Among all the light sources, IPL combined with ALA PDT has been the most extensively studied for use in photorejuvenation; this largely stemming from the fact that IPL has independently been shown to rejuvenate skin while spanning wavelengths that activate PPIX. The advantage of IPL (spanning the 400-1200 nm range) is the ability to target both melanin and hemoglobin, thereby improving both dyspigmentation and vascularity. The term “photorejuvenation” was coined to describe the global improvements in photoaging that are observed with the IPL. Filters are placed to exclude shorter wavelengths, thereby selectively targeting various chromophores and typically 5-6 monthly treatments are administered in order to achieve substantial clinical results. IPL alone has yielded modest clinical improvement in rhytides, while pigment and vascular abnormalities of photoaged skin are markedly improved [59 ] . When studied for rhytide-reduction, histologic evidence of neocollagenesis was observed six months after treatment [60]. Such histologic changes indicative of a dermal remodeling effect, such as an increase in extracellular matrix proteins and neocollagenesis are consistently reported [61]. Patient perception of efficacy is high due to the visible improvements in dyspigmentation and vascularity, which are more easily detectable than mild changes in rhytides, making this device a mainstay in nonablative resurfacing.
The addition of topical ALA prior to IPL has augmented the efficacy observed per treatment, with greater pigmentary, vascular, and rhytide improvement [62-64]. The term photodynamic photorejuvenation has been applied to the use of IPL in the treatment of AK and photodamage [62]. The IPL is an appealing light source for ALA PDT since it spans wavelengths from the blue to the infrared range activating the multiple peaks along the PpIX absorption spectrum. The IPL has been the most rigorously studied light source for the use of PDT in photorejuvenation. A randomized, split-face design clinical study comparing ALA IPL to IPL alone demonstrated greater improvement on the ALA side in erythema, dyspigmentation, and fine rhytides following two monthly treatments [63]. Another IPL following a 1-2-hour incubation of topical ALA resulted in crusting when fluences above a certain threshold were delivered [64]. ALA IPL appears to be more variable in clinical response and side-effect profile, likely due to the variability of different IPL devices in wavelength irradiances. Overall, the response and accompanying side effects from IPL PDT may range from none to marked. The advantages of this light source therefore include its versatility; however, the disadvantage is also its variability in level or response and side effects. Figure 21.3A and B shows a patient with photoaging prior to and following PDT with ALA and IPL, respectively, with improvement in keratoses, erythema, texture, and fine rhytides.