Department of Ophthalmology, Shimane University Faculty of Medicine, Izumo, Japan.
Ushio Inc., Tokyo, Japan.
Photochem Photobiol. 2023 Jul-Aug;99(4):1142-1148. doi: 10.1111/php.13750. Epub 2022 Dec 14.
Basal cells in the corneal limbus play an important role in the turnover cycle because they are the source of all cells that constitute the corneal epithelium. We examined the penetration depth of ultraviolet (UV) light in the corneal limbus and assessed the safety of Far-UV-C on stem cells in the basal area of the corneal limbus. Rats were irradiated with UV at peaks of 207, 222, 235, 254 and 311 nm while under anesthesia. The UV penetration depth in the rat corneal limbal epithelium was wavelength dependent: 311 nm UV-B and 254 nm UV-C reached the basal cells of the epithelium, and 235 nm radiation reached the middle area; however, 207 and 222 nm UV-C reached only the superficial layer of the epithelium. Porcine cornea, which is similar to the human eye in size and structure, were irradiated with 222 and 254 nm UV-C. As in rats, 222 nm UV-C reached only the superficial layer of the porcine corneal limbal epithelium. These results indicate that Far-UV-C, such as radiation of wavelengths of 207 and 222 nm, could not reach corneal epithelial stem cells, i.e. the cells remained intact. It is unlikely that the turnover of the corneal epithelium is obstructed or disrupted by exposure to Far-UV-C.
角膜缘的基底细胞在细胞更新周期中起着重要作用，因为它们是构成角膜上皮的所有细胞的来源。我们研究了角膜缘的紫外线（UV）光的穿透深度，并评估了远 UV-C 对角膜缘基底区干细胞的安全性。在麻醉下，用峰值为 207、222、235、254 和 311nm 的 UV 照射大鼠。大鼠角膜缘上皮的 UV 穿透深度与波长有关：311nm UV-B 和 254nm UV-C 到达上皮的基底细胞，235nm 辐射到达中间区域；然而，207nm 和 222nm UV-C 仅到达上皮的浅层。与人眼大小和结构相似的猪角膜被 222nm 和 254nm UV-C 照射。与大鼠一样，222nm UV-C 仅到达猪角膜缘上皮的浅层。这些结果表明，远 UV-C（例如波长为 207nm 和 222nm 的辐射）无法到达角膜上皮干细胞，即细胞保持完整。远 UV-C 照射不太可能阻碍或破坏角膜上皮的更新。
