| 词条 | Astigmatism |
| 释义 |
| name = Astigmatism | image = astigmatism text blur.png | caption = Blur from astigmatic lens at different distances | field = Ophthalmology, optometry | symptoms = Distorted or blurred vision at all distances, eyestrain, headaches[1] | complications = Amblyopia[2] | onset = | duration = | types = | causes = Unclear[3] | risks = | diagnosis = Eye exam[1] | differential = | prevention = | treatment = Glasses, contact lenses, surgery[1] | medication = | prognosis = | frequency = 30 and 60% of adults (Europe, Asia)[6] | deaths = }}Astigmatism is a type of refractive error in which the eye does not focus light evenly on the retina.[1] This results in distorted or blurred vision at all distances.[1] Other symptoms can include eyestrain, headaches, and trouble driving at night.[1] If it occurs early in life it can result in amblyopia.[2] The cause of astigmatism is unclear.[3] It is believed to be partly related to genetic factors.[6] The underlying mechanism involves an irregular curvature of the cornea or abnormalities in the lens of the eye.[1][3] Diagnosis is by an eye exam.[1] Three options exist for the treatment: glasses, contact lenses, and surgery.[1] Glasses are the simplest.[1] Contact lenses can provide a wider field of vision.[1] Refractive surgery permanently changes the shape of the eye.[1] In Europe and Asia astigmatism affects between 30 and 60% of adults.[4] People of all ages can be affected.[1] Astigmatism was first reported by Thomas Young in 1801.[3][5] Signs and symptomsAlthough astigmatism may be asymptomatic, higher degrees of astigmatism may cause symptoms such as blurry vision, double vision, squinting, eye strain, fatigue, or headaches.[6] Some research has pointed to the link between astigmatism and higher prevalence of migraine headaches.[7] Types{{Technical|section|date=October 2017}}Axis of the principal meridian
In with-the-rule astigmatism, the eye has too much "plus" cylinder in the horizontal axis relative to the vertical axis (i.e., the eye is too "steep" along the vertical meridian relative to the horizontal meridian). Vertical beams of light focus in front (anterior) to horizontal beams of light, in the eye. This problem may be corrected using spectacles which have a "minus" cylinder placed on this horizontal axis. The effect of this will be that when a vertical beam of light in the distance travels towards the eye, the "minus" cylinder (which is placed with its axis lying horizontally – in line with the patient's excessively steep horizontal axis/vertical meridian) will cause this vertical beam of light to slightly "diverge", or "spread out vertically", before it reaches the eye. This compensates for the fact that the patient's eye converges light more powerfully in the vertical meridian than the horizontal meridian. Hopefully, after this, the eye will focus all light on the same location at the retina, and the patient's vision will be less blurred.{{mcn|date=August 2017}} In against-the-rule astigmatism, a plus cylinder is added in the horizontal axis (or a minus cylinder in the vertical axis).[9] Axis is always recorded as an angle in degrees, between 0 and 180 degrees in a counter-clockwise direction. Both 0 and 180 degrees lie on a horizontal line at the level of the center of the pupil, and as seen by an observer, 0 lies on the right of both the eyes.{{mcn|date=August 2017}} Irregular astigmatism, which is often associated with prior ocular surgery or trauma, is also a common naturally occurring condition.[10] The two steep hemimeridians of the cornea, 180° apart in regular astigmatism, may be separated by less than 180° in irregular astigmatism (called nonorthogonal irregular astigmatism); and/or the two steep hemimeridians may be asymmetrically steep—that is, one may be significantly steeper than the other (called asymmetric irregular astigmatism). Irregular astigmatism is quantified by a vector calculation called topographic disparity.[11] Focus of the principal meridianWith accommodation relaxed:
Throughout the eyeAstigmatism, whether it is regular or irregular, is caused by some combination of external (corneal surface) and internal (posterior corneal surface, human lens, fluids, retina, and eye-brain interface) optical properties. In some people, the external optics may have the greater influence, and in other people, the internal optics may predominate. Importantly, the axes and magnitudes of external and internal astigmatism do not necessarily coincide, but it is the combination of the two that by definition determines the overall optics of the eye. The overall optics of the eye are typically expressed by a person's refraction; the contribution of the external (anterior corneal) astigmatism is measured through the use of techniques such as keratometry and corneal topography. One method analyzes vectors for planning refractive surgery such that the surgery is apportioned optimally between both the refractive and topographic components.[12][13] DiagnosisA number of tests are used during eye examinations to determine the presence of astigmatism and to quantify its amount and axis. A Snellen chart or other eye charts may initially reveal reduced visual acuity. A keratometer may be used to measure the curvature of the steepest and flattest meridians in the cornea's front surface.[14] Corneal topography may also be used to obtain a more accurate representation of the cornea's shape.[15] An autorefractor or retinoscopy may provide an objective estimate of the eye's refractive error and the use of Jackson cross cylinders in a phoropter or trial frame may be used to subjectively refine those measurements.[16][17][18] An alternative technique with the phoropter requires the use of a "clock dial" or "sunburst" chart to determine the astigmatic axis and power.[19][20] A keratometer may also be used to estimate astigmatism by finding the difference in power between the two primary meridians of the cornea. Javal's rule can then be used to compute the estimate of astigmatism. A method of astigmatism analysis by Alpins may be used to determine both how much surgical change of the cornea is needed and after surgery to determine how close treatment was to the goal.[21] Another rarely used refraction technique involves the use of a stenopaeic slit (a thin slit aperture) where the refraction is determined in specific meridians – this technique is particularly useful in cases where the patient has a high degree of astigmatism or in refracting patients with irregular astigmatism. There are three primary types of astigmatism: myopic astigmatism, hyperopic astigmatism, and mixed astigmatism. TreatmentAstigmatism may be corrected with eyeglasses, contact lenses, or refractive surgery. Various considerations involving eye health, refractive status, and lifestyle determine whether one option may be better than another. In those with keratoconus, certain contact lenses often enable patients to achieve better visual acuity than eyeglasses. Once only available in a rigid, gas-permeable form, toric lenses are now available also as soft lenses. Laser eye surgery (LASIK and PRK) is successful in treating astigmatism.[22] EpidemiologyAccording to an American study nearly three in 10 children (28.4%) between the ages of five and 17 have astigmatism.[23] A recent Brazilian study found that 34% of the students in one city were astigmatic.[24] Regarding the prevalence in adults, a recent study in Bangladesh found that nearly 1 in 3 (32.4%) of those over the age of 30 had astigmatism.[25] A Polish study published in 2005 revealed "with-the-rule astigmatism" may lead to the onset of myopia.[26] A number of studies have found the prevalence of astigmatism increases with age.[27] HistoryAs a student, Thomas Young discovered that he had problems with one eye in 1793.[28] In the following years he did research on his vision problems.[29] He presented his findings in a Bakerian Lecture in 1801.[30] Independent from Young, George Biddell Airy discovered the phenomenon of astigmatism on his own eye.[31] Airy presented his observations on his own eye in February 1825 at the Cambridge Philosophical Society.[32][33] Airy produced lenses to correct his vision problems by 1825,[31][34] while other sources put this into 1827[35] when Airy obtained cylindrical lenses from an optician from Ipswich.[36] The name for the condition was not given by Airy, but from William Whewell.[37][38][39] By the 1860s astigmatism was a well established concept in ophthalmology,[40] and chapters in books described the discovery of astigmatism.[41][42] See also
References1. ^1 2 3 4 5 6 7 8 9 10 11 12 {{cite web|title=Facts About Astigmatism|url=https://nei.nih.gov/health/errors/astigmatism|website=NEI|accessdate=29 September 2016|date=October 2010|deadurl=no|archiveurl=https://web.archive.org/web/20161002081657/https://nei.nih.gov/health/errors/astigmatism|archivedate=2 October 2016|df=dmy-all}} 2. ^1 {{cite journal|last1=Harvey|first1=EM|title=Development and treatment of astigmatism-related amblyopia.|journal=Optometry and Vision Science|date=June 2009|volume=86|issue=6|pages=634–9|pmid=19430327|doi=10.1097/opx.0b013e3181a6165f|pmc=2706277}} 3. ^1 2 3 {{cite journal|last1=Read|first1=SA|last2=Collins|first2=MJ|last3=Carney|first3=LG|title=A review of astigmatism and its possible genesis.|journal=Clinical & Experimental Optometry|date=January 2007|volume=90|issue=1|pages=5–19|pmid=17177660|doi=10.1111/j.1444-0938.2007.00112.x}} 4. ^1 2 {{cite journal|last1=Mozayan|first1=E|last2=Lee|first2=JK|title=Update on astigmatism management.|journal=Current Opinion in Ophthalmology|date=July 2014|volume=25|issue=4|pages=286–90|pmid=24837578|doi=10.1097/icu.0000000000000068}} 5. ^{{Cite news|url=https://www.britannica.com/biography/Thomas-Young|title=Thomas Young {{!}} British physician and physicist|work=Encyclopedia Britannica|access-date=2017-08-28|language=en|deadurl=no|archiveurl=https://web.archive.org/web/20170829001636/https://www.britannica.com/biography/Thomas-Young|archivedate=29 August 2017|df=dmy-all}} 6. ^{{cite web|title=Astigmatism|url=http://www.onhealth.com/astigmatism/article.htm|work=MedicineNet|publisher=OnHealth.com|accessdate=8 September 2013}} 7. ^{{cite journal |doi=10.1097/01.opx.0000200680.95968.3e |title=The Correlation Between Migraine Headache and Refractive Errors |year=2006 |last1=Harle |first1=Deacon E. |last2=Evans |first2=Bruce J. W. |journal=Optometry and Vision Science |volume=83 |issue=2 |pages=82–7 |pmid=16501409}} 8. ^1 2 {{cite book |author1= Gilbert Smolin |author2= Charles Stephen Foster |author3= Dimitri T. Azar |author4= Claes H. Dohlman |title= Smolin and Thoft's The Cornea: Scientific Foundations and Clinical Practice |url= https://books.google.com/books?id=93s6aes5ob0C&pg=PA173|year=2005|publisher=Lippincott Williams & Wilkins|isbn=978-0-7817-4206-1 |pages= 173–}} 9. ^{{cite book|author1=Carlo Cavallotti|author2=Luciano Cerulli|title=Age-Related Changes of the Human Eye|url=https://books.google.com/books?id=JuilJ7R-uqwC&pg=PA49|date=31 May 2008|publisher=Springer Science & Business Media|isbn=978-1-59745-507-7|pages=49–}} 10. ^{{cite journal |pmid=2369353 |year=1990 |last1=Bogan |first1=SJ |last2=Waring Go |first2=3rd |last3=Ibrahim |first3=O |last4=Drews |first4=C |last5=Curtis |first5=L |title=Classification of normal corneal topography based on computer-assisted videokeratography |volume=108 |issue=7 |pages=945–9 |journal=Archives of Ophthalmology |doi=10.1001/archopht.1990.01070090047037}} 11. ^{{cite journal |pmid=9610446 |year=1998 |last1=Alpins |first1=NA |title=Treatment of irregular astigmatism |volume=24 |issue=5 |pages=634–46 |journal=Journal of Cataract and Refractive Surgery |doi=10.1016/s0886-3350(98)80258-7}} 12. ^{{cite journal |pmid=9100110 |year=1997 |last1=Alpins |first1=NA |title=New method of targeting vectors to treat astigmatism |volume=23 |issue=1 |pages=65–75 |journal=Journal of Cataract and Refractive Surgery |doi=10.1016/s0886-3350(97)80153-8}} 13. ^{{cite journal |pmid=9456408 |year=1997 |last1=Alpins |first1=NA |title=Vector analysis of astigmatism changes by flattening, steepening, and torque |volume=23 |issue=10 |pages=1503–14 |journal=Journal of Cataract and Refractive Surgery |doi=10.1016/s0886-3350(97)80021-1}} 14. ^{{cite web|title=Keratometry|url=http://www.stlukeseye.com/eyeq/keratometry.html|work=St. Luke's Cataract & Laser Institute|accessdate=8 September 2013|deadurl=yes|archiveurl=https://web.archive.org/web/20131029195026/http://www.stlukeseye.com/eyeq/keratometry.html|archivedate=29 October 2013|df=dmy-all}} 15. ^{{EMedicine|OPH|711|Corneal Topography and Imaging}} 16. ^{{cite journal |pmid=13900989 |year=1962 |last1=Graff |first1=T |title=Control of the determination of astigmatism with the Jackson cross cylinder |volume=140 |pages=702–8 |journal=Klinische Monatsblätter für Augenheilkunde und für Augenärztliche Fortbildung}} 17. ^{{cite journal |pmid=3808608 |year=1986 |last1=Del Priore |first1=LV |last2=Guyton |first2=DL |title=The Jackson cross cylinder. A reappraisal |volume=93 |issue=11 |pages=1461–5 |journal=Ophthalmology |doi=10.1016/s0161-6420(86)33545-0}} 18. ^{{cite journal |pmid=8320415 |year=1993 |last1=Brookman |first1=KE |title=The Jackson crossed cylinder: Historical perspective |volume=64 |issue=5 |pages=329–31 |journal=Journal of the American Optometric Association}} 19. ^{{cite web|title=Basic Refraction Procedures|url=http://www.quantumoptical.com/CoursePage.asp?id=936|work=Quantum Optical|accessdate=8 September 2013|deadurl=no|archiveurl=https://web.archive.org/web/20131029200102/http://www.quantumoptical.com/CoursePage.asp?id=936|archivedate=29 October 2013|df=dmy-all}}{{MEDRS|date=May 2012}} 20. ^{{cite web|title=Introduction to Refraction|url=http://www.nova.edu/hpd/otm/nbeo/refract1.htm|work=Nova Southeastern University|accessdate=8 September 2013}}{{dead link|date=May 2012}} 21. ^{{cite book|last1=Boyd|first1=Benjamin F.|title=Modern Ophthalmology The Highlights.|date=2011|publisher=Jaypee Brothers Medical Pub|location=Panama|isbn=9789962678168|page=388|url=https://books.google.ca/books?id=ScSRF23P6b4C&pg=PA388|deadurl=no|archiveurl=https://web.archive.org/web/20160115115239/https://books.google.ca/books?id=ScSRF23P6b4C&pg=PA388|archivedate=15 January 2016|df=dmy-all}} 22. ^{{cite book|last=Azar|first=Dimitri T.|title=Refractive surgery|year=2007|publisher=Mosby Elsevier|isbn=9780323035996|edition=2nd}} 23. ^{{cite journal|doi=10.1001/archopht.121.8.1141 |title=Refractive Error and Ethnicity in Children |year=2003|last1=Kleinstein |first1=R. N. |journal=Archives of Ophthalmology |volume=121 |issue=8|pages=1141–7 |pmid=12912692 |last2=Jones |first2=LA |last3=Hullett |first3=S |last4=Kwon|first4=S |last5=Lee |first5=RJ |last6=Friedman |first6=NE |last7=Manny |first7=RE|last8=Mutti |first8=DO |last9=Yu |first9=JA|displayauthors= 3}} 24. ^{{cite journal|doi=10.1590/S0004-27492005000300009 |title=Prevalence of refractive errors in students in Northeastern Brazil |year=2005 |last1=Garcia |first1=Carlos Alexandre de Amorim |last2=Oréfice|first2=Fernando |last3=Nobre |first3=Gabrielle Fernandes Dutra |last4=Souza |first4=Dilene de Brito |last5=Rocha |first5=Marta Liliane Ramalho |last6=Vianna |first6=Raul Navarro Garrido|journal=Arquivos Brasileiros de Oftalmologia |volume=68 |issue=3 |pages=321–5|pmid=16059562}} 25. ^{{cite journal|doi=10.1016/j.ophtha.2003.09.046 |title=Prevalence of refractive error in Bangladeshi adults*1Results of the National Blindness and Low Vision Survey of Bangladesh |year=2004|last1=Bourne |first1=R |journal=Ophthalmology |volume=111 |issue=6 |pages=1150–60|pmid=15177965 |last2=Dineen |first2=BP |last3=Ali |first3=SM |last4=Noorul Huq |first4=DM|last5=Johnson |first5=GJ}} 26. ^{{cite journal |pmid=16052807 |year=2005 |last1=Czepita |first1=D|last2=Filipiak |first2=D |title=The effect of the type of astigmatism on the incidence of myopia |volume=107 |issue=1–3 |pages=73–4 |journal=Klinika Oczna}} 27. ^{{cite journal |doi=10.1007/s10384-004-0152-1 |title=Relationship Between Astigmatism and Aging in Middle-aged and Elderly Japanese |year=2005 |last1=Asano |first1=Kazuko |last2=Nomura|first2=Hideki |last3=Iwano |first3=Makiko |last4=Ando |first4=Fujiko |last5=Niino|first5=Naoakira |last6=Shimokata |first6=Hiroshi |last7=Miyake |first7=Yozo |journal=Japanese Journal of Ophthalmology |volume=49 |issue=2 |pages=127–33 |pmid=15838729}} 28. ^{{cite journal|doi = 10.1056/NEJM189302091280603| title = Notes on the Centennial Anniversary of the Discovery of Astigmatism| first = David | last = Coggin | journal =Boston Med Surg J | year = 1893 | volume = 128 |issue = 6| pages = 136–137}} 29. ^{{cite journal|last1 =Atchison|first1 =David A|last2 =Charman|first2 =W Neil|title =Thomas Young's contributions to geometrical optics|journal =Clinical and Experimental Optometry|pages =333–340|year =2011|doi =10.1111/j.1444-0938.2010.00560.x|pmid =21214628|volume=94|issue =4}} 30. ^{{cite journal | url =https://books.google.de/books?id=3I9JAAAAYAAJ&pg=PA23-IA3 | title =Philosophical transactions of the Royal Society of London | author1 =Thomas Young | year =1801 | journal =Philosophical Transactions of the Royal Society of London | volume =91 | doi =10.1098/rstl.1801.0004 | pages =23–88 | deadurl =no | archiveurl =https://web.archive.org/web/20161107011557/https://books.google.de/books?id=3I9JAAAAYAAJ&pg=PA23-IA3 | archivedate =7 November 2016 | df =dmy-all }} 31. ^1 {{cite journal | doi = 10.1098/rsnr.1966.0017 | last1 = Levene | first1 = J. R. | title = Sir George Biddell Airy, F.R.S. (1801-1892) and the Discovery and Correction of Astigmatism | journal = Notes and Records of the Royal Society of London | volume = 21 | issue = 2 | pages = 180–199 | year = 1966 | jstor=531067}} 32. ^{{cite book | url =https://books.google.de/books?id=Zzp2ukRsvEkC&pg=PA4 | title =Irregular Astigmatism: Diagnosis and Treatment | isbn =9781556428395 | author1 =Wang, Ming | date =2007-10-22 | deadurl =no | archiveurl =https://web.archive.org/web/20161028021612/https://books.google.de/books?id=Zzp2ukRsvEkC&pg=PA4 | archivedate =28 October 2016 | df =dmy-all }} 33. ^{{cite journal | url =https://books.google.de/books?id=myA8AAAAMAAJ&pg=PA267 | title =On a peculiar Defect in the Eye, and a mode of correcting it | journal =Transactions of the Cambridge Philosophical Society | author1 =George Biddell Airy | year =1827 | deadurl =no | archiveurl =https://web.archive.org/web/20161028083723/https://books.google.de/books?id=myA8AAAAMAAJ&pg=PA267 | archivedate =28 October 2016 | df =dmy-all }} 34. ^{{cite journal|last1 =Read|first1 =Scott A|last2 =Collins|first2 =Michael J|last3 =Carney|first3 =Leo G|title =A review of astigmatism and its possible genesis|journal =Clinical and Experimental Optometry|volume =90|issue =1|pages =5–19|year =2007|pmid =17177660|doi =10.1111/j.1444-0938.2007.00112.x}} 35. ^{{cite book | url = https://books.google.de/books?id=uhmCGrG5X88C&pg=PA4 | title = Adaptive optics for vision science: principles, practices, design, and applications | isbn = 9780471679417 | author1 = Porter, Jason | year = 2006 | deadurl = no | archiveurl = https://web.archive.org/web/20161028021618/https://books.google.de/books?id=uhmCGrG5X88C&pg=PA4 | archivedate = 28 October 2016 | df = dmy-all }} 36. ^{{cite book | url = https://books.google.de/books?id=hHc6AAAAIAAJ&pg=PA100 | title = Thomas Young Natural Philosopher 1773-1829 | author1 = Wood, Alexander | author2 = Oldham, Frank | deadurl = no | archiveurl = https://web.archive.org/web/20161028022116/https://books.google.de/books?id=hHc6AAAAIAAJ&pg=PA100 | archivedate = 28 October 2016 | df = dmy-all | year = 1954 }} 37. ^{{cite book | url = https://books.google.de/books?id=62eCFmfb0_wC&pg=PA381 | title = Die Anomalien der Refraction und Accommodation des Auges | author1 = Donders, Franciscus Cornelis | year = 1866 | deadurl = no | archiveurl = https://web.archive.org/web/20161028022016/https://books.google.de/books?id=62eCFmfb0_wC&pg=PA381 | archivedate = 28 October 2016 | df = dmy-all }} 38. ^{{cite book | url = https://books.google.com/books?id=Zzp2ukRsvEkC&pg=PA3 | title = Irregular Astigmatism: Diagnosis and Treatment | isbn = 9781556428395 | author1 = Wang, Ming | date = 2007-10-22 | deadurl = no | archiveurl = https://web.archive.org/web/20110629012853/http://books.google.com/books?id=Zzp2ukRsvEkC&pg=PA3 | archivedate = 29 June 2011 | df = dmy-all }} 39. ^{{cite journal | url =http://archopht.ama-assn.org/cgi/reprint/73/4/587.pdf | title =The Rev. Mr. Goodrich and His Visual Problem | journal =Archives of Ophthalmology | volume =73 | issue =4 | pages =587–589 | deadurl =no | archiveurl =https://web.archive.org/web/20120306080022/http://archopht.ama-assn.org/cgi/reprint/73/4/587.pdf | archivedate =6 March 2012 | df =dmy-all | doi =10.1001/archopht.1965.00970030589023 | year =1965 | last1 =Snyder | first1 =C. }} 40. ^{{cite journal| doi = 10.1056/NEJM186311050691404|title = A Few Remarks on Astigmatism | first =J. F. | last = Bumstead| journal = Boston Med Surg J | year = 1863 | volume = 69 | issue = 14| pages = 280–284}} 41. ^{{cite book | url = https://books.google.de/books?id=nBA_AAAAcAAJ&pg=PA129 | title = Astigmatismus und cylindrische Gläser | author1 = Donders, Franciscus C | year = 1862 | deadurl = no | archiveurl = https://web.archive.org/web/20161106185405/https://books.google.de/books?id=nBA_AAAAcAAJ&pg=PA129 | archivedate = 6 November 2016 | df = dmy-all }} 42. ^{{cite journal|last1 = Artal|first1 = Pablo|last2 = Tabernero|first2 = Juan|title = Optics of human eye: 400 years of exploration from Galileo's time|journal = Applied Optics|volume = 49|issue = 16|pages = D123–30|year = 2010|pmid = 20517354|doi = 10.1364/AO.49.00D123|bibcode = 2010ApOpt..49G.123A}} External links{{Medical resources| ICD10 = {{ICD10|H|52|2|h|49}} | ICD9 = {{ICD9|367.2}} | MedlinePlus = 001015 | DiseasesDB = 29648 | OMIM = 603047 | MeSH = D001251 | eMedicineTopic = }}{{wiktionary|astigmatism}}
4 : Disorders of ocular muscles, binocular movement, accommodation and refraction|Vision|RTT|RTTNEURO |
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