A shooting optometrist tells pistol and rifle competitors how to use bifocals to get more 10s, when to shoot left-handed, and what not to bring to your eye-doctor’s office.
I am a retired optometrist, and many facets of my former prac-tice—vision stress, adaptation patterns, vision therapy, contact lenses, and the relationship between the visual perceptual pattern and the general behavioral pattern (that is, how what you see affects how you live, work, and play)—continue to fascinate me. Shooters, especially, ask me intriguing questions about the link between vision and performance, and as a target shooter for more than 35 years, I have studied many aspects of sight and shooting, including effects of lens color, eyeglass prescription, eye fatigue, and many other problems. However, the two questions shooters most often ask me about are the problems of strong-eye dominance and the effects of aging on their ability to see and hit targets. Here’s what I tell them:
Aging and Shooting
In our forties, the eyes start to lose their focusing ability. Most commonly, this problem manifests itself when the shooter entering middle age is no longer able to hold a good iron-sight picture. He cannot make his sights and target appear clear at the same time.
When the eyes are healthy, there are a few solutions to this problem. First is the use of the scope. For stationary target shooting where scopes are permitted, optics can remove all or most focusing problems in the blink of an eye.
Another approach is to have your glasses prescription (of course, you’re using industrial-level safety lenses and frames) modified for shooting. In most cases, your street glasses are clear for distance, but the sights are somewhat blurred. For shooting, you’ll need to bring your gun to your eye doctor, with your street glasses and a copy of the eyeglass prescription. (What not to bring: ammunition in the gun, magazine, or case). Then, looking out a window while wearing your regular glasses, look over the sights at a distant target. At this point, your doctor will place a modifying lens over your shooting-eye lens. This will clear the front sight, but blur the target. Most world-class handgun shooters usually have a clear front sight and estimate the location of the target in the downrange blur. This tradeoff between target clarity and sight blur is inescapable. Once a satisfactory shooting-eye lens is determined, your doctor will then balance the non-shooting eye’s lens so this special prescription does not confuse you when you walk around on the range. Of course, your range glasses will be unsuitable for daily wear. If you currently don’t wear glasses, you can still benefit from having a special set of glasses ground just for shooting. The procedure is the same as I’ve described above, except you don’t start the process with your glasses on.
If you are a bifocal wearer, the PAL (Progressive Additive Lens) bifocal may be helpful. This bifocal is different from the standard-line bifocal in that the power for distance use in the upper part of the lens gradually changes to power for close work as you use the lower part of the lens. In the line bifocal, there is an abrupt power change from distance to reading prescription, with no intermediate powers. The trifocal lens does give an intermediate power between far and near, but there is still no continuous power change.
Using the PAL, the shooter can raise his head and look a bit down from the distance part of the lens and find a spot of the lens that slightly blurs the target but somewhat clears the sights of your handgun. On a handgun, the distance between front and rear sights is less than the distance between sights on a rifle. Thus, on the handgun, the sights clear more nearly equally than on the rifle when you use a shooting prescription.
Rifle shooters who compete in iron-sight matches have a more complicated problem because the rear sight is closer to the eye than the rear sight of a handgun. The closer two items are to the same focal plane, the more clearly the eye can resolve them. Increasing the distance between the rear sight, front sight, and target means that some part of the sight picture will have to be noticeably out of focus. Prescription shooting glasses can solve part of the problem, but for some rifle shooters, there’s another aid worth having.
If the rifle has a rear peep-sight, as the M-1 Garand, the front sight and target may be clear enough for you. However, the rear peep will appear a bit blurred, and you will have to estimate its center. However, if another peep-sight is affixed to your glasses, then the rifle peep sight will be clearer and its center easier to estimate.
The peep-sight for your glasses is called an occluder. Inexpensive brown or black plastic versions are usually available from the office where you got your glasses or from an optician. The occluder is a circle of plastic about 2 inches in diameter, with two lugs, or ears that snap over your eyeglass frame. A slot about 3/8-inch wide and about 1/2-inch deep is cut out between the lugs to spot the target. Then a dot is put on the front surface by a friend, along your line of sight. You then drill a hole (with the glasses off) about 0.06 inch in diameter, at that dot. Now it is ready to use. Snap it over your glasses and sight through it. If the lugs have to be adjusted, warm the occluder to avoid snapping off the lug, then chill it in cold water to set it. A hole less that 0.060 inch may cause optical interference. A too-large hole may lose some sight picture clarity as it brings in more light. You’ll have to experiment for yourself.
Rifle shooters may also choose a more sophisticated device—an adjustable-iris diaphragm rear right to clear their sight picture. Of course, they are more expensive than the simple occluder. Also, both the occluder and the adjustable rear sight must have sufficient light to operate properly. Another problem occurs when your shooting eye is not your lead, or “dominant” eye. In this case, some visual confusion may result. You can either close the non-shooting eye, which may cause eye fatigue, or put a full occluder over it and blank it out. The resulting sight picture should be clear and stable.
The Resolution of Dominance: Eye or Hand?
Shooting involves two important functions: seeing and holding the gun. For seeing, we have two eyes, one of which is the lead, or “dominant” eye. (I use quotation marks because there is still no hard definition for what dominance means in visual terms.) For holding the gun, we have a dominant hand that influences our posture. Athletically-inclined men tend to be cross-dominant; that is right-hand and left-eye. When this cross-dominance occurs in a situation like pistol or revolver shooting, the effects can be dramatic. With the body about 45 degrees from the line connecting us with the target, we may not be using our “dominant” eye. Since the sight picture is important, we should be shooting with our dominant eye.
But if you don’t, it’s not the end of the world. If you shoot right handed and the right eye is not dominant, but close in function to the left, dominant eye, you may not be handicapped that much. However, if there is a significant difference between the eyes, then you need to rethink how you shoot. One solution most shooters choose is to learn to use the non-dominant eye and cover the non-shooting dominant eye to avoid visual confusion. This way, your posture stance may not have to be changed, if this is your usual stance. But if you are cross-dominant with a strongly dominant eye, then you will have to change your stance to accommodate that eye or you will never shoot well. Eye dominance is a strongly-set function, probably from birth. I strongly recommend not trying to change eye dominance. It could lead to problems in seeing and getting around. In fact, I have never seen a change of eye dominance in all my years as an optometrist. In sum, if you are right-handed, but shoot left-eye, you should consider changing to left-shoulder your rifle or use your left hand for pistol shooting. Otherwise, you will fight the urge to move your head across the stock so your lead eye sees the target. If you don’t change hands, then you’ll need to use an occluder to block the dominant eye. However, I only recommend that solution for people whose left and right eyes are fairly balanced. If you don’t, you’ll give up too much by not seeing the sight picture clearly.