Thanks for the reply. So only red and white are the colours they use for the modified. I wonder if they would allow a practice run before doing the actual test. I'm sure I could pass the modified or the signal, I just want to have another option. I have passed other colour blind tests, but fail miserably with the Ishihara and obviously did not do well with the Farnsworth - the lights are just so small. My vision has been sharpened with laser surgery, so I may have better success at focusing and identifying the lights. During the farnsworth I did take, I got an average of three errors on the second and third runs (series of nine lights), with the third run having zero errors. Does that constitute a fail for a farnsworth I wonder.