use your firearm entirely. Red dot sights, for example, can often appear distorted or have a ‘starburst’ effect. While not everyone with astigmatism experiences this effect, there’s a good portion of enthusiasts who do.  

This makes it increasingly difficult to properly use your rifle, as the optic isn’t going to be as precise as it should be. Not only is this detrimental to your shooting ability, but it can also be incredibly discouraging. This is where the venerable prism scope comes into play. 

Prism scopes are one of the best optic variants available for those affected by astigmatism. And fortunately, there are a plethora of great prism scopes available to choose from. From their construction to reticle type, they make a great option to add to your rifle if you suffer from astigmatism. 

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Understanding Prism Scopes 

So, what are prism scopes? Prism scopes are a type of prismatic scope that uses prisms to shorten the optical pathways within the optic by folding the light that passes through it. Unlike red dots that project the reticle from a rear diode that’s reflected off the objective lens, a prism scope uses an etched reticle like LPVOs and most other variable power optics. 

Etched reticles are ideal for enthusiasts with astigmatism, as they make it much easier to see and are less susceptible to distortion. Combined with an adjustable diopter, the etched reticle can be fine-tuned to fit the user’s prescription. The result is a reticle with clean edges, providing a definitive point of aim for optimal precision. 

Unlike most of today’s rifle scopes, prism scopes have a fixed magnification instead of variable magnification. While this may seem like a drawback, it isn’t all bad. You can choose a magnification that’s tailored specifically to your rifle’s purpose, and the wide field-of-view and compact footprint will give you a great image. If you’re on the fence about magnification, our guide on selecting the right prism scope magnification breaks down each magnification level and the benefits each one provides.  

Another key facet of prism scopes is their reticle illumination. Though they use different technologies, prism scopes can be illuminated similarly to red dot sights, giving them the same degree of visibility without suffering from distortion due to astigmatism. It’s worth noting that since the reticle is etched, you can still see the reticle without illumination.  

Our article on red dot sights vs. prism scopes gives an expanded analysis on how prism scopes compare to red dots, especially when looking at low magnification prisms like our SLx® 1x MicroPrism™.  

Advantages of Prism Scopes for Astigmatism 

Optics with etched reticles tend to provide a better, clearer sight picture for enthusiasts who suffer from astigmatism. This makes prism scopes one of the best choices for enthusiasts, as you essentially get the best of both worlds from red dot sights and variable power optics. A prism scope will provide you with a few extra advantages:  

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Improved Clarity and Image Sharpness 

Most prism scopes available today use high-quality components to enhance the overall clarity and image sharpness of the reticle and sight picture. A clear and sharp reticle will make it much easier to quickly acquire when speed is necessary. Additionally, if shooting at long range, advanced reticle patterns and magnification will make it much easier to adequately compensate for bullet drop and other factors like wind.  

Enhanced Target Acquisition 

Another key facet of prism scopes is that, depending on the magnification you choose, they have offered a similar eye relief to red dot sights. Keep in mind that the more you increase magnification, the restrictive your eye box becomes, but at lower magnifications like 1x and 2x, the prism scope can be just as quick as a red dot sight.   

At lower magnifications, it’s incredibly easy to quickly acquire targets with practice. If you’re worried about magnification negatively affecting your speed, we recommend a 1x prism scope with a magnifier. That said, 2x and 3x power optics still allow to you shoot with both eyes open and allow you to have magnification without sacrificing speed, but they will not be compatible with a flip-to-side magnifier (our 1x MP is one of the few that are).  

Enhanced Accuracy 

One of the last key enhancements of prism scopes, when compared to red dot sights, is their accuracy. Now, it should be known that accuracy is subjective, but prism scopes generally offer more in terms of bullet drop compensation and ranging stadia. In most cases, red dot sights either have a single dot or a circle dot reticle. Like variable power optics, the etched reticles in prism scopes can form complex elements like BDC and ranging stadia.  

A great example is our SLx MicroPrism™ series optics which, depending on the model, have a wide array of reticle options like our ACSS Griffin, ACSS Aurora, and ACSS Raptor reticles, to name a few. Reticles like these make it easier to make holds for distance as well as ranging targets at farther distances.  

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Primary Arms Optics Prism Scopes 

Primary Arms Optics has become well known throughout the industry for its high-quality prism scopes. Each is built with high quality, durable materials, and undergoes serious physical testing to ensure that they can perform in adverse conditions. We offer quite a few models, each with different features, reticles, and magnification levels.  

Our SLx MicroPrism™ series has quickly become one of our most popular product lines for all the reasons mentioned above. These optics are much smaller compared to other prism scopes on the market while still providing great glass clarity, durability, and magnification. Also, they work well with most budgets.  

There is even a plethora of accessories available as well. They’re capable of being used in tandem with different mounts, including the renowned FAST Mount from Unity Tactical. Likewise, there are many other accessories for them as well, such as kill flash devices and offset mounts.  

We mentioned previously that our MicroPrism™ scopes come in a variety of configurations with different magnifications and reticle patterns. Some of these reticles are optimized for use with specific calibers such as 5.56NATO, 7.62NATO, 300 Blackout, and even 7.62×39. Because of this, you can easily pick out an optic that suits your needs and caliber preference. One such reticle is the ACSS Raptor. It’s available and optimized for each of the calibers. So regardless of the platform you prefer, there are some solid options to choose from.   

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Other Prism Scope Manufacturers 

Some of the most popular prism optic manufacturers are Vortex Optics and Trijicon. Vortex Optics’ Spitfire Prism Scope series is a durable optic that comes in three magnifications: 1x, 3x, and 5x. All three optics feature etched reticles and solid construction. While the 3x and 5x optics utilize the AR-BDC4 Reticle, the 1x model comes with a simpler DRT MOA Reticle. Both reticles are great options for a variety of calibers, and all models can be illuminated.  

Trijicon arguably makes one of the most recognizable prism scopes ever made, that being the Advanced Combat Optical Gunsight, or ACOG. The ACOG has been a popular prism scope since its inception in 1987. Since then, it’s seen its fair share of upgrades, including updated reticles, different magnification levels, and more durable construction.  

Some of the ACOGs utilize dual illumination. Instead of using a battery powered illumination system, these ACOGs use a fiberoptic tube and tritium. In daylight, the fiber optic tube brightens the reticle. The tritium, which stays bright for a long time, enabling the optic to be illuminated constantly when there is little to no ambient light.  

Our article on prism sight magnification that we mentioned earlier goes into more detail on both of these prism scope options. 

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Choosing the Right Prism Scope 

Now that you know about the advantages of prism scopes provided along with some of the popular options available, which one should you choose? Whether you’re a newcomer to the optic platform or new to firearm ownership and customization, it can be confusing to choose one optic out of a sea of near endless options and configurations. 

It’s important to take your needs into consideration first. If you’re looking for a lightweight optic that’s fast and with little magnification, a 1x to 3x prism scope will serve you well. For longer ranges and precision shooting, it’s worth opting for anywhere from a 4x to 5x optic. Manufacturer websites provide additional information on specific reticles and optics to make an informed decision. 


Astigmatism can be detrimental to using an optic when shooting, causing the reticle in red dots to become distorted or misshaped. Prism scopes and other optics with etched reticles make up for these shortcomings, making it easier for enthusiasts with astigmatism to be able to effectively use their optics.  

Though there are other optic options like LPVOs, prism scopes provide similar benefits while having a smaller overall footprint and lighter weight. Still, our article on prism scopes vs. LPVOs breaks down the key aspects of both optic variants in a head-to-head comparison.  

If you’re suffering from astigmatism, a prism scope might be a better optic choice for your setup. With similar performance to red dot sights at lower magnifications, they can provide many advantages to enhance your rifle’s setup.