## 4 Discussion
In our research, examining the skin before and after the micropeeing treatment, it was observed that the reduction in the thickness of the stratum corneum increased the reflectance coefficient in the range of the radiation length corresponding to UVA, UVB and UVC. This may be related to the alignment of the surface of the stratum corneum. This is an argument supporting the use of directional-hemispherical reflectance in assessing the correctness of micropeeing treatment, because the skin after the properly performed procedure will be characterized by higher reflectance. To study the effect of other procedures and active ingredients that are intended to smooth the skin surface, the suggested method can also be used. In the case of reflection/scattering of infrared radiation a particularly high correlation coefficient can be observed. It has been shown that in 100% of volunteers the increase in reflectance after the procedure occurred. However, in the case of visible radiation with a spectral range of 480-600 nm, a decrease in the directional reflectance coefficient was observed after the micropeeing treatment. It may be related to increase in the absorption of radiation in this spectral range. Most of the skin's chromophores have absorption maxima in this spectral range. The absorption of oxyhemoglobin and deoxyhemoglobin peaks at wavelengths of 400-420 nm and 540-577 nm. In contrast, deoxyhemoglobin has an absorption maximum peak at 420 nm and a second peak at 580 nm. Oxidized hemoglobin (oxyhemoglobin) shows the highest absorption at 410 nm and 550-600 nm. Melanin also strongly absorbs radiation in this spectral range [16, 17]. Therefore, it was suggested that the reduction in the thickness of the stratum corneum due to microdermabrasion treatment resulted in deeper penetration into the dermis by solar radiation beam (defined as the radiation energy range). The dermis and the deepest part of the epidermis--the basal layer--contain the vast majority of skin chromophores. The increase in the penetration of radiation into the dermis and the basal layer of the epidermis in the spectral range of 480-600 nm caused more efficient absorption of radiation by chromophores and the reflectance decreased. It should be emphasized that the influence of microdermabrasion on the skin's direct reflectance coefficient for a wide spectrum of solar radiation has not been investigated yet. The proposed method of directional-hemispherical reflectance can be used not only to assess the effectiveness of microdermabrasion treatment, but also to examine other procedures and products intended to affect the smoothness of the epidermis [18]. The decrease in the reflectance for the spectral range amount of 480-600 nm also indicated that more effective sun protection is needed after procedures that reduce the thickness of the stratum corneum. Radiation in this range carries less energy than ultraviolet radiation, but prolonged exposure and a relatively high penetration depth may have a clinically significant damaging potential. The implication of the results of [PERSON] et al. [19] was that visible light could possibly play a crucial role in producing darker and longer lasting pigmentation in populations with skin types IV-VI. Currently, there is no effective organic filter in sunscreens that protects against it. Moreover, a visible light has been shown to affect dermatoses such as melasma, post-inflammatory hyperpigmentation, solar urticaria, and erythropoietin protoporphyria [20]. However, there is a lack of cosmetic products that effectively protect against radiation other than ultraviolet radiation, because so far no standards or procedures have been developed to verify the effectiveness of sunscreen protection in the non-UV spectrum. To sum up, the conducted research showed a significant influence of microdermabrasion on skin reflectance in the spectrum of solar radiation. An effective, quantitative method for measuring reflectance is the use of a directional-hemispherical reflectometer.