Sized for your screen on open. No pinching, no zooming.
Sizing the chart for your screen.
Hold at 40 cm
about elbow to knuckles · one eye at a time · readers on
The 20/20 line is half a millimetre tall. It is meant to look this small, and it stays black on white in dark mode because reversing the contrast changes the acuity you measure.
Optotype
Check the size
Hold a credit card, driver license, or hospital badge flat against the screen. The outline should match it on all four sides. Any card of this type is the same size, so any of them works.
Match this outline to your card
Printable version
A reference sheet with all three optotype sets, plus a sheet of six pocket cards to cut out. Opens the print dialog at actual size on its own.
Write it as near acuity with the distance: near 20/40 at 40 cm, right eye, with readers.
Note whether correction was worn. A patient over 40 without readers will test poorly on any near card, and that is presbyopia rather than the finding you are looking for.
Near acuity is a screening substitute for a calibrated distance chart. Say so in the note so the number is read in context.
Record the level reached, and for counting fingers the distance as well: CF at 2 feet, right eye.
If an open globe is suspected
Do not press on the eye and do not ask the patient to squeeze the lids shut. Vision can be estimated without touching the eye, and an open globe changes the order of everything that follows.
Optotypes are sized from the standard five arcminute definition at the selected distance. Screen sizing is matched to published device geometry for iPhone, iPad, Galaxy, and Pixel, and confirmed against a card on anything else; letterforms approximate Sloan geometry in a system font. Intended for bedside screening, not research grade acuity. Draft for committee review.