Copyright 2002 American Medical Association. All Rights Reserved.
Applicable FARS/DFARS Restrictions Apply to Government Use.2002
We read with great interest the article by Manivannan et al1 on the clinical investigation of a color scanning
laser ophthalmoscope. The use of the term "true color" is scientifically incorrect
and may be confusing for readers. It is a well-established principle of physics
that a laser light source has only a single wavelength. The authors have developed
an instrument that has 3 wavelengths of light (blue, 488 nm; green, 532 nm;
and red, 670 nm). Each laser emits a very narrow spectrum of light, and the
authors combined all 3 lasers to yield the appearance of white light. The
spectrum of the light is, however, not continuous. Only 3 discrete sections
of the spectrum are present. There is no interaction among the 3 colors. If
one were to view the blue and green lights mixed, they would appear to be
yellow light. The retina, however, will not reflect the yellow illumination
light. It will reflect blue light and green light separately.
Bartsch D, Freeman WR, Lopez AM. A False Use of "True Color". Arch Ophthalmol. 2002;120(5):675–676. doi:
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