NationMaster - Encyclopedia: 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. The International Statistical Classification of Diseases and Related Health Problems (commonly known by the abbreviation ICD) is a detailed description of known diseases and injuries. ... The following codes are used with International Statistical Classification of Diseases and Related Health Problems. ... The International Statistical Classification of Diseases and Related Health Problems (commonly known by the abbreviation ICD) is a detailed description of known diseases and injuries. ... The following is a list of codes for International Statistical Classification of Diseases and Related Health Problems. ... Defect is the n00b of the animating world, everybody knows that he cannot and will not animate. ... The visual system is the part of the nervous system which allows organisms to see. ... gonfly]].]] In most vertebrates and some mollusks, the eye works by allowing light to enter it and project onto a light-sensitive panel of cells known as the retina at the rear of the eye, where the light is detected and converted into electrical signals, which are then transmitted to... Light from a single point of a distant object and light from a single point of a near object being brought to a focus by changing the curvature of the lens. ... The focus or image point is the point where light rays, originating from a point in the object, converge [1]. The principal focus or focal point of a lens or parabolic mirror is the point onto which collimated light parallel to the axis is focused. ... Distance is a numerical description of how far apart things lie. ...

People with hyperopia can experience blurred vision, asthenopia, accommodative dysfunction, binocular dysfunction, amblyopia, and strabismus.^[1] Image File history File links Hypermetropia. ... Image File history File links Hypermetropia. ... In optics, defocus is the one aberration familiar to nearly everyone who has ever needed eyeglasses or used a camera, videocamera, microscope, telescope, or binoculars, as it simply means out of focus. ... Asthenopia is an ophthalmological condition that manifests itself through unspecific symptoms such as fatigue, eye strain, pain in or around the eyes, blurred vision, headache and occasional double vision. ... Light from a single point of a distant object and light from a single point of a near object being brought to a focus by changing the curvature of the lens. ... Binocular vision is vision in which both eyes are used synchronously to produce a single image. ... Amblyopia, or lazy eye, is a disorder of the eye. ... Strabismus prevents bringing the gaze of both eyes to the same point in space Strabismus, also known as heterotropia, squint, crossed eye, wandering eye, or wall eyed, is a disorder in which the eyes do not point in the same direction. ...

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] Presbyopia is the eyes diminished power of accommodation that occurs with aging. ... Amplitude of accommodation (AA) is a measurement of the eyeâ€™s ability to focus clearly on objects at near distances (i. ... The lens or crystalline lens is a component of the eye. ...

Classification of hyperopia

Hyperopia is typically classified according to its clinical appearance, its severity, or how it relates to the eye's accommodative status.^[1] Light from a single point of a distant object and light from a single point of a near object being brought to a focus by changing the curvature of the lens. ...

Classification by clinical appearance

Classification by severity

Hyperopia is often categorized by the amount of refractive error:^[6] Refraction error, also known as refractive error, is an error in the focusing of light by the eye and a frequent reason for reduced visual acuity. ...

A dioptre (also diopter) is a unit of curvature equal to one per metre; that is, inverse metres, or 1/(metres). ...

Classification by accommodative status

Prevalence

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,^[7] and a recent Polish study found that 1 in 5 (21%) students between the age of 6 and 18 was hyperopic.^[8] A recent Australian study found that nearly 4 in 10 (38.4%) children between the ages of 4 and 12 were hyperopic.^[9] A recent Brazilian study, however, found that nearly 7 in 10 (71%) of the students in one city were hyperopic.^[10] A study of Jordanian adults aged 17 to 40 found only 1 in 20 (5.7%) were hyperopic.^[11] 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.^[12]

Treatment

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. An eye care professional is an individual who provides a service related to the eyes or vision. ... Ophthalmology is the branch of medicine which deals with the diseases of the eye and their treatment. ... Optometrists are primary care practitioners for vision and ocular health concerns. ... An optician is an individual who makes and adjusts optical aids. ... Categories: Medicine stubs | Ophthalmology | Medical tests ... An eyeglass prescription is a written order by an ophthalmologist or an optometrist to an optician for eyeglasses. ... A corrective lens is a lens worn on or before the eye, used to treat myopia, hypermetropia, presbyopia and astigmatism. ...

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. A lens. ... Glasses, spectacles, or eyeglasses are frames bearing lenses worn in front of the eyes, sometimes for purely aesthetic reasons but normally for vision correction or eye protection. ... A soft contact lens A contact lens (also known as contact, for short) is a corrective or cosmetic lens placed on the cornea of the eye atop the iris. ... A dioptre, or diopter, is a non-SI unit of measurement of the optical power of a lens or curved mirror, which is equal to the reciprocal of the focal length measured in metres (i. ... Refractive eye surgery is any eye surgery used to improve the refractive state of the eye and decrease dependency on glasses or contact lenses. ...

Notes

^ ^a ^b 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.
^ ^a ^b 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
^ 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.

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