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A. Colenbrander, P. Runge; Can Jaeger Numbers Be Standardized. Invest. Ophthalmol. Vis. Sci. 2007;48(13):3563. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
To determine whether the wide variety of font sizes used on current cards can be standardized.
After collecting 20 samples of current Jaeger cards, the print sizes used were measured, rounded and plotted against a logarithmic scale in M-units.
The table shows the range of M sizes found for each J-number.
After 152 years, the variability among Jaeger cards is baffling. All current cards use print sizes that are larger than Jaeger’s original (starred numbers). New Jaeger cards based on the original sizes would show worse performance than current cards and might not be widely accepted. Confusion would persist between the new and the currently used cards.The only basis for a verifiable standard remains the use of M-units, based on Snellen’s mathematical definition of visual angle (1862), which applies to near as well as to distance measurements.#
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