Wikipedia

Farsightedness

"Hyperopia" redirects here. Not to be confused withHyperepia.

Far-sightedness,also known aslong-sightedness,hypermetropia,andhyperopia,is a condition of theeyewhere distant objects are seen clearly but near objects appear blurred. This blur is due to incoming light being focused behind, instead of on, theretinadue to insufficientaccommodationby the lens.[6]Minor hypermetropia in young patients is usually corrected by their accommodation, without any defects in vision.[2]But, due to this accommodative effort for distant vision, people may complain ofeye strainduring prolonged reading.[2][7]If the hypermetropia is high, there will be defective vision for both distance and near.[2]People may also experienceaccommodative dysfunction,binocular dysfunction,amblyopia,andstrabismus.[3]Newborns are almost invariably hypermetropic, but it gradually decreases as the newborn gets older.[6]

Far-sightedness
Other namesHypermetropia, hyperopia, longsightedness, long-sightedness[1]
Far-sightedness without (top) and with lens correction (bottom)
SpecialtyOphthalmology,optometry
SymptomsNear blur, Distance and near blur, Asthenopia[2]
ComplicationsAccommodative dysfunction,binocular dysfunction,amblyopia,strabismus[3]
CausesAxial length of eyeball is too short, lens or cornea is flatter than normal, aphakia[2]
Risk factorsAgeing, hereditary[2]
Diagnostic methodEye exam
Differential diagnosisAmblyopia,retrobulbar optic neuropathy,retinitis pigmentosa sine pigmento[4]
TreatmentEyeglasses,contact lenses,refractive surgeries,IOL implantation[2]
Frequency~7.5% (US)[5]

There are many causes for this condition. It may occur when the axial length of eyeball is too short or if thelensorcorneais flatter than normal.[2]Changes in refractive index of lens, alterations in position of the lens or absence of lens are the other main causes.[2]Risk factors include a family history of the condition,diabetes,certain medications, andtumorsaround the eye.[5][4]It is a type ofrefractive error.[5]Diagnosis is based on aneye exam.[5][8]

Management can occur witheyeglasses,contact lenses,or refractive corneal surgeries.[2]Glasses are easiest while contact lenses can provide a widerfield of vision.[2]Surgery works by changing the shape of the cornea.[5]Far-sightedness primarily affects young children, with rates of 8% at 6 years old and 1% at 15 years old.[9]It then becomes more common again after the age of 40, known aspresbyopia,affecting about half of people.[4]The best treatment option to correct hypermetropia due toaphakiaisIOLimplantation.[2]

Other common types of refractive errors arenear-sightedness,astigmatism,andpresbyopia.[10]

Signs and symptoms

edit

In young patients, mild hypermetropia may not produce any symptoms.[2]The signs and symptoms of far-sightedness includeblurry vision,frontal or fronto temporalheadaches,eye strain,tiredness of eyes etc.[2]The common symptom is eye strain. Difficulty seeing with both eyes (binocular vision) may occur, as well as difficulty with depth perception.[1]The asthenopic symptoms and near blur are usually seen after close work, especially in the evening or night.[6]

Complications

edit

Far-sightedness can have rare complications such asstrabismusandamblyopia.At a young age, severe far-sightedness can cause the child to have double vision as a result of "over-focusing".[11]

Hypermetropic patients with short axial length are at higher risk of developingprimary angle closure glaucoma,so routinegonioscopyand glaucoma evaluation is recommended for all hypermetropic adults.[12]

Causes

edit

Simple hypermetropia, the most common form of hypermetropia, is caused by normal biological variations in the development of eyeball.[2]Aetiologically,causes of hypermetropia can be classified as:

  • Axial: Axial hypermetropia occur when the axial length of eyeball is too short. About 1 mm decrease in axial length cause 3 diopters of hypermetropia.[2]One condition that cause axial hypermetropia is nanophthalmos.[12]
  • Curvatural: Curvatural hypermetropia occur when curvature of lens or cornea is flatter than normal. About 1 mm increase inradius of curvatureresults in 6 diopters of hypermetropia.[2]Cornea is flatter in microcornea and cornea plana.[12]
  • Index: Age related changes in refractive index (cortical sclerosis) can cause hypermetropia. Another cause of index hypermetropia is diabetes.[2]Occasionally, mild hypermetropic shift may be seen in association with cortical or subcapsularcataractalso.[12]
  • Positional: Positional hypermetropia occur due to posterior dislocation of Lens or IOL.[2]It may occur due to trauma.[citation needed]
  • Consecutive: Consecutive hypermetropia occur due to surgical over correction of myopia or surgical under correction in cataract surgery.[2]
  • Functional: Functional hypermetropia results from paralysis of accommodation as seen in internal ophthalmoplegia,CN III palsyetc.[2]
  • Absence of lens: Congenital or acquired aphakia cause high degree hypermetropia.[13]

Far-sightedness is often present from birth, but children have a very flexible eye lens, which helps to compensate.[14]In rare instances, hyperopia can be due todiabetes,as well as problems with theblood vesselsin theretina.[1]

Diagnosis

edit
Far-sighted vision on left, normal vision on right
Human eye cross-section

A diagnosis of far-sightedness is made by utilizing either a retinoscope or an automated refractor-objective refraction; or trial lenses in a trial frame or a phoropter to obtain a subjective examination. Ancillary tests for abnormal structures and physiology can be made via aslit lamptest, which examines the cornea,conjunctiva,anterior chamber, andiris.[15][16]

In severe cases of hyperopia from birth, the brain has difficulty in merging the images that each individual eye sees. This is because the images the brain receives from each eye are always blurred. A child with severe hyperopia can never see objects in detail. If the brain never learns to see objects in detail, then there is a high chance of one eye becoming dominant. The result is that the brain will block the impulses of the non-dominant eye. In contrast, the child withmyopiacan see objects close to the eye in detail and does learn at an early age to see objects in detail.[medical citation needed]

Classification

edit
Choroid folds in high hyperopia (fluorescein angiography)

Hyperopia is typically classified according to clinical appearance, its severity, or how it relates to the eye'saccommodative status.[citation needed]

Clinical classification

edit

There are three clinical categories of hyperopia.[3]

  • Simple hyperopia:Occurs naturally due to biological diversity.
  • Pathological hyperopia:Caused by disease, trauma, or abnormal development.
  • Functional hyperopia:Caused by paralysis that interferes eye's ability to accommodate.

Classification according to severity

edit

There are also three categories severity:[3]

  • Low:Refractive errorless than or equal to +2.00diopters(D).
  • Moderate:Refractive error greater than +2.00 D up to +5.00 D.
  • High:Refractive error greater than +5.00 D.

Components of hypermetropia

edit

Accommodation has significant role in hyperopia. Considering accommodative status, hyperopia can be classified as:[7][2]

  • Total hypermetropia:It is the total amount of hyperopia which is obtained after complete relaxation of accommodation using cycloplegics likeatropine.
  • Latent hyperopia:It is the amount of hyperopia normally corrected by ciliary tone (approximately 1 diopter).
  • Manifest hyperopia:It is the amount of hyperopia not corrected by ciliary tone. Manifest hyperopia is further classified into two, facultative and absolute.
    • Facultative hyperopia:It is the part of hyperopia corrected by patient's accommodation.
    • Absolute hyperopia:It is the residual part of hyperopia which causes blurring of vision for distance.

So, Total hyperopia= latent hyperopia + manifest hyperopia (facultative + absolute)[7]

Treatment

edit

Corrective lenses

edit

The simplest form of treatment for far-sightedness is the use ofcorrective lenses,i.e. eyeglasses or contact lenses.[17][18]Eyeglasses used to correct far-sightedness haveconvex lenses.[19]

Surgery

edit

There are also surgical treatments for far-sightedness:

Laser procedures

  • Photorefractive keratectomy(PRK): This is a refractive technique that is done by removal of a minimal amount of the corneal surface.[19][20]Hyperopic PRK has many complications like regression effect, astigmatism due to epithelial healing, and corneal haze.[21]Post operative epithelial healing time is also more for PRK.[22]
  • Laser assisted in situ keratomileusis(LASIK): Laser eye surgery to reshape the cornea, so that glasses or contact lenses are no longer needed.[20][23]Excimer laser LASIK can correct hypermetropia up to +6 diopters.[21]LASIK is contraindicated in patients withlupusandrheumatoid arthritis.[21]
  • Laser epithelial keratomileusis (LASEK): Resembles PRK, but uses alcohol to loosen the corneal surface.[19]
  • Epi-LASIK:Epi-LASIKis also used to correct hyperopia.[22]In this procedure, use of epikeratome eliminates the use of alcohol.[22]
  • Laser thermal keratoplasty (LTK):Laser thermal keratoplastyis a laser based non-destructive refractive procedure used to correct hyperopia and presbyopia.[22]It uses Thallium-Holmium-Chromium (THC): YAG laser.[22]

IOL implantation

  • Aphakia correction: High degree hypermetropia due to absence of lens (aphakia) is best corrected using intraocular lens implantation.[citation needed]
  • Refractive lens exchange (RLE): A variation ofcataract surgerywhere the naturalcrystalline lensis replaced with an artificialintraocular lens;the difference is the existence of abnormal ocular anatomy which causes a high refractive error.[24]
  • Phakic IOL:Phakic intraocular lensare lenses that implanted inside eye without removing the normal crystalline lens. Phakic IOLs can be used to correct hypermetropia up to +20 diopters.[22]

Non laser procedures

  • Conductive keratoplasty (CK):Conductive keratoplastyis a non laser refractive procedure used to correct presbyopia and low hypermetropia (+0.75D to +3.25D) with or without astigmatism (up to 0.75D).[22][25]It uses radiofrequency energy to heat and shrink corneal collagen tissue. CK is contraindicated in pregnant/breastfeeding women, centralcorneal dystrophiesandscarring,history ofherpetic keratitis,type 1 diabetes etc.[25]
  • Automated lamellar keratoplasty (ALK): Hyperopicautomated lamellar keratoplasty(H-ALK) and Homoplastic ALK are ALK procedures that corrects low to moderate hyperopia.[26]Poor predictability and the risk of complications limits usefulness of these procedures.[26]
  • Keratophakia and epi-keratophakia are another two non laser surgical procedures used to correct hypermetropia.[26]Keratophakia is a surgical technique developed by Barraquer for treating high hypermetropia and aphakia. Poor predictability and induced irregularastigmatismare complications of these procedures.[26]

Etymology

edit

The termhyperopiacomes fromGreekὑπέρhyper"over" and ὤψōps"sight" (GENὠπόςōpos).[27]

References

edit
  1. ^abcLowth, Mary."Long Sight (Hypermetropia)".Patient.Patient Platform Limited.Archivedfrom the original on 2016-03-03.Retrieved2016-02-26.
  2. ^abcdefghijklmnopqrstuvKhurana, AK (September 2008). "Errors of refraction and binocular optical defects".Theory and practice of optics and refraction(2nd ed.). Elsevier. pp. 62–66.ISBN978-81-312-1132-8.
  3. ^abcdMoore, Bruce D.; Augsburger, Arol R.; Ciner, Elise B.; Cockrell, David A.; Fern, Karen D.; Harb, Elise (2008)."Optometric Clinical Practice Guideline: Care of the Patient with Hyperopia"(PDF).American Optometric Association.pp. 2–3, 10–11. Archived fromthe original(PDF)on 2006-07-17.Retrieved2006-06-18.
  4. ^abcKaiser, Peter K.; Friedman, Neil J.; II, Roberto Pineda (2014).The Massachusetts Eye and Ear Infirmary Illustrated Manual of Ophthalmology E-Book.Elsevier Health Sciences. p. 541.ISBN9780323225274.Archivedfrom the original on 2017-09-08.
  5. ^abcde"Facts About Hyperopia".NEI.July 2016. Archived fromthe originalon 8 July 2017.Retrieved11 July2017.
  6. ^abcRamjit, Sihota; Radhika, Tandon (15 July 2015). "Refractive errors of the eye".Parsons' diseases of the eye(22nd ed.). Elsevier.ISBN978-81-312-3818-9.
  7. ^abcPablo, Artal (2017).Handbook of visual optics-Fundamentals and eye optics and.CRC Press.ISBN978-1-4822-3785-6.
  8. ^Eye Examination Guide
  9. ^Castagno, VD; Fassa, AG; Carret, ML; Vilela, MA; Meucci, RD (23 December 2014)."Hyperopia: a meta-analysis of prevalence and a review of associated factors among school-aged children".BMC Ophthalmology.14:163.doi:10.1186/1471-2415-14-163.PMC4391667.PMID25539893.
  10. ^"Facts About Refractive Errors".National Eye Institute.October 2010.Archivedfrom the original on 28 July 2016.Retrieved30 July2016.
  11. ^"Complications of long-sightedness".NHS Choices.National Health Service. 2014-07-09. Archived fromthe originalon 2016-03-05.Retrieved2016-02-26.
  12. ^abcdJohn F., Salmon (2020).Kanski's clinical ophthalmology: a systematic approach(9th ed.). Edinburgh: Elsevier.ISBN978-0-7020-7713-5.OCLC1131846767.
  13. ^Khurana, AK (2015). "Errors of refraction and accommodation".Comprehensive ophthalmology(6th ed.). Jaypee, The Health Sciences Publisher. pp. 37–38.ISBN978-93-86056-59-7.
  14. ^"Normal, near-sightedness, and far-sightedness".MedlinePlus Medical Encyclopedia.Archivedfrom the original on 2016-03-05.Retrieved2016-02-26.
  15. ^"Farsightedness".MedlinePlus Medical Encyclopedia.Archivedfrom the original on 2016-02-24.Retrieved2016-02-26.
  16. ^"Slit-lamp exam".MedlinePlus Medical Encyclopedia.Archivedfrom the original on 2016-03-05.Retrieved2016-02-26.
  17. ^Chou, Roger; Dana, Tracy; Bougatsos, Christina (2011-02-01)."Introduction".Screening for Visual Impairment in Children Ages 1-5 Years: Systematic Review to Update the 2004 U.S. Preventive Services Task Force Recommendation(Report). Evidence Syntheses. Vol. 81. Rockville, MD: Agency for Healthcare Research and Quality.PMID21542544.Archivedfrom the original on 2017-09-08 – via PubMed Health.
  18. ^"Farsightedness (Hyperopia): Treatments".PubMed Health.U. S. National Library of Medicine.Archivedfrom the original on 2017-09-08.Retrieved2016-02-26.
  19. ^abc"Treating long-sightedness".NHS Choices.National Health Service. Archived fromthe originalon 2016-03-05.Retrieved2016-02-26.
  20. ^abSettas, George; Settas, Clare; Minos, Evangelos; Yeung, Ian Yl (2012-01-01)."Photorefractive keratectomy (PRK) versus laser assisted in situ keratomileusis (LASIK) for hyperopia correction".Cochrane Database of Systematic Reviews.6(6): CD007112.doi:10.1002/14651858.CD007112.pub3.ISSN1469-493X.PMC7388917.PMID22696365.
  21. ^abcGulani, Arun C (9 November 2019)."LASIK Hyperopia: Background, History of the Procedure, Problem".
  22. ^abcdefgKhurana, AK (September 2008). "Refractive surgery".Theory and practice of optics and refraction(2nd ed.). Elsevier. pp. 307–348.ISBN978-81-312-1132-8.
  23. ^"Laser Eye Surgery".MedlinePlus.Archivedfrom the original on 2016-03-06.Retrieved2016-02-26.
  24. ^Alió, Jorge L.; Grzybowski, Andrzej; Romaniuk, Dorota (2014-12-10)."Refractive lens exchange in modern practice: when and when not to do it?".Eye and Vision.1:10.doi:10.1186/s40662-014-0010-2.ISSN2326-0254.PMC4655463.PMID26605356.
  25. ^ab"Conductive Keratoplasty".eyewiki.aao.org.
  26. ^abcdRefractive surgery.Azar, Dimitri T. (2nd ed.). Philadelphia: Mosby / Elsevier. 2007.ISBN978-0-323-03599-6.OCLC853286620.{{cite book}}:CS1 maint: others (link)
  27. ^"hyperopia".Online Etymology Dictionary.Douglas Harper.Archivedfrom the original on 2017-09-08.
edit
Scholiahas atopicprofile forFarsightedness.
Retrieved from "https://en.wikipedia.org/w/index.php?title=Farsightedness&oldid=1259902034"