In vitro impact of laser irradiation on platelet aggregation.

The review of blood optical and rheological parameters plays an important role in many medical routine diagnosis and therapeutic applications and is the best way to understand the mechanism of action of low-level laser irradiation on biological tissues. The aim of this study was to investigate the in vitro effect of laser radiation on platelet count and aggregation. Blood samples were obtained from 30 healthy volunteers; each sample was divided into four aliquots, one of them was considered as a control while the other three were exposed to three different laser doses. A wavelength of 532 nm and a low power of 100 mW were used for irradiation with a 4-mm-diameter beam spot. The irradiation times were 1.8, 3.7, and 6.2 s giving doses of irradiation 1.5, 3, and 5 J/cm2, respectively. Microsoft Excel was used for statistical analysis. Low laser irradiation induced significant changes in platelet aggregation in the presence of weak agonists such as adenosine diphosphate (ADP) (P ≤ 0.05) and epinephrine (P ≤ 0.01). Low-level laser therapy has no influence on platelet count; however, it promotes platelet aggregation in response to weak agonists, specifically ADP and epinephrine.