Editing Visual acuity (section)

== History ==
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!Year
!Event
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!1843
|Vision test types are invented in 1843 by the German ophthalmologist [[Heinrich Küchler|Heinrich Kuechler]] (1811–1873), in [[Darmstadt]], Germany. He argues for need to standardize vision tests and produces three reading charts to avoid memorization.
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!1854
|[[Eduard Jäger von Jaxtthal]], a [[Vienna]] oculist, makes improvements to eye chart test types that were developed by Heinrich Kuechler. He publishes, in German, French, English and other languages, a set of reading samples to document functional vision. He uses fonts that were available in the State Printing House in Vienna in 1854 and labels them with the numbers from that printing house catalogue, currently known as Jaeger numbers.
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!1862
|[[Herman Snellen]], a Dutch ophthalmologist, publishes in [[Utrecht]] his book, ''Probebuchstaben zur Bestimmung der Sehschärfe [Test letters for measuring visual acuity'', containing charts for measuring visual acuity.<ref>{{Cite book |last=Snellen |first=Herman |url=https://archive.org/details/probebuchstaben01snelgoog |title=Probebuchstaben zur Bestimmung der Sehschärfe [Test letters for measuring visual acuity |date=1862 |publisher=P. W. Van De Weijer |location=Utrecht |access-date=12 September 2023}}</ref>

In later editions of his book, Snellen called the letters of his charts [[optotypes]] and advocated for standardized vision tests.<ref>{{Cite book |last=Snellen |first=Herman |url=https://babel.hathitrust.org/cgi/pt?id=uc1.c3209243&seq=5 |title=Optotypi ad visum determinandum secundum formulam = d/D. Ed. 8, metrico systemate [ |date=1885 |publisher=Williams and Norgate |edition=8 |location=London |access-date=12 September 2023}}</ref> Snellen's optotypes are not identical to the test letters used today. They were printed in an "[[Slab serif|Egyptian]] Paragon" font (i.e. using [[serif]]s).<ref>{{Cite web |last=Enerson |first=Ole Daniel |year=2017 |title=Herman Snellen |url=http://www.whonamedit.com/doctor.cfm/2075.html |website=Whonamedit?}}</ref><ref name="Colenbrander-2001">{{Cite web |last=Colenbrander |first=A |name-list-style=vanc |year=2001 |title=Measuring Vision and Vision Loss |url=http://www.ski.org/Colenbrander/Images/Measuring_Vis_Duane01.pdf |url-status=dead |archive-url=https://web.archive.org/web/20141204193231/http://www.ski.org/Colenbrander/Images/Measuring_Vis_Duane01.pdf |archive-date=4 December 2014}}</ref>
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!1888
|[[Edmund Landolt]] introduces the broken ring, now known as the Landolt ring, which later becomes an international standard.<ref>{{Cite journal |last=Landolt |first=E. |name-list-style=vanc |year=1888 |title=Méthode optométrique simple |trans-title=A simple optometric method |journal=Bulletins et Mémoires de la Société Française d'Ophtalmologie |language=fr |issue=6 |pages=213–214}}</ref><ref>{{Cite journal |last1=Grimm |last2=Rassow |last3=Wesemann |last4=Saur |last5=Hilz |year=1994 |title=Correlation of optotypes with the Landolt Ring – a fresh look at the comparability of optotypes |journal=Optometry and Vision Science |volume=71 |issue=1 |pages=6–13 |doi=10.1097/00006324-199401000-00002 |pmid=8146001 |s2cid=24533843}}</ref>

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!1894
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Theodor Wertheim in Berlin presents detailed measurements of acuity in [[peripheral vision]].<ref name="Strasburger-2011" /><ref>{{Cite journal |last=Wertheim |first=T |name-list-style=vanc |year=1894 |title=Über die indirekte Sehschärfe |trans-title=On indirect visual acuity |journal=Zeitschrift für Psychologie und Physiologie der Sinnesorgane |language=de |issue=7 |pages=172–187}}</ref>
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!1978
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Hugh Taylor uses these design principles for a "Tumbling E Chart" for illiterates, later used<ref>{{Cite journal |last=Taylor |first=HR. |name-list-style=vanc |year=1981 |title=Racial Variations in Vision |journal=Am. J. Epidemiol. |volume=113 |issue=1 |pages=62–80 |doi=10.1093/oxfordjournals.aje.a113067 |pmid=7457480}}</ref> to study the visual acuity of [[Australian Aboriginal]]s.<ref name="Colenbrander-2001" />
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!1982
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[[Rick Ferris]] et al. of the [[National Eye Institute]] chooses the [[LogMAR chart]] layout, implemented with Sloan letters, to establish a standardized method of visual acuity measurement for the [[National Eye Institute#Early Treatment Diabetic Retinopathy Study (ETDRS)|Early Treatment of Diabetic Retinopathy Study]] (ETDRS).
These charts are used in all subsequent clinical studies, and did much to familiarize the profession with the new layout and progression. Data from the ETDRS were used to select letter combinations that give each line the same average difficulty, without using all letters on each line.
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!1984
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The International Council of Ophthalmology approves a new "Visual Acuity Measurement Standard", also incorporating the above features.
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!1988
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Antonio Medina and Bradford Howland of the Massachusetts Institute of Technology develop a novel eye testing chart using letters that become invisible with decreasing acuity, rather than blurred as in standard charts. They demonstrate the arbitrary nature of the Snellen fraction and warn about the accuracy of visual acuity determined by using charts of different letter types, calibrated by Snellen's system.<ref>{{Cite journal |last1=Medina |first1=A. |last2=Howland |first2=B. |name-list-style=vanc |year=1988 |title=A novel high-frequency visual acuity chart |journal=Ophthalmic Physiol Opt |volume=8 |issue=1 |pages=14–8 |doi=10.1016/0275-5408(88)90083-x |pmid=3419824}}</ref>

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