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Dr. Ogle was asked to comment on the foregoing. He replied:
To the Editor:
—I think Dr. Rubin has a point, but I am not sure it is as great a factor as he believes it to be, unless the myope is undercorrected. We can agree that probably one should avoid use of a slide entirely opaque except for blue lines. But if there are also white lines on the chart or graph, this would seem to me to be less important. The chromatic aberration between the F (blue) and D (yellow) lines is probably at least three-quarters diopter—for the D and C (red) lines it is less than one-half diopter. In the semidarkness of most auditoriums, where pupils will be larger than normal, one half the depth of focus should be three-eighths diopter, so the amount of uncorrected myopia due to the blue light would be about three-eighths diopter.