Amblyopia Signs and Symptoms - Amblyopia generally develops in young children, before age six. Symptoms are not always obvious but may include favoring one eye or a tendency to bump into objects on one side. If a child squints or completely closes one eye to see, he or she may have amblyopia. Other signs include overall poor visual acuity, eyestrain and headaches.
 

Amblyopia in Children - 3 Main Causes

1. Difference in Refractive Error - When there is a marked difference in the refractive state of the two eyes, the condition is called "anisometropia". One eye may be normal and not require a corrective lens but if the other eye has a significant refractive error, amblyopia can develop. This is because the eye that needs a corrective lens will have a blurred image projected to the back of the eye (retina). In turn, the brain tends to ignore information from the blurry eye and rely mainly on the clearer eye. Uncorrected farsighted (hyperopic) refractive errors are most likely to result in amblyopia but very large nearsighted (myopic) refractive errors can sometimes cause amblyopia as well. Without the stimulation provided by a clear image, the area of the brain responsible for processing visual information from the affected eye does not develop normally. If the refractive error is later corrected, the eye may not see normally because the affected cells in the brain are now "hard wired" and may not respond significantly to stimulation. Anisometropic amblyopia is often not detected because the child appears to see normally and parents think there is no reason for the child to see an eye doctor for an eye exam. This condition is also called "refractive" amblyopia. 2. Misaligned Eyes - When a misalignment of the eyes exists such that one eye points  straight ahead and the other eye turns in toward the nose (esotropia) or one eye turns outward (exotropia) the child is child is said to be "strabismic."  When the eyes are not aligned, the brain will receive two very different images from the eyes and to prevent seeing double (diplopia) the brain will suppress one of the images. It's believed that this suppression or turning-off of one eye's input to the brain leads to reduced vision in the suppressed eye. Inward or outward turning of the eye can cause problems but it is an eye that turns in toward the nose that is the most likely to become amblyopic. An inward eye turn can be subtle and hard to detect. 3. Deprivation - The third type of amblyopia is often referred to as deprivational amblyopia. If a child is born with a cataract or cloudy lens, such that one eye receives a clear image and the eye with the cataract receives a blurred image, then the eye with the cataract will become amblyopic. Corneal opacities or a droopy eyelid (ptosis) can also prevent a clear image from reaching the retina and result in deprivational amblyopia.

Amblyopic children can be treated with vision therapy, the correct prescription for nearsightedness or farsightedness or sometimes, surgery. Vision therapy exercises the eyes and helps both eyes work as a team. Vision therapy for someone with amblyopia forces the brain to use the amblyopic eye, thus restoring vision. The eye doctor or vision therapist may place a patch over the stronger eye to force the weaker eye to be used. Patching can continue for weeks or months. If the child has become amblyopic due to a strong uncorrected refractive error or a large difference between the refractive errors of both eyes, amblyopia can be treated with glasses or contact lenses.

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