Reading is a very complex process that requires many areas of the brain to work in harmony to allow us to turn these small shapes we call letters and words into meaningful symbols. It is no wonder that many children and even some adults struggle with the process of reading. It also makes sense that the processing and coordination of our visual system which plays a critical role in our reading ability can often interfere with this basic and critical aspect of our daily lives.
From a vision standpoint, reading requires 4 basic areas of function.
1. Oculomotor skills
When we read, we must move our eyes from word to word to word. These eye movements are some of the smallest and most precise movements of the human body. We assume that these movements develop appropriately in children, but often they do not. Inaccurate eye movements can easily lead to word skipping. It can also significantly impact handwriting, copying from the board, and cause slower and more labored reading.
Inside each eye is a biological lens. The role of this lens is to keep our world clear. The ciliary muscle works to change the shape of this lens, allowing us to focus on objects at different distances. Again, we assume that this process develops normally for everyone, but accommodative dysfunction is very common. Resulting symptoms include words that blur in and out when reading, even if the child has 20/20 vision and does not need a pair of glasses. They can also struggle from headaches, eye strain and tired eyes.
We have two eyes that must work in perfect coordination for our eyes to focus on the page when we read. If both eyes are not pointed at the same spot on the page, then we may see a doubling or overlapping of the words when we read. If the eyes are not aligned on the page, it can also make the words appear to move or float on the page as well. Obviously this can make it very difficult to read. Many children struggle to point the eyes together on the page when they read. This can cause the words to double or move on the page as mentioned, but it can also cause headaches and eye strain as the child struggles to force the eyes to focus together.
1. Visual Perception
Apart from visual function, our brain must also process and understand all of the visual information we see. It is possible, however, for the brain to struggle to understand our visual world and in turn we can confuse what we are seeing. Symbol and pattern confusion are common symptoms of visual perceptual difficulties.
At an early age, we learn the concept of form constancy. This is the ability to look at an object, for example a cup, and know it is a cup no matter it’s direction or orientation.. This means we learn to name it as a cup no matter which direction it is facing. However, when we learn our letters, the letter “b” and “d” are the exact same object facing different directions. Everything in our visual development up to that time tells us that these two objects should have the same name, but instead we learn that direction matters. This is visual perceptual development in action and is partly why we expect young children to make letter reversals initially.
Unfortunately, as with all areas of development, there can be delays, particularly if a child is struggling to track or focus their eyes. Children may continue to struggle with letter reversals or other areas of visual perception such as visual discrimination and visual memory; the ability to see small differences between two objects or remember what they have seen, respectively.
The problem is that even though children can experience words blurring and doubling on the page when they read, they often don’t know how to explain these symptoms, and many times assume it is just normal. As parents, we often do not know what questions to ask our children about their vision and assume that if they pass the school vision screening or a vision screening at the doctor’s office then their vision must be okay. In other words, we assume that if our children can read small letters at 20 ft one eye at a time, then they must have the vision needed to read. While these screenings are important in catching obvious reduced vision, they do little to assess how our children’s eyes function for 5-6 hours a day during demanding near visual activity.
Difficulties in the function and coordination of our vision are not rare. Some studies show that as many as 1 in 4 children may have a vision problem that is impacting their learning. Other studies show that over 50% of those children in special education struggle with vision problems. Early intervention and increased awareness are the best defense against missing these treatable vision problems.