Heavy metal deposition and parameter change of soft contact lenses by exposure to particulate matter: Parameter change of SCL due to exposure to PM and heavy metal deposition

Background: Particulate matter (PM) is known to contain heavy metals and be harmful to the tissues and organs of the human body including the eyes. As such, in this study, the deposition of heavy metals from PM on soft contact lenses was examined, and changes in the lens parameters were further investigated. Methods: Six types of soft contact lenses were exposed to captured PM₁₀ for eight hours. The central thickness, water content, refractive power, and oxygen transmissibility of each contact lens were measured after analyzing the amounts of six heavy metals adsorbed on the contact lenses. Results: Lead, manganese, barium, arsenic, vanadium, and cadmium were detected in the captured PM, and only lead was adsorbed on all soft contact lenses except senofilcon C. The largest deposition was 23.21 ± 0.70 (10^{− 3})µg/lens of the lead on lotrafilcon B. The oxygen transmissibility of nelfilcon A exhibited statistically significant changes, however, it was within the ISO standard tolerance. Nevertheless, changes in the central thickness, water content, and refractive power of each soft contact lens were not statistically significant. Conclusions: This study revealed that a considerable amount of lead in PM₁₀ was adsorbed on soft contact lenses. Amongst lens parameters, only oxygen transmissibility changed significantly. Thus, wearing soft contact lenses under high PM₁₀ concentration might affect the physiology of the eyes.