domingo, 25 de noviembre de 2018

Amblyopia Types

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By Ananya Mandal, MDReviewed by Sally Robertson, B.Sc.

Amblyopia is the medical term for “lazy eye,” which refers to a childhood condition where the vision in one eye fails to develop adequately. This usually affects the child’s ability to see using the weaker eye, meaning they come to rely on their stronger eye.

Some examples of the physical eye problems that can cause a lazy eye to develop include:

A squint or strabismus, where the weaker eye is orientated upwards, outwards, downwards or inwards of the direction the normal eye is facing
One eye may have become cloudy due to the development of a cataract
One eyelid may be drooping and partly covering the eye. This is called ptosis.

Types of amblyopia

There are several forms of amblyopia and all of them cause reduced vision in the affected eye. The three types of amblyopia are described below:

Strabismic amblyopia

In this form of amblyopia, a squint develops due to a mismatch between the muscles that support the position of the eyes. The brain effectively “ignores” the eye that is not straight, while the brain relies on the images generated by the stronger eye. Treatment approaches include eye exercises to try and re-train the child’s weak eye muscles and covering the “good” eye with an eye patch to encourage use of the “bad” eye.

Refractive or anisometropic amblyopia

This refers to when the refractive error is greater in one eye than in the other. The brain “turns off” the more far-sighted eye and relies instead on the eye that provides a clearer picture. However, the weaker eye remains straight, meaning the problem may go unnoticed by parents or a GP. Refractive amblyopia may not be identified until the child has a vision test. This condition can be treated with corrective glasses or contact lenses.

Deprivation or occlusion amblyopia

This refers to when one eye is “deprived” of vision due to the development of a blockage such as a cataract. The ocular media becomes opaque, which prevents visual information from reaching the retina and then the brain. This form of amblyopia can affect one or both eyes and needs to be caught early to prevent the child form developing poor vision.