Experimental substantiation of the selectivity effect of «green» laser light at hemoglobin-containing tissues

Abstract

Currently, medical specialists still face problems while treating pathological subepithelial capillary structures, in particular, capillary angiodysplasias of the skin. One of the promising techniques for their removal is photothermolysis by laser light of yellow-green spectral range which is selectively absorbed by pigments, hemoglobin, blood in the vessels with further vessel hardening and regression. Purpose . To make a comparative trial in vitro at experimental models so as to confirm the effect of selectivity of «green» laser light at hemoglobin-containing tissues, in particular, at subepithelial vascular structures. Material and methods : An experimental solid-state semiconductor laser, generating green light with wavelength 525 nm which is near the absorption peak of hemoglobin and oxyhemoglobin, was used. Experimental models were cooled samples of the liver, skin and a preparation combined of them as well as laboratory minipigs of Svetlogorsk population. In the trial, the researchers compared changes developed after the irradiation of abovementioned objects with «green» laser light. To make comparison, morphological, macroscopic and histological findings from irradiated zones were analyzed. Results . Specific differences in the damaged zones of experimental models as well as in the liver and skin were found. While examining the liver, one can see locally more pronounced changes and a minus destruction looking like a narrow sphenoid-shaped crater with relatively narrow zones of compact and cellular necrosis, clear boundaries between them as well as unchanged adjacent tissues. On the skin, one can see a minus destruction of much smaller size with zone of peripheral coagulation 3–5 times wider and without compact and cellular layers; there are also no clear boundaries with unchanged tissues. In the combined sample, green laser light – which is less absorbed by the skin- penetrates through it, thus affecting the underlying liver where one can see more pronounced thermal changes, if to compare with the skin. Conclusion . The selectivity effect of «green» laser light with wavelength 525 nm at hemoglobin-containing tissues has been confirmed. This conclusion is a promising finding for applying the selective photothermolysis in pathological subepithelial capillary structures which will ensure precise treatment with minimal damage to skin tissues.