Binocular vision conditions are a lot more common than you may think and discovering them is half the battle.
Most binocular vision conditions are not as easy to identify as strabismus or amblyopia.
Case history is your best friend and one of the easiest ways to determine which binocular vision condition your patient may have. In today’s world of smartphones, tablets, and computers, children and young adults are having difficulty with the increased demand on their visual system for near work. However, these patients might not be so quick to tell you about the problems they face every day.
Here are the main binocular vision conditions I come across every day and how I diagnose them:
1) Convergence Insufficiency
Have you ever had a child sit in your chair and complain about words moving when they read or needing to use their finger to keep their place in a sentence?
Probably not, because chances are those kids have been experiencing those symptoms throughout their school career while being told they are poor readers. Next time you’re sitting near your trial lens kit, try reading about that house in Rockport, Massachusetts made entirely of newspaper while rotating a 4 Prism Diopter Base In lens in front of your eye every five words and see how far you get.
Asking specific questions such as, “Do you lose your place while reading if you don’t use your finger or a ruler?” or, “Do words move around on the page when you try to read them?” will let your patients know that you are not concerned if they can read the 20/20 line but how easy it is for them to read.
Listen to how well they read the near visual acuity card and quickly check their near point of convergence.
2) Accommodative Infacility
Does it seem a little strange when you get patients coming in, adamant they need a new prescription, and yet your refraction shows no change?
They complain that they cannot see the board at school or that driving in the morning is a lot easier than driving home in the evening. As you ask more in your case history, you will hear they spend a lot of time on the computer or do a lot of switching between reading and distance targets.
A big giveaway is when they nod their head in agreement after you ask them, “Does it take you a bit of time to focus your eyes on something far away after you’ve been on your phone or computer?”
3) Accommodative Insufficiency
A lot of people get headaches throughout the day or eye fatigue.
Some of them do not realize the correlation while others will comment about how it started once they began their new job with increased computer or desk-work. Again, case history will help you and your patient make the connection on where the headaches and eye fatigue are coming from.
If you realize that there is a connection with increased near work, a quick way to confirm is with binocular minus and plus acceptance or positive and negative relative accommodation for my American Optometrists.
Unfortunately, in today’s society, it is a little unrealistic to expect your patient to listen to your recommendation of limiting their time on electronic devices, especially if it is part of their job or education. Taking breaks during near work would be ideal but try telling a lawyer, accountant or engineer to take breaks every 20 minutes.
4) Oculomotor Dysfunction
This condition is difficult to identify through case history alone because it has similar symptoms to other common binocular vision conditions.
Inadequate pursuits or saccades could be the reason they can’t read without using their finger, why they have headaches and eye fatigue, or why their eyes take time to focus. The best way to assess for this is through the Northeastern State University College of Optometry (NSUCO) Oculomotor Test. This testing incorporates head movements and body movements observed while performing pursuits and saccades to determine the accuracy and ability of those pursuits and saccades.
The paper, “Northeastern State University College of Optometry’s Oculomotor Norms” by Drs. Maples, Atchley, and Ficklin outlines how to perform the test and how to score the results.
Another helpful tool is the Developmental Eye Movement Test developed by Dr. Jack Richman and Dr. Ralph Garzia. Although it does not measure saccadic or pursuit abilities, this test can show correlations to reading performance and visual processing speed.1
These are four of the main binocular vision conditions that I come across in everyday practice.
If you start adding a few of these questions to your case history or short tests to your exam, you will be surprised at the increase in binocular vision conditions you will find in your patient base.
Even more importantly, you will be able to help these patients immensely because you will find the answers to a lot of their daily struggles.
1. Ayton, L. N., L. A. Abel, T.R. Fricke, and N.A. Brien. “Developmental Eye Movement Test: What Is It Really Measuring?” Optometry and Vision Science : Official Publication of the American Academy of Optometry. U.S. National Library of Medicine, n.d. Web. 08 Feb. 2017.