The 24-hour follow-up photos followed the same overall trend, but there was an improvement in the erythema. Additionally, the erythema was characterized by more of a reddish-brown tone. Lentigines and pigmentation also lightened in color (Figure 1D).
The 1-week follow-up photos demonstrated further resolution of the erythema. Scant crusting was noted in 515 nm single pulse squares at all fluence ranges and pulse durations, as well as 560 nm single pulse squares at 20 J/cm2 for all pulse durations. Degree of crusting was co-observed with immediate postprocedure erythema response (Figure 1E).
All crusting resolved by the 2-week follow-up visit. Although most of the original crust resolved without any sequela, some of the crusted areas (515 nm, single pulse, 10 ms pulse duration, 18 and 20 J/cm2 fluence) was replaced by well-demarcated hairless hypopigmented square-shaped patches (Figure 1F). These same two patches were further demarcated at the 4-week follow-up.
The overall clinical outcome at the 4-week follow-up visit demonstrated greatest improvement in erythema and pigmentation using the 515nm filter. Clear demarcated areas of improvement were observed with the longer pulse duration (ie, 10 ms), single pulse, high fluences (ie, 18 and 20 J/cm2).
The 1-week follow-up photos demonstrated further resolution of the erythema. Scant crusting was noted in 515 nm single pulse squares at all fluence ranges and pulse durations, as well as 560 nm single pulse squares at 20 J/cm2 for all pulse durations. Degree of crusting was co-observed with immediate postprocedure erythema response (Figure 1E).
All crusting resolved by the 2-week follow-up visit. Although most of the original crust resolved without any sequela, some of the crusted areas (515 nm, single pulse, 10 ms pulse duration, 18 and 20 J/cm2 fluence) was replaced by well-demarcated hairless hypopigmented square-shaped patches (Figure 1F). These same two patches were further demarcated at the 4-week follow-up.
The overall clinical outcome at the 4-week follow-up visit demonstrated greatest improvement in erythema and pigmentation using the 515nm filter. Clear demarcated areas of improvement were observed with the longer pulse duration (ie, 10 ms), single pulse, high fluences (ie, 18 and 20 J/cm2).
DISCUSSION
The results of this case study conceptually align with our understanding of IPL therapy. Erythema response was inversely observed with filter wavelength (eg, the 515 nm filter had the strongest erythema response vs the 590 nm filter had the weakest erythema response). Given that IPL devices filter out wavelengths shorter than the selected filter wavelength, a 515 nm filter would allow for a greater spectrum of wavelengths to target the tissue chromophores at higher absorption coefficients. At 515nm, the IPL targets melanin at higher absorption due to the downward sloping nature of melanin’s absorption curve. Additionally, A 515 nm filter targets oxyhemoglobin at all major (ie, 540 nm and 577 nm) and minor (ie, 920–940 nm) absorption peaks.19 Lastly, it targets water in the infrared wavelength range. By targeting melanin, oxyhemoglobin/deoxyhemoglobin, and water, an IPL can treat pigmented lesions, vascular lesions, and stimulate collagen remodeling.20 The 560 nm filter did not produce as strong of an erythema response likely because it did not target the 540 nm oxyhemoglobin absorption peak. The vascular filter had an erythema response comparable to the 560 nm filter likely because it targets the same oxyhemoglobin peaks. The 590 nm filter had the weakest erythema response likely because it did not capture both the 540 and 577 nm oxyhemoglobin peaks. Subtle darkening of lentigines was seen with more robust erythema responses, which can be explained by the fact that shorter wavelengths allows for improved targeting of melanin at a higher absorption coefficient.
Erythema response was also observed with higher fluence levels, as well as longer pulse duration. Conceivably, delivery of greater energy to interact with tissue chromophores will produce a stronger response. Additionally, longer pulse durations facilitates greater interaction time with targeted chromophores. This likely explains the extensive crusting, hair removal, and well-demarcated hypopigmentation noted with the following settings: 515 nm, single pulse, 10 ms pulse duration, 18–20 J/cm2 fluence. In regard to pulsing, the fewer the number of pulses, the more exuberant the erythema response. Conversely, dividing a certain fluence over multiple pulses allowed the use of lower fluences for each stacked pulse, keeping the tissue response to a minimal. This allowed the surrounding tissue to cool while the target chromophores sequentially heat up. This is a safety benefit of MSP when treating darker and ethnic skin types.
Improved clinical response at the 4-week follow-up visit was observed where a greater erythema response was noted during the healing process. This finding was most apparent at the
Erythema response was also observed with higher fluence levels, as well as longer pulse duration. Conceivably, delivery of greater energy to interact with tissue chromophores will produce a stronger response. Additionally, longer pulse durations facilitates greater interaction time with targeted chromophores. This likely explains the extensive crusting, hair removal, and well-demarcated hypopigmentation noted with the following settings: 515 nm, single pulse, 10 ms pulse duration, 18–20 J/cm2 fluence. In regard to pulsing, the fewer the number of pulses, the more exuberant the erythema response. Conversely, dividing a certain fluence over multiple pulses allowed the use of lower fluences for each stacked pulse, keeping the tissue response to a minimal. This allowed the surrounding tissue to cool while the target chromophores sequentially heat up. This is a safety benefit of MSP when treating darker and ethnic skin types.
Improved clinical response at the 4-week follow-up visit was observed where a greater erythema response was noted during the healing process. This finding was most apparent at the
