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单词 nearsightedness
释义

nearsightedness


near·sight·ed·ness

N0041550 (nîr′sī′tĭd-nĭs)n. See myopia.
nearsightednesstop: A normal eye focuses light on the retina.bottom: An elongated eyeball causes light to focus in front of the retina.

near·sight·ed·ness

(nîr′sī′tĭd-nĭs) The ability to see objects at close range better than distant objects. Nearsightedness is caused by the eye focusing light in front of the retina instead of directly on it, usually as a result of an elongated eyeball or a misshapen cornea. Also called myopia. Compare farsightedness.
Thesaurus
Noun1.nearsightedness - (ophthalmology) eyesight abnormality resulting from the eye's faulty refractive abilitynearsightedness - (ophthalmology) eyesight abnormality resulting from the eye's faulty refractive ability; distant objects appear blurredmyopia, shortsightednessophthalmology - the branch of medicine concerned with the eye and its diseasesametropia - (ophthalmology) faulty refraction of light rays in the eye as in astigmatism or myopia
Translations
Kurzsichtigkeit

nearsightedness


nearsightedness

or

myopia,

defect of vision in which far objects appear blurred but near objects are seen clearly. Because the eyeball is too long or the refractive power of the eye's lens is too strong, the image is focused in front of the retina rather than upon it. Corrective eyeglasseseyeglasses
or spectacles,
instrument or device for aiding and correcting defective sight. Eyeglasses usually consist of a pair of lenses mounted in a frame to hold them in position before the eyes.
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 with concave lenseslens,
device for forming an image of an object by the refraction of light. In its simplest form it is a disk of transparent substance, commonly glass, with its two surfaces curved or with one surface plane and the other curved.
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 compensate for the refractive error and help to focus the image on the retina. Hard corneal contact lenses or soft hydrophilic contact lenses are another option, usually offering better acuity and peripheral vision than do eyeglasses. (Contact lenses may be troublesome for people who tend to get eye infections or have hand tremors, however.) Nearsightedness can also be corrected by using laser cornea surgery and a device called a microkeratome to flatten the eye, or by surgically implanting a corrective lens behind the iris.

nearsightedness

[′nir¦sīd·əd·nəs] (medicine) myopia

nearsightedness


myopia

 (M) [mi-o´pe-ah] a defect of vision" >vision consisting of 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, so that vision for near objects is better than for far. This results from the eyeball being too long from front to back. Called also nearsightedness. adj., adj myop´ic. 
Myopia generally appears before the age of 8, often becoming gradually worse until about the age of 20, when it ceases to change much. In later years the nearsighted person may find he or she can read comfortably without glasses. In children the most frequent symptoms of myopia are attempts to brush away blurriness, frequent rubbing of the eyes, and squinting at distant objects. Myopia can almost always be corrected with eyeglasses or contact lenses. Surgical procedures to correct it include keratotomy" >radial keratotomy, keratectomy" >photorefractive keratectomy, and lasik.Refraction and correction in myopia. From Ignatavicius and Workman, 2000.
curvature myopia myopia due to changes in curvature of the refracting surfaces of the eye, especially of the cornea.index myopia myopia due to abnormal refractivity of the media of the eye.malignant myopia (pernicious myopia) progressive myopia with disease of the choroid, leading to retinal detachment and blindness.progressive myopia myopia that continues to increase in adult life.

my·o·pi·a (M),

(mī-ō'pē-ă), That optic condition in which only rays from a finite distance from the eye focus on the retina. Synonym(s): near sight, nearsightedness, short sight, shortsightedness [G. fr. myo, to shut, + ōps, eye]

nearsightedness

(nîr′sī′tĭd-nĭs)n. See myopia.

nearsightedness

Myopia, see there.

my·o·pi·a

(mī-ō'pē-ă) That optic condition in which parallel light rays are brought by the ocular media to focus in front of the retina.
Synonym(s): nearsightedness, shortsightedness.
[G. fr. myo,to shut, + ōps, eye]

Nearsightedness

A condition in which one or both eyes cannot focus normally, causing objects at a distance to appear blurred and indistinct. Also called myopia.Mentioned in: Laser Surgery

myopia (M)

Refractive condition of the eye in which the images of distant objects are focused in front of the retina when the accommodation is relaxed. Thus distance vision is blurred. In myopia the point conjugate with the retina, that is the far point of the eye, is located at some finite point in front of the eye (Fig. M16). The percentage of myopes in Caucasian populations is about 24-28%, it is much higher among Chinese (70-80%). Syn. nearsight; short sight. See gene-environment interaction; photorefractive keratectomy; orthokeratology; pseudomyopia; lattice degeneration of the retina; Marfan's syndrome; use-abuse theory.
acquired myopia Myopia appearing after infancy, or in adulthood. Almost all myopias are acquired. Those myopias developing in the late teens and adulthood are usually referred to as late-onset myopia (or adult-onset myopia), whereas those occurring earlier are often referred to as early-onset myopia (or juvenile-onset myopia).
myopia control Term used to encompass the various methods aimed at slowing or arresting the progression of myopia. They include bifocals, contact lenses, pharmaceutical agents, incorrect single vision lenses (undercorrection, overcorrection), vision therapy and feedback strategies. None has yet been found to be reliably effective.
degenerative myopia See pathological myopia.
early-onset myopia See acquired myopia.
empty-field myopia See space myopia.
false myopia See spasm of accommodation.
form-deprivation myopia Myopia developing in children when the retina is stimulated by a blurred image during the critical period of development. It may occur as a result of a pathological condition, such as cataract, vitreous haemorrhage, ptosis, eyelid closure, or in inordinately long occlusion therapeutic sessions. See critical period; occlusion therapy.
high myopia Myopias above 6.0 D or more are usually considered as high myopias. See open-angle glaucoma; high index lens; pathological myopia.
hypertonic myopia See spasm of accommodation.
index myopia See lenticular myopia.
instrument myopia A temporary increase in accommodation induced by looking through an optical instrument. See resting state of accommodation.
juvenile-onset myopia; late-onset myopia See acquired myopia.
lenticular myopia Myopia attributed to an increase in the index of refraction of the lens. As a result there is an increase in refractive power. Such a change usually accompanies the development of some cataracts. This type of myopia may also accompany or follow an increase in blood sugar level, in which case it is usually of a transient nature, i.e. the power of the crystalline lens diminishes after the blood sugar level returns to normal. Syn. index myopia. See nuclear cataract; diabetes; micro-spherophakia.
low myopia Myopias of 3.0 D or less are usually considered as low myopias.
malignant myopia See pathological myopia.
medium myopia Myopias between 3.0 and 6.0 D are usually considered as medium myopias.
night myopia An increase in ocular refraction (essentially accommodation) occurring at low levels of illumination. See resting state of accommodation.
pathological myopia Myopia attributed to retinal and choroidal degeneration resulting from excessive elongation of the eye. The myopia usually exceeds 8-10 D, tends to increase rapidly during adolescence and continues to increase during adulthood. Visual acuity is usually subnormal after correction. Pathological myopia is a potential cause of blindness. Syn. degenerative myopia; malignant myopia; progressive myopia. See choroideremia; myopic crescent; macular hole; retinal detachment; sclerochoroiditis; Fuchs' spot; anterior staphyloma; vitreous detachment.
physiological myopia This is the most common type of myopia. It is believed that high myopia is due mainly to genetic factors whereas low myopia is more likely due to environmental influences. It occurs because of a failure in correlation of the refractive power of lens and cornea, and the length of the eye. Thus, the power of the eye is too great for its length. Unlike pathological myopia, this myopia usually stabilizes when the growth process has been completed. It is associated with normal visual acuity after correction. Syn. simple myopia; typical myopia.
progressive myopia See pathological myopia.
senile lenticular myopia See second sight.
simple myopia See physiological myopia.
space myopia An increase in accommodation occurring when viewing a field without any stimuli to accommodation as, for example, a clear sky. Syn. empty-field myopia. See resting state of accommodation.
spurious myopia See spasm of accommodation.
typical myopia See physiological myopia.enlarge picture" >Fig. M16 A myopic eye looking at a distant axial pointenlarge pictureFig. M16 A myopic eye looking at a distant axial point
Table M10 Approximate relationship between uncorrected myopia and visual acuity
Snellen visual acuity
myopia(m)(ft)
−10.0 D6/60020/2000
−6.00 D6/23220/775
−5.00 D6/17050/565
−4.00 D6/12620/420
−3.00 D6/8520/285
−2.50 D6/6820/225
−2.00 D6/5020/165
−1.50 D6/3320/110
−1.00 D6/2020/65
−0.50 D6/920/30

Table M11 Common ocular and systemic diseases with myopia as an associated sign
Marfan's syndromeretinopathy of prematurity
Ehlers-Danlos syndromeStargardt's disease
Down's syndromehomocystinuria
Cornelia de Lange syndromechoroideraemia
Weil-Marchesani syndromegyrate atrophy
Laurence-Moon-Bardet- Biedl syndromerod monochromat
Riley-Day syndromeectopia lentis
Turner's syndromeFabry's disease
congenital stationary night blindness
Stickler's syndromeWagner's syndrome
pigment dispersion syndrome

my·o·pi·a

(mī-ō'pē-ă) The optic condition in which parallel light rays are brought by the ocular media to focus in front of the retina.
Synonym(s): nearsightedness, shortsightedness.
[G. fr. myo, to shut, + ōps, eye]

Patient discussion about nearsightedness

Q. Is there a laser vision correction operation that will correct both near and farsightedness? My optometrist said that typical laservision would require that I wear glasses for reading since it only corrects farsightedness. I'm leery of the technique of doing only one eye for distance and leaving the other "as is" for reading. I seem to recall a brief news report of some new laser vision technique that corrects both near- and farsightedness. Is that true or were they referring to the "one eye for closeup and one eye for distance" type of correction that I'm skeptical about? Thanks!!A. my mother-in-law had that done about a yeara ago,for both near and far,they make them the oppisite,i had my near sightness fixed two years ago and i love it should of done it sooner.....

More discussions about nearsightedness

nearsightedness


  • noun

Synonyms for nearsightedness

noun (ophthalmology) eyesight abnormality resulting from the eye's faulty refractive ability

Synonyms

  • myopia
  • shortsightedness

Related Words

  • ophthalmology
  • ametropia
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更新时间:2024/12/22 14:12:17