Over the past few years, I have found that communicating the connection that exists between ADHD and Vision-Related Learning Difficulties takes a certain degree of finesse. When suggesting that some of the signs and symptoms of ADHD may be rooted in a source outside of the diagnosis itself you are certainly opening up yourself to criticism. This is especially true when asserting that something as seemingly intangible as vision may be the root cause. The fact is the signs and symptoms of Vision-Related Learning Difficulties can be remarkably similar to those observed in a child with ADHD. As I’ve alluded to in this blog many times before, the visual issues that I’m referring to go much beyond clarity or possessing 20/20 vision. Issues with binocularity, or eye-teaming, and visual information processing in particular tend to be areas of visual function that may preclude a true diagnosis of ADHD.
To understand one of the more common visual findings that may masquerade as a deficit in attention, we have to look at the nature of how our two eyes work as a team. As you move your eyes across these sentences, it takes an incredible amount of communication between both the cortical and subcortical regions of your brain. While these mechanics were once thought to be reflexive in nature, we now know this not to be true. The mechanical act of reading is very much a learned skill. Historically, the majority of society has only been reading since the mid 1700’s, which is hardly enough time for the required eye movements to become evolutionarily favoured traits. The eye-teaming cascade that occurs at near requires precise coordination between our accommodative (focusing) and vergence (teaming) systems – all while making rapid, sequential eye movements across a page (saccades). For some emerging readers, this cascade can frequently break down, resulting in subtle deviations in ocular alignment. While these subtle deviations may seem inconsequential to some, they actually have many implications for someone learning to read text or perform well in a classroom. When one eye deviates, even slightly, it results in the brain receiving mixed signals about where something truly is in space. When this occurs while looking at text, an individual may experience words blurring, doubling, swimming or dancing across the page. Now, you may very well think that this is something that a child would alert his parents or teachers to – but I can tell you from experience that this is rarely the case. When a child experiences visual confusion, they often assume that this is the way things are meant to be seen. I have personally worked with countless children who have been seeing double for years, and yet never once expressed this until questioned at their eye examination.
The problem with experiencing blurring, swimming or doubling of text is that it understandably makes engaging in detailed near-based tasks such as reading and writing extremely labourious. A child can very quickly learn that this is a not a task they are comfortable with or good at, and thus disengage. As someone who has personally dealt with these issues for most of my life, I can tell you that the strain it can create can at times be unbearable. And herein lies the link to ADHD – a child whose visual system is not equipped to team effectively and accurately is far less likely to engage with visual tasks presented to them at school or otherwise. At this point of the conversation, I am usually liable to hear the comment that we can’t truly be certain that it is the eye-teaming system or the attention centres in the brain that are the cause of the deficit. The old chicken or the egg scenario indeed. To be honest though, it doesn’t really matter all that much clinically. If we assume the premise that seeing clearly and singly is a preferable visual world in which to reside, then treatment is prudent. Years of clinical experience has shown me that alleviating double vision or tracking issues in children almost always improves their ability to sustain attention, especially at near. A growing body of studies have helped to confirm this assertion, with further work in this area on the way (citt-art.com).
When it comes to evaluating the link between ADHD and Vision-Related Learning Difficulties, it is important to remember that very few cases are black and white. Vision Therapy is not meant as to act as an all-encompassing solution for all children with attentional issues – just as medication should not be either. The important message of this article is to ensure that if you are investigating attentional issues with your child, you should endeavor to have their vision functionally assessed. With measurable deficits in eye-teaming known to be 3x higher in the ADHD population, the link is far too strong to not investigate. Whether an uncovered eye-teaming issue is acting as a comorbidity or the true root cause of the attention issues in a given child is not always easy to tell – but Vision Therapy as a means by which to improve visual efficiency, confidence and comfort in the classroom is rarely an unreasonable treatment option to consider.
Until next month,
Paul Rollett, OD
Improvement in academic behaviors after successful treatment of convergence insufficiency.
Improvement of Vergence Movements by Vision Therapy Decreases K-ARS Scores of Symptomatic ADHD Children
The Relationship Between Convergence Insufficiency and ADHD