The human eye is an amazingly sophisticated organ, with millions of highly specialized, light-sensitive cells that all work together to detect the most minute traces of light energy. It seems uniquely adapted to performing this one incredibly important function, but that begs the question: why do we have two? While it is obviously helpful to have a spare in case one gets damaged, this is actually only one of the many benefits that come from having two eyes arranged as they are, and when a health concern disrupts that arrangement visual impairment can be the result. At Georgia Eye Physicians and Surgeons we work to educate our patients about all aspects of their vision. Here are the most important things that you need to know about something that we call binocular vision.
Many animals, like fish or some birds and mammals, have two eyes on opposite sides of the head, giving them the ability to see in two different directions at once. While this may seem like a definite advantage, particular useful in avoiding danger, having two eyes next to one another, focused in the same direction, is actually a significant improvement and an important characteristic in how the eyes work. Because the eyes are separated horizontally, the images that we see in the two eyes are slightly different from one another. These tiny differences are proportional to the relative distance of the objects from the eyes. The visual areas in the brain measure these differences, called binocular disparity, and use this information to calculate depth in the visual scene, providing a major means of depth perception. Binocular vision helps with performance skills such as catching and grasping, which is why front-oriented eyes are more common in predators (who have to catch other animals) than in prey (who merely need to detect movement and run away.) Moreover, binocular vision allows humans to walk over and around obstacles, judge distances for jumping and climbing, and generally move at greater speed and with more assurance.
When the two eyes are misaligned however, or when a visual deficit prevents the brain from accurately interpreting the information it receives from the two eyes and resolving it into a single image, a form of visual impairment called diplopia, or double vision, can result. Double vision can be caused by an injury to one of the small muscles that are responsible for eye movement, and may be correctable with simple strengthening exercises, or may be an indicator that nerve damage has occurred from a more serious condition. Similarly, crossed eyes, or strabismus occurs whenever both eyes do not look at the same place at the same time. It usually occurs in people who have poor eye muscle control or are very farsighted and if left untreated, can potentially lead to permanently reduced vision in one eye, a condition called amblyopia or lazy eye.
The eyes are a fascinating subject, and if you would like to learn more about them please follow us on Facebook, Twitter, and Google+ to get more informative blogs and updates. More importantly, if you are concerned about your visual health, or would simply like to schedule your annual eye exam, please contact Georgia Eye Physicians and Surgeons to make an appointment with Dr. William Segal or Dr. Marc Lay today.