Photoadaptation during Narrowband Ultraviolet-B Therapy Is Independent of Skin Type: A Study of 352 Patients

Abstract

Understanding how photoadaptation differs between individuals is important when considering susceptibility to the beneficial and harmful effects of sunlight exposure and when determining optimal phototherapy regimens. Most narrowband UVB (NB-UVB) regimens start with 70% of the minimal erythema dose (MED) with 20% increments at each treatment thereafter. We retrospectively studied 352 skin types I-IV psoriatic patients having twice weekly treatment with this regimen. Patients with high skin types tended to have high MEDs (P<0.001). By session 20 the proportion of patients who had developed erythema was approximately 60% regardless of MED. Among patients who developed erythema, the number of treatments before erythema occurred did not differ between skin types (P=0.33). We conclude that patients with high skin types photoadapt approximately equally per physical unit of UVR in comparison to those with low skin types, but they have greater photoadaptation in absolute terms because they are able to tolerate a higher initial dose of radiation. Differences in skin type or MED are not associated with clinically important differences in tendency to erythema during a standard 70/20% NB-UVB twice-weekly regimen. This regimen is suitable for all skin types I-IV patients regardless of skin type or MED.

Effect of ultraviolet adaptation on the ultraviolet absorption spectra of human skin in vivo

“…Interestingly, Palmer et al . (26) also found that photoadaptation is independent of skin type in a recent study. The fact that photoadaptation seems to become more and more dependent on phototype at shorter wavelengths – as our measurements indicate – points at keratin absorption as a possible factor for differences between the adaptation mechanisms of UV‐sensitive vs. UV‐insensitive skin types.…”

Ultraviolet radiation therapy and UVR dose models

“…This seems to work well for all skin types, as evidence suggests that regardless of skin type, patients adapt approximately equally per physical unit of UVR. 39 In essence, human skin adapts to increasing amounts of UVR by increasing production of melanin and other chromophores. This process is called melanogensis and it triggers tanning in human skin.…”

Estimation of skin phototypes with optical parameters: an experimental study using newly developed fibre optic detection device

“…By this means, one averaged reflectance spectrum was obtained for each subject. Then, the absorption spectrum, the tristimulus and the L*a*b* values were calculated using equation (2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14). The AUCs within the wavelength range from 400 to 430 nm (AUC 400-430 ), from 415 to 445 nm (AUC 415-445 ) and from 450 to 615 nm (AUC 450-615 ) were computed.…”