A comparison of four methods for determining viability in human dermal fibroblasts irradiated with blue light

(1) The four assays differed in their levels of sensitivity to cell viability. (2) The adverse effect of increasing doses seems to manifest as alteration of mitochondrial metabolism, followed by lysosomal dysfunction, membrane disruption and finally loss of cell membrane integrity. (3) Overall, irradiation with 3 J/cm2 or 55 J/cm2 did not adversely affect cell viability. Thus, doses below 110 J/cm2 appear safe.