When babies are born until they are around 7 years old, the brain is developing and improving the visual pathways between the eye and the visual cortex of the brain to give us sharp vision. Children with no abnormalities within the visual system learn to use both eyes together. The brain gets an image from the right eye and the left eye and then fuses the two images into one. This is called binocularity. If for some reason the image from one of the eyes is blurry or distorted, the brain can decide to ‘shut down’ or block the blurry image. This is called suppression and leads to a lazy eye – the correct term for this is amblyopia. If this happens within the critical time that the visual pathways are being developed, the child may never develop good vision in that eye. There are two primary reasons for suppression in children. One is refractive.
In this case, one of the eyes may be much more nearsighted or farsighted than the other. In this case, that eye, which sees a blurry image, doesn’t develop properly. Unfortunately, since the child is seeing okay with the other eye, the parents may not pick up on the fact that there is a problem with an eye and it’s not till the child has a proper eye examination that the problem is recognized. In this case, the suppression will probably have been going on for a long time and treatment may not be as successful. At that time, the optometrist will prescribe glasses to manage the refractive error (nearsightedness or farsightedness) and then try to patch the good eye to force the bad one to improve. If caught early enough, this type of amblyopia benefits best from patching therapy, and vision can be significantly improved. The other reason is due to a turned or crossed eye (strabismus). In this case, because one of the eyes is turned in, or out, or up or down, the child sees two images that are separated from each other – double vision. The brain learns to shut down the image from the turned eye to get a clear picture, and the turned eye becomes lazy (amblyopic).
What does the patching
do? What is involved?
Patching the good eye forces the brain to use the visual signal from the bad eye and improves the connections between the brain and the bad eye. In general, the younger the child is when the problem is picked up and treated, the better the visual outcome.
If your child must wear a patch, the doctor will tell you when and for how long. Make sure you follow the schedule properly. Not wearing the patch for the appropriate time is the main reason this therapy may fail.
Try to prevent your child from removing the patch or looking around it. Wearing a patch can be difficult and uncomfortable, especially for young children. They may be confused or afraid about wearing the patch, and other children may tease them. Children at school can be particularly mean and tease your child. Newer studies have found that patching after school hours is just as successful as full-time patching. If your child is old enough to understand, cover one eye then the other and have them look at something. They will see blurry from the bad eye. Explain to them that the patching is to improve the vision in that eye. The object is to force that eye to work, so have them read, colour, paint, do crafts, etc. It is obviously very important for children to develop equally good vision in both eyes in order to succeed in school. For this reason, it is important for parents to have their child’s eyes examined by an optometrist as early as possible so any potential visual problems can be detected and treated. It is recommended that children have their first eye exam by three years of age.
