"Construction Defects" of the Eye

A visually impaired eye is medically fit but cannot have normal vision due to "construction defects" at birth or in an early developmental phase. There are three different types of "construction defects" or vision impairments:

1) Short-sightedness (Myopia)

This is the most common vision impairment. A short-sighted eye has an elongated eyeball. The entering light rays are compiled before the retina and as such an un-sharp, fuzzy picture is reproduced on the retina itself.

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2) Long-sightedness (Hyperopia)

A shortened eyeball causes entering light rays to be compiled behind the retina. The result: close-up imes are blurred. Seeing is difficult and often results in headaches.

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3) Astigmatism

Astigmatism is caused by a cornea that is not uniformly spherical, but rather one that is warped and curved in different places. As such light rays fall differentially as a bar rather than a point onto the retina. Imes thus appear distorted and out of focus.

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4) Old eye - Presbyopia

Classic presbyopia is not correctable by laser treatment due to a loss of flexibility, caused by ing, in both the lens and the eye's ciliary muscle. The eye loses its ability to focus on different distances. For short-sighted people the possibility exists to rectify this via the mono-vision principle. In this procedure one eye is optimally corrected to take over the long-sighted vision, the other eye is left slightly short-sighted. This eye thus takes over the near-sighted vision. As such, even in later years the menu in a restaurant can be read without glasses. This procedure, however, can somewhat diminish depth of vision.