If your eyes see 20/20, can they still interfere with the ability to learn to read or read to learn? Most definitely they can, and 20/20 is only one very small measurement of the entire visual system. We have five times the sensory input to the brain from the visual system of any other sense that we have.
In the vast majority of the states, the school “vision screening” involves looking at an eye chart twenty feet away. How much of the time is spent in a classroom looking twenty feet away when studying?
Dr. Herman Snellen developed the eye chart back in 1862 when he was looking for ways to help measure the ability to see of troops going into the Civil War. Unfortunately, technology for school eye screenings has not quite kept up with the times. We are now doing so much more sustained near-point close work, yet the school screening does little to pick up people who are having difficulties seeing near print. Moreover, over 95 percent of people with vision-related learning disabilities see 20/20, so eyesight is not the problem.
We take reading for granted, but we really shouldn’t. Here’s why.
When one starts looking at the complexity of the visual system, it truly is remarkable that anyone learns to read. Consider this: the eyes are the only organs in the body that have different components being controlled by two different nervous systems coordinating at the same time.
The central nervous system controls our eye movements. There are six muscles going to each eye that require coordination. More recent research has realized that each of those six muscles has two branches and would be considered more like twelve muscles per eye.
It gets even more nuanced from that. Dr. Richard Bruenech, PhD, from Norway mentions that each muscle actually has four components. Ongoing research continues to show more and more complexity of our visual system.
The eye muscles of the body are the strongest muscles for what they need to do of any muscle in our body. Our eye is a one-ounce object, and the eye muscles are one hundred to two hundred times stronger than they need to be.
When we look at the accuracy of movements, the eye has the ability to move the very smallest of degrees. Our leg muscles have one nerve fiber going to about one thousand muscle fibers. In comparison, the eye has the lowest nerve to muscle ratio of any muscles in our body. It is a one-to-twelve ratio with one nerve for every twelve muscle fibers allowing for very small, precise eye movements.
What is a “scan path” and why is it so important?
With such a fine controlled system, why would people have problems keeping their place with reading? Why would they tend to skip words or get to the end of the line and lose their place when they go to look to the next line? It is because of the interaction with the other components of the visual system where problems can arise.
When we are beginning readers, we are still learning how to improve accuracy of eye movement. Tracing large letters in kindergarten and first grade is part of what helps develop eye movements. Over thirty years ago, researchers took infrared monitoring devices that would record where a person fixates or points their eyes when shown different object. Since an angled line provides more information than a straight line, fixations tended more often toward angles.
When researchers would show people a picture, every person had a particular scan path or order in which their eyes moved about the object. Though in general people’s eye movements gave a similar pattern, the order in which each person moved their eyes was unique. What was of further interest is when they continued to repeat the process, after a few repetitions, suddenly 35 percent of the time when people would look at the picture, their eyes no longer moved.
Researchers concluded that part of the memory of an object initially is involved with the eye movements that lay down a scan path or order of movement. When a person goes to look at the object again, the eyes start repeating and replicating the scan path to help identify the object. Later, it can be more of an internal shift of attention not requiring eye movements.
What if during the scan process, someone does not have the ability to accurately control their eyes? What if when they look at the object, they make a scan path, and then when they go to look at the same object, they make a slightly different scan path? As their brain starts reviewing, it realizes, “This is a novel scan path, so I don’t know what this object is.”
This very likely accounts for some of the frustration in learning to read when a person sees a new word; they learn what it is, and then in the next paragraph, they cannot recall what that word was that they just saw.
Maybe on another day when they are more rested and they have improved eye movements, they can identify the word. Then later on in the day when they are more fatigued, they have less efficiency and less accuracy, and they are no longer able to replicate the previous scan path. Once again, they “don’t know” the word.
Putting it into focus.
Another part of the visual system that is crucial for doing near-point work is our “accommodative” or “focusing” system. This changes the shape of the lens in our eye in order to focus the light precisely on the retina so we see clearly.
The eye is definitely not like a camera. A camera takes a picture, and all of the picture should be in focus. With the eye, only the straight-ahead vision common from the macular or pinpoint of sharpest sight is capable of providing clarity.
Of an over 180-degree retina, it is the central one degree that has enough light receptors to provide clear detail as well as color. It is also that central one degree that causes the focusing system to respond. Once again, the person’s ability to accurately point their macula at the proper target in the proper order is crucial for the focusing system as well.
Convergence can put strain on the eyes, making reading far more difficult.
The third main component involving the eyes for reading is the ability for the eyes to point or converge at the reading material. This aiming ability is absolutely crucial for efficient reading.
We have all seen people who have an eye that wanders out or crosses. That is a strabismus or eye deviation. In many of their cases, reading is not hugely interfered with because they have already learned how to turn off or suppress the central vision in the eye that is deviated. However, they can have difficulties in other areas of day-to-day life, like depth perception and night driving difficulties.
This ability to easily align the eyes for reading is absolutely essential for the ability to read quickly as well as will influence a person’s ability to comprehend what they are reading. I personally have experienced a convergence insufficiency or difficulty aiming eyes inward for reading. Another imbalance is a convergence excess or a tendency for the eyes to cross or over aim. There can also be a tendency for one eye to want to aim slightly higher than the other. Any of these imbalances can be devastating for the reading process.
Over twenty-five years ago at the Pacific University College of Optometry, Dr. Bill Ludlam supervised a study involving forty-eight third-year optometry students. These would have been people with six to seven years of college education.
Vision imbalances can be so subtle because they do not have anything to do with clarity of sight but have all to do with the amount of energy and effort it takes to make the different components of the visual system function.
They made two pairs of glasses. One pair was essentially window glass and had no power in it. The other pair had nine units of prism positioned so it would give the simulation of someone who had a convergence excess or tendency for their eyes to over aim. To compensate for this, the person would have to spend energy aiming their eyes outward from the target in order to keep clear and single vision. Prior to the test, they confirmed there was no blurring and no doubling at any time during the reading.
They gave the forty-eight optometry students four equally weighted sections of the California Achievement Test for reading speed and comprehension. They did two tests with each pair of glasses, and the participants did not know which pair of glasses they were looking through. The results of the study were that forty out of forty-eight of the grad students had a statistically significant drop in reading speed and reading comprehension when they were wearing the pair that made them have to spend extra energy to keep their eyes aligned. This interference with reading comprehension occurred with no blurring and no doubling of vision.
This once again shows how subtle vision imbalances can be because they do not have anything to do with clarity of sight but have all to do with the amount of energy and effort it takes to make the different components of the visual system function.
I use this demonstration in my office frequently when I have parents who have brought in their son or daughter with reading difficulties. About three out of four times, I am able to give the parent a “vision-related” learning problem where suddenly they now have difficulty with reading speed, keeping their place with reading, or comprehending what they are reading, or they will feel significant visual strain or eyes aching while reading. Suddenly, the parent has a great deal of empathy for their child as far as the amount of hard work they are spending in the reading process.
How to get treatment for vision-related learning disabilities.
Treatment for vision-related learning disabilities can run the gamut. Simple reading glasses that help balance the aiming and focusing system and allow for greatly improved performance are one option. Another option is yoked prism lenses.
Vision therapy, more accurately described as vision neurorehabilitation procedures, are quite effective in helping a person’s brain learn how to gain better control and coordination over the various parts of the visual system. As a person develops improved control with less effort they can then learn how to utilize the information the eyes are taking in.
Vision perception is utilizing the information coming in through our eyes and applying that to our previous memory. Accurate visual perception provides a clear, understandable picture of where we are in space and synchronizes with hearing, balance, and body awareness or proprioception.
The good news is that there is treatment and hope for children or adults with vision-related learning disabilities. It is trainable at any time. A number of years ago, I had a husband and wife who brought their ten-year-old son in for evaluation. He was very bright but was having significant difficulties in keeping his place when reading. He would frequently reread the same line.
He had a difficult time concentrating and paying attention when doing his schoolwork. He definitely had a visual imbalance, and we began doing the vision neurorehabilitation.
About two weeks later, his father came in for an exam. He was a CPA. He told me he was working roughly eighty hours a week just trying to keep up with the paperwork. He would go home every night absolutely exhausted and found it difficult to spend time with his family because his eyes and head hurt, and he was so fatigued. On further questioning, reading had always been difficult. He said he had literally blocked out most of his high school memories because he had to work so hard for school. Boy, talk about someone who picked a profession that was not conducive to a poorly operating visual system!
Nevertheless, it was found that he indeed had a vision-related learning disability just like his son. The two of them, father and son, began doing the rehabilitation. I will never forget the visit when the father came in and was describing how for the first time in his life, he was enjoying reading.
It was also the first time in his life he was able to appreciate 3D vision. He was driving along one of the streets in Spokane Valley, and all of a sudden the world “popped 3D.” It took him totally by surprise. He pulled off the side of the road and just looked around in awe, seeing the added dimension he was now able to perceive. He had no idea that the world really looked three-dimensional.
As he continued on, he was becoming more and more efficient with reading and doing his work. By the end of the therapy he was able to get more work done in forty hours a week than he had been able to do in an eighty hour week. He, his wife and son were thrilled with the increased family time they could enjoy each week!