Abstract: Objective To study the effect of variable pulse width 1064 nm Nd:YAG laser on port wine stain(PWS)in an animal model.Methods Leghorn chicken was used as an animal model.Ten chickens were divided into 5 groups,the combs of which were irradiated with variable pulse width 1064 nm Nd:YAG laser at different doses(0,90,100,110,120 J/cm²)with a pulse width of 11.5 ms and facula diameter of 6 mm.The comb of every chicken was irradiated at 4 areas.The appearance of the comb was observed daily until the 37th day after the irradiation.And,one week after the irradiation,pathological exam-ination was performed on these combs to analyze the histological and vascular changes.Results After one session of irradiation,the color of treated area became lighter.Under light microscopy,there was thinning of the vascular layer,and some blood vessels showed atresia with few or no red blood cells in their cavities. The vessel number decreased significantly compared to that before the irradiation(P<0.05).Within a certain range,the higher the energy,the more obvious the changes.Conclusion Variable pulse width 1064 nm Nd: YAG laser could treat PWS by inducing atresia of vessels,decreasing the number of blood vessels,and reducing the thickness of the layer.

Key words: Port-wine stain, Lasers, Disease models, animals, Chickens