Emmetropia Health Dictionary

Emmetropia: From 2 Different Sources


The normal condition of the EYE as regards refraction of light rays. When the muscles in the eyeball are completely relaxed, the focusing power is accurately adjusted for parallel rays, so that vision is perfect for distant objects.
Health Source: Medical Dictionary
Author: Health Dictionary
n. the state of refraction of the normal eye, in which parallel light rays are brought to a focus on the retina with the accommodation relaxed. Distant objects are seen clearly without any effort to focus. Compare ametropia; hypermetropia; myopia.
Health Source: Oxford | Concise Colour Medical Dictionary
Author: Jonathan Law, Elizabeth Martin

Ametropia

n. any abnormality of *refraction of the eye, resulting in blurring of the image formed on the retina. See astigmatism; hypermetropia; myopia. Compare emmetropia.... ametropia

Hypermetropia

(long-sightedness) n. the condition in which parallel light rays are brought to a focus behind the retina when the *accommodation is relaxed (see illustration). Moderate degrees of hypermetropia may not cause blurred vision in children and young adults because of their ability to accommodate, but for older people and those with greater degrees of hypermetropia near vision is more blurred than distance vision. Normal vision can be restored by wearing spectacles with convex lenses. Compare emmetropia; myopia.... hypermetropia

Myopia

(short-sightedness) n. the condition in which parallel light rays are brought to a focus in front of the retina (see illustration). Closer objects are clearer as compared to distant objects. Myopia is corrected by wearing spectacles with concave lenses; contact lenses and surgery can also be used to correct myopia (see excimer laser; LASEK; LASIK). Compare emmetropia; hypermetropia. —myopic adj.... myopia



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