Tool to present Snellen Chart. The Snellen Chart is an an optometric test to determine visual acuity of a person in ophthalmology
Snellen Chart - dCode
Tag(s) : Raw Data
dCode is free and its tools are a valuable help in games, maths, geocaching, puzzles and problems to solve every day!
A suggestion ? a feedback ? a bug ? an idea ? Write to dCode!
Tool to present Snellen Chart. The Snellen Chart is an an optometric test to determine visual acuity of a person in ophthalmology
The chart is intended to be used at a distance of 20 feet (about 6 meters) but can be closer if reading difficulties are presented. The person tested must open one eye at a time. The examiner/the optician randomly select letters on each row and notes the right and wrong answers.
The score per eye is the result of the distance divided by the value of the smallest line read correctly. A visually healthy person can read the 20/20 row.
The result of the score enable to make a decision on whether or not to wear a visual correction device (glasses).
The Snellen scale uses different letters depending on the country, the principle is that they are quite easily discernible.
In the original version, the letters were
A,C,E,G,L,N,P,R,T,5,V,Z,B,D,4,F,H,K,O,S,3,U,Y,A,C,E,G,L,2
But can be different and suitable for any type of audience.
Example: C,D,E,F,L,O,P,T,Z in the above image
The size of the letters decreases on each row which makes it possible to evaluate with a fraction or a decimal number the most value read by a person tested.
The table should be printed so that the first letter E is 88mm high.
Snellen created it in 1862.
dCode retains ownership of the online 'Snellen Chart' tool source code. Except explicit open source licence (indicated CC / Creative Commons / free), any algorithm, applet or snippet (converter, solver, encryption / decryption, encoding / decoding, ciphering / deciphering, translator), or any function (convert, solve, decrypt / encrypt, decipher / cipher, decode / encode, translate) written in any informatic language (PHP, Java, C#, Python, Javascript, Matlab, etc.) no data, script, copy-paste, or API access will be for free, same for Snellen Chart download for offline use on PC, tablet, iPhone or Android !
Please, check our community Discord for help requests!