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Noninvasive Tests
Published in Vineet Relhan, Vijay Kumar Garg, Sneha Ghunawat, Khushbu Mahajan, Comprehensive Textbook on Vitiligo, 2020
Hemant Kumar Kar, Gunjan Verma
Several studies have shown that the tristimulus colorimeter can be useful in the quantitative evaluation of UV-induced erythema, pigmentation, and disease severity. It is authorized by the Commission Internationale de l'Eclairage (CIE) and is regarded as the standard for colorimetry in industrial fields [14]. Tristimulus analysis converts intensity versus wavelength data (i.e., spectral information) into three numbers that indicate how the color of an object appears to a human observer.
The 21-day cumulative irritation assay in man: a half-century summary and re-evaluation
Published in Cutaneous and Ocular Toxicology, 2021
In 1993, Lahti et al. compared visual grading, a spectroradiometer, a laser Doppler flowmeter, a two-channel erythema metre, and a tristimulus colorimeter (Minolta chromameter) on erythema arising from immediate contact reactions and found a correlation between visual grading and results measured by these instruments27. Among the 100 patch tests assessed, only three had poor correlations, including dithranol and sodium hydroxide reactions. Held et al. in 1998 also compared visuals with a spectroradiometer (DermaSpectrometer) and found readings from a DermaSpectrometer that did not give better information than visual readings28. Based on the discussed studies, visual assessment is probably sufficient for evaluating erythema in clinical settings. However, Lahti et al. worked with Caucasian subjects only, and the other two studies did not disclose their subjects' skin types of ethnicity. Since the visual evaluation is different from a skin type to another, future studies regarding correlations between visual assessment and instruments on pigmented skin should be conducted29. Farage provides an in-depth literature analysis comparing visual to instrumental grading, suggesting that so far, the human eye has not been surpassed by instruments - at least for allergic contact dermatitis grading30.