Biological effects have also been noted with non laser light sources which casts doubt on the need for either monochromaticity or coherence. Additionally, laser light loses both its collimation and coherence, once it penetrates into the tissue. 31 Multiple in vivo and in vitro effects have been ascribed to laser application. Human in vitro effects ascribed to lasers have often been the result of non peer reviewed literature, anecdotal reports, uncontrolled studies, published abstracts, controlled studies in which the study methodology has been poorly described, as well as controlled studies with contradictory results. These results do not support the use of cold lasers for the treatment of such conditions.
Several studies do suggest that cold lasers are effective in the treatment of rheumatoid arthritis.
As previously noted however, these studies suffer from significant flaws in methodology or reporting and publication. In addition, the study by Goldman indicated that rheumatoid patients treated with cold laser on only one hand, with placebo treatment of the other, experienced significant improvement in both. 45 One study provides preliminary support for the use of the cold laser in the treatment of trigger points. 47 Laser application was found to increase skin resistance, which in a previous study had been associated with a resolution of the condition. A study of the cold laser for the treatment of lateral epicondylitis revealed some improvement in objective measures but no change in subjective pain reports.