Jaeger chart

{{Short description|Diagnostic tool}}

The Jaeger chart is an eye chart used in testing near visual acuity. It is a card on which paragraphs of text are printed, with the text sizes increasing from 0.37 mm to 2.5 mm.{{cite book |title=Medical Assisting Administrative and Clinical Competencies |first1=Michelle |last1=Blesi |first2=Barbara |last2=Wise |first3=Cathy |last3=Kelley-Arney |publisher=Cengage Learning |year=2011 |url=https://books.google.com/books?id=7XMJAAAAQBAJ&pg=PA888 |pages=888–890|isbn=978-1133706960 }} This card is to be held by a patient at a fixed distance from the eye dependent on the J size being read. The smallest print that the patient can read determines their visual acuity.{{cite book|author1=G.K. & Pal|author2=Pal|author3=Pravati|title=Textbook Of Practical Physiology|edition=2nd|url=https://books.google.com/books?id=XpUAihQ7Ib4C&pg=PA328|date=1 February 2006|publisher=Orient Blackswan|isbn=978-81-250-2904-5|pages=328–}}

The original 1867 chart had a text containing seven paragraphs and a corresponding seven-point scale.{{cite book |title=Theory and Practice of Optics and Refraction |author=Khurana |publisher=Elsevier India |year=2008 |page=49 |isbn=9788131211328 |url=https://books.google.com/books?id=qYeD3VHi8OsC&pg=PA49}}

Jaeger cards are not standardized, and the variability of the actual size of test letters on different Jaeger cards currently in use is very high.{{cite conference |first1=August |last1=Colenbrander | first2=Paul E.| last2=Runge |title=Can Jaeger Numbers be Standardized? (Poster 3563)| conference=Association for Research in Vision and Ophthalmology (ARVO) 2007 Annual Meeting, Fort Lauderdale|date=May 2007| url=http://iovs.arvojournals.org/article.aspx?articleid=2386268|journal=Investigative Ophthalmology & Visual Science| volume=48| page=3563}} Therefore, test results with different Jaeger cards are not comparable.

More commonly, distance vision acuity is tested using the Snellen chart, familiarly seen wall mounted with a large letter at the top.