A split axilla comparison study of axillary hair removal with low fluence high repetition rate 810 nm diode laser vs. high fluence low repetition rate 1064 nm Nd:YAG laser

Background A low fluence, high repetition rate 810 nm diode laser using constant motion technique has been recently introduced with advantages of less treatment discomfort and fewer side effects compared with traditional laser hair removal. Objective To compare hair reduction and side effects of low fluence high repetition rate 810 nm diode with high fluence low repetition rate 1064 nm Nd:YAG lasers. Methods Forty‐nine subjects were randomly received five monthly treatments with diode laser on one side of their axilla and long‐pulsed Nd:YAG laser on the other side. Hair count was recorded at baseline, 1‐ and 6‐month follow‐up visits. Results Percentage of axillary hair reduction at 1‐month follow‐up visit after receiving diode and Nd:YAG laser treatment were 71.0% and 82.3%, respectively, and at 6‐month follow‐up were 35.7% and 54.2%, respectively. There were significant differences in hair reduction between both laser systems at 1‐ and 6‐month follow‐ups (P < 0.001 and P < 0.001, respectively). Patients reported lower pain on the diode laser side (P < 0.001). Side effects of both laser systems were mild and transient erythema and swelling. Conclusions High fluence low repetition rate Nd:YAG laser was superior in hair reduction and provided higher patient satisfaction. However, low fluence high repetition rate diode laser was less painful.     

Safety and efficacy of low-fluence,high-repetition rate versus high-fluence,low-repetition rate 810-nm diode laser for permanent hair removal – A split-face comparison study

Abstract

Background: This study was designed to evaluate the hypothesis that low-level fluences done repetitively on a hair follicle will produce permanent hair removal with less discomfort and fewer side effects than a single high-fluence pulse. Objective: To compare the safety and efficacy of a low-fluence, high-repetition rate versus a high-fluence, low-repetition rate 810-nm diode laser for permanent hair reduction in patients with facial hirsutism. Methods: Forty-two female patients with confirmed polycystic ovaries by ultrasonography with facial hirsutism were subjected to the low-fluence, high-repetition Soprano^® XL laser in SHR mode and the LightSheer? laser on each side of the face using preset parameters once a month for six sessions. Hair counts were done at the end of the sixth session using a ‘Hi Quality Hair Analysis Program System’ and the pain score was recorded by a visual analog scale. Results: The overall median reduction of hair was 90.5% with the Soprano XL and 85% with the LightSheer, with a standard deviation of 7 and 8.5 respectively. Discussion: This new technology, with low fluence and high repetition, showed a statistically insignificant increase in hair reduction compared to the LightSheer, but did show a significant reduction in hair thickness and a low pain score.     

Split-leg comparison of low fluence diode laser and high fluence intense pulsed light in permanent hair reduction in skin types III to IV

Background/Objectives: All the standard light‐based techniques for permanent hair reduction, like laser and intense pulsed light (IPL) employ the highest tolerable fluence with a single pass. As opposed to standard techniques, a new diode laser technique employs low fluence with multiple passes. Here we evaluate and compare the efficacy, treatment time, comfort and safety of the low fluence multiple pass diode laser with high fluence single pass IPL for permanent hair reduction in Type III to IV Asian patients. Methods: Thirty Asian patients with Type III to IV black hair were enrolled and received three sessions of treatments at 6‐weekly to 8‐weekly intervals. A split‐leg study was performed in which the IPL was applied to one leg of each patient while the laser was applied to the other. The patients were followed up for 12 months. Results: All patients were satisfied with the results of the long‐term hair reduction without long‐term side effects. There was no statistically significant difference in hair reduction and treatment time between the laser (76.85%, 21.39 min) and the IPL (74.53%, 22.17 min) (P > 0.05). The visual analogue scale (VAS) pain score of the IPL (5.96) was higher than that of the laser (3.10) (P < 0.01). Conclusions: A series of high fluence single pass IPL and low fluence multiple pass diode laser treatments were performed with similar efficacy, speed and safety for permanent hair reduction. However, low fluence multiple pass diode laser treatment was less painful than high fluence single pass IPL.     

Novel 755-nm diode laser vs. conventional 755-nm scanned alexandrite laser: Side-by-side comparison pilot study for thorax and axillary hair removal

Background: Alexandrite (755 nm) and diode lasers (800–810 nm) are commonly used for hair removal. The alexandrite laser technology is somewhat cumbersome whereas new diode lasers are more robust. Recently, alexandrite-like 755 nm wavelength diodes became available. Objectives: To compare the efficacy, tolerability, and subject satisfaction of a 755 nm diode laser operated in conventional (HR) and non-conventional in-motion (SHR) modes with a conventional scanned alexandrite 755 nm laser for chest and axillary hair removal. Materials and methods: A prospective, single-center, proof of principle study was designed to evaluate the safety, efficacy and handling of a 755 nm diode laser system in comparison to a standard alexandrite 755 nm scanning hair removal laser. Results: The new 755 nm diode is suitable to be used in SHR and HR mode and has been tested for its safety, efficacy and handling in a volunteer with success. Overall, both systems showed a high efficacy in hair reduction (88.8% 755 nm diode laser vs. 77.7% 755 nm alexandrite laser). Also, during the study period, no severe adverse effects were reported. Conclusion: The new 755 nm diode laser is as effective and safe as the traditional 755 nm alexandrite laser. Additionally, treatment with the 755 nm diode laser with HR and SHR modes was found to be less painful.     

Effects of the 810-nm diode laser on hair and on the biophysical properties of skin

Abstract

Introduction: Laser therapy is clinically effective in hair removal; however, despite the development of various strategies, laser procedures still present a risk of adverse effects due to the overheating of the skin. Objective: To investigate the effects of 810-nm diode laser treatment on hair and on the biophysical properties of skin by using various non-invasive techniques on various parameters, including hair analysis, surface color changes, integrity of skin barrier, sebum production rate and pH level. Methods: In this randomized, right–left comparison study, 35 women with axillary hair received single-session diode laser therapy. Hair analysis and biophysical properties of the skin were assessed before treatment and at weeks 2, 4 and 6 after the therapy. Results: Hair density and thicknesses statistically significantly decreased after the first post-treatment evaluation. Regarding comparison of the biophysical properties of the skin, there was no statistically significant difference in the assessments, except for the increase determined during the second week in the erythema index in the laser-treated areas. Conclusion: The findings of this study showed that the diode laser can perform a significant reduction in the hair amount without significant epidermal damage, at least for a short period.     

Histological hair removal study by ruby or alexandrite laser with comparative study on the effects of wavelength and fluence

BACKGROUND: Several different laser systems are currently used to remove unwanted hairs. In this study, we studied follicular changes following hair removal with ruby or alexandrite lasers at different fluences.

METHODS: Unwanted hairs were treated with a ruby laser (Chromos 694, ICN PhotonIcs, UK) at 10, 14 or 18?J/cm² or with an alexandrite laser (LPIR, Cynosure, USA) at 11, 14 or 17?J/cm². A 3?mm skin punch biopsy was taken immediately after each laser exposure and also 1 month later. Specimens were stained for histological observation. They were observed using immunohistochemistry with antibodies recognizing factor VIII related antigen or PCNA, and also by the TUNEL method. Similarly, electron microscopic observation was examined.

RESULTS: Immediately after the laser exposure, moderate follicular damage was observed following treatment with either type of laser. One month later, cystic formation of hair follicles and foreign body giant cells were observed in skin treated with either type of laser. A similar fluence with either laser treatment resulted in similar histological changes.

CONCLUSION: In this study, the histological changes following treatment with a ruby or an alexandrite laser at the same fluence are similar.     

Comparison of hair reduction with three lasers and light sources: Prospective,blinded and controlled study

Abstract

Objective: The main goal of this study was to compare the hair removal efficacy of three methods: intense pulsed light (IPL), a combination of IPL and radio frequency (RF) and diode laser (810 nm). Methods: Forty participants were treated within three standardized squares on lateral sites on their legs. Each of these squares was treated twice with an interval of 4–6 weeks. The fourth square was left as a control. A blinded physician counted the hairs in each square before the first treatment and 8 months after the second treatment. Immediate and delayed side effects as well as pain scores were recorded. Results: The mean hair count reduction achieved by the diode laser, IPL and IPL+RF was 49.90%, 39.16% and 47.15%, respectively. This study did not show any serious side effects and the number of side effects was minimal. The mean pain scores for the first and second treatments by diode laser, IPL and IPL+RF were 4.65 and 4.58, 2.43 and 2.53, and 3.95 and 4.03, respectively. At the end of the study, a free hair removal treatment for both legs was chosen by patients in the proportion 20 diode laser, 10 IPL and eight IPL+RF. Conclusions: The combination of RF and optical energies proved its safety and efficacy for hair removal, which is comparable with diode lasers and approximately 20% more efficient than ‘pure’ IPL.     

810 nm diode laser for hair reduction with Chill-tip technology: prospective observational analysis of 55 patients of Fitzpatrick skin types III,IV,V

ABSTRACT

Background: Various light based technologies like Diode, long pulsed Nd:Yag and Intense Pulsed Light are used commonly for long-term hair reduction. The commonest indication is hirsutism.

Aim: 1. To evaluate efficacy and safety of 810 nm Diode laser in Fitzpatrick skin types III, IV and V.

2. To assess percentage of cases on the basis of indications, average number of sessions, fluence required, the long-term results and complications using diode laser in darker skin types.

Methods: A prospective observational study of 55 consecutive patients who came for laser hair reduction by 810 nm Light Sheer Diode laser with Chill tip technology was carried out. The sessions were conducted at an interval of 4–6 weeks and the patients were followed up over a period of 2 years. Data was analyzed using software SPSS (Statistical Package for Social Science. Ver.12, Inc. Chicago, USA).

Results: Fifty-five patients (51 females and 4 males) were studied. 67.3% (n = 37) had skin type IV. The most common area treated was chin (n = 23). The average growth reduction of terminal hair at the end of three sessions was 61.25%. Only 8% (n = 4) had short-term side effects.

Conclusion: Diode laser is highly effective for long-term hair reduction of terminal hair growth in Fitzpatrick skin type III, IV and V with no permanent side effects.

Abbreviations: LHR (Laser Hair Reduction)     

Efficacy and Safety of Hair Removal with a Long-Pulsed Diode Laser Depending on the Spot Size: A Randomized,Evaluators-Blinded,Left-Right Study

Background

The efficacy of the long-pulsed diode laser (LPDL) in hair removal is determined with various physical parameters. Recently, LPDLs with a larger spot size are commercially available; however, the independent effect of spot size on hair removal has not been studied.

Objective

This study aimed to compare the efficacy of the LPDL in hair removal depending on the spot size.

Methods

A randomized, evaluators-blind, intrapatient comparison (left vs. right) trial was designed. Ten healthy Korean women received three hair removal treatment sessions on both armpits with the 805-nm LPDL and followed for 3 months. A 10×10 mm handpiece (D1) or a 10×30 mm handpiece (D3) was randomly assigned to the right or left axilla. The fluence, pulse duration, and epidermal cooling temperature were identical for both armpits. Hair clearance was quantified with high-resolution photos taken at each visit. Postprocedural pain was quantified on a visual analogue scale. Adverse events were evaluated by physical examination and the patients'' self-report.

Results

The mean hair clearance at 3 months after three treatment sessions was 38.7% and 50.1% on the armpits treated with D1 and D3, respectively (p=0.028). Procedural pain was significantly greater in the side treated with D3 (p=0.009). Serious adverse events were not observed.

Conclusion

Given that the pulse duration, fluence, and epidermal cooling were identical, the 805-nm LPDL at the three times larger spot size showed an efficacy improvement of 29.5% in axillary hair removal without serious adverse events.     

An efficacy comparison of hair removal utilizing a diode laser and an Nd:YAG laser system in Chinese women

Abstract

Background: The 800 nm diode laser and the 1064 nm Nd:YAG laser have been used successfully for hair removal for many years. Objective: To compare the efficacy of a diode laser with a Nd:YAG laser regarding axillary fossa hair removal in Chinese women. Methods: Twenty-nine Chinese women underwent three treatment sessions at 4-week intervals with a diode laser (34–38 J/cm²) on one side and a Nd:YAG laser (34–40 J/cm²) on the other side. Assessments included the reduction of hair diameter following treatment, the regrowth rate in hair length, total hair reduction and the immediate pain associated with the treatments. Results: At follow-up visit number 1 (4 weeks after the first session), the average reduction in hair diameter on the diode laser side and the Nd:YAG laser side was 2.44 μm and –0.6 μm, respectively. The regrowth rates of the hair were 61.93 μm/day and 59.84 μm/day, respectively, which were not statistically significant (p > 0.05). At follow-up visit number 1, hair reduction was 60.09% and 41.44%, respectively. At follow-up visit number 2 (4 weeks after the second session), hair reduction was noted to be 78.56% and 64.50%, respectively, which were both statistically significant (p < 0.05). Immediate pain scores at the first session were 6.97 and 6.17, respectively; at the second session were 5.48 and 6.69, respectively; and at the third session were 5.76 and 7.45, respectively; all statistically significant (p < 0.05). Conclusions: The diode laser showed more efficacy and was found to be more comfortable than the Nd:YAG laser for axillary fossa hair removal in Chinese women.     

Evaluation of a super long pulsed 810-nm diode hair removal laser in suntanned individuals

BACKGROUND: Laser hair removal is based on the dual concepts of selective photothermolysis and thermal relaxation time. In most laser hair removal systems, light with emitted pulse durations of 2–50 ms targets hair follicles. Such pulse durations usually lead to post-inflammatory pigmentary changes in suntanned individuals. OBJECTIVE: In this pilot study, we evaluated the clinical efficacy and side effect profile of a modified 810–nm diode laser device (Palomar SLP 1000Á, Burlington, MA, USA) operating in a super long pulse mode (200–1000 ms). METHODS: Five suntanned subjects with Fitzpatrick skin types II–IV received either one or two laser treatments at eight test sites. Treatments were delivered to suntanned skin. Pulse durations of 200–1000 ms were evaluated with delivered fluences ranging from 23 to 115 J cm 2 . Subjects were followed for 6 months after the first treatment. Subjects were evaluated for hair removal efficiency, optimal pulse duration and delivered fluence, one versus two treatments, and associated complication rate. RESULTS: The average hair reduction, 34%, did not significantly vary with pulse duration or fluence. Clinical evaluations rated two treatments superior to one. CONCLUSION: The results show that efficacious and safe hair removal can be accomplished with an 810–nm diode laser delivering super long pulse durations at a wide range of settings in suntanned individuals. For optimal safety in tanned patients, the highest fluence (115 J cm 2 ) and pulse duration (1000 ms) should be avoided.     

Hair removal using an 800-nm diode laser: comparison at different treatment intervals of 45, 60, and 90 days

BACKGROUND: Some laser irradiation parameters such as wavelength, fluence, pulse duration, and spot size have been shown to influence the damage of any target inside the skin, however, the role of some patients' factors such as hair growth cycle is still under debate. OBJECTIVE: To determine the association of treatment interval and laser treatment outcome. METHODS: In a retrospective chart review of 176 patients undergoing laser-assisted hair removal with a diode laser 24 patients were selected. All accepted to cease the therapy, and be followed-up for 5 months. At the end of the study the patients were questioned about the efficacy of the treatment as well as the adverse effects. Hair counting was also performed. The adverse effects (pain, blister or erosion, hyperpigmentation, hypopigmentation, and folliculitis) were questioned during the follow-up period. RESULTS: The mean hair reduction was 78.1%, 45.8%, and 28.7% in 45, 60, and 90-day interval groups, respectively (P < 0.0001). CONCLUSION: The treatment interval was related to the treatment outcome in our study.     

A 12-month follow-up of hypopigmentation after laser hair removal

Abstract

Introduction: Laser hair removal is becoming an increasingly popular alternative to traditional methods such as shaving, waxing, among other methods. Semiconductor diode lasers are considered the most efficient light sources available and are especially well suited for clinical applications including hair reduction. The effectiveness of laser hair reduction depends on many variables, including the skin type of the patient. Material and Methods: A patient with Fitzpatrick Skin Type IV was submitted to laser hair removal of the arms with a high-power diode laser system with long pulses with a wavelength of 800 nm, a fluence of 40 J/cm² and a pulse width of 20 ms. A 12-month follow-up assessment was performed and included photography and questionnaire. Results: Hypopigmentation was observed after a single laser hair removal section. After 6 months with the area totally covered, a gradual suntan with a sun screen lotion with an SPF of 15 was prescribed by the dermatologist. After 12 months of the initial treatment, a complete recovery of the hypopigmentation was achieved. Conclusion: Although a safe procedure, lasers for hair removal may be associated with adverse side effects including undesired pigment alterations. Before starting a laser hair removal treatment, patients seeking the eradication of hair should be informed that temporary, and possibly permanent, pigmentary changes may occur.     

Is paradoxical hair growth caused by low-level radiant exposure by home-use laser and intense pulsed light devices?

Introduction and objectives: This qualitative review of paradoxical hair growth, following professional treatments reviews, clarifies whether low fluence is the most probable cause of unwanted hair regrowth after at home light-based treatments. Materials and methods: The proposed causes of unexpected hair regrowth are examined, and our scientific understanding of absorption and scattering of light in turbid tissue is reviewed. Published reports of paradoxical hair growth are assessed. Results: Early laser hair removal studies failed to record the occurrence of hair induction despite the significant numbers of subjects treated. Neither published paradoxical hair growth studies following home-based laser or intense pulsed light (IPL) hair removal treatments, nor randomised or controlled studies documenting paradoxical hair growth following professional treatments could be found. Several authors directly proposed inflammatory response to be the primary cause of hair growth induction. Conclusions: It is unlikely that hair regrowth several centimetres or more away from the irradiated tissue can be attributed to the laser or IPL used. In many cases of paradoxical hair growth, other causes may be responsible for the unexpected hair growth. The primary cause of instances of ‘true’ paradoxical hair growth is probably limited to darker phototypes with one or more other characteristics including polycystic ovarian syndrome or other androgen hormonal irregularities following high energy treatments with the corresponding inflammatory sequelae.     

Paradoxical darkening of unperceived tattoo ink after relatively low fluence from a Q‐switched Nd:YAG (1064‐nm) laser in the course of treatment for melasma

Although Q‐switched (QS) lasers are the mainstay of modern tattoo removal, paradoxical darkening of tattoo ink may occur. This darkening of tattoo ink is dependent on laser wavelength, pulse duration and fluence, with high‐energy, nanosecond‐pulsed lasers more prone to induce tattoo‐ink darkening. Laser toning, consisting of multiple‐passed QS neodymium:yttrium–aluminum–garnet (Nd:YAG), 1064‐nm laser treatment with low fluence, short pulse duration (< 10 ns), and a repetition rate of 10 Hz has been successful in the treatment of melasma. A mistake commonly made during laser toning is to scorch scalp hair, eyebrows or eyelashes, but this phenomenon is reversible. A more problematic error is caused by treatment of eyeliner or eyebrow tattoos. We report a patient who experienced changes in unperceived, skin‐coloured tattoos, turning them blue after QS Nd:YAG laser treatment of melasma.     

Ein neuer Ansatz in der Laser-Haarreduktion

Background

Photoepilation has been an essential field of application of dermatologic laser therapy for many years. The present article evaluates whether the use of a new operation mode of a long-pulsed diode laser can be effective, nearly painless, with few side effects and independent of the skin type. To this aim, its use has been compared to an established method of photoepilation.

Material and methods

In a controlled prospective study with 18 (♀=12, ♂=6) patients aged between 22 and 58 years, the effects of photoepilation with the long-pulsed alexandrite laser and the long-pulsed diode laser, operated in the Super Hair Removal mode (SHR), were compared.

Results

The alexandrite laser is slightly more effective with fair skin types; the SHR mode is clearly more effective with dark skin types. Regarding painfulness, the SHR mode is clearly superior. In terms of speed, the two systems are comparable. The alexandrite laser is more user-friendly because of its light and small handpiece.

Conclusion

The major advantages of the SHR mode are its effectiveness in dark skin types and its lack of pain. The alexandrite laser is slightly more effective with fair skin types, slightly faster and its handling is considerably more comfortable. None of the two systems has yet brought about a breakthrough with fair hair.     

Hair removal with a novel,low fluence,home-use intense pulsed light device

Objective: To evaluate the reduction in unwanted body and facial hair at various body sites of Fitzpatrick skin types I–III and the efficacy, comfort and safety of this treatment intended for home-use by the general public. Methods: In this non-randomized study, 29 individuals were given three sequential weekly treatments on a total of 31 body and facial areas including the axilla, bikini area, abdomen, neck, chin and upper lip using a novel intense pulsed light device. All participants completed a simple self-assessment questionnaire, as well as an evaluation of pain/discomfort. Results: The mean reduction in terminal hair counts was 47% at 4 weeks' follow-up and 41% at 6 months' follow-up after completing three sequential weekly treatments. Overall, 84% of participants showed a significant percentage of hair reduction (p<0.01) at the 6-month follow-up, with a mean of 51% (range 25–86%). No treatment-related side effects were reported, with little or no discomfort reported during the treatment. Only mild erythema was noted immediately post-treatment. In total, 85% of the participants were either pleased or very pleased with the results 1 month after the third treatment. Conclusions: In simulated consumer use, this home-use IPL demonstrated a significant, quantifiable and sustainable reduction in unwanted body and facial hair with minimal side effects.     

Hair removal with an 800-nm pulsed diode laser

BACKGROUND AND OBJECTIVE: Laser hair removal is a relatively new procedure. Our purpose was to study the efficacy and safety of a high-power, pulsed diode laser array for removing unwanted hair. METHODS: A total of 38 subjects were treated with a prototype of the 800-nm diode laser system. Fluences ranging from 10 to 40 J/cm(2) (mean, 33.4 J/cm(2)) were used and 1 to 4 treatments (mean, 2.7) were performed. Evaluation of hair loss was performed at least 4 months after the last treatment (mean, 8.7 months) by a blinded assessment of clinical photographs. RESULTS: A total of 59% of the subjects had only sparse hair regrowth at the final follow-up. Higher fluences and multiple treatments produced greater long-term efficacy. Transient pigmentary changes occurred in 29% of the subjects and were more common in darker skin types IV to VI (P =. 047). CONCLUSION: The 800-nm diode laser is an efficient and safe technique for hair reduction. Adverse pigmentary effects occur, but are transient.     

Clinical comparison of four hair removal lasers and light sources

Background and objective: There are few clinical studies directly comparing the efficacy of multiple hair removal systems in the same individual. This study evaluates the efficacy of four highly popular systems for laser hair removal. Methods: In this prospective comparison study, 10 subjects underwent treatment of unwanted hair on the back or thigh. Subjects were skin types I–III, aged 18–55 years. All were treated twice with (1) an intense pulsed light with a red filter; (2) an intense pulsed light with a yellow filter; (3) an 810?nm diode laser; and (4) a 755?nm alexandrite laser. Four treatment areas, using commonly accepted parameters for permanent hair reduction, as well as a control non‐treated area were selected. Each treatment area was evaluated with a camera system specifically designed for hair counts at 1, 3, and 6 months after the second treatment by a blinded non‐treating physician. Clinical results and adverse events were also noted. Results: Evaluation of photographs at 1, 3, and 6 months revealed a significant decrease in hair counts (～50%) and hair coverage (～55%). In the hairs that remained after two treatments, no statistical difference was noted in hair length or diameter. There was no statistical difference in efficacy between the four different light devices. Minimal transient adverse effects were noted from all systems. The cryogen spray‐based alexandrite laser showed the highest pain scores. Conclusion: Although hair removal with commonly used systems is, as expected, highly effective, treatment with light‐based devices can cause less pain, yet show efficacy similar to laser systems.     

Photodynamic therapy of actinic keratosis at varying fluence rates: assessment of photobleaching, pain and primary clinical outcome

BACKGROUND: Although photodynamic therapy (PDT) is becoming an important treatment method for skin lesions such as actinic keratosis (AK) and superficial basal cell carcinoma, there are still discussions about which fluence rate and light dose are preferable. Recent studies in rodents have shown that a low fluence rate is preferable due to depletion of oxygen at high fluence rates. However, these results have not yet been verified in humans. OBJECTIVES: The objective was to investigate the impact of fluence rate and spectral range on primary treatment outcome and bleaching rate in AK using aminolaevulinic acid PDT. In addition, the pain experienced by the patients has been monitored during treatment. PATIENTS/METHODS: Thirty-seven patients (mean age 71 years) with AK located on the head, neck and upper chest were treated with PDT, randomly allocated to four groups: two groups with narrow filter (580-650 nm) and fluence rates of 30 or 45 mW cm(-2), and two groups with broad filter (580-690 nm) and fluence rates of 50 or 75 mW cm(-2). The total cumulative light dose was 100 J cm(-2) in all treatments. Photobleaching was monitored by fluorescence imaging, and pain experienced by the patients was registered by using a visual analogue scale graded from 0 (no pain) to 10 (unbearable pain). The primary treatment outcome was evaluated at a follow-up visit after 7 weeks. RESULTS: Our data showed a significant correlation between fluence rate and initial treatment outcome, where lower fluence rate resulted in favourable treatment response. Moreover, the photobleaching dose (1/e) was found to be related to fluence rate, ranging from 4.5 +/- 1.0 J cm(-2) at 30 mW cm(-2), to 7.3 +/- 0.7 J cm(-2) at 75 mW cm(-2), indicating higher oxygen levels in tissue at lower fluence rates. After a cumulative light dose of 40 J cm(-2) no further photobleaching took place, implying that higher doses are excessive. No significant difference in pain experienced by the patients during PDT was observed in varying the fluence rate from 30 to 75 mW cm(-2). However, the pain was found to be most intense up to a cumulative light dose of 20 J cm(-2). CONCLUSIONS: Our results imply that the photobleaching rate and primary treatment outcome are dependent on fluence rate, and that a low fluence rate (30 mW cm(-2)) seems preferable when performing PDT of AK using noncoherent light sources.