Akademik

Myopia
Nearsightedness, the ability to see close objects more clearly than distant objects. Myopia can be caused by a longer-than-normal eyeball or by any condition that prevents light rays from focusing on the retina. Most forms of myopia can be managed with corrective lenses. Surgery is available to permanently correct some forms of myopia, although long-term effectiveness and safety has not been fully determined.
* * *
That optical condition in which only rays from a finite distance from the eye focus on the retina. SYN: near sight, nearsightedness, short sight, shortsightedness. [G. fr. myo, to shut, + ops, eye]
- axial m. m. due to elongation of the globe of the eye.
- curvature m. m. due to refractive errors resulting from excessive corneal curvature.
- degenerative m. SYN: pathologic m..
- index m. m. arising from increased refractivity of the lens, as in nuclear sclerosis.
- malignant m. SYN: pathologic m..
- night m. in dark adaptation the eye becomes more sensitive to shorter wavelengths (Purkinje shift), and visual acuity depends on parafoveal blue cones. Shorter wavelengths come into focus in front of the retina, and this chromatic aberration accounts for some of the relative m. that a normal eye experiences at night; much of the remainder is due to an increase in accommodative tone in the dark.
- pathologic m. progressive m. marked by fundus changes, posterior staphyloma, and subnormal corrected acuity. SYN: degenerative m., malignant m..
- prematurity m. m. observed in infants of low birthweight or in association with retrolental fibroplasia.
- senile lenticular m. SYN: second sight.
- simple m. m. arising from failure of correlation of the refractive power of the anterior segment and the length of the eyeball.
- space m. a type of m. arising when no contour is imaged on the retina.
- transient m. m. observed in accommodative spasm secondary to iridocyclitis or ocular contusion.

* * *

my·o·pia mī-'ō-pē-ə n a condition in which the visual images come to a focus in front of the retina of the eye because of defects in the refractive media of the eye or of abnormal length of the eyeball resulting esp. in defective vision of distant objects called also nearsightedness compare ASTIGMATISM (2), EMMETROPIA

* * *

n.
the condition in which parallel light rays are brought to a focus in front of the retina. Distant objects are blurred and cannot be made sharp by accommodation. Myopia is corrected by wearing spectacles with concave lenses and can now be treated by surgery (see excimer laser, intrastromal keratomileusis, LASEK, LASIK, radial keratotomy). Compare emmetropia, hypermetropia.
• myopic adj.

* * *

my·o·pia (M) (mi-oґpe-ə) [Gr. myein to shut + -opia] an error of refraction in which rays of light entering the eye parallel to the optic axis are brought to a focus in front of the retina, as a result of the eyeball being too long from front to back (axial m.) or of an increased strength in refractive power of the media of the eye (index m.) Called also nearsightedness, because the near point is less distant than it is in emmetropia with an equal amplitude of accommodation. myopic adj

Myopia: error of refraction in a myopic eye (A), contrasted with normal refraction in an emmetropic eye (B).


Medical dictionary. 2011.