Many researchers are now considering and comparing the properties, differences and benefits of SLED arrays and LASERs. It has been proven that more intensity is NOT necessarily better.
To consider which is best, we must take into account:
- The wavelength (nm) colour of the light;
- The coherency – is it coherent LASER or non-coherent SLED light;
- The dose or timed duration;
- The power or fluency (j/cm2);
- The pulse and frequency of the pulse;
- The polarisation; and
- Lastly, does the light stimulate systemic effects throughout the tissues?
The qualitative picture described explains why coherent and non-coherent light with the same parameters (i.e., wavelength, dose, intensity) produce the same biological effects on cell monolayers (Karu et al., 1982a, b), and in dilute cell suspensions (Karu et al., 1983; Bertoloni et al., 1993), as well as on tissue surfaces (e.g., the healing of peptic ulcers; (Karu et al., 1984; Sazonov et al., 1985). In these cases, the healing effect of irradiation is occurring via absorption of light by photoacceptors (cytochrome C oxidase in particular, Karu, 1999, 2003).
However, some additional (therapeutic) effects from coherent and polarized radiation, in addition to those caused by light absorption by photoacceptors molecules, can appear in deeper layers of bulk tissue. In any case, the main therapeutic effects occur due to light absorption by cellular photoacceptors. (Karu 2011)