There are three materials that lenses are made of for shooting glasses. These being crown glass ( which can be heat treated), CR 39 plastic, and polycarbonate. The CR 39 plastic and polycarbonate lenses can be anti-scratch coated. In terms of the best safety lens, polycarbonate ranks at the top, followed by CR 39 and then heat treated crown glass. Today, 90% of all prescriptions are filled with CR 39 anti-scratch coated lenses. Both the CR 39 and polycarbonate lenses are less than half the weight of glass lenses. It makes sense to use either of these lens materials in a pair of shooting glasses. Polycarbonate material has outstanding impact resistance,but it must be handled carefully in the uncoated form to prevent scratching. Polycarbonate lenses are more expensive than CR 39. They require special handling techniques and machines to generate curves , edge and tint. This leaves the CR 39 with anti-scratch coating, the material of choice for your shooting glasses. In games such as skeet and sporting clays where you are shooting incoming targets you are often bombarded with fragments of clay targets. Shooters who do not wear protective eyewear put themselves at a greater risk of an eye injury. Fragments from these types of projectiles can cause corneal abrasions, or foreign bodies embedded in the cornea or conjunctiva. This can cause serious problems with infection if not treated promptly. The best way to avoid these problems is to wear protective safety lenses. Walking through the bush, bench rest shooting, and black powder shooting all have the potential for serious eye injuries. Why not protect your eyes with the proper lenses?
As far as protection from ultra violet radiation is concerned, this is most important, especially with our depleting ozone layer. Here are a few facts about UV radiation:
1) Ultra violet does no good! (Besides the production of vitamin D in reaction with the melanin in our skin. Our North American diet precludes us from this worry.)
2) UV radiation causes keratitis, an inflammation of the cornea.This condition is commonly known as "Snow Blindness"
3) UV radiation contributes to the development of cataracts.
4)UV radiation has been shown to cause degeneration of the retinal pigment epithelium.Recent studies have linked exposure to UV radiation with an acceleration of age related macular degeneration. This is a major cause of blindness in North America today.
5) UV radiation can cause tumors of the eyelid. Basal and squamous cell carcinomas are common and serious. They require surgical removal. A malignant melanoma will be fatal in almost all cases.
Do I have your attention? Protection from UV radiation is important. Many quality sunglasses do block UV radiation. Clear lenses are made with UV protection. We have all heard and read advertisements about ' blue blocking lenses'. Are they useful? The theory behind them is good. The lens is supposed to block the shorter wavelengths of light. These shorter wavelengths are scattered more by fog and mist. If we eliminate the shorter blue wavelengths, it should enhance our vision on foggy overcast days. Does it work and is it useful? These lenses offer few advantages. The selective absorption of these lenses make it difficult for some people to differentiate red from green lights while driving. Red lights may appear nearer or further away than they actually are. These lenses negatively affect your depth perception. The physiological optical term for this is chromostereopsis.
What if you are wearing a "blue blocking lens" while driving home at dusk and a man wearing a blue jacket is walking down the road. Remember the blue wavelengths are blocked with these lenses. You probably would not see this man as soon as you would if you were wearing a clear lens.
So what is the best type of lens to use for protection from UV radiation? For low light levels the best lens is a clear lens with a super anti-reflective coating(super AR) and a UV filter. The amount of light transmitted through a clear lens is 92%. Eight percent of the light is lost to reflection. The super AR coating increases the amount of light transmitted to 99%. A 7% increase in the amount of light transmitted is within our just noticeable difference threshold criteria. This means that we can tell the difference with an increase of 7% in the amount of light transmitted.
These super anti-reflective coatings are the same types of coatings you find in cameras, binoculars and rifle scope lenses. They are more expensive but they are worth every penny. The other advantage of super AR coatings is that they do eliminate ghost images, eg. multiple reflections under low light conditions. These reflections can be annoying for some shooters. Under low light conditions we see better through lenses that are super AR coated. These are advantageous for night driving or trap shooting.
The UV filter is essential. It selectively blocks wavelengths of light under 400 nanometres. I have previously mentioned the ocular hazards of UV and why it is important that we protect our eyes from it.
As far as tints are concerned some people see better with a light gold tint at dawn or dusk. The reason for this in my opinion is that we associate gold with sunlight. The apparent increase in brightness with a gold lens is psychological in nature. My personal preference for a low light lens is still a clear lens super AR coated with a UV filter.
For sporting clays, skeet and trap under bright light the most popular tint is a light medium target orange (LMTO). This tint decreases the amount of light to your eye and enhances target recognition.
In conversations with the Decot people in Arizona, the LMTO tint is the most popular tint for sporting clays, trap and skeet shooters.
I must add that the preference for tinted lenses is largely personal in nature. A comfortable tint for one person may be unacceptable for another. I would recommend a super AR clear lens for low light conditions and a LMTO with UV protection for bright light conditions. These two lenses will give you UV protection and the best visual comfort for most situations, be it pistol, rifle,or shotgun shooting.
Shooting sports, especially shotgunning requires spectacle frames designed specifically for shooting. When your shotgun is mounted, your head is on the stock and your eye on that side becomes the rear sight of the shotgun. Dress frames are not designed to see your target clearly when you are "into your gun." With a dress frame you are looking through the top part of the lens or through the top eyewire of the frame. The unwanted prismatic effect and the position of the eyewire decreases your ability to pick up the targets quickly. The people who make and market shooting glasses know about these problems and they design frames for shooting.
I shoot skeet, sporting clays and social trap with some regularity and I note a common irony with people who participate in these games. They drive up to the range in an expensive automobile, go to their trunk and pull out a custom made leather case. They walk into the gun club and open the case. There sits a very expensive Italian, German or Japanese over and under shotgun with an extra set of barrels. The fit and finish are excellent and the wood is a marvel to behold. These people are dressed for the cover of GQ magazine with matching gloves, vest and shoes. They spoil this scenario when they pull out a $19.00 pair of drug store quality, aviation style frames with cheap yellow lenses. Something is wrong with this picture!
What type of frame should you be using and how should the frames be designed? One of the oldest and most popular frames used today is designed by Bud Decot of Arizona. These Decot frames are large and they sit high on your bridge so that when your head is down on the stock of your shotgun, your eyes are looking through the optical centers of the lenses. These frames are available in three sizes and two colors (yellow gold and matte black). These frames are light, durable and you can interchange lenses easily with no tools. The interchangeable lens feature is useful as light conditions change. Other important features of these frames include rubber covered cable temples, silicone nose pads, and sweat bars for greater stability. Impact resistant cases with storage for extra lenses, cleaning cloths and belt clips are included. These features are additive and the result is a frame design that is specific for shooting.
Another more recent arrival in the frame department is Randolph - Ranger shooting glasses. These are similar in design to the Decot frames but have the added advantage of flex temples.
If you need prescription lenses they should be ground into your shooting glasses. Small amounts of farsightedness, nearsightedness and astigmatism should be corrected for in your shooting glasses. The resultant in focus retinal image will enhance your ability to pick up the target quickly, see it clearly and break it. The improved visual acuity also enhances depth perception that is important in tracking a moving target in three dimensions.
Properly designed and fitted ophthalmic quality eyewear is necessary for precision, dead center shooting. The lenses should be optically correct with your distance prescription incorporated in the lenses no matter how small or insignificant it may seem. The lenses should be CR 39 material with a super AR coating, anti-scratch coating and have a UV filter. Spare lenses are useful for changing light conditions. Protective, prescription eyewear fitted properly will improve your scores and may prevent a serious eye injury. They sharpen your vision, provide safety and enhance performance. Smart shooters are aware of this fact and that is another reason they post better scores.