Comparison of responses to picosecond and nanosecond lasers in the treatment of hyperpigmented skin lesions

( Minkee Park ),( Hye Young Kang ),( Mi Soo Choi ),( Jong Gu Kim ),( Byung Cheol Park ),( Myung Hwa Kim ),( Seung Phil Hong ) 대한피부과학회 2015 대한피부과학회 학술발표대회집 Vol.67 No.2

Background: In the field of the treatment of pigmentary lesion, the picosecond 755 Кalexandrite laser has been recently introduced, hoping for a better effect on tattoo removal and pigmentation disorders. Objectives: This study compared the efficacy of the picosecond based alexandrite laser (750 Э, 755 К) with nanosecond based conventional Q-switched Nd:YAG lasers (10 Ю, 532 and/or 1064 К) lasers in the treatment of both epidermal pigmented and multi-colored dermal tattoo lesions. Methods: KIWA:A1 guinea pigs with epidermal hyperpigmentation induced by UVB irradiation were treated with each of 755 Кpicosecond laser or 532 КQs-Nd:YAG laser. 6 different color tattoos (red, orange, yellow, green, blue, and black) on the back of albino guinea pigs were treated with one session of 755 К picosecond, 1064 Кor 532 КNd:YAG laser treatment. Results: Although both picosecond and Nd:YAG lasers showed the same effect on epidermal hyperpigmentation, the Nd:YAG laser had more initial tissue reaction and latterly developed post-inflammatory hyperpigmentation. The picosecond laser was superior for removing blue and green color tattoos only, whereas it was inferior or similar for other colors. Conclusion: Picosecond laser is better than conventional Qs-Nd:YAG laser in the treatment of epidermal pigmented lesions, because of no damage to surrounding tissue. However, this device may be less effective in the treatment of color tattoo lesions.

Case series of split-face, single-blinded, randomized controlled comparison of Nd:YAG 1064-nm picosecond laser versus Nd:YAG 1064-nm nanosecond laser in the treatment of pigmentary disorders

( Myoung Eun Choi ),( Seung Hwan Paik ),( Ik Jun Moon ),( Woo Jin Lee ),( Chong Hyun Won ),( Mi Woo Lee ),( Jee Ho Choi ),( Sung Eun Chang ) 대한피부과학회 2019 대한피부과학회 학술발표대회집 Vol.71 No.1

Introduction: : Q-switched nanosecond lasers demonstrated their efficacy in various pigmentary disorders. However, there are limited data to compare Q-switched ruby and neodymium (Nd:YAG) nanosecond laser to Nd:YAG picosecond laser in the treatment of mottled pigmentation, lentigo and melasma. Methods: Picosecond 1064-nm Nd:YAG laser with spot size of 7 mm, fluence of 0.6 to 0.8 J/cm2, repetition rate of 10 Hz, 3 pass was delivered with a zoom hand piece to one side of face. Nanosecond 1064-nm Nd:YAG laser was delivered to the other side of face with spot size of 7 mm, fluence of 2.0 to 2.2 J/cm2, repetition rate of 10 Hz, 3 pass. Results: Three patient of Fitzpatrick skin type 3 and two patients of Fitzpatrick skin type 4 were enrolled. Pigmentary lesions assessed with global assessment scale from 0 (no pigmentation) to 4 (severe pigmentation) decreased from 2.8 to 1.25 in average after 6 sessions. The response was faster in nanosecond laser site. One patient showed postinflammatory hyperpigmentation (PIH) after nanosecond laser treatment. Patient satisfaction was meased with global assessment scale implying that all patients were comparably satisfied with both laser treatment. Discussion: Pigmentary lesions show faster response to nanosecond laser compared to picosecond laser. Nanosecond laser was more efficient in severe cases while PIH can result in dark skin. General skin tone becomes clear and bright after picosecond laser.

In Vivo and Ex Vivo Skin Reactions after Multiple Pulses of 1,064-nm, Microlens Array-type, Picosecond Laser Treatment

Herin Lyu,Jinyoung Park,Hee Chul Lee,이상주,Young Koo Kim,Sung Bin Cho 대한의학레이저학회 2020 MEDICAL LASERS Vol.9 No.2

Background and Objectives A picosecond-domain laser treatment using a microlens array (MLA) or a diffractive optical element elicits therapeutic micro-injury zones in the skin. This study examined the patterns of tissue reactions after delivering multiple pulses of 1,064-nm, MLA-type, picosecond neodymium:yttriumaluminum- garnet laser treatment. Materials and Methods Multiple pulses of picosecond laser treatment were delivered to ex vivo human or brown micropig skin and analyzed histopathologically. A highspeed cinematographic study was performed to visualize the multiple pulses of picosecond laser energy-induced skin reactions in in vivo human skin. Results In the ex vivo human skin, a picosecond laser treatment at a fluence of 0.3 J/cm2 over 100 non-stacking passes generated multiple lesions of thermally-initiated laser-induced optical breakdown (TI-LIOB) in the epidermis and dermis. In the ex vivo micropig skin, stacking pulses of 20, 40, 60, 80, and 100 at a fluence of 0.3 J/cm2 generated distinct round to oval zones of tissue coagulation in the mid to lower dermis. High-speed cinematography captured various patterns of twinkling, micro-spot reactions on the skin surface over 100 stacked pulses of a picosecond laser treatment. Conclusion Multiple pulses of 1,064-nm, MLA-type, picosecond laser treatment elicit marked TI-LIOB reactions in the epidermis and areas of round to oval thermal coagulation in the mid to deep dermis.

Treatment of Melasma and Post-Inflammatory Hyperpigmentation by a Picosecond 755-nm Alexandrite Laser in Asian Patients

( Ye Jin Lee ),( Ho Jeong Shin ),( Tai-kyung Noh ),( Kwang-ho Choi ),( Sung-eun Chang ) 대한피부과학회 2017 Annals of Dermatology Vol.29 No.6

The picosecond lasers have shown to effectively treat tattoo pigments that are intractable to previous multiple Q-switched (QS) laser treatments. Therefore we hypothesized that a picosecond laser would show better efficacy with minimal adverse events in the treatment of melasma and post-inflammatory hyperpigmentation (PIH) that are difficult to treat with conventional QS lasers. Two patients with melasma and one patient with PIH were treated with a Picosecond 755-nm Alexandrite Laser (Cyanosure, USA). All patients were Korean with skin type IV and no longer responding to QS laser treatments. Laser treatment was well tolerated in all the patients. Adverse events such as PIH were not reported during 8 weeks of follow up period. After the multiple treatment sessions, one patient reported fair improvement and two patients reported good improvement. Consistent with the clinical results, ex vivo skin model irradiated with a Picosecond 755-nm Alexandrite Laser also showed decreased epidermal keratinocyte necrosis compared with the 532-nm QS Neodymium-Doped Yttrium Aluminium Garnet Laser (Lutronic, Korea) yet decreased melanin content. In conclusion, the Picosecond 755-nm Alexandrite Laser may be useful for effective treatment of intractable melasma and PIH with fewer adverse events in dark Asian skin. (Ann Dermatol 29(6) 779∼781, 2017)

Combination Treatment of Nd:YAG Picosecond-domain Laser and Fractional CO2 Laser for Contracted Neck Scar with Hyperpigmentation

Woo Jung Choi,Eun Soo Park,Min Sung Tak,Sang Gue Kang 대한의학레이저학회 2021 MEDICAL LASERS Vol.10 No.1

There is growing interest in minimizing postoperative scarring after a thyroidectomy. Among the many treatment types, laser therapy, especially picosecond-domain laser therapy, is accepted as a standard method. In the present case, a patient with a pigmented, contracted scar was treated using the combination of a picosecond laser and ablative fractional (AF) CO2 laser. After 15 sessions of 1,064-nm picosecond with micro lens array (MLA) and AF CO2 laser application, the patient showed significant improvement in their pigmented lesions and scar contracture with no noticeable side effects for 16 months. These results suggest that a combination of picosecond laser with MLA and AF CO2 laser can treat pigmented, contracted scars safely and effectively.

A Split-Face, Single-Blinded, Randomized Controlled Comparison of 532 nm Picosecond Neodymium-Doped Yttrium Aluminum Garnet Laser versus 532 nm Q-Switched Neodymium-Doped Yttrium Aluminum Garnet Laser in the Treatment of Solar Lentigines

( Jung Yup Kim ),( Junghwa Yang ),( Gyoo Huh ),( Young-jun Choi ),( Won-serk Kim ) 대한피부과학회 2020 Annals of Dermatology Vol.32 No.1

Background: Solar lentigines are the most common form of benign epidermal pigmentation and one of the major cosmetic concerns in Korea. A 532 nm Q-switched neodymium: yttrium-aluminum-garnet (QSND) laser is typically used for the treatment, but the occurrence of post-inflammatory hyperpigmentation (PIH) is not rare. Recently, the use of picosecond (PS) lasers has emerged in pursuit of better outcomes. Objective: To objectively compare the efficacy and safety of 532 nm PS and QSND lasers for the treatment of solar lentigines. Methods: Twenty patients with solar lentigines were enrolled in a prospective, randomized split-face, single- blind study. One side of each face was treated using a 532 nm PS laser, and the other side using a 532 nm QSND laser. After one treatment, all patients were followed up for evaluation after 2, 4, 8, and 12 weeks. The clinical clearance was assessed by three blinded dermatologists using a 5-point quartile improvement scale (QIS). Subjective satisfaction, development of PIH, pain scale during treatment, and adverse problems were also recorded. Results: Clinical clearance measured by QIS showed that the PS laser was more effective than the QSND laser. Subjective satisfaction and pain scale did not significantly differ between the two groups. The incidence of PIH was 5% in sides treated with the PS laser, and 30% with the QSND laser. Conclusion: Both 532 nm PS laser and QSND laser were effective for the treatment of solar lentigines, but the PS laser was more effective with less PIH development. (Ann Dermatol 32(1) 8∼13, 2020)

Histopathological analysis of 1064-nm Nd:YAG picosecond laser-induced tissue reactions in vivo human skin

( Chang Jin Jung ),( Myoung Eun Choi ),( Seung Hwan Paik ),( Woo Jin Lee ),( Chong Hyun Won ),( Mi Woo Lee ),( Jee Ho Choi ),( Sung Eun Chang ) 대한피부과학회 2019 대한피부과학회 학술발표대회집 Vol.71 No.1

Picosecond lasers have become popular recently in Korea, but occurrence of laser induced optical breakdown (LIOB) is still unclear. The present study is designed to evaluate in vivo tissue reaction after fractional 1064-nm Nd:YAG picosecond laser. Fractional 1064-nm Nd:YAG picosecond laser at the fluence of either 250 mJ/cm2 or 500 mJ/cm2 was delivered to the back of 60-year-old man whose skin was Fitzpatrick skin type III. Skin biopsy was done before treatment, 30 minutes, 1 day and 1 month after laser irradiation. Histopathological study revealed the superficial cystic cavitation by LIOB in the specimen treated with the fluence of 250 mJ/cm2. At 1 day and 1 month after the treatment, in line with the increase of dermal thickness, both elastic fibers and collagen fibers increased. Both type IV collagen was and CD31 (+) vascular structure were intact. MMP-1 and MMP-3 were observed to increase in the dermis in compared with untreated skin, at 30 minutes, 1 day and 1 month after the treatment. Dermal remodeling with the increase of collagen and elastic fiber with release of MMP-1 and -3 was well demonstrated after photomechanical effect of fractional 1064-nm Nd:YAG picosecond laser. LIOB was observed to a limited extent, since the treated area was the back with little melanin. Our study suggests that fractional 1064-nm Nd:YAG picosecond laser may be effective for skin tightening through objective dermal remodeling in human skin.

Clinical trial for evaluating the efficacy and safety of laser treatment of fractional 1064-nm picosecond laser on skin rejuvenation

( Chung Hyeok Lee ),( Dong In Keum ),( Seung Phil Hong ) 대한피부과학회 2019 대한피부과학회 학술발표대회집 Vol.71 No.2

Background: Fractional laser technology is routinely used in the treatment of acne scarring, with thermal injury resulting in collagen synthesis and remodeling. Objectives: Investigate whether use of a Fractional treatment with a wavelength 1,064-nm picosecond-domain laser is effective for the treatment of wrinkles and acne scars. Methods: Patients received 3 laser treatments. Laser treatment were performed with a 1064-nm picosecond laser with fractional hand-piece. At 8-week after treatment, the final assessment was performed. Results: Three individual dermatologists compared the blinded pre- and post-treatment photo to assess the clinical improvement. Skin topography and elasticity were measured using Antera 3dTM and CutometerTM respectively. Fifteen women and 7 men (mean age, 39 years; age range, 21-66 years) are enrolled including 12 wrinkle and 10 acne scar patients. There were statistically significant clinical improvements after treatment compared with baseline (3 weeks: 19.1%, p<0.01; 6 weeks: 25.9%, p<0.01; 14 weeks: 35.2%, p<0.01). Skin topography analysis including wrinkle, texture, depression and pores revealed significant improvement compared with the baseline However, skin elasticity showed no significant differences. Post-treatment erythema, mild edema, and petechiae were the only side effects noted. Conclusion: This study revealed the treatment of fractional 1064-nm picosecond laser is an effective way to achieve skin rejuvenation.

A split-face, single-blinded, randomized controlled comparison of 532nm picosecond Nd:YAG laser versus 532nm Q-switched Nd:YAG laser in the treatment of solar lentigines

( Junghwa Yang ),( Yeon Gu Choi ),( Gyoo Huh ),( Hyeon Jeong Park ),( Yun Ho Lee ),( Sunmin Yim ),( Jung Yup Kim ),( Heun Joo Lee ),( Young-jun Choi ),( Ga-young Lee ),( Won-serk Kim ) 대한피부과학회 2019 대한피부과학회 학술발표대회집 Vol.71 No.2

Background: 532 nm wavelength of Q-switched neodymium: yttrium-aluminum-garnet (QSNY) laser is widely used for the treatment of solar lentigines. Recently, picosecond (PS) laser is emerging as a better treatment option for solar lentigines. Objectives: To evaluate the clinical efficacy and safety of 532 nm PS and QSNY laser in a split-face design. Methods: A prospective, randomized, split-face study of 532 nm PS laser and 532 nm QSNY laser was designed. Two laser sessions were performed at 2-week intervals. Clinical improvement was assessed by the number of lentigines, melanin index from 3D camera analysis, and 5-point quartile improvement scale (QIS). Development of PIH were also assessed. Results: A total of 24 subjects (23 females and 1 male) with Fitzpatrick skin types III to IV, mean age 50 years, were enrolled. The reduction of lentigo counts was not significantly different between the two groups, but the melanin index change showed a more significant improvement in the pico-arm. (p < 0.05). QIS showed 532 nm PS laser was more effective than 532nm QSNY laser. (p < 0.05) The incidence of PIH was 5% in 532nm PS laser, and 30% in 532nm QSNY laser. Conclusion: Both 532 nm PS laser and 532 nm QSNY laser are effective for the treatment of solar lentigines, however, 532 nm PS laser removed solar lentigines more effectively with less PIH.

피코초 레이저를 이용한 니켈의 미세가공 특성

신동식(D. S. Shin),이제훈(J. H. Lee),서정(J. Suh),노지환(J. H. Noh),정용운(Y. W. Chung),김재구(J. G. Kim) 한국정밀공학회 2006 한국정밀공학회 학술발표대회 논문집 Vol.2006 No.5월

In case of ultrashort laser ablation of metals, the transfer of energy from the electronic system causing strong absorption of laser light to the lattice needs relaxation times of the order of some picoseconds. Under the above theoretical background, nickel was ablated using femtosecond, picosecond and nanosecond laser. As a result, nickel ablation by picosecond laser and femtosecond laser, which are called ultrashort laser, has similar machinability because of relaxation time of metals, whereas nanosecond Nd:YAG laser has lower absorption, higher thermalization effect in comparison with ultrashort laser.