The Cure of Imperfect Sight by Treatment
Without Glasses - online book

The Original Bates Method, for correcting vision defects

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A Danger Greatly Exaggerated        185
As for danger from the heat effects of light, they con sider this to be "ruled out of consideration by the imme diate discomfort produced by excessive heat." They conclude, in short, that "the eye in the process of evolu tion has acquired the ability to take care of itself under extreme conditions of illumination to a degree hitherto deemed highly improbable." In their experiments, the eyes of rabbits, monkeys and human beings were flooded for an hour or more with light of extreme intensity, with out any sign of permanent injury, the resulting scoto-mata1 disappearing within a few hours. Commercial illuminants were found to be entirely free of danger un der any ordinary conditions of their use. It was even found impossible to damage the retina with any arti ficial illuminant, except by exposures and intensities enormously greater than any likely to occur outside the laboratory. In one case an animal succumbed to heat after an exposure of an hour and a half to a 7 50-watt nitrogen lamp at twenty centimeters-about eight inches; but in a second experiment, in which it was well protected from the heat, there was no damage to the eye whatever after an exposure of two hours. As for the ultra-violet part of the spectrum, to which exaggerated importance has been attached by many recent writers, the situation was found to be much the same as with respect to the rest of the spectrum; that is, "while under conceivable or realizable conditions of over-exposure, in jury may be done to the external eye, yet under all prac ticable conditions found in actual use of artificial sources of light for illumination, the ultra-violet part of the spec trum may be left out as a possible source of injury." The results of these experiments are in complete ac-
1 Blind areas.