Understandings of Behavioural Optometrists
We do not 'see' with our eyes, we see with our brain. Our eyes are sensory organs that detect light. Eveything we see is a picture constructed in and by our brain, after the event has occured.
Traditionally, vision has been considered to be similar to the workings of a camera - light enters the pupil / apeture, is focused by the lens onto the retina / film, where the image is captured. This is not entirely incorrect, but far from the complete story. The eye, like the ear, nose or taste buds, is a sensory organ. The retina senses light and sends electrical messages along the nerves to the vision area in the brain. Here the brain assembles all the information and forms a picture or image. It also sends information to many other areas in the brain to integrate what is seen with what is felt and heard, etc, to understand or interpret what is seen.
Vision, vestibular and proprioception
Vision and balance are inseparable - our eyes, vestibular system and proprioception work together - if the information from one channel does not match the others we may start to feel unbalanced, dizzy, disorientated or sick. For example when reading in a car: your eyes may be looking at words and not the scenery, but your vestibular system feels acceleration, deceleration and bumps and may get confused.
Vision's main purpose is not to see the smallest letters on an eye chart, but rather to direct movement in space
We think of vision's main purpose as being able to see small details, like letters on a page when reading, but actually vision's main purpose is to direct action and movement. Unless you are blind, vision guides our every movement from walking, driving and writing. It informs us how quickly we need to cross a road to avoid being hit by a car. Although we may be born with 'sight', ie we can see a car, vision requires learning. A parent will hold their child's hand when crossing a road, while they are still building this skill - to estimate the speed of the car and how far and quickly they need to cross. If the space we 'see' as a picture in our heads does not match the space around us, we feel insecure in space. We may misjudge distances when driving, have to touch things to confirm what we see, or may resort to unwanted behaviors to help us cope. Vision therapy addresses visual-spatial confusion.
Vision develops over time
As mentioned above, we are born with eyesight but vision (our abilty to interpret what we see and direct action) is learned. Because not all children develop at the exact same time and in the same sequence, some children may not have developed the visual skills required for classroom learning. They may have 'perfect sight' but be unable to track across a page when reading or battle to sustain focus up close for required periods of time. These children may benefit from anti-stress glasses in the classroom, or exercises to address underdeveloped skills, or purposeful play to naturally develop those skills. Anything that is learned can be taught and / or 'learned better'.
There are also those who have 'perfect eyesight' but have difficulty interpreting or making sense of what they see, ie extracting the important information from the background (figure-ground) or being able to easily remember what the have seen (visual memory). They may have difficulty with integrating their vision with fine motor skills (eye hand coordination) or may not have learned to use their vision to direct these skills. In Vision Therapy we address these developmental delays, and many other, visual dysfunctions.
It is better to have only one eye (or walk around with one eye covered) than have two eyes that don't work well together
We often see children who have not yet learned to use their eyes as a coordinated team. The majority have no observable signs at all. Very few complain of uncomfortable vision or of seeing double or of words moving on a page, because they don't know that this is not 'normal'. Many diligent students adjust their posture by moving in close to their work or tilting their head to the side (so that they only have to look with one eye). Others avoid near tasks such as reading or give up easily and stare out the window. Inefficient eye teaming results in tired eyes and reduced comprehension, yet is something that can easily be trained. With todays digital world's focus on excessive near visual tasks, we regularly see both children and adults who did learn to use their eyes together as a team but find that this skill has regressed due to eye stress. This too can easily be helped with vision therapy, prisms and/ or reading lenses.