Lethal photosensitization of oral pathogens via red-filtered halogen lamp.

UNLABELLED: OBJECTIVE OF INVESTIGATION: The ability of laser irradiation in the presence of photosensitizing agent to induce lethal effect on oral bacteria is well documented. We designed an in-vitro experiment to achieve phototoxic results on two common oral pathogens, using a high intensity, red filtered halogen lamp. Our goal was to determine the minimum duration of light exposure and drug dilution to achieve at least 50% reduction in bacteria counts. METHODS: Two common oral pathogens, Porphyromonas gingivalis and Prevotella intermedia were used in experiments. The source for light energy was a continuous working, high intensity, red filtered, halogen lamp (HL) with light transmitted through a flexible light guide over petri dishes containing live bacteria. Microorganisms were exposed to light for 5, 10 and 20 min. Methylene Blue (MB) in concentrations of 0.1, 0.075, 0.05, 0.025 and 0.01% was used as a photosensitizing agent. Light energy alone and MB alone was used as controls. RESULTS AND DISCUSSION: Optimum lethal photosensitization (50% or more bacteria killing) of oral pathogens was achieved using halogen light illumination for 5 min and longer with 0.05% MB or exposure to light for 20 min in the presence of 0.025 and 0.01% MB. Light exposure of 20 min in the absence of MB was not effective in killing bacteria. In the absence of light, MB at concentrations of 0.025 and 0.001% was not effective. Reduction of bacteria with the use of 0.05% MB alone was also insignificant. However, 0.075 and 0.1% MB, even in the absence of light was found to be bacteriocidal. CONCLUSIONS: Our in-vitro data indicate that we were able to achieve lethal photosensitization of two common oral pathogens with high intensity red filtered HL in the presence of diluted MB. In this era of increased incidence of antibiotic resistance, bacterial killing with laser or light energy in the presence of photosensitizing agent can prove to be a valuable treatment modality.

Laser myringotomy in different age groups.

OBJECTIVE: To study the qualities of laser myringotomy (LM) as a treatment for middle ear ventilation problems. DESIGN: Prospective study and follow-up of consecutive cases of adults, children, and infants. Patients were observed for up to 2 years. SETTING: Children underwent LM, with or without adenoidectomy, under general anesthesia in the operating room. Adults and infants underwent LM under topical anesthesia, as an outpatient procedure. PATIENTS: All consecutive patients with either secretory otitis media (SOM) (adults and children) or acute otitis media (AOM) (infants) who agreed to participate were included without selection. INTERVENTION: Myringotomy was performed using new laser equipment, enabling a 0.1-second ablation with changeable diameter. OUTCOME MEASURES: Close follow-up, with microscopic examination of all ears. Findings were noted on the medical charts. RESULTS: Among all age groups, 136 ears were followed up. Perforation lasted a mean 22 days in adults, 17 days in children, and 11 days in infants. Patient age was found to be a significant determining factor for duration of perforation (P =.002). Laser myringotomy in the anterior and inferior areas lasted longer than posterior LM (P<.001). In patients with SOM, during the time the LM was patent, all ears were ventilated. In children, 38% of SOM cases resolved after a single LM treatment. All infants with AOM recovered promptly without antibiotic treatment. CONCLUSIONS: Laser myringotomy is a convenient, quick procedure that can be performed in the medical office with the use of topical anesthesia and is suitable for patients with AOM or for those who need short-term ventilation for SOM. It was found to be a safe alternative to ventilation tubes in these patients. In AOM, it was used instead of antibiotics and gave prompt relief from symptoms and cure of the AOM.

Dark skin tissue reaction in laser assisted hair removal with a long-pulse ruby laser.

BACKGROUND: Photo-epilation has become an accepted modality for the removal of unwanted hair. However, adverse effects may occur in darker skin patients. Treatment with the ruby laser is generally advised for skin types I-III. Treatment of over 3000 patients (skin types I-III) in our clinic has resulted in a minimal percentage (approximately 3%) of adverse effects. Increasing pulse duration should allow the epidermis to cool and thus minimize thermal damage so that treatment can be extended to dark skin patients. OBJECTIVES: The purpose of our study was to compare tissue reaction in dark skin patients (skin type IV) after treatment with a long-pulse (20 msec) ruby laser and compare the reaction with a 1 msec ruby laser treatment. RESULTS: Hair removal efficacy was determined to be similar with both pulse durations, but tissue reaction was more severe, including eschar and hypopigmentation, following treatment of dark skin patients with the 1 msec protocol. Increasing the pulse duration to 20 msec appears to result in safe and efficacious ruby laser treatment even for darker skinned patients.

Quenching of backward stimulated Raman scattering by broadband forward Raman radiation.

Experiments on backward stimulated Raman scattering of an injection-locked XeF (351.1-nm) laser beam are presented. Because the XeF laser is inhomogeneously broadened, its output is composed of both a narrow-band component (50-60% of the energy) and an unlocked broadband component. It is found that the presence of forward Raman scattering from the broadband unlocked component of the XeF energy terminates the backward Raman scattering of the narrow- (~1-GHz) bandwidth-locked component of the radiation. The results are of a general nature and would apply to scattering from any inhomogeneously broadened injection-locked laser.

Attainment of the theoretical minimum input power for injection locking of an unstable-resonator KrF laser.

We report attaining a ratio of output to injected power as high as 10(8) in a KrF system, the limit being reached when injected power equals the noise per mode in the resonator. We find that, because of coherence effects, adjustment of the cavity length for correct value of the equivalent Fresnel number can change the threshold power for frequency locking by at least 2 orders of magnitude. The laser's locked bandwidth is <0.1 A, and the line can be tuned over a range exceeding 10 A. The beam divergence is near (i.e., 1.5x) the diffraction limit.

Transform-limited-bandwidth injection locking of an XeF laser with an Ar-ion laser at 3511 A.

We report attainment of transform-limited bandwidth in an XeF laser by injection locking a positive-branch confocal unstable resonator with 1 W of power from an Ar-ion laser at 3511 A. A diffraction-limited beam of >2-MW power, with a bandwidth of ~50 MHz (~1 x 10(-4) A), is generated. We find that since the XeF UV emission lines start from differentupper vibrational levels of the B state, ~40% of the B ? X energy is not available to be channeled into the locked line.

Optoacoustic detection of ethylene in the presence of interfering gases.

A study of the limitations of optoacoustic detection of ethylene in gas mixtures using a (12)C(16)O(2) laser is presented. Particular emphasis is given to the detection of ethylene in urban areas and in fruit storage chambers. Calculations indicate that in most cases of interest the practical minimum detectable and identifiable concentration of ethylene is about 5 ppb. A concentration of 1% of CO(2) may increase this limit to 50 ppb. These limits are primarily due to inaccuracy in a priori knowledge of ir spectral signatures of interfering gases. As a practical example of the monitoring of ethylene in a realistic environment, a meausrement with a sensitive resonant optoacoustic cell in an urban area is reported. The same cell is also used to demonstrate the effectiveness of NaOH scrubbers for the elimination of interfering CO(2). Measurements of absorption coefficients of ethylene for several (12)C(16)O(2) laser transitions are reported and compared with those given in the literature. Data are also given for the isotopic (13)C(16)O(2) laser transitions which may be useful in overcoming CO(2) interference.

SilkTouch: a new technology for skin resurfacing in aesthetic surgery.

We describe layer-by-layer char-free facial skin resurfacing at very low CO2 laser power levels with a miniature "SilkTouch" microprocessor-controlled optomechanical flashscanner. This device provides excellent ablation depth control with minimal thermal damage to the dermis. Indications for the laser in aesthetic surgery include perioral, lips, and periorbital wrinkles, among others.

Pulsed alexandrite laser technology for noninvasive hair removal.

OBJECTIVE: Determination of the efficacy of pulsed Alexandrite Laser technology for rapid noninvasive hair removal. SUMMARY BACKGROUND DATA: Although previous studies have already shown that Ruby lasers are capable of noninvasive hair removal, a technology for the substantial increase of treatment speed is of great interest. METHODS: We have used a 2 msec free running pulsed Alexandrite (lambda = 755 nm) laser operated at a repetition rate of up to 5 pps at energy fluences of 25-40 J/cm2 to treat a wide range of body sites on 126 patients in conjunction with a fiber delivery system and a transparent target ruler. A transparent gel was used as epidermal heat sink. The study lasted 15 months. Pretreatment as well as follow-up hair count per cm2 was performed to determine the level of success. Treatments were repeated when 1-2 mm growth was observed. RESULTS: The average hair count before the second treatment was found to be close to 65% of the pretreatment count. The average hair count 3 months after the last treatment, was found to be lower than 12%. The interval between treatments ranged from 4 weeks to 3 1/2 months. CONCLUSIONS: The 2 msec pulsed Alexandrite laser technology is effective for the removal of unwanted hairs, ranging from fair to dark, except when hairs are absent in the shaft depending on the stage of their growth cycle. This results in the necessity of a few treatments or touchups. Adverse effects are minimal and transient.

Statistical properties of He-Ne laser radiation reflected through a turbulent atmosphere.

Statistical properties of a He-Ne laser beam (0.63 microm) propagating through atmospheric folded paths of 1 and 12 km were investigated experimentally using direct and heterodyne detection. Measured scintillation histograms, power spectra, time autocorrelations, and phase fluctuations are reported. The turbulence parameters derived from the optical measurements were found to be in good agreement with those obtained from measurements of in situ temperature fluctuations.

Efficient phase conjugation of an ultraviolet XeF laser beam by stimulated Brillouin scattering.

We report efficient, diffraction-limited, phase conjugation of an XeF (3511-A) laser beam using stimulated Brillouin scattering. Approximately 70% of the 1-GHz bandwidth-locked portion of an injection-locked XeF laser output is phase conjugated by focusing the laser beam at 5 GW/cm (2) into hexane or isopropanol.

Middle ear laser office ventilation (LOV) with a CO2 laser flashscanner.

BACKGROUND: Laser assisted ventilation of the middle ear with a defocused laser beam has been performed on adults in an office setting without anesthesia. OBJECTIVE: The purpose of this study was to evaluate the efficacy and safety of a highly controlled, char-free CO2 flashscanner technology for the ventilation of the middle ear in young children, at this stage under general anesthesia, and later without anesthesia. METHODS: A CO2 flashscanning laser, in conjunction with a micromanipulator, was used on 21 SOM patients ages 3-7 years old, with followup at 2 months. Operating time is approximately 5 minutes. RESULTS: Postoperative results show average patency of 2-3 weeks without adverse effects. Of the treated patients, 53% did not require a second treatment, whereas 47% still suffered from otitis media and needed a second treatment. CONCLUSION: The CO2 flashscanner laser technology is effective and safe for middle ear ventilation and provides excellent control of the perforation diameter. It is already being performed in an office setting with sedation on a limited basis with very promising preliminary results. Based on the current study and on 70 additional cases with longer interval followup, we anticipate the office technique to become widely used in the future.

Laser-assisted hair removal by selective photothermolysis. Preliminary results.

BACKGROUND: Laser-assisted hair removal with the long pulsed ruby laser is a promising new technique based on selectively targeting melanin in hair follicles. OBJECTIVE: The purpose of this study was to evaluate the efficacy and safety of the long pulsed ruby laser (EpiTouch) for hair removal. METHODS: The Epitouch laser was used for hair removal of the arms of 20 patients. The areas were evaluated immediately post-treatment, and at 1, 4, 8, and 12 weeks, for efficacy and complications. RESULTS: Postoperative results showed 40-80% regrowth after 12 weeks. CONCLUSION: Selective melanin-based photothermolysis with a free running pulsed ruby laser seems to be a promising, noninvasive technique for long-term hair removal. More than one treatment is necessary since only anagen hair will be affected.

The role of laser and intense light sources in photo-epilation: a comparative evaluation.

The method for laser and light assisted hair removal is based on the theory of selective photothermolysis. Selective absorption of hair chromophores from lasers and broad band light sources results in destruction of hair follicles while leaving the skin undamaged. A discussion of the basic principles of selective photothermolysis as it applies to hair removal by lasers and light sources is presented, followed by a comparative review of three melanin target based systems: Ruby laser, Alexandrite laser, and a broad band intense pulsed light. These systems are efficient and safe with proper patient selection. Multiple treatments are necessary due to the nature of the hair growth cycle.

A neodymium:YAG fiber delivery system for interstitial photothermal therapy.

We describe here a highly durable 600-mu optical fiber with a 20-mm frosted distal tip protected by a smooth transparent cover that is capable of remaining in contact with tissue for prolonged periods. When used with a neodymium:YAG (Nd:YAG) laser, the active fiber surface diffuses optical radiation in a radial pattern, delivering up to 40 W power, and thus providing consistent and uniform interstitial photothermal therapy. Preliminary animal studies have demonstrated the feasibility of using these fibers to treat a variety of soft-tissue tumors, including benign prostatic hyperplasia.

Applications of the laparoscopic ultrasonic aspirator for advanced gynecologic operative endoscopic procedures.

We evaluated the efficacy of a new laparoscopic ultrasonic aspirator and applied it in gynecologic endoscopy. Two procedures were selected for preliminary evaluation of the instrument; ultrasonic aspiration for selective presacral neurectomies and total laparoscopic hysterectomy (TLH). The aspirator worked successfully in evacuating soft tissue and in adequately exposing the presacral plexus. In TLH we were able to skeletonize the broad ligament adventitia all the way to the level of the uterine arteries bilaterally, including exposure of the ureters. The time required for the procedures varied from case to case, and strongly depended on tissue type and on instruments used to dissect and improve visualization of the operative field. The aspirator may prove useful as an adjunctive in the surgical management of endometriosis, in laparoscopic lymphadenectomy, and in treating complex adhesions after further evaluation is completed.