The absorption of UV light by the human body can cause complex biological effects, one of which is the promotion of melanin synthesis. After the skin absorbs UV light, the number of melanocytes per unit area of epidermis does not increase, but the volume of melanocytes increases, dendrites lengthen, tyrosinase activity is enhanced, melanin synthesis increases, thus increasing the epidermal melanin content and skin color deepens. The clinical application of photochemotherapy, low-pressure mercury lamp or high-pressure mercury lamp irradiation for the treatment of vitiligo can achieve better results, activation of tyrosinase activity is the main mechanism.
The complexity of the biological effect of UV on skin determines the duality of UV on vitiligo treatment. UV irradiation is currently recognized as the standard treatment for vitiligo and can achieve better results. However, it is also found clinically that some vitiligo patients after strong sunlight irradiation in summer and autumn season make their disease aggravated, suggesting that strong UV irradiation may be one of the factors to induce or aggravate vitiligo.
In view of the above reasons, vitiligo patients should strictly observe the number, dose and irradiation time of UV irradiation when they undergo irradiation treatment. You should avoid sun exposure in summer and autumn, and it is advisable to apply sunscreen to the exposed parts of the skin when working outdoors to prevent UV burns to the skin.