Aphakia, Refractive Eye Disorder
The eye normally creates a clear image because the cornea and lens bend (refract) incoming light rays to focus them on the retina. The shape of the cornea is fixed, but the lens changes shape to focus on objects at various distances from the eye. By becoming thicker, the lens allows near objects to be focused; by becoming flatter, the lens allows objects farther away to be focused. A refractive error occurs when the cornea and lens cannot focus the image of an object sharply on the retina.
The absence of a lens (as a result of birth defect, eye injury, or eye surgery for cataract) is called aphakia. This condition can affect one or both eyes. Congenital aphakia is the lack of a lens at birth. True aphakia is extremely rare and usually is associated with severe arrest in ocular development so that severe microphthalmia or congenital cystic eye is the result.
In microphakia the lens is smaller than normal. It may be an isolated lesion or occur as part of a syndrome of multiple ocular anomalies. If not already cataractous at birth, it often will opacify later in life. Accompanying ocular defects usually preclude removal of these lenses for therapeutic purposes.
Aphakia can be corrected using plano bandage contact lenses and hydrogel contact lenses.
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