Acrylate yellow filters in operating lights protect against photosensitization tissue damage

Background: Photosensitized patients are exposed to bright lights when unde rgoing intraoperative photodynamic therapy or fluorescence measurements. Ac rylate yellow filters might reduce unwanted tissue damage. Methods: To investigate the protective value of these filters, the spectral power distribution of the operating lights and light energy densities with and without an acrylate yellow filter were measured. Subsequently the effe cts of light exposure on the survival of a human hepatocellular carcinoma c ell line and the photodamage induced in pig tissues after the administratio n of 5-aminolaevulinic acid were also studied. Results: The light energy density in the ultraviolet and blue region of the light spectrum emitted by the operating light was reduced up to 50 per cen t by the acrylate yellow filter. The survival of photosensitized cells was longer and photodamage induced in pig tissues was less when exposed to filt ered light. Conclusion: Photodamage induced by operating lights can be reduced by filte ring out ultraviolet and blue light by means of acrylate yellow filters.