Free Radic Res.2019 Jun;53(6):611-617. doi: 10.1080/10715762.2019.1603378. Epub 2019 May 27.

Evaluation of acute corneal damage induced by 222-nm and 254-nm ultraviolet light in Sprague-Dawley rats


Sachiko Kaidzu1, Kazunobu Sugihara1, Masahiro Sasaki2, Aiko Nishiaki2, Tatsushi Igarashi2 and Masaki Tanito1 

1 Department of Ophthalmology, Faculty of Medicine, Shimane University, Izumo, Japan 

2 Ushio Inc., Tokyo, Japan 



 Ultraviolet rays (Far UV-C) at 222 nm generated by krypton-chlorine excimer lamps and filters inactivate bacteria, but the effects of 222 nm exposure on the eyes are unknown. Therefore, we evaluated acute corneal injury induced by 222 nm and 254 nm UV light irradiation in albino rats. Under deep anesthesia, radiation was performed. Irradiance was 30, 150 and 600 mJ/cm2 for each wavelength. Corneal epithelial defects were detected by fluorescein staining. Superficial punctate keratitis occurred at doses of 150 mJ/cm2 and above at 254 nm, and corneal erosion was observed at doses of 600 mJ/cm2. Hematoxylin and eosin staining also showed corneal epithelial defects upon 254 nm UV-C irradiation. No damage was observed in the corneal epithelium with 222 nm with Filter Far UV-C irradiation. UV-induced DNA damage was confirmed by positivity for cyclobutanepyrimidine dimers. In normal corneas, some epithelial cells were weakly stained, and in corneas irradiated with 254 nm at 600 mJ/cm2, desquamated epithelial layers were strongly stained. No staining was observed at 222 nm with Filter. From these, it is suggested that there is no damage to rat eyes within the 222 nm with Filter(Far UV-C) irradiation energy range, and that it may be useful for bacterial inactivation and infection prevention. 


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