Visual Perceptual Disorders
Updated: Mar 18, 2020
In this post I've tried to put together the neurological perspective of how a specific ocular motor dysfunction can impact or create hindrances in the acquisition of learning for students. As we are aware that all learning takes place in the brain but our brain is dependent upon the ‘input ‘ it receives from our sensory system like the vision, auditory, speech, tactile and kinaesthetic. In the following text, I'll emphasize "visual acuity and its disorders. Under-developed functioning of any of the sensory channels can result ; as in lack of binocular vision i.e when both eyes don't work together as a team; Lazy eye - as in when one of the eyes has a lesser vision and consequently its input is suppressed by the occipital region of the brain. Accommodation as when eyes can shift focus easily from a near and far distance back and forth e.g copying from the board without blurring. Eye movement control- i.e how well the eyes perform saccadic moments/jumping from word to word without losing its place when tracking across the line of print. Such as overshooting or undershooting words while reading. Also, when eyes have to make reverse movement upon reaching the end of the line. Besides this, visual discrimination, eye-hand coordination, depth perception, visualization, and visual memory are also among the vital skills required in learning situations.
All of the conditions can manifest in students as visual fatigue, eye strain, watery and blinking of eyes and consequently avoidance of the tasks that require sustainment of gaze for a specific amount of time with concentration. Moreover, these conditions are not measured in standard visual examination with the regular optometrists. The conventional eye exam looks for general eye health and a 20/20 vision i.e if a person can see at a distance of 20 feet and if an individual is in need of eyeglasses. So, consequently, the near vision visual acuity generally remains undiagnosed. These above mention challenges are related to specifically "near vision" concerns. I've learned about them in a course work called "Visual Vestibular Assessment and Treatment" in the year 2011 from San Antonio, Texas. The preliminary "screening process" is not a part of medical screening, instead, it is an " educational assessment" to determine a compromised near vision abilities, and also if a student possesses basic foundational skills necessary for learning.
The following text entails a detail description of a lack of binaural vision called Strabismus and in-office vision therapy. Here is an excerpt from the training manual that I would like to share; In patients with Strabismus, the two eyes do not line up together properly to look at the same object. In some people with strabismus, the condition can be very obvious to any onlooker who will immediately notice that the eyes are clearly misaligned, crossed or turned outward or turned inward. Strabismus is often called "crossed eyes" when the eyes are turned inward towards the nose or "wall eyes" when the eyes are turned out towards the wall. However, it is important to be aware that in some cases strabismus is only obvious to an eye doctor but still must be taken seriously and treated. Because any “ perceived stress” for example, when asked to read, tends to turn eyes inwards or outwards. Moreover, when we start to look at something, each of the two eyes are focused on a different object, when different images are sent to the brain from each eye- it is not considered normal. As two different images cannot be simultaneously processed by the brain then the brain is forced to ignore one of the images. Over time, the constant ignoring makes that eye much weaker in vision. If the strabismus is not treated, the eye that the brain ignores will never see well, causing a condition called amblyopia in the ignored eye. Amblyopia is often called "lazy eye." The onset of the two conditions may also be reversed with the patient first having amblyopia, which then causes strabismus. Other vision problems associated with strabismus include stereopsis (the inability to see in three dimensions) and diplopia (double vision). Vision therapy addresses the root cause of strabismus: it addresses the problem with the eye-brain connection. Therefore, vision therapy is a rehabilitative therapy for the eyes and the brain. And proves to be a better choice to safely and effectively treat Strabismus. The goal of vision therapy is different than that of surgery. Vision therapy treats the cause rather than the symptom. It trains the eyes and brain to work properly so that all of the six muscles involved in eye movement are properly. I'm enclosing a very interesting video to further enhance understanding. I hope this can be helpful to keep an eye out for early signs. https://www.youtube.com/watch?v=XCCtphdXhq8&feature=youtu.be