When my son was in 4th grade he started having trouble computing Math addition/ subtraction Problems that were stacked 3 - 4 high. He did not have the ability to visually hold the numbers in place & have his mind compute the problem. Went for eye testing. There are 17 complex process's the eyes & brain work together to take information from the environment , analyze it, and have output. People use Dyslexia for a trash can word that encompasses all 17. Son was found to be deficient in 7 of the 17.
For example, one process is called Automoticity: the ability to see a sign/signal/number, process the info and have output. Academically, think of flashcards. Athletically, think 3rd base coach giving a sign to the hitter. Another process is called Binocular Fusion: the ability for both eyes to see an image and relay it to the back of the retina and give the brain a single image. Academically, reading from a textbook, Athletically, the high pop fly in center field falling fast ! Another process is called Binocularity: where it takes binocular fusion and adds the depth perception component. Academically, reading the blackboard from the back row, Athletically, watching the fastball approach @ 83- 90mph, timing it & taking a swing.
Son spent 18 months doing vision therapy exercises & homework 15-20 minutes per night @ home & spending one 90 minute session per week in a session with Eye Dr. when he was 10 or 11 years old. Some exercises included isolating certain muscle groups in arms/legs and making a reverse motion with the opposing muscle from right to left side of the body.
He went into this purely for the Academics, but the field results were spectacular. In Little League that spring, he was accused of speed pitching, as he threw with methodical precision & speed. Hey , the batter was in the box ~He should be Ready! I remember one game when the opposing coach was so frustrated he threw a ball into left field from the dugout just to stop play!
As an aside, my 16 year old passed his Drivers Test for his License, but failed the vision test. Had to get eye glasses & retest before he was able to drive. All kids should have a complete vision test once they pass puberty (13-16yrs old) and again before they head off to college!