Multiple pass treatment methods (R20, as mentioned above, and R0) have generally shown to carry a greater risk of side effects, due to the increased amount of energy used in treatment. One caveat to this, however, is incorporating a perfluorodecalin (PFD) patch into the protocol. A PFD patch utilizes a clear silicone gel patch, with a small amount of PFD liquid applied to the treatment area immediately before each pass of laser application, and conducting the passes in rapid succession. The combination of the patch and liquid reduce the epidermal scatter, which can limit the predicted side effects typically seen in aggressive laser tattoo removal treatments (hyper and hypopigmentation, blistering, etc). Additionally, the liquid reduces the laser frosting very quickly, allowing for faster re-treatment, limiting the time of treatment while still improving efficacy. Early studies have been performed to indicate improved clearance with the use of this patch in 3-4 passes, in a single session, utilizing more energy than typically allowable with a traditional treatment methodology. All these physical properties of the patch work to substantially reduce the total number of laser treatment required for ink clearance. While the PFD patch is currently FDA cleared for use with all pico and nanosecond domain lasers and wavelengths, it is only cleared for Fitzpatrick Skin Types I-III. Early studies have shown anecdotally that there isn't necessarily increased risks with Fitzpatrick Skin Types IV-VI, though still not FDA cleared as an indication.