Does My Child Have A Lazy Eye?

• December 8th, 2010
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• Filed under: lazy eye

Sometimes the vision is still not 20/20 even with the correct glasses’ prescription. Does my child have a lazy eye?

That depends on the vision or more correctly, visual acuity, of the eye. A quick explanation of terms may help to make this topic easier to digest.

Amblyopia-decreased vision, usually in one eye, that happens when the eye is not being used by the brain. The eye itself is normal and healthy, with few exceptions.

Strabismus-a general term for eyes that are not straight. One eye can be turned in, out, up, down, or a combination.

Anisometropia-a significant difference in glasses prescription between the two eyes.

“Lazy eye” actually refers to amblyopia, which is the most common cause of decreased vision in children. An eye can be amblyopic due to strabismus, anisometropia or visual deprivation. Unfortunately, in our culture the term lazy eye has become synonymous with strabismus. Lazy eye does not always mean strabismus. Lazy eye always means amblyopia. The sound eye is the eye without amblyopia.

For example, Patient A has strabismus. His left eye is always straight and his right eye is always crossed in. The right eye probably has amblyopia because it is not being used. The left eye is doing all of the work and the brain is forgetting about the right eye. Patient B also has strabismus. She switches eyes. That is, sometimes the left eye crosses, sometimes the right eye crosses. Patient B probably does not have amblyopia (does not have a lazy eye) because both eyes are being used (although not at the same time).

In the case of anisometropia the eye with the stronger prescription will have amblyopia (lazy eye) even if both eyes are perfectly straight! The amblyopic eye will send a blurred image to the brain and the sound eye will send a much clearer one. A blurry image is not very useful and the brain stops using the eye.

Deprivation is caused by anything that blocks the visual axis in an infant or young child. Causes are cataract, severely drooped eyelid, tumor, or a cloudy cornea.

How do we treat lazy eye (amblyopia)?

Simply put, the goal of amblyopia treatment is to make the brain start using the eye. A lot of our brain function works on the “use it or lose it” principle and amblyopia treatment is no exception. Glasses are usually necessary to make a clear image on the retina and may be the only required treatment. The prescription must also be correct. In the majority of cases a cycloplegic refraction (done with dilating drops) must be done to ensure the proper prescription.
Patching is now needed. Wearing a patch over the good eye (while still wearing glasses) for a few hours daily as prescribed will force the brain to use the lazy eye. With time the visual acuity will improve.

Atropine eye drops have been shown to be an effective alternative to patching. This is sometimes referred to as a “liquid patch”. The principle is the same. Atropine is used on the good eye once daily to make the vision blurry at near. When child is playing a handheld game or doing homework he/she will start relying more on the amblyopic eye. Atropine will not work if the visual acuity at the beginning of treatment is not close enough. For example: the right eye sees 20/20 and the left eye sees 20/150. If Atropine brings the right eye to 20/80, the child still will use the right eye predominantly because this eye still sees better.

Amblyopia treatment is more effective in younger children. The visual system is still maturing up until the age of 8-10, though some newer data suggest that amblyopia may be treated in some cases up until the early teenage years. Once visual maturity occurs the eyes and brain are essentially “hard wired”. If the recommended treatment was not followed for many years and a 12 year old has only 20/100 vision, he’s unfortunately stuck with 20/100 vision. Glasses, contacts, or refractive surgery are unlikely to help him see better at that point.

Some children must be followed more closely than others. It is important to keep your child’s appointments with his/her ophthalmologist or optometrist, especially while the visual system is still maturing. Only by working together can we help your child reach his/her full visual potential.

Eric A. Pennock, MD