Pedić Lovre, Pondeljak Nives, Šitum Mirna
Department of Dermatovenereology, Zadar General Hospital, Zadar, Croatia.
Clinical Department of Dermatovenereology, Sestre milosrdnice University Hospital Center, Zagreb, Croatia.
Acta Dermatovenerol Alp Pannonica Adriat. 2020 Dec;29(4):201-207.
The main environmental element causing photoaging is ultraviolet (UV) light, and this involves an extrinsic mechanism of skin aging superimposed on an intrinsic process. Clinical (evident) characteristics of photoaging include the presence of deep wrinkles, deterioration of skin laxity, and hyperpigmentation. In the UV light spectrum, UVA and UVB radiation cause the most damage in photoaging. UVB light has shorter wavelengths and is mostly absorbed by the stratum corneum, causing erythema and changes in the epidermis, whereas UV rays with longer wavelengths (i.e., UVA) penetrate to the deepest layer of the skin (i.e., the dermis) and interact with DNA. As a result of UV radiation, chemical reactions in the skin produce reactive oxygen species (ROS), which cause protein denaturation, impairment of RNA and DNA synthesis, and damage to the skin structure. Using local sunscreen agents can not only prevent sunburn, but also help prevent photocarcinogenesis and photoaging. Therefore, many epidemiological studies have been conducted with results showing credible and positive evidence for the safety and efficacy of sunscreen to prevent photoaging and photocarcinogenesis.
导致光老化的主要环境因素是紫外线（UV），这涉及叠加在内在过程之上的皮肤老化外在机制。光老化的临床（明显）特征包括深层皱纹的出现、皮肤松弛的恶化以及色素沉着。在紫外线光谱中，UVA和UVB辐射在光老化中造成的损害最大。UVB光的波长较短，大部分被角质层吸收，导致红斑和表皮变化，而波长较长的紫外线（即UVA）可穿透到皮肤的最深层（即真皮）并与DNA相互作用。由于紫外线辐射，皮肤中的化学反应会产生活性氧（ROS），这会导致蛋白质变性、RNA和DNA合成受损以及皮肤结构破坏。使用局部防晒剂不仅可以预防晒伤，还有助于预防光致癌作用和光老化。因此，已经进行了许多流行病学研究，结果显示了防晒霜预防光老化和光致癌作用的安全性和有效性的可靠且积极的证据。
