Most people don’t necessarily know these terms but are familiar with the layman’s terms: crossed & wandering eyes or lazy eyes.
Crossed or wandering eyes (eye turn in or out) can happen in one eye or both eyes. The eye turn can be intermittent or all the time. Eye turns can also be worse when the person looks in the distance or at something up close.
A lazy eye is often when the brain doesn’t learn how to see 20/20 with an eye. Sometimes people refer to an eye that floats as a lazy eye as well. If the brain doesn’t point both eyes at the same place in space 1 of 2 things will happen:
- the person will see double OR
- the person will have to actively ignore one of the eyes to prevent double vision
Double vision is confusing to the brain so the brain will learn to ignore or “suppress” one of the eyes. When the brain ignores one of the eyes it prevents the brain from developing the proper cells in the brain to see clearly and process visual information accurately with that eye.
Studies have shown that an eye turn or lazy eye reduces how much and how quickly visual information can be processed. This leads to people who are slower at reading, test taking, and other tasks.
A common misconception with an eye turn is that a muscle is too weak. This is false! The muscles that control the eyes are significantly stronger than necessary. Rather the brain has not developed the proper neuro-pathways to control the muscle. Sometimes the neurological system purposely turns an eye because it is too much work to make the eyes work together and other times the pathways to make the eyes coordinate have not been developed so the eye turns.
Treatment
Surgical treatment is often what is first thought of for patients with an eye turn. However, surgical success is actually very low if you look at the studies. Surgery is simply a cosmetic fix and doesn’t develop the brain’s ability to use the two eyes together. It is common that a patient will have “straight eyes” after surgery, but because the brain doesn’t know how to use the two eyes together the eye will turn again. Patients often need multiple surgeries and will still not have learned how to use the eyes together to see depth. Surgery to “straighten” an eye requires cutting at least one muscle. Every time a muscle is cut, the nerves that control that muscle and sense what the muscle is doing are also damaged. This makes it even harder to control that muscle.
Vision therapy is a becoming a better-known treatment that is very successful. Vision therapy is specialized procedures that use feedback to help a person know how the brain is using the two eyes. A trained vision therapist then guides a patient to change how vision is used. Some patients have developed some ability to use both eyes together and other patients have not developed any ability for the brain to put the images from the two eyes together. A comprehensive evaluation with Dr. Bolin will determine a baseline of depth perception. Dr. Bolin will then be able to determine what likely outcomes are for therapy and approximately how much therapy will be needed. Patients with eye turns often need 1-2 years of vision therapy and possibly more depending on how the brain and visual system respond.
No Patching!
Previously patching was the gold standard treatment for patients with an eye that doesn’t see 20/20. The idea of forcing the visual system to use an eye more to develop vision can work. HOWEVER, there are some problems that prevent patching from being successful:
- The patient still sees better with the “good” eye so as soon as the “good” eye is uncovered, the brain goes back to using the “good” eye and turning off the “bad” eye.
- It is very hard to get patients to wear a patch, especially for enough time for the treatment to be effective.
- Binocularity, or eye teaming, is what maintains any improvements in visual acuity and what really helps people function better in daily life. Patching shuts down the eye teaming system reducing eye teaming skills and signaling to the brain that it is better to use one eye rather than both eyes.
- Commonly, the part of the retina a patient uses as the center is not assessed. Patching can then embed an off-center point and reduce chances of improving vision.
If not patching, do we do?
Vision therapy is specialized therapeutic procedures that develop areas of the brain for BOTH eye teaming and the poorer eye. The procedures are designed to:
- develop eye teaming skills
- maximize and equalize (as much as possible) the function of the two eyes
- reduce how much the brain ignores the poorer seeing eye
Some of the activities will involve specialized patching that involves eye hand coordination or a lens that blocks some, but not all information and light to the better seeing eye. This allows the brain to develop use of the poorer seeing eye while using both eyes simultaneously.
But I was told we can’t do anything after 8 years old….
This is an out-of-date theory that is based on the “critical period”. It was previously thought that after 8 years old the brain is no longer neuroplastic (able to change and develop new pathways). However, we all know that you can learn new skills at any age. There are phases of life that changes in the brain happen faster making progress easier and less energy intensive. Younger children have also not embedded poor compensation mechanisms. With all that in mind, even adults can improve clarity of vision. A comprehensive binocular evaluation with Dr. Bolin is a great starting place to determine what the potential outcomes of therapy could be.
