Ocular safety of 222-nm far-ultraviolet-c full-room germicidal irradiation: A 36-month clinical observation

The ocular safety of 222-nm far-ultraviolet-C (UV-C) irradiation, widely recognized for its germicidal properties, was evaluated in a clinical setting to assess its long-term health effects on the human eye. This prospective observational study involved a 36-month follow-up of physicians working in an ophthalmic examination room equipped with 222-nm UV-C lamps. Initially, a 12-month observation showed no signs of acute or chronic ocular damage. To further substantiate these findings, the study period was extended to 36 months, during which four participants underwent regular ocular examinations, including assessments of visual acuity, refractive error, and corneal endothelial cell density. The irradiation dose was meticulously controlled to remain within the previous threshold limit of 22 mJ/cm² over an 8-h period, as advised by the ACGIH prior to 2022. Results indicated no significant changes in these parameters, suggesting no clinically significant ocular hazards associated with prolonged exposure to 222-nm UV-C irradiation under real-world conditions. Additionally, no delayed side effects, such as pterygium, keratopathies, or cataracts, were observed. Our study supports the safe use of 222-nm UV-C for microbial disinfection in occupied environments and provides a robust foundation for updated safety guidelines.