If you want to improve your vision with natural vision improvement techniques,
such as the Bates Method, you need an eye chart.
With an eye chart, you can perform various eye exercises, and, of course,
an eye chart provides an objective way for you to see your progress as you
improve your visual fitness. As you experiment with various vision improvement techniques, the eye chart can help you decide which exercises
work and which ones don't work for you.
Check out the eyechart download section for free eye charts, ready to print out (or use on screen) and use in measuring and training various aspects of vision; or, follow the instructions on how to
make your own eye chart!
The chart is usually read while standing at a distance of 20
feet. Acuity is represented as a fraction, with the distance at which
you are standing being the numerator (top part of fraction), and the
normal maximum legible viewing distance ("Distance" on the chart
above) as the denominator (bottom of fraction). So if, at 20 feet, you
can read the letters on the row marked "40", this means you have visual acuity
of 20/40 or better: 1/2 normal. From 10 feet, if the smallest letters
you could read were on the "40" line, this would give you an acuity of
10/40: 1/4 normal. If you are nearsighted, your vision will become
more normal the closer you stand to the chart.
How do you use your eye chart? Tell us about it on the mailing list!
For those enterprising souls out there who would like to laserprint or
draw by hand their own eye chart, or if you would like to verify that
your printout is of the correct proportions, here are the specs:
- Classic Eye Chart: Joel Schneider's 3-page Snellen Chart plus near vision testing card
- Modern Standard: ETDRS charts based on those provided on the National Eye Institute's charts page. The following charts have correctly-labelled lines from 40ft to 2ft suitable for printing on letter sized paper, and feature vector graphics for a sharper image (unlike the maximum 300dpi, not-to-scale charts provided by the N.E.I.).
- Interactive Eye Chart: Alejandro Saksida's Flash-based Ultimate Random Snellen Chart generator, version 3.1 (updated January 12, 2006):
- Vision Training Charts from Ray Gottlieb, O.D., Ph.D., with instructions.
- Alex Eulenberg's 1-page Snellen Chart (20/20)
- in GIF format (browser-viewable,
also printable at 72 dpi)
- in Macintosh PICT format (hi-resolution,
downloadable & printable)
- in Encapsulated PostScript (.eps) format (compatible with, among other programs, WordPerfect for Windows.)
- in PDF format.
- Vic Cinc's Letter rows & grid of random tumbling E's
- Vic Cinc's Astigmatic mirror
- Egidio Rizzi's
- Vision Charts for Eyesight Improvement -- 10 charts for practicing fusion, convergence, divergence, with notes on each exercise's applicability for nearsightedness, farsightedness, and astigmatism.
- "Read Vertical" Vision Charts -- 20 more charts combining fusion with vertical reading, specifically conceived to reduce astigmatism in the vertical meridian, but also useful for near- and farsightedness.
- Allan Hytowitz's Dyop® (Dynamic Optotype) vision test (external link) -- rotating rings of black and white segments offer higher precision and more consistency than traditional static eye charts (requires Flash).
Distance (feet) 70 60 50 40 30 20 15 10 7 4
letter ht (mm) 31 27 22 18 13 9 7 4 3 2
letter ht (pt) 88 76 63 50 38 25 19 13 9 5
font size (pt) 152 130 108 87 65 43 33 21 15 9
With the University at Buffalo's Interactive Visual Acuity Chart, you can display the letters or symbols for a specified Snellen line on your computer monitor at exactly the right size (note: you must follow the instructions for calibration).
Interpreting the table
"Distance" in the above table refers to the furthest distance from the
chart at which a normal eye is able to read the letter. On a Snellen eye
chart, rows of letters of a given size have the corresponding distance
number next to them. Thus the row of 18mm letters is marked "40".
The font must be Courier (or Courier Bold) in
order for the "font size" in points to correspond to the indicated
letter height. Courier Bold is the PostScript font that most closely
approximates the official Snellen letters.
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Revised 23 Feb 2017