Photoaging is damage caused by prolonged exposure of the skin to sunlight, and light induces premature aging changes in the skin. Photoaging is the damage caused by long-term exposure of skin to sunlight, which is manifested as rough skin, thickening, laxity, deep and coarse wrinkles, excessive local pigmentation or capillary dilation, and even various benign or malignant tumors may appear, such as solar keratosis, squamous cell carcinoma, malignant melanoma, etc. Clinical manifestations of photoaging: 1. Epidermal thickening and dryness After photoaging, the skin shows obvious dryness and flaking, and the skin becomes rough. The main reason is that after photoaging, the cell renewal rate slows down, the vitality of keratinocytes decreases, and the skin barrier function is weakened. At the same time, UVR degrades collagen fibers and elastin, the structure of extracellular matrix is damaged, collagen fibers are reduced, elastic fibers are disordered, and the ability of extracellular matrix to combine water is reduced, resulting in thickened and dry skin. 2, skin relaxation, wrinkles increase The most important feature of skin photoaging is the formation of wrinkles, according to the degree of wrinkles will be divided into four major types of skin photoaging. That is, early photoaging, there are few wrinkles produced on the face; medium-term photoaging, parallel laugh lines begin to appear; late photoaging, visible wrinkles in the stationary; end photoaging, that is, intensive distribution of wrinkles, that is, the face is all wrinkles, no normal skin. The imbalance of synthesis and degradation of extracellular matrix in the dermis, resulting in the formation of tiny dermal scar and not completely repaired, these are the important reasons for photoaging of skin and the appearance of wrinkles. 3, pigmentation UVR-induced skin pigmentation is the result of the increase and redistribution of pigments in the epidermis. Among them, UVR will directly affect the melanocytes within the epidermis, causing an increase in tyrosinase activity and a significant increase in synthesized melanin. In this condition, the skin shows two types of symptoms, rapid-onset hyperpigmentation and delayed-onset hyperpigmentation. Rapid onset hyperpigmentation occurs rapidly after UV irradiation and lasts from a few minutes to a few days, without necessarily producing new pigmentation, but due to the redistribution of melanin vesicles, the skin color therefore changes; late onset hyperpigmentation is detected after 3 to 4 days of sufficient UV irradiation and usually lasts about 3 or 4 weeks, when the number of melanocytes and melanin vesicles increases. 4, facial erythema, also known as “facial capillary dilation”, that is, the capillary wall elasticity is reduced, increased brittleness, resulting in continuous uneven expansion or even rupture of blood vessels, facial skin reddening, the naked eye can see the expansion of capillaries. This is usually accompanied by red or purplish patches, dots, lines or stellate damage. These skin types are very sensitive and become redder when they are too cold, too hot, or when they are emotionally disturbed. Benign or malignant tumors may appear on skin that has been exposed to strong sunlight for a long time, and various benign or malignant tumors, such as solar keratosis, squamous cell carcinoma, malignant melanoma, etc. Histopathological examination: thinning of the epidermis, increased melanin, sometimes dyskeratotic cells and atypical cells, reduced cellular components in the dermis, reduced collagen and elastic fibers, basophilic changes in the upper dermis, disorganized dermal capillary arrangement, curved expansion, inflammatory cell infiltration in the dermis, and changes in the dermal stromal components. Treatment methods 1.Laser and photodynamic therapy Laser and photodynamic therapy have been increasingly used in the treatment of skin photoaging, which has the characteristics of quick effect, does not affect daily work and has small side effects. In particular, ultra-pulsed CO2 laser reverses the photoaging changes of epidermis and dermis, OPT and photodynamic therapy (PDT) stimulate the deep collagen regeneration of the skin, which has a significant effect on brightening the skin tone and rejuvenating the skin. 2.Vitaminic acid is the most popular drug for skin photoaging. 0.05% vitaminic acid can be applied to the face once a day, and some of the manifestations of skin photoaging, such as wrinkles, pigment spots, roughness and sagging, can be slightly improved with consistent use. 3, antioxidants commonly used antioxidants such as VE, VC, β-carotene, etc. can be used in regular doses and adhere to take is an effective way to prevent skin photoaging damage, coenzyme Q10 can be used topically to penetrate into the epidermis of all layers, can effectively combat ultraviolet radiation, all help to combat the occurrence of photoaging. Skin photoaging prevention: 1, clothing clothing has a good light protection, whether natural or synthetic, have a good protective effect on ultraviolet radiation, fabric thickness determines the size of fabric protection, and the type of fabric color or thickness for the size of the protective effect is small. 2, hat hat for the head, neck skin to provide light protection, wear a general duck tongue cap can also be in a certain degree of protection of the face, but the main is protected by the forehead, should use the wide edge of the hat up to 7cm, in order to effectively protect the nose, cheek, neck, back and other parts. 3, sunglasses sunglasses on UV protection effectiveness depends on its lens size and shape, add the lens in the UV-absorbing raw materials, as well as the lens surface of the UV reflection strength. 4, cosmetic protection The use of sunscreen cosmetics containing UV absorbers and isolation is the most effective means of protection against sun damage, the reasonable use of sunscreen products can not only prevent skin photoaging, but also help repair damaged skin. The ideal sunscreen should be spectral sunscreen or UVB full-band protection. The sunscreen’s protection against UVB is expressed by the sun protection factor, and within a certain range, the larger the SPF value of the sunscreen, the stronger the sun protection effect. The protection effect of sunscreen on UVA is expressed by UVA protection factor, which mainly reflects the sun tanning effect on UVA, and the larger the PFA value in a certain range, the stronger the sun tanning effect.