Originally appeared in
Earth Star Magazine February/March 2007
Rosemary Gaddum Gordon, D.B.O., M.A.
When I was little, I was standing in a crowd waiting for a parade and overheard a parent saying “Don’t cross your eyes, Tommy, the wind may change and they’ll get stuck that way.” It sounded horrifying. It wasn’t until I was studying at Moorfields Eye Hospital that I discovered how important it is to be able to cross or converge the eyes when looking at something up close.
As our vision develops, our eyes need to learn to work together as a team so that we can aim each eye onto the same target. This is a learned skill called fusion. It develops naturally between eight to twelve months of age, as we interact with what is going on around us. Since we have two eyes the brain receives two images. Over time we learn to coordinate our eyes so that we can fuse these images and instead of seeing two mommys approaching us, we see one. If the anatomy or physiology of the brain or eyes is not normal, or if there is trauma during this developmental stage the ability to coordinate the eyes may be compromised, resulting in strabismus.
Different activities in our lives can strengthen or weaken our fusion. Playing sports like tennis, ping pong and baseball develop fusion, as do near activities like embroidery and blocks. However, activities that require us to use just one eye, like monocular microscopes, or covering one eye with bangs, can disrupt our fusional abilities.
As we grow up our ability to fuse may become weakened through tiredness, bumps to the head or other stressors. There are, however, simple ways to strengthen and maintain this ability. One of them is to practice crossing our eyes – just the opposite of what many of us heard as children.
If you’d like to explore your convergence in the near range, hold a pencil at arms length and look at the tip. Do you have a single image? If you do, bring the pencil towards your nose as you blink and breathe. You are asking your eyes to cross. Stop if you see two pencils or if you experience any discomfort. Now bring the pencil away from you as you continue to blink and breathe, noticing when it becomes single again. Follow it out to arms length and then look at something as far in the distance as possible.
If the pencil never went double and looking at it on your nose was perfectly comfortable, then you need not practice. If you experienced doubling or discomfort, practice this little exercise a few times a day for short periods. Be gentle with your eyes so you don’t further weaken them by trying to go too fast. Over time the muscles will strengthen, the eyes become better coordinated and you will have greater stamina for reading, sewing and working at the computer.