A B L A T I V E A N D N O N A B L A T T V E S K I N R E J U V E N A T I O N A N D T E L A N G I E C T A S I A
It has been suggested that the erbium:yttrium-aluminum- garnet [Er:YAG) laser is associated with less erythema and a lower risk of hyperpigmentation and, therefore, is particularly useful for dark-skinned patients. For laser
resurfacing, we adopt the combination approach in which three passes with a COz laser are followed immediately by one pass with an Er:YAG laser In our experience, such a combination can reduce the degree of erythema and PIH More recently, long-pulsed Er:YAG lasers have been used to achieve better hemostasis and some degree of collagen contraction. Jeong and Kye (2001J studied the use of such a system among skin type III and IV patients with pitted acne scars. They found a good-to-excellent response in 930/o of patients, but erythema lasting more than 3 months was seen in 54o/o Single pass CO2 laser skin resurfacing has recently been shown to be effective in the treatment of acne scar and wrinkle reduction in dark-skinned patlents, with reductions in the severity and duration of laser-associated complications.
As mentioned earlier, fractional resurfacing can now be performed by multiple methods either through the use of scanning or stamping modes. In the initial scanning mode, the typical setting for the treatment of acne scarring and wrinkle reduction is l6-20 rr'J, 125 microthermal zones (MTZsl per pass for 4-8 passes. In one of the authors' (HC) experience, reducing the number of passes per treat- ment session reduces the pain and risk of PIH. The disad- vantage of this approach is that more treatments are generally necessary to obtain the optimal clinicai outcome.
A new version ofthe scanning device allows greater depth of penetration by automatic adjustment of the spot size when higher energy is used In one of the authors' (HC) experience, the pain that is associated with the procedure has decreased significantly despite the use ofhigher energy.
For this device, much higher energy can be used for the treatment of acne scarring and wrinkle reduction (30- 40 mJ, treatment level 8-9]. The typicai treatment inter- val for acne scarring and wrinkle reduction is 4-6 weeks.
These delayed intervals between treatments allow the inflammation at the epidermal-dermal junction to settle, thus further reducing the risk of PIH. The specific risk of PIH, with this new scanning device, is not known but is likely to be less than the initial scanning model due to reduction in bulk tissue heating. For melasma, lower energy but higher density should be used (6-7 mJ, 250MTZ, 6-10 passes) The use of topical bleaching agents, as adjunctive therapy for melasma treatment, is important to further enhance the result. For resistant cases, one of the authors (HC) has used a large spot size QS 1064-nm Nd:YAG [7-mm spot size, 1.6 l/cmz) immediately before fractional resurfacing to further enhance the result. This approach has been successful in
S O M E C A S C S ,
For nonablative skin rejuvenation, using a 1320-nm Nd:YAG laser, a spot size of 10 mm is used with three passes performed (2 precooling and I postcoolingJ Using real time temperature monitoring, the fluence is adjusted so that the skin temperature reaches 42-45'C immedi- ately after laser exposure for the precooling passes and less than 40"C for the postcooling pass. Patients should receive monthly treatment for 5-6 treatment sessions, and should be followed up 4-6 weeks after their last treatment
8 l L a s e r T r e a t m e n t o f E t h n i c S k i n
for final assessment. For nonablative skin rejuvenation, using a 1540-nm erbium:glass laser, we tend to use higher fluences than previously documented, and treat the perr- orbital area with three stack oulses of l0J/cm2 and the rest of the Face with five stacli pulses of l0 J/cmz.
For IPl-induced nonablative skin rejuvenation, the main clinical end point is mild erythema. If significant erythema persists after IPL treatment/ especially in a non- pigmented area, we apply a moderate-potency topical steroid immediately after treatment. The use of an icepack after treatment can reduce the IPl-induced ohotothermal effect and is best avoided.
For the treatment of lentigines in ethnic skin, test areas using different lasers might be considered. When usrng a variable pulse 532-nm Nd:YAG laser, without cooling, the suggested parameters are aZ-mmspot size and 6.5-8 J/cm2, with an ashen gray appearance as the clinical endpoint If the variable pulse 532-nm Nd:YAG laser is attached to a cooling glass water chamber, then the fluence should be increased to 1,2-14 J/cmz to compensate for the reduction in photothermal effect. Recently, a pulsed dye laser attached to a compression handpiece has been developed to allow the laser to be used effectively for pigment removal. The intention is to press and empty the blood vessels and, in doing so, remove the competing hemogiobin chromophore. A recent study compared the efficacy and complications of the QS ruby laser with those of a long- pulsed 595-nm pulsed dye iaser, with an attached com- pression window, for the removal of lentigines among Japanese patients. The group treated with the compressron technique was associated with a lower risk of PIH than the group treated with QS laser, while the degree of efficacy was the same in both groups. The typical parameters for such long-pulsed dye lasers with compression windows are 7-mm spot size, I .5-ms pulse durations, and I l-13 J /cmz , wrth an ashen gray appearance as the end point
\A4ren using a QS laser, the clinician should use the lowest fluence and the smallest possible spot size (and therefore spare the surrounding normal epidermis) to obtain immediate whitening For example, for the QS 532- nm Nd:YAG laser, a 2-mm spot size with 0.9-l J/cm2 should be used In some devices, that are only available with larger spot size handpieces, such an approach is not possible for mechanical reasons, and it is best to use the lowest possible fluence. In all cases, a moderate-potency steroid mix with antibiotic is applied once immediately after the treatment to reduce the risk of PIH.
ABNOM tends to be more resistant to therapy, and such patients should be treated more frequently, with the laser procedures repeated every 4 weeks The idea behind such an aggressive approach is to treat the area before epidermal repigmentation. In doing so/ more laser energy can reach the dermal target chromophore through a hypopigmented epidermis without the competitive absorption of epidermal melanin. For resistant cases (failure to improve after 4 treatment sessions), QS alex- andrite laser treatment is followed immediately bV QS 1064-nm Nd:YAG laser treatment. The fluence should
be lower (4-5 J/cn'? for both lasers), and the repetition rate should be reduced (to no more than 3 Hz) in order to reduce the risk of adverse effects. Nonetheless, a tran- sitory post-treatment pigmentary alteration is not uncom- mon, and patients should be warned about this before their treatment.
In principle, the clinical end point for IPL and long- pulsed laser treatment of facial and leg telangiectasia is immediate vessel disappearance or darkening of the vessel hyperemia For the shorter pulse width lasers, purpura is the end point \A/hen such lasers/lPl are used for the treatment of vascular lesions in dark-skinned patients, it is important to achieve optimal cooling to ensure adequate epidermal protection. The high epidermal melanin context is such that inadequate cooling can lead to a higher risk of complications. However, overcooling can lessen efficacy by reducing the photothermal effect on the dermal vessels.
Furthermore, cold-induced injury can also occur, leading to blister formation and pigmentary disturbances Although many devices are used for cooling, data on dark-skinned patients are limited. Cold air has been used in conjunction with pulsed dye lasers for the treatment of port-wine stains in light-skinned patients, but there is no published data on the efficacy of cold air as a cooling device when used with a vascular laser in dark-skinned patients. Contact cooling can offer good epidermal protection, but in areas such as the alar folds good contact is difficult and addi- tional cold gel is necessary. It is also important, when contact cooling is used, to reduce the laser repetition rate to ensure adequate time for pre-, parallel, and post- cooling It is also undesirable to press the contact cooling glass chamber too firmly against the skin, as this empties the vessel and reduces efficacy. For cold gel, adequate uniform cooling is difficult and can only be achieved ifthe gel is applied to a small area. Cold gel should be kept in an ice bucket between applications so that the gel tem- perature remains cold. Cryogen spray has also been used with IPL handpieces, and as with cold gel a repeat spray is necessary to maintain adequate cooling. Of these cooling devices, dynamic cooling with cryogen spray has been best studied in dark-skinned patients. For pulsed dye laser treatments/ the optimal parameter in our own unpub- lished data for skin types III and IV appears to be 40-ms spray time followed by a 20-ms delay. For skin types V and VI, a study indicated that the high epidermal melanin concentration can reduce the protective effect of cryogen spray cooling More recently, multiple intermittent cryogen spurts and laser pulses have been proposed to provide adequate epidermal protection while permitting PWS photocoagulation for darker-skinned patients [Fitz- patrick skin type III-VI). This has now been studied using heat diffusion, light distribution, and thermal damage computational models.
The combined approach for skin rejuvenation involves the use of several devices in the same treatment session, with the intention of optimizing the clinical outcome. To reduce the possibility of adverse effects, lower fluences should be used. In one of the authors' (HC) experrence,
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L a s e r s a n d L i g h t s V o t u m e l l
this approach can be verv cffcctive fbr nonablative skin reluvenation Typically, a r.ascular laser and an infrarecl laser are used, follor'r.cd b.v selective treatment r,r.ith a pigmented laser/lPL For erarlple, the lr'hole facc is treated rvith either a largc spot size 532-nm Nd:YAG l a s e r ( 1 0 - m n r s p o t s i z c , 7 J / c m 2 , 2 0 m s f o r I p a s s ) , o r pulsed dye laser [595 nm, 1O-mm spot sizc, 7 5-9 J/cm2, Dvnamic Coohng Device (DCDI 40ms/20ms delayJ, fbllor'r.ed by either long-pulsed l064-nm Nd:YAG lascr ( 1 0 - m m s p o t s i z e , 4 0 J / c t n 1 , 4 5 - m s p u l s e s ) , o r a 1 5 4 0 - n n r E r : Y A G l a s e r fl0J/crnr,3 stack pulses.). I m m e d i a t c l r , afteru.ard, a prgrnentcd laser is used to remo\,e individual l e n t i g i n c s ( F i g s 5 . r r a n d 5 . r z )
For laser hair removal, long-pulsc pulsed diode, alex- andrite, and 1064-nm Nd:YAG lasers can all be uscd Detailed treatment parameters are drscussed in anl' hair removal textbook A longer u.avelength 1aser, offcring .r
F i g . 5 . 1 1 N o n a b l a t i v e s k i n r e j u v e n a t i o n u s i n g a c o m b i n a t i o n o f devices to improve pigmentation (cross polarized view)
greater dcgrcc of epidermal protection, is more appropri- ate rvhen used rn dark-skinned patients Adequate cooling is once again important for laser/lPl hair removal Fur- thermore, for dark-skinned patients a lor'r. fluence ."r,.ith long pulse duration can reduce the risk of comphcations When using a diode laser equipped u'ith contact cooling, the adhesron of burned hair to the chill tip can be a problem This ar.oidable complication can cause burns and s u b s e q u e n t P I H ( F i g . 5 . t 3 ) .
. The prevention and management of postinflam matory hyperpigmentation
Postinflammatory hyperpigmentation is the most common complicatron in dark-skinned patients, and effectire pre- vention and subsequent management is important All patlents should use sun protection and avord sun exposure before laser or IPL surgery It is not uncommon for patlents to misunderstand the meaning of sun avoidance, and to onl1, avoid sunbathing. It is important to emphasize
F i g . 5 . 1 2 N o n - a b l a t i v e s k i n r e j u v e n a t i o n u s i n g a c o m b i n a t i o n o f devices to improve pore size (parallel polarized view)
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to all patients that they should apply sun block (preferably containing titanium dioxide and zinc oxide) every day for 2 weeks before laser/lPl surgery, whether or not they engage in any outdoor activities. Ultraviolet light pro- tected clothing is also useful. The application of moder- ate-potency topical steroid immediately after laser and IPL surgery may also reduce the risk of PIH.
The use of topical bleaching agents before and after treatment may also be important. Many different combi- nation topical agents, containing tretinoin, hydroquinone, topical steroid, alpha-hydroxy acid (AHAJ, kojic acid, and/or azelaic acid, have been advocated In our practice, all patients are given a combination of azelaic acid mixed with 40lo hydroquinone and a moderate-potency steroid one day before treatment and then for 4 weeks after treat- ment. Tretinoin is added if the patient experiences no irritation If PIH develops despite the use of such agents, we add 50/o glycolic acid in the morning to further reduce the hyperpigmentation. Depending on the degree of irrita- tion, we add other bleaching agents, including vitamins C and E, and kojic acid. If PIH persists, then we perform a mild glycolic acid peel (20-35%J about 6 to 8 weeks after the treatment The use of microdermabrasion may also be effective as an adjunctive means to improve superficial
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