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Medical Forum / General / Vision / May 2006Random Snellen Eye Chart Generator
Have tried to download the zip version here: http://www.i-see.org/random_snellen/random_snellen.html But found it to be an invalid archive :-) Anyone have a working copy of this? TIA Gary Online charts arent accurate unless you print them out. Here is a great one: http://www.eyecharts.50megs.com/printtumblechart.html Just figure one out...a 20/20 E subtends an angle of 5 minutes of one degree at 20 feet away. A 20/40 E subtends 5 minutes of arc at 40 feet, etc. This means that the 20/60 letter will be 3 times the size of the 20/20 letter. For small angles the sine of theta is theta. Don't forget to use radians. It is not a valid test if it is closer than 20 feet because refraction begins to enter into the equation. Ted. Or to make it clear: 20/20 means 0.9 cm letters at 6 meters 20/40 means 1.9 cm letters at 6 meters. etc. Otis Or to make it clear: 20/20 means 0.9 cm letters at 6 meters Or 6 x 0.0015 = 0.009 meters (Approximately) 20/40 means 1.8 cm letters at 6 meters. etc. Otis Or Gary, if that fails, just use the neat Random Snellen on my site: www.myopiafore.com As eye-chart 2 (IVAC) Very easy to use -- and you can not memorize the letters. Best, Otis Thanks for the replies, however I did contact the site owner and the zip archive has now been fixed :-) Dear Gary, Subject: Substitute Random Snellen. There is an easy-to-use Snellen on my site (IVAC) as eye-chart 2, on the lower right side. www.myopiafree.com Hope that meets your requirement. Otis > Dear Gary, > [quoted text clipped - 10 lines] > > Otis I would simply advise that you *strenuously* avoid the book that he's selling on that site. At $24.95 for 129 pages, or 19 cents per page, that's very expensive toilet paper. Take care, Neil > I would simply advise that you *strenuously* avoid the book that he's > selling on that site. > > At $24.95 for 129 pages, or 19 cents per page, that's very expensive > toilet paper. Oh geeez, here he said he didn't make any money from his website. Hmmm, maybe I need to post after each one of his posts to avoid the spammer. Allen > > I would simply advise that you *strenuously* avoid the book that he's > > selling on that site. [quoted text clipped - 8 lines] > > Allen Ohhhh, no. He's still in the business: http://www.i-see.org/otis_brown/ I think he advertises it on his site, too. I felt better when I thought he was just insane. Now I realize he's just in it for money. I think this is worse.... |
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