Quantitative fluorescein angiography following diode laser retinal photocoagulation.

OBJECTIVE: An in vivo study was done to establish if laser-induced damage of the retina could be quantified using fluorescein angiography. METHOD: This study was carried out on rabbit eyes (n = 6) with an 810 nm diode laser (spot diameter: 500 microm, pulse duration: 1 second, power: 100 mW-400 mW) adapted on a slit lamp. Fluorescence measurements were performed with a fundus camera connected to a fluorescence imaging system. Fluorescence staining of the retina was evaluated by mathematical modeling. Lesions were correlated to laser parameters and to histologic data. RESULTS: Image analysis shows that the laser lesions stained progressively. Fluorescence appears first at the borders of the lesion exhibiting a fluorescent ring. A progressive increase of the fluorescence into the central zone is observed. The maximum fluorescence intensity into the center of the laser spot is obtained after a delay depending on the laser energy. Below 100 +/- 20 mW, lesions are detectable by fluorescence imaging only. A fluorescence plateau appears for a threshold light dose above 200 +/- 20 mW. Mathematical modeling demonstrates that quantitative assessment of laser-induced damage to the retina is feasible using fluorescence imaging. CONCLUSION: The quantification of fluorescence staining in terms of both intensity and time can contribute to a better quantification of laser-induced damage. At last, since laser damage may mimic naturally occurring pathology, this method should also be considered to quantify different types of lesions.     

Laser-Induced Release of Liposome-Encapsulated Dye: A New Diagnostic Tool

This paper reviews applications of laser-induced release of liposome-encapsulated dye as a diagnostic tool. The technique consists of encapsulating a fluorescent dye into liposomes at high concentration. Before injection, liposomes are not fluorescent. After systemic liposome injection, a laser beam is used to increase the temperature at a specific site (blood vessel, biological structures, etc.). This increase of temperature causes leakage of liposomal content. The dye is released in the surrounding medium and then diluted, leading to the appearance of fluorescence. Recent experiments in animals have demonstrated that this technique could be used in ophthalmology for the simultaneous measurements of blood flow in the retinal arteries, veins and capillaries of the macula and optic nerve. Since many diseases of the retina result in changes in retinal circulation, information on haemodynamics can be important in the diagnosis of these diseases and the evaluation of current and new therapies. Similarly, laser-induced thermal damage can be quantified by this technique. In that particular case, the phase-transition temperature of the liposomes is adapted to the tissue temperature range. Since tissue thermal damage is unwanted, the laser wavelength is chosen to avoid any direct absorption of light by the dye entrapped into the liposomes. Different fluorescence images can clearly document tissue thermal damage depending on target (blood vessel or parenchyma) and energy deposition in tissue. One of the most significant applications of this experimental technique could be the evaluation of various degrees of tissue thermal damage. The application of this new diagnostic tool for general clinical practice would require consideration of the use of liposomes in humans.     

Laser-induced release of liposome-encapsulated dye to monitor tissue temperature: A preliminary in vivo study

Background and Objective: The objective of this in vivo study was to assess the possible use of temperature-sensitive liposomes as a new approach to monitor the temperature induced by a laser. Study Design: An in vivo/ex vivo study was performed in rat liver after i.v. injection of liposomes loaded with a fluorescent dye. Materials and Methods: Temperature-sensitive liposomes (DSPC: Di-Stearoyl-Phosphatidyl-Choline) were loaded with carboxyfluorescein. These liposomes (1 ml solution) were injected into adult male Wistar rats. Two hours later, the liver was exposed and irradiated with a 100 W Nd:YAG laser using pulses lasting from 100 to 260 ms. Simultaneously, the surface temperature was recorded with a thermographic camera. The fluorescence emission was measured with a fluorescent imaging system. Results: The results showed that the dye was released in response to laser energy. The amount of the drug release increased linearly with increasing temperature in the range 42–60°C. Moreover, the release occurred in a short period of time upon brief exposure to its phase transition temperature. Conclusion: The feasibility of temperature monitoring by using laser-induced release of liposome-encapsulated dye was demonstrated. This procedure could conceivably prove useful for controlling the thermal coagulation of biological tissues such as blood vessels. © 1995 Wiley-Liss, Inc.     

Chitosan adhesive for laser tissue repair: in vitro characterization

BACKGROUND AND OBJECTIVES: Laser tissue repair usually relies on hemoderivate protein solders, based on serum albumin. These solders have intrinsic limitations that impair their widespread use, such as limited tensile strength of repaired tissue, poor solder solubility, and brittleness prior to laser denaturation. Furthermore, the required activation temperature of albumin solders (between 65 and 70 degrees C) can induce significant thermal damage to tissue. In this study, we report on the design of a new polysaccharide adhesive for tissue repair that overcomes some of the shortcomings of traditional solders. STUDY DESIGN/MATERIALS AND METHODS: Flexible and insoluble strips of chitosan adhesive (elastic modulus approximately 6.8 Mpa, surface area approximately 34 mm2, thickness approximately 20 microm) were bonded onto rectangular sections of sheep intestine using a diode laser (continuous mode, 120 +/- 10 mW, lambda = 808 nm) through a multimode optical fiber with an irradiance of approximately 15 W/cm2. The adhesive was based on chitosan and also included indocyanin green dye (IG). The temperature between tissue and adhesive was measured using a small thermocouple (diameter approximately 0.25 mm) during laser irradiation. The repaired tissue was tested for tensile strength by a calibrated tensiometer. Murine fibroblasts were cultured in extracted media from chitosan adhesive to assess cytotoxicity via cell growth inhibition in a 48 hours period. RESULTS: Chitosan adhesive successfully repaired intestine tissue, achieving a tensile strength of 14.7 +/- 4.7 kPa (mean +/- SD, n = 30) at a temperature of 60-65 degrees C. Media extracted from chitosan adhesive showed negligible toxicity to fibroblast cells under the culture conditions examined here. CONCLUSION: A novel chitosan-based adhesive has been developed, which is insoluble, flexible, and adheres firmly to tissue upon infrared laser activation.     

Laser skin welding: in vivo tensile strength and wound healing results

BACKGROUND AND OBJECTIVE: Laser skin welding was investigated as a general model for laser tissue closure. Scanned delivery of near-infrared laser radiation in combination with a dye can produce strong welds with limited thermal damage. STUDY DESIGN/MATERIALS AND METHODS: Two-centimeter-long, full-thickness incisions were made on the backs of guinea pigs. Wounds were closed either by laser welding or sutures and then biopsied at 0, 3, 6, 10, 14, 21, and 28 days postoperatively. Welding was achieved by using continuous-wave, 1. 06-micrometer, Nd:YAG laser radiation scanned over the incisions to produce a dwell time of approximately 80 msec. The cooling time between scans was fixed at 8 seconds. A 4-mm-diameter laser spot was maintained during the experiments, and the power was kept constant at 10 W. The operation time was fixed at 10 minutes per incision. India ink was used as an absorber of the laser radiation at the weld site, and clamps were used temporarily to appose the incision edges. RESULTS: Acute weld strengths of 2.1 +/- 0.7 kg/cm(2) were significantly higher than suture apposition strengths of 0.4 +/- 0.1 kg/cm(2) (P < 0.01), and weld strengths continued to increase over time. Lateral thermal damage in the laser welds was limited to 200 +/- 40 micrometer near the epidermal surface with less thermal damage deeper within the dermis. CONCLUSION: Our welding technique produced higher weld strengths and less thermal damage than reported in previous skin welding studies and may represent an alternative to sutures.     

CO2 and argon laser vascular welding: acute histologic and thermodynamic comparison

CO2 and argon lasers have been used successfully for vascular welding in both experimental and clinical settings. This study compared the thermodynamics during CO2 and argon laser welding of 1-cm longitudinal arteriotomies in a canine model. Continuous recordings using an AGA 782 digital thermographic system with spatial and thermal resolution of +/-0.2 mm and +/-0.2 degree C, respectively, were analyzed. A HGM argon laser using a 300-microns optic fiber held at 1 cm from the vessel edges (spot diameter = 2.8 mm) with concomitant room temperature saline irrigation (1 drop/sec) was used for argon welds. Total exposure time was 150 sec/cm. CO2 welds were performed with a Sharplan CO2 laser (spot diameter = 0.22 mm) with no irrigation for total exposure time of 10 sec/cm. Thermodynamic results and laser parameters are summarized as follows: Argon-n = 20; power = 500 mW; energy fluence = 1,400 J/cm2; Tmax = 48.8 degrees C; T mean +/- S.D. = 45.1 +/- 2.7 degrees C; CO2-n = 20; power = 150 mW; energy fluence = 3,000 J/cm2; Tmax 84.0 degrees C; T mean +/- S.D. = 60.7 +/- 9.8 degrees C. There was a significant difference (P less than .05) in thermal measurements between successful CO2 and argon vascular welds. Temperature rise during the argon welds was limited by saline irrigation. In contrast, during CO2 laser welding, the temperature rose quickly to its maximum and was maintained at a relatively high level as the laser progressed (0.1 cm/sec) along the anastomosis.(ABSTRACT TRUNCATED AT 250 WORDS)     

Laser irradiative tissue probed in situ by collagen 380-nm fluorescence imaging

BACKGROUND AND OBJECTIVE: There is no ideal method to detect molecular changes in situ of laser-irradiated tissue without removing a section of tissue for histologic examination. A new method is reported to evaluate laser-induced thermal tissue damage in situ by using 380-nm native fluorescence imaging under 340-nm excitation. STUDY DESIGN/MATERIALS AND METHODS: Native fluorescence imaging was performed on laser irradiated bovine tendon tissue and compared with light illuminated photography and histology with picrosirius red F3BA stain. RESULTS AND CONCLUSION: The results indicate that a decrease in collagen fluorescence at 380 nm was observed in laser-induced thermally damaged tissues. The injured region of tissue defined by its fluorescence image coincided with an area defined by photography and histology.     

Carotid artery anastomosis with albumin solder and near infrared lasers: a comparative study.

BACKGROUND AND OBJECTIVE: Laser tissue-welding has been used for anastomosis of carotid arteries. During welding, thermal injury sustained by the vessel walls should be minimized to prevent thrombosis. Two different types of lasers were used and effects on tissue damage were studied in vitro and in vivo. STUDY DESIGN/MATERIALS AND METHODS: End-to-end anastomosis of dog carotid arteries (n = 10) was performed by using a human albumin solder (HAS) in conjunction with Nd:YAG or diode lasers (lambda = 1.32 microm and 1.9 microm, respectively). The arteries were evaluated for patency and evidence of histologic injury after 21 days. Another group of arteries was laser soldered in vitro to measure the intimal and adventitial temperatures by using thermocouples. RESULTS: The arteries repaired with the diode laser sustained significantly less thermal damage than those repaired with Nd:YAG laser, both in vitro and in vivo. In particular, the intimal temperature was significantly lower (P < 0.05) for the diode than for the Nd:YAG repairs (approximately 35 degrees C and approximately 50 degrees C, respectively). In the latter group, the patency rate was 75%, but thrombosis occurred in 75% of the specimens at 21 days. All diode anastomoses were patent and thrombosis developed in only 17% of the arteries. CONCLUSION: Use of the diode laser and albumin solders may provide a means to successfully repair carotid arteries with minimal thermal damage.     

Exogenous chromophores for the argon and Nd:YAG lasers: a potential application to laser-tissue interactions.

Chromophore dyes can be employed to modify laser-tissue interaction. A number of dyes have been investigated for their effect on the absorption and transmission of argon and Nd:YAG laser energy by vascular tissue in vitro. Three histological dyes have been assessed as potential chromophores for the argon laser and four infrared dyes for the Nd:YAG. Segments of porcine coronary artery to which dye had been applied were lased (1,064 nm, 2.5 W, 83 W/cm2, 60 s and 488/514 nm, 400 mW, 10.5 W/cm2, 60s) and the tissue temperature measured remotely using an infrared thermometer. In addition, energy transmission was measured with a photodiode and tissue morphological changes assessed histologically. All three argon dyes significantly increased energy absorption (typically 60 degrees C v. 20 degrees C at 60 s, P less than 0.001, 2-way ANOVA). Three of the four infrared dyes behaved similarly (40-70 degrees C v. 20 degrees C, P less than 0.001). All dyes significantly increased the initial rate of rise in tissue temperature during lasing. A reduction in energy transmission was observed for each of the Argon dyes but not for the Nd:YAG dyes. Histological evidence of thermal damage in control tissue first occurred for the argon and Nd:YAG lasers at 800 mW and 7.5 W without chromophore and at 400 mW and 2.5 W with the chromophore, respectively. A number of effective chromophores have therefore been identified at each wavelength.     

Sutureless nerve repair with laser-activated chitosan adhesive: a pilot in vivo study

OBJECTIVE: The anastomosis of peripheral nerves is a demanding procedure that has potential complications due to foreign body reactions elicited by sutures. In this study, the sutureless in vivo anastomosis of rat tibial nerves was successfully performed, using for the first time a chitosan-based laser-activated adhesive. The nerve thermal damage caused by the laser irradiation was quantitatively assessed. MATERIALS AND METHODS: A novel adhesive composed of chitosan, indocyanine green, acetic acid, and water, was fabricated in thin sheets. Its adhesive strength was tested in vitro by bonding strips (surface area approximately 20 mm2, thickness approximately 20 microm) onto rat sciatic nerves and sheep intestine by laser activation with low fluence ( approximately 50 J/cm2), using a fiber-coupled diode laser (n = 13). The tensile strength of the adhesive/tissue bonds was measured after tissue repair. The chitosan adhesive was then used to perform sutureless anastomosis of tibial nerves in vivo (n = 6). Adhesive strips were also bonded in vivo onto intact rat sciatic nerves (n = 6) in order to quantitatively assess, by counting myelinated axons, the thermal damage induced by the laser. RESULTS: The adhesive bonded well to tissue with a tensile strength of 12.5 +/- 2.6 KPa (mean +/- SD; n = 13). The in vivo anastomosed nerves were in continuity 3 d after surgery. Axon counting showed the number and morphology of myelinated axons were normal proximally ( approximately 96%) compared with intact nerves (100%). Axon demyelination was observed at the operation site ( approximately 49%) and distally ( approximately 27%), and was attributed to laser-induced thermal damage. CONCLUSIONS: Nerve anastomosis, performed by the laser-adhesive procedure, was successful 3 d postoperatively. Proximal myelinated axons were not significantly damaged by the low laser fluence.     

Ablative targeting of fatty-tissue using a high-powered diode laser

BACKGROUND AND OBJECTIVE: Concerning current clinical practice, laser-assisted lipoplasty is still secondary to other procedures. In order to evaluate effects of thermal interaction with fatty-tissue, a near infrared diode laser was examined under reproducible conditions. METHODS: Based on optical spectroscopy of fatty-tissue, a high-powered diode laser (lambda = 940 nm) was used to irradiate n = 59 fat samples of fresh corpses in non-contact mode. Thermal effects were histologically evaluated by computer based metric measurements. Calculated values included ablation rate (AR) and the ratio of cavity diameter to diameter of collateral damage (CCD(ratio)). Pearson's correlation and analysis of covariance (ANCOVA) were used for statistical evaluation. P values of less than 0.05 were considered to indicate statistical significance. RESULTS: Regarding the conditions examined, irradiances from 250 to 400 W/cm(2) revealed both increased ablation capacities and decreased collateral damages. An average irradiance of 370+/-0 W/cm(2) shows an average CCD(ratio) of 2:1 and an average AR of 9.98+/-7.65 mm(3)/second. CONCLUSION: Near infrared high-powered diode laser energy proved to be eligible for tissue protective ablation of fat in vitro. Further studies are necessary to improve efficiency and safety of this procedure.     

Trans-scleral application of a semiconductor diode laser

We used a diode laser with an output power of 1 W through a fiberoptic light pipe (200 microns diameter) to deliver laser energy through the sclera of pigmented rabbits. Ciliary body destruction occurred with energy levels of 300-400 mW and exposure time of 0.5 sec. Retinal photocoagulation was achieved with energy levels of 200-500 mW in 0.5 sec. Histologic examination of acute lesions demonstrated thermal destruction of ciliary body processes and retina. Chorioretinal scar formation was observed clinically and histologically within 2-3 weeks. Our data indicate that the transscleral diode laser may be used for destruction of the ciliary body processes or peripheral retinal coagulation in pigmented eyes.     

Selective occlusion of choroidal neovascularization by photodynamic therapy with a water-soluble photosensitizer, ATX-S10

BACKGROUND AND OBJECTIVE: To determine the optimal treatment parameters for selective occlusion of choroidal neovascularization (CNV) by photodynamic therapy (PDT) by using the photosensitizer ATX-S10 and a diode laser (wavelength = 670 nm). MATERIALS AND METHODS: Experimental CNV was induced in rat fundi by argon laser photocoagulation. The distribution of ATX-S10 in the chorioretina was analyzed by fluorescence microscopy, and the optimal treatment parameters for selective occlusion of CNV were investigated by changing the dosage and timing of laser irradiation. CNV closure and resulting damage of the surrounding tissue were documented by fluorescein angiography and light and electron microscopies. RESULTS: Fluorescence of ATX-S10 was observed to be localized in the vascular lumen of the retina and choroid within 5 min after dye injection and increased in intensity in CNV up to 2-6 h and decreased rapidly in normal tissue. Laser irradiation with radiant exposures of 7.4 J/cm2 applied immediately after dye injection or with 22.0 J/cm2 at 2-4 h later effectively occluded the induced CNV without causing significant damage to normal retinal capillaries and large choroidal vessels. CONCLUSIONS: PDT using ATX-S10 can selectively occlude CNV. ATX-S10 is a potentially useful photosensitizer for the treatment of CNV.     

Microbial reduction in periodontal pockets under exposition of a medium power diode laser: an experimental study in rats

BACKGROUND AND OBJECTIVE: This work evaluates the application of a 810 nm diode laser operating in the range of 400-1,200 mW for bacterial reduction at periodontal treatment. The aim of this study is to examine the immediate effect of the diode medium power laser in reducing the bacterial concentration at periodontal pockets induced in Wistar rats. STUDY DESIGN/MATERIALS AND METHODS: Two bacterial collections were performed on each animal. Microbiological samples were collected before and immediately after laser irradiation. In each group of laser power, eight animals were used, totaling 40 animals. RESULTS: The initial and the final bacterial count revealed that laser irradiation induces considerable bacterial elimination, especially for Prevotella sp, Streptococcus beta-hemolitico, Fusobacterium sp, Pseudomonas sp. CONCLUSIONS: Our results indicate that this laser can constitute an alternative device to traditional infrared systems for bacterial reduction, with some advantage when economical and practical standpoints are considered.     

Epidermal and vascular damage analysis of in vivo human skin in response to 595 nm pulsed laser irradiation

BACKGROUND AND OBJECTIVES: Laser irradiation is the current modality for treatment of cutaneous hypervascular malformations such as port wine stains and telangiectasia. Although cryogen spray cooling (CSC) is used to protect the epidermis from non-specific laser-induced thermal damage in moderately-pigmented skin types, individuals with high melanin content are still at risk for epidermal damage using the current laser irradiation and CSC parameters. The objective of this study was to investigate the influence of the spray Weber number (1,100 or 5,100) on epidermal protection and examine vascular coagulation in response to pulsed dye laser irradiation. STUDY DESIGN/MATERIALS AND METHODS: Normal, in vivo human skin from eight subjects of Fitzpatrick skin types I-V were precooled with either low or high Weber number cryogen sprays and subsequently irradiated with a pulsed dye laser at 595 nm. Analysis of gross purpura, morphological vascular damage, and apoptosis of the vascular walls were performed. RESULTS: Results demonstrated a high Weber number spray of 5,100 decreased the level of epidermal damage in darker and moderate pigmented individuals compared to a Weber number spray of 1,100. This study also established a positive correlation between gross purpura and the level of vessel wall apoptosis. CONCLUSIONS: This study has demonstrated that CSC with a high Weber number spray can decrease nonspecific thermal damage to the epidermis in response to laser irradiation in vivo. We have also established a positive correlation between gross purpura and the level of vessel wall apoptosis. Lasers Surg. Med. (c) 2005 Wiley-Liss, Inc.     

Two-layer film as a laser soldering biomaterial.

BACKGROUND AND OBJECTIVES: A two-layer solder was developed to weld at low laser intensity and to provide a new method of measuring solder-tissue temperature. STUDY DESIGN/MATERIALS AND METHODS: A film solder consisted of a white layer (bovine serum albumin (BSA) and distilled water) and a black layer (BSA, carbon black (CB), and distilled water). This two-layer solder was used with a diode laser to weld sections of dog small intestine (lambda = 810 nm, power = 200 +/- 20 mW, radiation dose = 18 +/- 1 J/mg). Sections of intestine were welded only with one-layer black solders as control group. The temperature difference between the external solder surface and the tissue-solder interface was evaluated during welding. RESULTS: The two-layer solder performed welds as strong as the one-layer solder ( approximately 0.12 N) but with less laser intensity on the black layer. The temperature difference between the external surface of the solder and the solder-tissue interface was significantly less for the two-layer solder than for the one-layer solder ( approximately 6 degrees C and approximately 15 degrees C, respectively; P < 0.05). CONCLUSIONS: The two-layer solder appeared to be more efficient at soldering biomaterials than the one-layer solder. Furthermore, the heat diffusion from the black midplane of the two-layer solder decreased the difference in temperature recorded on the solder external surface and on the solder-tissue interface.     

Laser soldering of rat skin, using fiberoptic temperature controlled system

BACKGROUND AND OBJECTIVE: Laser soldering of tissues is based on the application of a biological solder on the approximated edges of a cut. Our goal was to use laser soldering for sealing cuts in skin under temperature feedback control and compare the results with ones obtained using standard sutures. STUDY DESIGN/MATERIALS AND METHODS: Albumin solder was applied onto the approximated edges of cuts created in rat skin. A fiberoptic system was used to deliver the radiation of a CO(2) laser, to heat a spot near the cut edges, and to control the temperature. Laser soldering was carried out, spot by spot, where the temperature at each spot was kept at 65-70 degrees C for 10 sec. RESULTS: The tensile strength of laser-soldered cuts was measured after 3-28 days postoperatively and was found comparable to that of sutured cuts. Histopathological studies showed no thermal damage and less inflammatory reaction than that caused by standard sutures (P = 0.04). CONCLUSIONS: Temperature controlled laser soldering of cuts in rat skin gave strong bonding. The cosmetic and histological results were very good, in comparison to those of standard sutures.     

In vitro and in vivo tissue repair with laser-activated chitosan adhesive

BACKGROUND AND OBJECTIVES: Sutures are currently the gold standard for wound closure but they are still unable to seal tissue and may induce scarring or inflammation. Biocompatible glues, based on polysaccharides such as chitosan, are a possible alternative to conventional wound closure. In this study, the adhesion of laser-activated chitosan films is investigated in vitro and in vivo. In particular we examine the effect of varying the laser power, as well as adding a natural cross-linker (genipin) to the adhesive composition. STUDY DESIGN/MATERIALS AND METHODS: Flexible and insoluble strips of chitosan films (surface area approximately 34 mm(2), thickness approximately 20 microm) were bonded to sheep intestine using several laser powers (0, 80, 120, and 160 mW) at 808-nm wavelength. The strength of repaired tissue was tested by a calibrated tensiometer to select the best power. A natural cross-linker (genipin) was also added to the film and the tissue repair strength compared with the strength of plain films. The adhesive was also bonded in vivo to the sciatic nerve of rats and the thermal damage induced by the laser assessed 4 days post-operatively. RESULTS: Chitosan adhesives successfully repaired intestine tissue, attaining a maximum repair strength of 14.7+/-4.3 kPa (n = 30) at the laser power of 120 mW. The chitosan-genipin films achieved lower repair strength (9.1+/-2.9 kPa). The laser caused partial demyelination of axons at the site of operation, but the myelinated axons retained a normal morphology proximally and distally. CONCLUSIONS: The chitosan adhesive effectively bonded to tissue causing only localized thermal damage in vivo, when the appropriate laser parameters were selected.     

Continuous laser radiation effect at 1.06 microns on gastrointestinal tract

The thermal effect of 1.06 microns YAG:Nd laser irradiation at temperature conditions up to 100 degrees C without crater formation on gastrointestinal (GI) tissue samples was investigated. The theoretical and experimental data show that at an intensity of 160-400 W/cm2 laser-induced heating of the tissue with an initial temperature of 20 degrees C leads to coagulation lesions at a temperature no less than 60 degrees C and at a depth of 1.7-2.1 mm.     

A pilot study of ICG laser therapy of acne vulgaris: photodynamic and photothermolysis treatment

BACKGROUND AND OBJECTIVES: The near-infrared (NIR) laser radiation due to its high penetration depth is widely used in phototherapy. In application to skin appendages, a high selectivity of laser treatment is needed to prevent light action on surrounding tissues. Indocyanine green (ICG) dye may provide a high selectivity of treatment due to effective ICG uploading by a target and its narrow band of considerable absorption just at the wavelength of the NIR diode laser. The goal of this study is to demonstrate the efficacy of the NIR diode laser phototherapy in combination with topical application of ICG suggested for soft and thermal treatment of acne vulgaris. STUDY DESIGN/MATERIALS AND METHODS: Twenty-two volunteers with facile or back-located acne were enrolled. Skin sites of subjects were stained by ICG and irradiated by NIR laser-diode light (803 or 809 nm). One mg/ml solution of ICG was applied for 5 or 15 minutes to the cleaned skin site. Untreated, only stained and only light irradiated skin areas served as controls. For soft acne treatment, the low-intensity (803 nm, 10-50 mW/cm(2), 5-10 minutes) or the medium-intensity (809 nm, 150-190 mW/cm(2), 15 minutes) protocols were used. The single and multiple (up to 8-9) treatments were provided. The individual acne lesions were photothermally treated at 18 W/cm(2) (803 nm, 0.5 seconds) without skin surface cooling or at 200 W/cm(2) (809 nm, 0.5 seconds) with cooling. RESULTS: The observations during 1-2 months showed that soft acne treatment decreased the number of active elements, reduced erythema and inflammation, and considerably improved the skin state without any side effects. At high power densities (up to 200 W/cm(2)), ICG stained acne inflammatory elements were destroyed for light exposures of 0.5 seconds. CONCLUSIONS: Based on the concept that hair follicle, especially sebaceous gland, can be intensively and selectively stained by ICG due to dye diffusion through pilosebaceous canal and its fast uptake by living microorganisms, by vital keratinocytes of epithelium of the canal and sebaceous duct, and by rapidly proliferating sebocytes, new technologies of soft and thermal acne lesions treatment that could be used in clinical treatment of acne were proposed.