Difference between revisions of "Hyperopia" - New World Encyclopedia
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| − | ''' | + | '''Hyperopia''' or '''hypermetropia''', is most commonly known as '''farsightedness''' or '''longsightedness,''' where objects are more visible at a further distance. Hyperopia occurs when light rays enter the eye and reach behind the [[retina]] and create a blurred object, instead of hitting directly on the retina to create a focused object. This defect can be attributed to the length of the [[eye]], if it is too short, or the roundness of the [[Lens (anatomy)|lens]], if it is not round enough, both causing the inability to [[Focus (optics)|focus]] on near objects. An extreme case of this defect of [[visual system|vision]] is the incapability to focus on objects at any [[distance]]. As an object moves towards the eye, the eye must increase its power to keep the image on the [[retina]]. If the power of the cornea and lens is insufficient, the image will appear blurred. |
[[Image:Hypermetropia.svg|thumb|250 px|right|Hyperopia, and restoring of vision with convex lens]] | [[Image:Hypermetropia.svg|thumb|250 px|right|Hyperopia, and restoring of vision with convex lens]] | ||
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People with hyperopia can experience [[defocus aberration|blurred vision]], [[asthenopia]], [[accommodation (eye)|accommodative dysfunction]], [[binocular vision|binocular dysfunction]], [[amblyopia]], and [[strabismus]].<ref name="AOA Hyperopia">American Optometric Association. ''[http://www.aoa.org/documents/CPG-16.pdf Optometric Clinical Practice Guideline: Care of the patient with hyperopia.]'' 1997.</ref> | People with hyperopia can experience [[defocus aberration|blurred vision]], [[asthenopia]], [[accommodation (eye)|accommodative dysfunction]], [[binocular vision|binocular dysfunction]], [[amblyopia]], and [[strabismus]].<ref name="AOA Hyperopia">American Optometric Association. ''[http://www.aoa.org/documents/CPG-16.pdf Optometric Clinical Practice Guideline: Care of the patient with hyperopia.]'' 1997.</ref> | ||
Revision as of 21:12, 6 October 2007
| [[Image:{{{Image}}}|190px|center|]] | |
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| ICD-10 | H52.0 |
| ICD-O: | {{{ICDO}}} |
| ICD-9 | 367.0 |
| OMIM | {{{OMIM}}} |
| MedlinePlus | {{{MedlinePlus}}} |
| eMedicine | {{{eMedicineSubj}}}/{{{eMedicineTopic}}} |
| DiseasesDB | {{{DiseasesDB}}} |
Hyperopia or hypermetropia, is most commonly known as farsightedness or longsightedness, where objects are more visible at a further distance. Hyperopia occurs when light rays enter the eye and reach behind the retina and create a blurred object, instead of hitting directly on the retina to create a focused object. This defect can be attributed to the length of the eye, if it is too short, or the roundness of the lens, if it is not round enough, both causing the inability to focus on near objects. An extreme case of this defect of vision is the incapability to focus on objects at any distance. As an object moves towards the eye, the eye must increase its power to keep the image on the retina. If the power of the cornea and lens is insufficient, the image will appear blurred.
People with hyperopia can experience blurred vision, asthenopia, accommodative dysfunction, binocular dysfunction, amblyopia, and strabismus.[1]
Hyperopia is often confused with presbyopia [2][3], another condition that frequently causes blurry near vision. [4] Presbyopes who report good far vision typically experience blurry near vision because of a reduced accommodative amplitude brought about by natural aging changes with the crystalline lens.[4] It is also sometimes referred to as farsightedness, since in otherwise normally-sighted persons it makes it more difficult to focus on near objects than on far objects.[5]
Classification of hyperopia
Hyperopia is typically classified according to clinical appearance, its severity, or how it relates to the eye's accommodative status.[1]
Classification by clinical appearance
- Simple hyperopia
- Pathological hyperopia
- Functional hyperopia
It also occurs when light entering the eye focuses behind the retina.
Diagnosis
Visual acuity is affected according to the amount of hyperopia, as well as the patient's age, visual demands, and accommodative ability.[1]
Treatment
Various eye care professionals, including ophthalmologists, optometrists, orthoptists, and opticians, are involved in the treatment and management of hyperopia. At the conclusion of an eye examination, an eye doctor may provide the patient with an eyeglass prescription for corrective lenses.
Minor amounts of hyperopia are sometimes left uncorrected, however, larger amounts may be corrected with convex lenses in eyeglasses or contact lenses. Convex lenses have a positive dioptric value, which causes the light to focus closer than its normal range.
Hyperopia is sometimes correctable with various refractive surgery procedures.
Notes
- ↑ 1.0 1.1 1.2 American Optometric Association. Optometric Clinical Practice Guideline: Care of the patient with hyperopia. 1997.
- ↑ "Eye Health: Presbyopia and Your Eyes." WebMD.com. October, 2005. Accessed September 21, 2006.
- ↑ Chou B. "Refractive Error and Presbyopia." Refractive Source.com Accessed September 20, 2006.
- ↑ 4.0 4.1 American Optometric Association. Optometric Clinical Practice Guideline: Care of the patient with presbyopia. 1998.
- ↑ Kazuo Tsubota, Brian S. Boxer Wacher, Dimitri T. Azar, and Douglas D. Koch, editors, , Hyperopia and Presbyopia, New York: Marcel Decker, 2003
External links
- pupilEyes - Learn how Hyperopia happens
- DocShop.com - Hyperopia Treatments
- Scottish Sensory Centre - Medical Info on Hypermetropia
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