Color Blindness?

Question

i am conducting color blindness test on atleast 600 students in a month and my ishihara chart is five years old, naturally it is exposed to natural daylight 600 times in a month and 7200 times in a year and also to dust. should i use a new one? how do i know if the colors have faded?

Answer 1

I have an old Titmus vision tester gathering dust in my basement, and indeed, the slide for color blind testing is badly faded. However, the color panels in the book that remains in my former office is still quite serviceable. I would think that the dyes in your copy should still be useful. Test it on persons with known normal color vision as well as on persons with known color blindness. If you get consistent results, it should be OK.

I just searched for Ishihara testing books, and the price ranges from $130 - $200. That's a lot to pay for a small book, so one tends to keep the old one as long as it remains useful.

Answer 2

I've taken many color blindness tests in my life and they always seem to be from ancient books and charts.  I have yet to pass any of them.  I doubt that the age of the book will have much of an effect.  Regardless of how old the set is, I can't see anything in the dumb circles while the administrator had no trouble.

I recently had an FAA medical exam that included a color blindness test.  The set of cards they had, if I remember correctly, were from the 1950's.  Same result, I failed, and the admin saw every pattern.

They then brought out a Farnsworth lantern that also looked like it was from the 50's.  Failed that test too.

Luckily, I was passed by actually going out to an airport and identifying the colors that I'd need to see.

I guess it depends on what your test is trying to do.  If you're just looking to identify who is / is not color blind, then any set will probably do.  If you're looking to get into the details of the many different types and degrees of color blindness then a new set might yield different results.