A method for evaluating the acceptability of light sources for clinical visual evaluation of cyanosis

The accurate identification of cyanosis depends on a number of factors including the quality and quantity of the lighting used. Requirements framed in terms of permissible limits on correlated colour temperature and colour-rendering indices worked satisfactorily for many years. However, the demise of halophosphate fluorescent lamp technology and its replacement with triphosphor technology has led to a need to reevaluate the former methods and acceptance criteria. The experimental methods of assessing previous light sources were long and involved. It is impractical to replicate them as each new light source or new lighting technology is developed. There is a need, therefore, for a colorimetric method of assessing light sources for this purpose. In this study, the spectral reflectance characteristics of blood with oxygen saturation levels from 95.6–0.7% are used to calculate colour changes with respect to a reference illuminant and correlated with the results of an extensive study, some years ago, of the influence of light sources in the detection of cyanosis. The results lead to a method of evaluation with a single value criterion for acceptability. The method lends itself to simple modeling techniques for phosphor mixtures and should simplify the design of appropriate fluorescent tube sources for clinical visual evaluation of cyanosis. © 1998 John Wiley & Sons, Inc. Col Res Appl, 23, 4–17, 1998.