Safety of Water-Filtered Infrared A (wIRA) on the Eye as a Novel Treatment Option for Chlamydial Infections

Abstract

AbstractwIRA has been shown to reduce chlamydial infections in vitro and in vivo and might therefore offer an innovative therapeutic approach for fighting trachoma. However, since the eye is a highly temperature- and radiation-sensitive organ, a safety assessment of the ocular structures affected by wIRA treatment is required to establish wIRA as a potentially successful treatment option for clinical application. A prerequisite for this is to demonstrate that wIRA does not have adverse side-effects such as inducing a non-physiological temperature increase which causes cell stress and damage to ocular tissues and which, in turn, is ultimately associated with impaired vision. Likewise, the potential negative impact of non-thermal photochemical effects of wIRA irradiation needs to be investigated. Data from our ex vivo studies in pig and mouse models, as well as in vivo data in a guinea pig model, provide good evidence for the safe use of wIRA to treat chlamydial infections. These studies have excluded a non-physiological temperature rise as well as the activation of heat and stress-induced proteins after wIRA irradiation with therapy-relevant irradiances. Nevertheless, additional detailed in vitro and in vivo studies are needed to further advance the clinical use of wIRA.