Functional vision is more than just 20/20! It describes how your entire visual system, including the eyes, visual pathway, and other areas of the brain, work together to help you understand, process, and engage with your environment. This can contribute to success in (or trouble with) academics, attention, sports, coordination, and even one’s self-confidence. Imagine growing up in a world where when you looked small objects up close they occasionally doubled, or words float on a page float, and not knowing that wasn’t normal. You could easily pass the “20/20” vision screening in school, or at the pediatrician, and everything else is just assumed normal.
Functional vision includes the following visual skill areas:
Eye Teaming
This refers to the ability to align and focus both eyes on the same point in 3-D space. Good eye teaming allows them to work together in unison, in a well-coordinated and precise way. This is important for comfortable, single vision, and it critical to developing good depth perception.
If the two eyes are not teaming well then the eyes won’t be aligned well. This can sometimes be obvious with an eye turn, but most times, poor teaming is subtle and not obvious. If the eyes aren’t aligned, the brain gets different images from each eye, and the visual processing centers won’t be able to combine them into a clear 3-D picture. This can lead to poor (or no) depth perception, double vision, the perception that there is ghosting around the edges of objects, or the appearance of text ‘bleeding.’ This can obviously lead to eyestrain, fatigue, headaches, avoidance of detailed tasks, frustration, and more.
Eye Focusing Control
This skill is the ability to move or shift your clear focus between objects at different distances. Imagine looking at a piece of paper in front of you, then looking up and across the room at a distance target, like a blackboard. Moving the focusing of the eye back and forth, smoothly, efficiently, and evenly (between the eyes) is important. Strength is important, but so is control, accuracy, and facility.
Someone may have difficulty keeping their reading material clear and in focus, but distance focus may be fine. The opposite is also common – the focus may start good, at 20/20, but after a few minutes of viewing the eye may lose focus and blur. Many people have the skill to see 20/20 at near and/or at distance, but don’t have the skills to control their focus, move it back and forth, or maintain focus.
Eye Movement Skills
This includes is the ability of the eyes to maintain targeting, or fixation, on an object moving through space. It also includes the ability to move fixation from one object to another, and to hold fixation on a stationary object. Imagine you’re aiming two movie cameras at the same target, each one has to move perfectly in sync with each other to maintain a clear image.
This skill allows easy shifting of the eyes along the lines of print, a speedy and accurate return to the next line, effective scanning of vertical columns in math, accurate targeting (not focusing) from the desk to chalkboard and back, and efficient visual inspecting of three-dimensional objects as in arts and crafts.
Following a softball into your glove, focusing on the center bull’s-eye of a target in archery, and moving your eyes across a line of text in a book, all require accurate and efficient eye movements.
Depth Perception Skills
This skill is the ability of the brain to fuse the two images, one from each eye, into a complete picture with depth, or information of distance. Imagine two streams smoothly matching up to form a larger river; this is essentially what is happening with the information from each eye. It allows effective craft inspection, superior judgment of “me-it” relationships in athletic endeavors, and sureness and security in general movement. Educational writers consistently mention difficulties in comprehension when stereopsis (central depth perception) is deficient.
Visual Perceptual Skills, or Visual Information Processing (VIP)
Visual information processing skills take the visual input from eyes, relate it to past experiences and the other senses, make sense out of it, and plan for action. These skills include form recognition, size and shape constancy, laterality and directionality, visual manipulation, and visualization. When these skills are inefficient, the visual input does not efficiently add to one’s understanding of his or her world.