Hyperopia in Wikipedia
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It uses material from the Wikipedia article "Hyperopia".
(Source - Retrieved 2006-09-07 14:15:35 from http://en.wikipedia.org/wiki/Hyperopia)
Hyperopia, also known as hypermetropia or colloquially as farsightedness or longsightedness, is a defect of vision caused by an imperfection in the eye (often when the eyeball is too short or when the lens cannot become round enough), causing inability to focus on near objects, and in extreme cases causing a sufferer to be unable 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, as in hypermetropia, the image will appear blurred.
Hypermetropia, and restoring of vision with convex lens
People with hyperopia may experience blurred vision, asthenopia, accommodative dysfunction, binocular dysfunction, amblyopia, and strabismus.
Classification of hyperopia
Hyperopia is typically classified according to its clinical appearance, its severity, or how it relates to the eye's accommodative status.
Classification by clinical appearance
- Simple hyperopia
- Pathological hyperopia
- Functional hyperopia
Classification by severity
Hyperopia is often categorized by the amount of refractive error:
- Low hyperopia is a refractive error of +2.00 diopters (D) or less.
- Moderate hyperopia is a refractive error from +2.25 to +5.00 D.
- High hyperopia is a refractive error of +5.25 D or more.
Classification by accommodative status
- Facultative hyperopia
- Absolute hyperopia
- Manifest hyperopia
- Latent hyperopia
An American study published in Archives of Ophthalmology found that more than 1 in 8 (12.8%) children between the ages of 5 and 17 have hyperopia, and a recent Polish study found that 1 in 5 (21%) students between the age of 6 and 18 was hyperopic. A recent Australian study found that nearly 4 in 10 (38.4%) children between the ages of 4 and 12 were hyperopic. A recent Brazilian study, however, found that nearly 7 in 10 (71%) of the students in one city were hyperopic. A study of Jordanian adults aged 17 to 40 found only 1 in 20 (5.7%) were hyperopic. A recent study involving first-year undergraduate students in the United Kingdom found that 18.8% of British whites and 17.3% of British Asians were hyperopic.
Various eye care professionals, including ophthalmologists, optometrists, 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.
- American Optometric Association. Optometric Clinical Practice Guideline: Care of the patient with hyperopia. 1997.
- ^ Augsburger AR. "Hyperopia." In: Amos JF, ed. Diagnosis and management in vision care. Boston: Butterworths, 1987:1010-19.
- ^ Kleinstein RN, Jones LA, Hullett S, Kwon S, Lee RJ, Friedman NE, Manny RE, Mutti DO, Yu JA, Zadnik K; Collaborative Longitudinal Evaluation of Ethnicity and Refractive Error Study Group. "Refractive Error and Ethnicity in Children". Arch Ophthalmol. 2003 Aug;121(8):1141-7. PMID 12912692.
- ^ Czepita D, Goslawski W, Mojsa A. "[Occurrence of hyperopia among students ranging from 6 to 18 years of age]." Klin Oczna. 2005;107(1-3):96-9. PMID 16052814.
- ^ Junghans BM, Crewther SG. "Little evidence for an epidemic of myopia in Australian primary school children over the last 30 years." BMC Ophthalmol. 2005 Feb 11;5(1):1. PMID 15705207
- ^ Garcia CA, Orefice F, Nobre GF, Souza Dde B, Rocha ML, Vianna RN. "[ Prevalence of refractive errors in students in Northeastern Brazil. ]" Arq Bras Oftalmol. 2005 May-Jun;68(3):321-5. Epub 2005 Jul 26. PMID 16059562
- ^ Mallen EA, Gammoh Y, Al-Bdour M, Sayegh FN. "Refractive error and ocular biometry in Jordanian adults." Ophthalmic Physiol Opt. 2005 Jul;25(4):302-9. PMID 15953114.
- ^ Logan NS, Davies LN, Mallen EA, Gilmartin B. "Ametropia and ocular biometry in a U.K. university student population." Optom Vis Sci. 2005 Apr;82(4):261-6. PMID 15829853.
Categories: Eye | Ophthalmology | Vision
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