This is an excellent question. Both of these lasers, the Pulse Dye laser, with a wavelength of 595nm and the KTP-YAG (one of the lasers within the Excel V) with a wavelength of 532nm, are great choices for rosacea. They are, in fact, the best choices for the redness and vascularity associated with rosacea--at least in my opinion. Both of these wavelengths target hemoglobin in the dermis and destroy the capillaries that cause redness. The difference is the down time. The PDL literally "explodes" or ruptures the capillaries. This can cause blood to seep out into the tissue and get "cooked" by the heat of the laser. The result is what I like to called a cooked bruise, or in medical terms, purpura, and takes awhile to go away. The KTP-Yag is gentler. It collapses the vessels and hopefully damages them enough that the body will absorb them. There is no bleeding or bruising so there is little down time. However, if the vessels are not damaged enough the body will heal them. So, there is less downtime but you may need more treatments. The PDL has significant down time but you may only need one or two treatments. It really comes down to patient preference.
