Physical measurement and evaluation of skin color changes under normal condition and post-ultraviolet radiation: a comparison study of Chromameter CM 2500d and Maxmeter MX18

摘要

Objective: To compare the data correlation between two kinds of instruments, Chromameter CM2500d and Max-meter MX18, in the measurement of skin color changes under normal condition and post-ultraviolet (UV) radiation. Method: The data points of Chromameter CM2500d are based on L*a* values, while Maxmeter MX18 are based on M and E values, in order to compare the data correlation between these two kinds of instruments in skin color measurement on both non-exposed and exposed sites. In addition, an evaluation of the correlation of post-UV irradiation between these two instruments was conducted. Four different kinds of parameters post-UV radiation were measured including minimal erythema dose (MED), immediate pigmentation dose (IPD), minimal persistent pigmentation dose (MPPD) and repeated UV radiation. The following UV radiation dosages were applied as Day 1 =1.0 MED, Day 2 = 0.5 MED and Day 3 = 0.5 MED for repeated UV radiation, of which the erythema and pigmentation changes were recorded. Result: Chromameter CM2500d and Maxmeter MX18 showed good data correlation when measuring both non-exposed and exposed sites on normal skin. L* values were affected more easily by UV-induced erythema than M values on skin color changes after 1 MED and repeated UV exposures. IPD, MPPD and the pigmentation data showed good correlations with the measurement of the intensive erythema formation induced by repeated UV exposures, a* value was shown to be equally effective as E value with skin erythema measurements in response to various MEDs. However, increased erythema induced by repeated UV radiations was able to reduce the correlations between a* and Evalues. On the other hand, a* and E were shown to be equally effective in recording the erythema change courses after strong erythema responses post-UV radiations. Conclusion: This comparative study showed that the data correlations between the two kinds of instruments were different depending on measurement conditions. Both Chromameter...