My career in optometry was inspired by my mother, who ran two practices and didn't retire until the age of 89.
She loved every minute of it and had a deep passion for helping children perform better in school by treating their vision-related learning problems.
Inheriting her passion, I went into optometry, and since graduating, I have specialized in areas that involve understanding how vision functions beyond 20/20 eyesight, with the mission of helping people take better care of their eyes.
Success requires more than 20/20 eyesight
Although I operate a comprehensive primary care optometric practice, my focus is on optometric vision therapy, neuro-optometric rehabilitation, and preventive eyecare.
One aspect of vision care that needs more attention is binocular vision dysfunction. Our eyes have evolved to provide binocular vision—a distinct image from each eye to provide the most information on the depth and motion of an object moving across three dimensions.1
A healthy eye produces a single clear image by fusing images from each eye by the synchronized contraction and relaxation of ciliary muscles based on whether the focused object is located nearby or farther, respectively, using mechanisms such as accommodation or convergence.2
Dysfunctions in any of these mechanisms make it challenging to merge these images in a sustained way for a prolonged time, which can lead to binocular vision dysfunction.3 The prevalence of non-strabismic binocular vision dysfunction is known to range from 22.26% to 36.71%, respectively, depending on the population and classification types.4,5
Conversely, the prevalence of accommodative and vergence dysfunctions ranges even higher from 54.66% to 73.69%.5 When we identify misalignment in a patient’s binocular vision, we look closely at their lifestyle and related symptoms to discover how we can help them.
Download the Binocular Vision Cheat Sheet here!
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All About Binocular Vision
This cheat sheet reviews foundational information related to binocular vision dysfunction and illustrates how optometrists can identify and test for BVD.
Testing for binocular vision
When a patient complains of symptoms, we perform an examination that includes several types of binocular vision tests. We want to understand how their eye misalignment relates to the symptoms and determine if there is over- or under-convergence.
This is done with a stand-up cheiroscope tracing unit, and we also have patients complete a questionnaire and assessment with the Neurolens N3 device to understand the symptoms they experience and how often they are affected.6
Additionally, we perform cover tests, phorias, and ductions through the phoropter to evaluate how the patients' eyes are aligned when working near versus far, which confirms the findings of the N3. During the phoria test, I demonstrate how far their eye alignment is from the normal expected phoria at near. I ask the patient if the targets appear to be moving back and forth.
I explain that their eyes are constantly trying to point at the target they are viewing and that constant movement triggers pain receptors in the eyes, head, and neck areas. This kickstarts a conversation about how their eyes are working harder all day long because they are not in sync.
When a patient qualifies for a Neurolens treatment, we use a few chairside demonstrations to reinforce how the misalignment of the two eyes impacts pain in the eye, neck, and shoulder areas. This demo consists of placing a 1 prism diopter Base In lens in front of one eye and having the patient feel the difference in visual and neck comfort compared to without the prism.
The impact of binocular vision dysfunction
Binocular vision dysfunction (BVD) can have a huge impact on many areas of life: academics, athletics, driving, career, and even social life.6 In school, BVD can lead to comprehension issues and falling asleep during reading, both of which can have adverse effects.7,8
For athletic patients, BVD can make it difficult to judge where the ball is in space, depending on whether they have a convergence or divergence problem.7,9 Compensation for these issues can slow down their performance, which can affect every aspect of sports, whether swinging too soon or too late in baseball or hitting the rim or the backboard in basketball.7,9
All these skills depend on how the eyes align and coordinate. I saw a golfer last week, and when I asked if he was putting short because he has a convergence excess, which makes him perceive targets as closer than they are, he was amazed that I knew his shortcomings.
In business, digital screens are everywhere, and they require two visual systems: accommodation and convergence. When these systems are unable to align, this results in pain, blurred vision, and slowness which can decrease productivity.10 These symptoms can be more noticeable at the end of the day, potentially having a secondary negative impact on family life and relationships.
The orientation and organization of visual space are communicated through the convergence system. It can affect everything we do. I have observed that my patients with convergence insufficiency often do not want to get close to people, so they back away. Conversely, those with convergence excess may stand quite close to others. Both scenarios can have other negative social implications.
Binocular vision issues hiding in plain sight
In the process of examining patients for symptoms of BVD, it is important to ask specific questions. This is particularly true when examining pediatric patients for whom treatment of BVDs can make a huge difference.
If I ask, "How are you doing in school?" a child may just answer, "Fine." So, instead, I ask, "What are your favorite and least favorite subjects?" Those who answer that recess or lunch is a favorite subject and reading or math is their least favorite subject are more likely to have a vision-related learning problem, which indicates the need for further evaluation.
Similarly, I do not ask if they like to read. Instead, I ask if they ever read a book for fun. If the answer is no, then I want to investigate more. If children are reading for fun, that is a good sign!
It is important to note that if they're an early reader, it's important to ensure that their vision system can handle the early visual demand because elevated ocular accommodation can contribute to the development and progression of myopia.11
Don't forget to check out the All About Binocular Vision Cheat Sheet!
Developing good visual hygiene habits
An avid reader in second grade must develop good visual hygiene habits, such as taking good visual breaks. One strategy I employ is "think and blink," meaning they should look up, think about what they're looking at, and blink, which gives their vision system a break. "Think and blink" is easy for them to remember to make a conscious effort to blink for a visual break.12
Teaching this habit at a young age helps to prevent potential vision problems. Many visual hygiene habits are established by creating positive environments for learning, such as good posture, book position, proper desk seats, and good lighting. Learning is also about creating a memorable visual image.
How many 2-year-olds can read the word "McDonald's"? Almost all of them, but they don't yet have phonetics. The visual experience they have with these words allows them to read the words easily. Good readers create images and pictures in their minds as they read—they can visualize. If you read a book and then see the movie about the book, the book is often better than the movie.
Our ability to visualize can be more creative than Hollywood. By fostering a visual system that can support visualization, children have better memory of the information they're learning.
BVD treatment options within sight
The available treatment options for BVD include lenses, prisms, occlusion, and optometric vision therapy. For example, occlusion therapy involves patching the dominant/healthy eye for several hours each day; however poor adherence has been a consistent issue that can result in residual amblyopia.13 Similarly, while vision therapy is considered effective, a significant burden in terms of time, economic burden, and patient cooperation is involved.14
One treatment application is contoured prism lenses. A contoured prism provides a 0.75 increase in Base In prism when viewing near targets, such as when reading. For example, if the prism is set at zero for distance, the near amount of prism is 0.75.
The change from near to far is gradual. By reducing the convergence demand, contoured prisms partially relieve the strain on the neural process, giving patients pain relief. Patients who continue to experience symptoms may need additional optometric tools. For patients with persistent issues, the options are bi-nasal occluders, optometric vision therapy, or light therapy.
Contoured prism lenses have made a huge difference to many of our patients. With these lenses, patients with headaches, vertigo, and dizziness, who have significantly limited functions, can get back to work and live a regular lifestyle. Patients continue to return every year, talking about all of the improvements that these lenses have made in their lives.
In my own experience, the constant arthritis and neck pain that I endured from a car accident decades ago disappeared after I wore contoured prism lenses. It's amazing how much those symptoms are relieved.
Envisioning a better world
Contoured prism lenses have also been excellent for building our practice. We've teamed up with other physicians—primarily neurologists—who have patients with these symptoms, but they haven't had much success with their typical treatment regimens.
Of everything we've implemented in our practice over the last 38 years, Neurolenses have been the easiest to integrate. They have had a huge impact on our profitability. Because of the Neurolens program, everyone at the practice understood what binocularity was within 30 days. This allowed our team to further improve patients' lives.
Most people don't realize that many of the challenges they face may have something to do with their eyes, so optometrists have an opportunity to educate them. People seem to believe that vision is only about 20/20 eyesight—if you can see clearly, everything is fine.
Contoured prism lenses help patients understand that glasses can be used for issues other than eyesight. When your vision works better, you are going to have a better life.
