Snellen Chart
 

Hi

Does anybody know where I can buy a Snellen chart from, or even better, download one online?

thanks

Make your own, it's just simple geometry and a lot less complicated than some of the questions you will be asked for even a private pilots licence.

http://www.i-see.org/eyecharts.html

Enjoy.

V1R :ok:

Slag

I am not opthalmologically trained, so although from the *geometric* side it MAY be easy to 'make my own' (if you have the correct dimensions for all the letters, please post henceforth), it would be ineffectual from the practical side because of my lack of knowledge on the SEQUENCE of the letters, which is, I believe, an important factor. Slag, if you could impart this knowledge to me, I would be grateful.


Rotate

Thank you for the link, and for taking the time to help

G_STRING

G_STRING,

Fair enough.

Slim_slag now slinks off and mutters about the youth of today wanting to be spoon fed everything and having no initiative or desire to actually understand the principles behind things anymore. Good job there are computers on flight decks, huh?

For those who might be interested, this is O-level physics stuff. It's not the size of the letters that matters on it's own, but the size together with the distance.

So, in a Snellen chart you change the size but not the distance. With a tape measure and a supermarket car park you can use the known height of the letters on a car number plate, but change the distance you stand from them to get the desired visual acuity numbers.

So one question G_STRING? What has the sequence of letters got to do with it? How do you think they measure the visual acuity of people who cannot read?

Cheers.

google throws up alot of links if you search for snellen chart.....

Slim Slag

Ever noticed how, (especially on 'smaller lines' such as 6/9 6/6), letters such as 'O' 'C' 'T' 'J' etc. are ofter together?........

Nope G_STRING, should I have?

Indeed blinkz, but that is too easy :)

For those who are interested in the SEQUENCE of the letters, I hope you don't think you can remember the chart to get through the eye exam. No doubt this happens but the docs are generally smarter than that.

At my friendly AME they have a chart (you look through what is like a microscope at very small letters) which reads a sentence, the words getting smaller and smaller as you go down the page. This tests both your visual acuity AND your ability to read and understand English. Very clever, wish I had thought that up :) But then they also have a chart where you have to tell which way up a series of horseshoes lie (which also answers the question G_STRING has trouble with)

I bet Dr Snellen (if that was his name) had an office where the longest dimension was 20 feet.

Slim Slag

You seem to enjoy making references to *the idleness of the young* - <in other words, G_STRING, why don't you get off your behind and find things out for yourself...>

The reason I decided to ask the people of pprune my original question was because, surely, that is one of the reasons that the website is here for us all; IF no one had been able to point me in the right direction, (thank you, Rotate), then I would have looked elsewhere. Conversely, I would like to think I could reciprocate that help if someone asked a question to which I knew the answer.

So, Slim Slag, get off your high horse, and let pprune do what it's good at - sharing information, exchanging opinions, and helping people - not slagging them off if their first port of call for help dares to be here.

Incidentally, I am neither THAT young, nor do I consider myself to be idle.

Don't tell Mr Snellen, as I believe a copyright still exists !!


(According to my old and wise University Lecturer).