“Cross dominance” is more than just winning first place in a drag show. It’s what you call it when your dominant hand is on the opposite side of your dominant eye, which can be a real hassle for shooters.
Anyone in a sport that requires aim should know that using both eyes (binocular vision) creates an effect called parallax, or the change in the perceived location of your target when seen along two lines of sight. Shooters will naturally rely more on their dominant eye to properly acquire a target.
However, if you’re cross-dominant, aiming might be a challenge for you. You’ll often see the term ‘dominant eye’ when reading about near-vision correction-so what does it mean?

What exactly is ocular dominance?
Wherever in the body there are two organs carrying out the same function, it is likely that one can be considered more dominant than the other. For instance, people can be left-handed or right-handed; and when it comes to your eyes, the right eye is commonly more dominant than the left, meaning it works harder and sends more visual messages to the brain.
Is there a link between being right handed and having a dominant right eye?
There is no link between handedness and ocular dominance, so if you are right handed and have a dominant right eye, it is merely a coincidence.
I can see fine with either eye, does this mean I don’t have a dominant eye?
Only a very small percentage of people have balanced ocular function, with over two thirds of the population having a dominant right eye. When you look into the distance using both eyes together, the vision of the dominant eye automatically compensates for the shortcomings of the non-dominant eye. The non-dominant eye takes a back seat and lets the dominant eye do most of the work.

A very simple test can be done at home to determine which eye is physically stronger. According to Positive Shooting, like 30 percent of all men (the numbers are a little more complex for women), my dominant hand and dominant eye don’t match. I write, throw, shoot and do damn near every other task with my right hand. But when I test for eye dominance, my left eye is the clear winner.
How do you test which eye is dominant? With both eyes open, hold out your finger and line it up with an object.

Using the trigger finger motion, extend your hand at arm’s length with both eyes open and the line of vision from your index finger aligned with a clear marker in the background
Once you have pinpointed your gaze onto the direct center of your target, close one eye.
If your extended index finger remains aligned with the target, then you are using your dominant eye.
If the marker has moved and is no longer aligned with your finger point, you are using your non-dominant eye.

Watch the video for more details on testing your eye domninance.

Does eye dominance weaken with age?
As you age, you may have noticed changes occurring in your vision capability, especially after you turned 40. The most common complaint is trouble reading near objects as they appear blurry and out of focus. The medical term for this condition is presbyopia and it is the completely natural effect of your eyes ageing.
If your dominant hand and your dominant eye match, you’ve got no worries in the shooting department. But if, like me, you’re cross dominant, there are some things you’re going to want to keep in mind.

Unfortunately, the best way to handle cross-dominance in long gun shooting is probably to shoot with your non-dominant hand, mounting the firearm on the same shoulder as your dominant eye, although many shooters advocate shooting with a patch over their dominant eye or shooting glasses, one author suggests.
What plainly doesn’t work is leaning your head way over the stock to line up your dominant eye with the sights. If you don’t believe me, go grab a long gun, mount it to your dominant shoulder, and try to sight in using your cross-dominant eye. It’s really not an option.

Handguns are a lot more forgiving of cross-dominance. Sure, you can learn to shoot with your non-dominant hand — if you’re carrying for self-defense that’s not a bad skill to have anyway. But there are other, simpler solutions that our instructors can suggest in your next class. As a cross dominant shooter, I prefer to use a modified Weaver stance with my head cocked or tilted to the right, which lines up my dominant left eye with the sights by bringing my right cheek close to my right shoulder. But another solution is to simply twist or rotate your head to line up your dominant eye with the sights. I find this somewhat awkward, as the sensation is disorienting to me. It also drastically reduces my left-side peripheral vision, which is not something I would train to do when practicing situational-awareness and self-defense. Best to retain peripheral sight equally on both sides, in my opinion.
A final option for overcoming cross-dominance is to cant your pistol toward the dominant eye. Unless you’re already an experienced shooter, don’t try this. It’ll affect your shooting technique and you’ll look like a wannabe gangster. As a last resort for the cross-dominant shooter who has already mastered the fundamentals of grip, stance, trigger control, and not otherwise looking like a thug, this technique may have something to recommend it.

If you are having trouble hitting the target, are a new shooter, or you’re training a new shooter, test for cross-dominance. It’s a common problem, and understanding it may well take you from “can’t hit the broad side of a barn” to ringing that gong every time.