hyperopia

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Related to Far sighted: astigmatism

Hyperopia

 

Definition

Hyperopia (farsightedness) is the condition of the eye where incoming rays of light reach the retina before they converge into a focused image.

Description

When light goes through transparent but dense material like the materials of the eye's lens system (the lens and cornea), its velocity decreases. If the surface of the dense material is not perpendicular to the incoming light, as is the case with the curved surfaces on lenses and corneas, the direction of the light changes. The greater the curvature of the lens system, the greater the change in the direction of the light.
When parallel light rays from an object go through the lens system of the eye, they are bent so they converge at a point some distance behind the lens. With perfect vision this point of convergence, where the light rays are focused, is on the retina. This happens when the cumulative curvature of the lens plus cornea and the distance from the lens to the retina are just right for each other. The condition where the point of focus of parallel light rays from an object is behind the retina is called hyperopia. This condition exists when the combined curvature of the lens and cornea is insufficient (e.g., flatter than needed for the length of the eyeball). This condition can be equivalently described by saying hyperopia exists when the eyeball is too short for the curvature of its lens system.
There is a connection between the focusing of the lens of the eye (accommodation) and convergence of the eyes (the two eyes turning in to point at a close object). The best example is during reading. The lens accommodates to make the close-up material clear and the eyes turn in to look at the print and keep it single. Because of this connection between accommodation and convergence, if the lens needs to accommodate to focus for distance (to bring the image back onto the retina) the eyes may appear to turn in even when looking at the distance. This can cause a condition known as accommodative esotropia in children. The eyes turn in and the cause is accommodation because of hyperopia.

Causes and symptoms

Babies are generally born slightly hyperopic. This tends to decrease with age. There is normal variation in eyeball length and curvature of the lens and cornea. Some combinations of these variables give rise to eyes where the cornea is too flat for the distance between the cornea and the retina. If the hyperopia is not too severe the lens may be able to accommodate and bring the image back onto the retina. This would result in clear distance vision, but the constant focusing might result in headaches or eyestrain. If the lens cannot accommodate for the full amount of the hyperopia the distance image would be blurry.
If the eyes are focusing for distance and now the person is looking at a near object, the eyes need to accommodate further. This may result in blurry near objects or headaches during near work.
Hyperopia, or farsightedness, is a condition of the eye where incoming rays of light impinge on the retina before converging into a focused image, resulting in difficulty seeing nearby objects clearly.
Hyperopia, or farsightedness, is a condition of the eye where incoming rays of light impinge on the retina before converging into a focused image, resulting in difficulty seeing nearby objects clearly.
(Illustration by Electronic Illustrators Group.)
Depending upon the amount of hyperopia, symptoms can range from none to clear distance vision but blurry near vision, to blurry distance and near vision. Headaches and eyestrain may also occur, particularly when doing near tasks. An eye turned in (esotropia) may be a result of hyperopia, particularly in children. However, because a turned eye may be a result of more serious causes it is very important to have it checked out.

Diagnosis

Because it is possible to have good visual acuity with some degree of hyperopia it is important to relax accommodation before the eye exam. This is done with the use of eyedrops and is called a cycloplegic exam or cycloplegic refraction. The drops relax the accommodation (thus making reading blurry until the drops wear off). Patients will usually be asked to have someone drive them home because of the blurriness. The doctor can then determine the patient's visual status with a hand-held instrument called a retinoscope and/or have the patient read from an eye chart while placing different lenses in front of the patient's eyes. Refractive error is measured in units called diopters (D).

Treatment

The usual treatment for hyperopia is corrective lenses (spectacles or contact lenses).

Key terms

Cornea — The clear, dome-shaped outer covering of the front of the eye. It lies in front of the iris and pupil.
Iris — The colored ring just behind the cornea and in front of the lens that controls the amount of light sent to the retina.
Pupil — The black hole in the center of the iris. Light enters here on the way to the lens and retina.
Refraction — Method of determining the optical status of the eyes. Lenses are placed before the patient's eyes while reading from an eye chart. The result is the eyeglass or contact lens prescription.
Retina — The inner, light-sensitive layer of the eye containing rods and cones; transforms the image it receives into electrical messages sent to the brain via the optic nerve.
Different surgical methods to correct hyperopia are under investigation. One approach is to implant corrective contact lenses behind the patient's iris. The first experimental implantable contact lenses were implanted in 1997. Another approach is to surgically increase the curvature of the eye's existing cornea or lens. Although there have been many reports of success using different kinds of lasers to increase corneal curvature, as of 1998 there are still problems with stability and predictability. The introduction of light-activated biologic tissue glue in 1997 holds promise for improvements in those areas.

Prognosis

The prognosis for fully corrected vision is excellent for patients with low to moderate amounts of hyperopia. Patients with very high hyperopia (+10.00D or more) may not achieve full correction. Moreover, surgery to correct hyperopia will probably be perfected and approved in the near future.
Hyperopia increases the chances of chronic glaucoma, but vision loss from glaucoma is preventable.

Prevention

Hyperopia is usually present at birth, and there is no known way to prevent it.

Resources

Organizations

American Academy of Ophthalmology. 655 Beach Street, PO Box 7424, San Francisco, CA 94120-7424. http://www.eyenet.org.
American Optometric Association. 243 North Lindbergh Blvd., St. Louis, MO 63141. (314) 991-4100. http://www.aoanet.org.

Other

Edmiston, Dave. "Hyperopia." Lasikpatient.org. 〈http://www.lasikpatient.org〉.

hyperopia

 [hi″per-o´pe-ah]
a defect of vision in which parallel light rays reaching the eye come to focus behind the retina, vision being better for distant objects than for near. Called also farsightedness.

Most children are born with some degree of farsightedness. As the child grows this decreases and usually disappears by the age of 8 years. If the child is excessively farsighted, however, the constant effort to focus may cause headaches and fatigue. Eyeglasses used to correct hyperopia are convex; that is, they bend the light rays toward the center, helping the lens of the eye to focus them on the retina.
Refraction and correction in hyperopia. From Ignatavicius and Workman, 2002.

hy·per·o·pi·a (H),

(hī'pĕr-ō'pē-ă),
Longsightedness; that optic condition in which only convergent rays can be brought to focus on the retina.
[hyper- + G. ōps, eye]

hyperopia

/hy·per·opia/ (hi″per-o´pe-ah) farsightedness; a visual defect in which parallel light rays reaching the eye come to a focus behind the retina, vision being better for far objects than for near. Symbol H.hypero´pic
Hyperopia.

absolute hyperopia  that which cannot be corrected by accommodation.
axial hyperopia  that due to shortness of the anteroposterior diameter of the eye.
facultative hyperopia  that which can be entirely corrected by accommodation.
latent hyperopia  that degree of the total hyperopia corrected by the physiologic tone of the ciliary muscle, revealed by cycloplegic examination.
manifest hyperopia  that degree of the total hyperopia not corrected by the physiologic tone of the ciliary muscle, revealed by cycloplegic examination.
relative hyperopia  facultative h.
total hyperopia  manifest and latent hyperopia combined.

hyperopia

(hī′pə-rō′pē-ə)
n.
An abnormal condition of the eye in which vision is better for distant objects than for near objects. It results from the eyeball being too short from front to back, causing images to be focused behind the retina. Also called farsightedness, hypermetropia.

hy′per·ope′ (hī′pə-rōp′) n.
hy′per·o′pic (-ō′pĭk, -ŏp′ĭk) adj.

hyperopia (h)

[-ō′pē·ə]
Etymology: Gk, hyper + ops, eye
farsightedness, or an inability of the eye to focus on nearby objects. It results from an error of refraction in which rays of light entering the eye are brought into focus behind the retina. Also called farsightedness, hypermetropia, hypermetropy. Compare myopia.
enlarge picture
Hyperopia

hyperopia

Farsightedness Ophthalmology A refractive error in which the cornea and/or lens focus images behind the retina, resulting in ↓ visual acuity for near objects, correctable with glasses or contact lenses. Cf Myopia.

hy·per·o·pi·a

(H) (hī'pĕr-ō'pē-ă)
An ocular condition in which only convergent rays can be brought to focus on the retina.
Synonym(s): farsightedness, hypermetropia.
[hyper- + G. ōps, eye]

hyperopia

or

hypermetropia

or

longsightedness

an inability to see nearby objects clearly, due to their image being focused behind the retina because the eye lens power is insufficient for the size of eye. Compare MYOPIA.

hyperopia (H)

Refractive condition of the eye in which distant objects are focused behind the retina when the accommodation is relaxed. Thus, vision is blurred. In hyperopia, the point conjugate with the retina, that is the far point of the eye, is located behind the eye (Fig. H6). At birth the mean refractive error is a hyperopia of about +2.00 D. As the child grows into adolescence the average refraction tends towards emmetropia. The percentage of people with hyperopia increases beyond the age of 40. Syn. far sight; long sight; hypermetropia. See choroidal folds; cornea plana; angle-closure glaucoma; ocular headache; luxation of the lens; pseudopapilloedema; sclerocornea; plus 1.00 D blur test.
absolute hyperopia That hyperopia which cannot be compensated for by accommodation.
acquired hyperopia Hyperopia resulting from changes in the refractive indices of the media due to either age or disease, or to surgery.
facultative hyperopia That portion of hyperopia which can be compensated for by accommodation.
latent hyperopia That portion of total hyperopia which is compensated for by the tonus of the ciliary muscle. It can be revealed wholly or partially by the use of a cycloplegic.
manifest hyperopia That portion of total hyperopia which can be determined by the strongest convex lens in a subjective routine examination while retaining the best visual acuity.
simple hyperopia Hyperopia uncomplicated by disease, trauma or astigmatism.
total hyperopia The sum of the latent and manifest hyperopia.
Fig. H6 A hyperopic eye looking at a distant axial pointenlarge picture
Fig. H6 A hyperopic eye looking at a distant axial point

Table H1 Approximate relationship between uncorrected absolute hyperopia and visual acuity
Snellen visual acuity
hyperopia(m)(ft)
+4.5D6/12020/400
+3.5D6/9020/300
+2.5D6/6020/200
+2.0D6/3620/120
+1.5D6/2420/80
+1.0D6/1820/60
+0.75D6/1220/40
+0.50D6/920/30

Table H2 Common ocular and systemic diseases with hyperopia as an associated sign
cornea plana
microphthalmia
sclerocornea
angle-closure glaucoma
branch retinal vein occlusion (BRVO)
fragile X syndrome
growth hormone deficiency
diabetes type 1
hypertension

hy·per·o·pi·a

(H) (hī'pĕr-ō'pē-ă)
An ocular condition in which only convergent rays can be brought to focus on the retina.
Synonym(s): farsightedness, hypermetropia.
[hyper- + G. ōps, eye]

hyperopia (hī´pərō´pēə),

n a condition in which vision improves for far objects rather than near.

hyperopia

hypermetropia.

Patient discussion about hyperopia

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 hyperopia