Double Vision

Have you ever had double vision? If you experienced it for the first time as an adult, you know that it can be scary. 

What is double vision? It is when you see two images of one object. Sometimes the images are completely separated from each other, but usually they overlap. Double vision can be horizontal, vertical, or diagonal (see image 1). 

There are several causes of double vision. Some of them are life-threatening. If you or your child experiences a sudden, constant onset of double vision, go to the emergency room right away. 

This article will focus on one cause of double vision that is not an emergency. It is called convergence insufficiency. This condition typically causes double vision when doing near tasks, such as reading or computer work. It happens when the eyes don’t work as a team. 

Because our eyes are separated by a nose, each eye sends a slightly different picture to the brain. You can demonstrate this right now. Close your right eye and, with your left eye open, point to an object across the room. Without moving your pointer finger, close your left eye and open your right. Are you still pointing at the same object? It should look like your finger moved to the left, even though you didn’t move it. 

When both eyes are open, the brain uses the slightly different perspective of each eye to generate a single, virtual, 3D image of our surroundings. This helps us to know where our bodies are in relation to our environment. It also helps us judge distances between objects. It is a wonderful design that adds beauty and useful information to our perception of the world. 

What happens when there is a glitch in the design? If both eyes don’t work together, you have double vision. Children are especially vulnerable to this. Their visual systems are still developing when they begin school. Schoolwork places a huge demand on the visual system. In addition, many young children are allowed to use tablets and phones at home. Between hours of schoolwork and hours of screen use, many children’s visual systems break down and they begin to see double. 

Double vision is distracting and frustrating. Just try to read the text in image 2. You likely will struggle to make sense of the passage. Now, imagine seeing it that way every time you need to read. Would you be a fast reader? Would you get good grades in school? Would you do everything possible to avoid doing your homework? 
 

Fortunately, there is treatment for children who see double in school. The brain tells the eyes how to move. If a child has double vision because their eyes don’t work together, then the brain is the real reason for the double vision. If we teach the brain how to use the eyes together, then the double vision will disappear.

The brain is very smart; it learns new skills every day. When we learn to play an instrument, ride a bike, or tie our shoes, our brains can change to learn new skills. In the same way, the brain can learn to use the eyes as a team. This learning process is called vision therapy. Studies have shown that vision therapy the most effective treatment for convergence insufficiency.1 

If you or your child has double vision when reading, seek care from an optometrist who specializes in vision therapy. 

References: 

1. CITT-ART Investigator Group. Treatment of Symptomatic Convergence Insufficiency in Children Enrolled in the Convergence Insufficiency Treatment Trial-Attention & Reading Trial: A Randomized Clinical Trial. Optom Vis Sci. 2019 Nov;96(11):825-835. doi: 10.1097/OPX.0000000000001443. PMID: 31651593; PMCID: PMC6855327.