By Robyn Dragoo, OD
Ever looked at someone and their two eyes are not looking at the same thing at the same time? Do you have two eyes that don’t always seem to “play” together? Well, you make up about 5% of our total population and contrary to popular belief, your eye is not LAZY it’s NICE.
In development, your two eyes learn to play or coordinate with one another through life experiences, and a series of developing steps occur from infantile reflex integration to gross motor development, all leading to fine motor development. The finest motor development we have is ocular motor development. This is the two eyes working together well and also leading your body through space and time.
When the two eyes cannot coordinate in such a way that they give your brain good data, the brain has choices as to how to differentiate the two conflicting sources of information.
You might know, your two eyes are each giving the brain a “picture” of what you see. One image comes in from the right eye and one from the left. When your two eyes are aligned, the two eyes give the brain a similar image and due to their relative positioning, they give a slightly different perspective, but nonetheless the same image, so the brain sees one object. When this alignment does not occur, the brain could see two images of the same object. You can see how this may not be advantageous unless of course, we were looking at two happy golden retrievers, two steak dinners, or two banana splits. (just kidding)
One of the ways the brain can dissociate the two conflicting pictures is by turning an eye to the blind spot. Yes, both of your eyes have a significant blind spot that corresponds directly to the anatomical connection where your optic nerve sits within your retinal tissue. No photoreceptors reside there. Therefore, no information to the brain is gathered there creating a blind spot.
Your brain is then eliminating one of the images so as to be able to function in your environment by turning the center of the eye to it. The brain does not want to see double.
Whether the brain is turning the eye in or out, it is achieving this.
That is when a person is considered to have a “lazy” eye by layman’s standards when truly, the eye that turns is not lazy, but just nice. Telling the dominant eye, the lead eye, or the “bully” eye, “you go first. You show the brain what we see, and I will go out of the sandbox because we cannot play well together at this time. “ This turned eye says, “ I will recede.``
The dominant eye is chosen by the brain to keep their relationship open. The non-dominant eye is then sent out of the “sandbox” per se. It’s put into a “time out.” That way, it does not send conflicting messages to the brain and life can be carried out without double vision. Clever move, genius move, and I can’t make this stuff up. Truly, this is what is happening in the brain.
When the object you are viewing is in the field corresponding to the turned eye, that eye is expected to lead. Many times this eye will then come to attention, lead and send the dominant eye out of the sandbox and to its blind spot. That would be considered alternating to the other eye.
In the same way, if we just use our hand and cover the dominant eye, the non-dominant eye will rise to the occasion and will be able to track, converge and perform functional eye movements without difficulty. There is seemingly nothing “wrong” with the eye that turns. It is not lazy at all. Therefore, there is no nerve that is innervating improperly nor a muscle that is too weak or too strong. It is the relationship between the two eyes, that is not coordinating or playing well together that causes the eye to turn. Lucky for us, there is a way to train this coordination through a series of vision exercises, much like teaching a person how to ride a bicycle. We need not strengthen muscles or have surgery to ride the bike, we simply need to teach the brain and the two eyes to play together in that sandbox and when we do, a glorious occurrence called BINOCULAR VISION is achieved. And that my friend is the best occurrence of all. It is what was intended for our visual system to provide the brain for optimal movement through space and time.