The author describes his experience with 400 intranasal laser surgical procedures done with the carbon dioxide laser and the surgical microscope. Procedures include excision and vaporization of polyps, turbinates, tumors, telangiectasia, synechia, nasal stenosis, intranasal cysts, papillomata, and septal spurs. The author describes a suction speculum and drape of his own design which provide smoke free access to the internal nose, and protection of the alar rim and the face from laser energy. Relief of obstruction is comparable to that obtained from the more traditional means of intranasal surgery. Intraoperative and early and delayed post operative bleeding is less with laser surgery than with any other means. Avoidance of technical problems is emphasized in this manuscript, since intranasal laser surgery is in some respects difficult to perform. Included are practical suggestions about patient positioning, use of protective devices, and patient selection.

A retrospective review of the author's series of 91 carbon dioxide (CO₂) laser myringotomy cases performed between 1983 and 1986 is presented. Patients with chronic otitis media with effusion (COME) were selected on the basis of possible benefit from shorter ventilation time than tympanostomy tube insertion. The proceedings were performed on an outpatient basis with topical iontophoretic anesthesia, which offers significant cost savings and a lack of possible complications. The CO₂ laser gives clean precise 0.8mm perforations which remain open for 2-4 weeks, this shorter ventilation time minimizing the period of water precautions and other side effects. The laser perforations heal well. With a success rate of 52 % reported, which could be increased with careful patient selection, we feel that the advantages of carbon dioxide laser myringotomy over myringotomy plus intubation outweight the risk of recurrent otitis media with effusion formation in those patients to whom this procedure is applicable.

In this paper, we discuss the possibilities of the clinical application of the contact method with various endoprobes, either alone or combination with other conventional treat ment such as endoscopic polypectomy, local injection therapy, intubation of prosthesis, radiation therapy and general chemotherapy. According to the type of lesions and the severity of the complicated diseases, endoscopic techniques were chosen and combined. It was generally recognized that all of the endoscopic treatments were not curative therapies but applied as local therapeutics. Therefore, during the management of high risk patients with GI cancer within the mucosa, contact endoscopic Nd:YAG laser therapy should be preferred to general surgery.

The advent of the CO₂ laser in 1964 aroused hope that the "silver bullet" in cancer therapy had arrived. Experiments were designed on laboratory animals and patients with varying results. Certainly, many of the requirements of adequate excisional surgery for cancer are obtained with the laser. The treatment of recurrent and particularly, metastatic cancer, seems to be possible. Palliation of cancer is possible in many cases. Relief of pain seems enhanced by the soft laser. All of these, with our aspirations for the near future will be discussed.

We discuss ten years of surgical experience with CO₂ Laser Neurosurgery involving 140 to mors. Nowadays there is a concept that the absolute indications for the use of the Laser in Neurosurgery are the "Midline Tumors of the Central Nervous System". This concept has to be reviewed in our opinion because the usefulness of different lasers is a dynamic fact in the day-by-day developments in the technical devices. We want to describe our 40 "Midline Tumors of CNS Tumors" that includes: Basal Meningionias (15), Third Ventricular Tumors (5), Pinealoma (1), Paraselar Tumors(3), Brainsten Tumors (6), Adherent to Brainsten (5), Spinal Cord Tumors (5). The atraumatic, bloodless, vaporization effect of CO₂ laser produces better results and less index of mortalify and morbidity. Evocated Potential and other advances are also important in this results. Key Words: Laser Neurosurgery, Microsurgery, Brain Tum

Low energy CO₂ laser was used to perform intestinal anastomosis by means of tissue welding in 10 Wistar rats. The post operative course in the studied animals was uneventful. The integrity of the anastomosis was investigated manometrically, immediately upon completion of the anasto-mosis and twenty days later. Ten Wistar rats served as control in which conventional interrupted one-layer anastomosis was performed. The results show a significant superior-ity (P<0.05) to those intestinal anastomoses which were constructed by means of laser tissue welding. The time to complete the anastomosis was also significantly shorter when the laser was used, as compared to hand suturing. Serial histological examinations up to 90 days following surgery revealed complete healing and epithelialization of the anastomotic site. The technical details of the CO₂ laser anastomosis are described.

Dye mediated, laser light induced photosensitization was tested in an in vitro model for its efficacy in eliminating the contaminating tumor cells for ex vivo autologous bone marrow purging. Daudi and U-937 cells (3 x 106/ml) in RPMI-1640 supplemented with 0.25% human albumin were mixed with 20 µg/ml and 25 µg/ml of MC-540, respectively. These cell-dye mixtures were then exposed to 514 nm argon laser light. Identical treatment was given to the normal bone marrow cells. Viability was determined by the trypan blue exclusion method. Results show that at 31.2 J/cm² irradiation, 99.9999% Daudi cells were killed while 87% of the normal bone marrow cells survived. No regrowth of Daudi cells was observed for 30 days in culture. However, a light dose of 93.6 J/cm² was required to obtain 99.999% U-937 cell kill with 80% normal bone marrow cell survival. Mixing of irradiated bone marrow cells with an equal number of lymphoma cells did not interfere with the photodynamic killing of lymphoma cells. Exposure of cells to low doses of recombinant interferon-alpha prior to photodynamic therapy increased the viability of lymphoma cells.

I have conducted laser hyperthermia, photodynamic therapy (PDT) and the combined therapy of laser hyperthermia and PDT for solid tumor of human pancreatic carcinoma transplanted to nude mice. Following experimental therapies have begun 5-6 weeks after transplantation. 1) Laser hyperthermia: The Frosted Probe was punctured under controlling temperature near the margin of a tumor at 42-43C with 3W for 10 minutes. This therapy caused 70-80% necrosis of the total area of pancreatic tumors after 7 days of the treatment. 2) PDT: Argon dye laser was irradiated into a tumor with 300-400mW in 72 hours after hematoporphyrine derivative (HpD) in a dose of 3mg/kg was intravenously injected. Histological changes detected 7 days after the therapy were coagulated necrosis and fibrosis in the tissues ranging from 30-50% of the area. 3) The combined therapy of laser hyperthermia and PDT: A new quartz fiber, which was originally designed to deliver both Nd:YAG laser and argon dye laser simultaneously, was used. Conditions of laser hyperthermia and PDT were same as above. Necrosis amounted 100% of the total area in tumors of 3 out of 6 mice histopathologically 7 days after the therapy. As for the remaining 3 mice, almost all tissues changed into necrosis. Effects of thermal and laser energy to the tumor tissues were also studied by in vitro experiments under the same conditions. The most remarkable decrease in viability was recognized in the combined therapy of laser hyperthermia and PDT among three types of therapies in vitro. The combined therapy of laser hyperthermia and PDT has proven to be highly effective by in vivo and in vitro study using human pancreatic cancer cell line. It will thus be possible to adopt the therapy, with the use of the new quartz fiber, as one of the useful endoscopic laser therapies.

From February 1984 to the present, we have treated 75 patients with bladder cancer through the contact Nd:YAG laser irradiation method. Eighteen males and two females (average age 62 years) were transurethrally treated with the contact Nd-YAG laser from 2 to 42 weeks prior to radical cystectomy. The pathological findings of the regions were summarized as follows: 1. Ulcers and granulations were formed., 2. The granulation reached to superficial and/or deep muscle of the bladder wall, but not to the serosa., 3. Foreign body giant cells resulting from carbonized tissue were observed in the granulation., 4. Hyperplasia of periheral tissue mucosa of the regions were observed., 5. There were no residual cancer cells at the irradiated area in all of the Pts. but in one Pts. with a clinical stage T 3, 6. There was no evidence of implantation and growth promotion of cancer cells. We are convinced that contact Nd-YAG laser surgery will play an important role in transurethral treatment of bladder cancers.

Helium-Neon LASER spectrometry of fluorescent dye WW 781 bound to heart tissues permits to collect optical signals significant from the electrical activity and from the electromechanical activity. It is also possible to image the electrical activity of a myocardial surface stained with WW 781 and illuminated with a direct or an unfocused Helium-Neon LASER beam using a Charge Coupled Device (CCD) video camera. Sheep ventricular fragments and right mouse atria were stained with Tyrode solutions containing from 0.4 to 1 g/1 WW 781. Focused or unfocused illuminations were performed with a 2 mW Helium-Neon LASER through a lens or an optical fiber. Direct illumination was performed with nine 5 mW Helim-Neon LASERs permitting to map the observed surface. CCD video camera was connected to a 70-220 Zoom-telelens and placed behind a 665 nm high pass optical filter. Video signals were amplified and recorded on a NTSC B. V. U professionnal magnetoscope. Video recordings were studied frame by frame. Fluorescent emissions from illuminated areas were monitored with a 200 um diameter optical fiber optrode using a monochromator-photomultiplier set. Direct illumination permitted to map on nine points and to follow the electrical activity propagation on sheep ventricular epicardium observing a 2/1 conduction block on a limited area. Fluorescent signals significant from electrical activity were simultaneously recorded. Unfocused lighting permitted to follow the depolarization of a 1.2 mm spot on sheep ventricular endocardium and to follow the propagation of the fluorescence on a 2 mm diameter area on mouse atrium. Such a technique appear to be of great imterest in the study of arrythmias on experimental models with foreseeable pharmacological applications.

A Coherent CR599 Argon laser pumped continuous wave tunable dye laser emitting at 577 nm has been used in the treatment of 100 patients with port wine stains. This laser produced a lightening of the port wine stain in 80% of patients treated with a low incidence of adverse effects. These results confirm the role of this laser as a treatment of port wine stains.

The ability to transmit trains of pulsed laser radiation through opaque liquids via a cavitation effect is demonstrated. We were able to cut lucite arid perspex immersed in such liquids. A simplified model describing the formation of stationary cavities is presented and a series of experiments confirming this model are described. Furthermore it is shown that the thermal heating of the liquid surrounding these cavities may be minimized by using pulses of a very short duration. This effect facilitates material cutting and laser surgical operation under blood or water by CO₂ or excimer lasers.

Laser devicea are becoming morn popular in surgery. They are mainly used for controling hemorrages through an endoscope, for radicalevaporating benign and small malignant tumors in esophagus, stomach, colon, and for palliative destruction of inoperable tumors to recanalize the lumen. According, to literature operations on abdominal parenchymal organs with laser are rather seldom. And the operations with laser on hollow organs of digestive tract are being mainly performed in the USSR, and they being rather effective.

In 1984 we developed laser hyperthermia (hereafter called laserthermia), a system for transmitting low power Nd:YAG laser energy (2 W) through an interstitial probe for local hyperthermia (43-44°C). We have investigated this method in experimental and clinical studies, and reported some of our results at the last conference. However, since the process by which laser thermia induces tumor destruction is still not fully understood, we first performed in-vivo and, later, in-vitro and detailed in-vivo studies and obtained the following results: 1) There are differences in the process of carcinoma cell destruction between laserthermia(low power, long time) and contact irradiation (high power, short time). 2) Changes due to laserthermia become detectable histologically 3h after irradiation. 3) Laser-light itself has the ability to cause carcinoma cell destruction. Consequently, we suggest that laserthermia has a synergistic effect of hyperthermia (thermal effect) and laser-light. In further clinical studies, laserthermia has proved to be safer and more reliable than conventional non-contact or contact laser irradiation in eradicating tumor tissue.

The thermal properties and maximum temperatures attained during CO₂ (n=20) and Argon (n=20) laser welded repair of arteries were compared in a canine model. An AGA 782 digital thermographic system with spatial and thermal resolution of +0.2mm and +0.2°C was used to continually record and analyze the measurements. Longitudinal incisions of 1 cm length were made in each vessel with a 6-0 prolene stay suture at each apex and the midpoint, forming two 5mm segments. A Sharplan CO₂ laser was used at an energy fluence of 1500 J/cm², 150mw power, spot size of .00049 cm² and exposure of 5 seconds to induce fusion of each 0.5 cm of vessel wall. Argon fusion was accomplished with the HGM Argon laser using a 300 micron diameter fiber held 1 cm from the surface of the vessel, energy fluence of 570 J/cm², 500mw power, spot size of 0.066cm² and total exposure of 75 seconds per 0.5cm length. Continuous irrigation of room temperature saline at 1 drop/second (approx. 3m1/min) was used during argon welding. With CO2 laser welding temperature increased quickly to its maximum (MAX=84.0, MEAN=60.7+ 9.8°C) which was maintained as the laser energy moved slowly (0.1cm/sec) along the vessel edges. In contrast the argon laser welding temperatures rose to a maximum (MAX=48.8, MEAN=45.1+2.7°C) and returned to a baseline temperature with each drop of saline. The thermal difference with these two laser wavelengths may bring about different welding mechanisms and provide an explanation for the increased incidence of thrombus aneurysm formation that has been reported in CO₂ laser fusion.

Contact Nd:YAG laser surgery is assuming a greater importance in endoscopic and open surgery allowing coagulation, cutting and vaporization with greater precision and safety. One of contact probe allows a wider angle of irradiation and diffusion of low power laser energy using the interstitial or the touch technique for local hyperthermia. Continuously monitoring temperature sensors are placed directly into the surrounding tissue or tumor. Using a computer program interfaced with the laser and sensors, a controlled and stable temperature (e.g., 42°C) can be produced in a known volume of tissue over a prolonged period of time (e.g., 20-40 min). Using pulsed Nd:YAG laser and photosensitiser, Pheophorbide-a either laser hyperthermia or POT into malignant tumor are possible from single laser resorce. Combination method with laser hyperthermia and POT will be promisive and exclusive laser modality for cancer.

Laser-induced fluorescence data for rats injected with the different tumor-marking drugs, dihematoporphyrin ether, poly hematoporphyrin esters, hematoporphyrin and phtalocyanine, are presented. Studies were performed at two different excitation wave-lengths. Comparisons between the different drugs are made with regard to fluorescence intensity and tumor demarcation capability. Further, the origin of the differences in fluorescence characteristics is briefly discussed.

Since 19843 we have been studying endoscopic laser induced hyperthermia (laserthermia) with SLT frosted contact probe and low power Nd-YAG laser irradiation under 5 watts" The endoscopic laserthermia have been reported endoscopically such as tumor reduction3. In this paper, we would like to discuss the comparative histological studies between the first prototype laserthermia system. with Medilas(M..B.B.) Nd-YAG laser and the new laser-thermia system with SLT Contact Laser on canine stomach, and report clinical application of endoscopic laserthermia to the gastric cancers. The computer controlled laserthermia will be possible to apply for the treatment of the malignant tumor in the gastrointestinal (GI) tract.

The extent of the resistance of human dental enamel against acid decalcification by using a normal pulse Nd:YAG laser was observed. Furthermore, specimens of human enamel were topically applied with a solution of acidulated phosphate fluoride (APF) before and after the laser irradiation. APF treatment after the laser irradiation caused the most remarkable acid resistance of the enamel with a greater fluoride uptake into the enamel structure, whereas the APF treatment before laser irradiation caused a lesser effect.

Significant differences between the optical spectra taken from sound regions of teeth and carious regions have been observed. These differences appear both in absorption and in laser induced fluorescence spectra. Excitation by the 488 nm line of an argon ion laser beam showed a peak in the emission intensity around 553 nm for the sound dental material while the emission peak from the carious region was red-shifted by approximately 40 nm. The relative absorption of carious region was significantly higher at 488 nm; however its fluorescence intensity peak was lower by an order of magnitude compared to the sound tooth. Implications of these results for a safe, reliable and early detection of dental caries are discussed.

The present study introduces a novel method for assessing the efficacy of so-called soft tissue lasers on the peripheral and central nervous systems. In any readily available method relying on low energy laser irradiation, one of the most critical factors is obviously the wavelength of the laser, for this will determine how much of the energy applied to the skin or muscle actually reaches the target nerve. The present findings reaffirm our conclusion that low energy laser irradiation is bene-ficial in the treatment of injured peripheral or central nervous system, the beneficial effect diminishing with decreasing wavelength from 632nm down to 465nm. Our results pave the way for a new approach to the treatment of traumatic paraplegia and argue in favor of a combination of laser irradiation and PNS or CNS transplantation for the treatment of spinal cord injury.

The authors have worked out a programme for combined treatment of purulent wounds with CO₂ laser. It consists of following components: a) laserinsision of suppurative wounds,necrectomy,or irradiation of the incised wound with the defocused laser beam; b )diplication of proteinerses and antiseptics immobilized on the textile dressing and dranaige materials; c) applications of biocompatible materials with the immobilized antiseptics and enzyme agents; d) application of low energy laser irradiation in the postoperative period; e) lavage of the sutured wound if indicated. The points of the above-mentioned programme can be used separately as independed methods in several thousands of patients. Their combined applications has been studied on 400 patients. Such treatment allowed to refuse the antibioticotherapy in 98,3% of cases,to reduce the terms of trestment in I,5-2 % times as compared with traditional methods, and to low significantely costs.

Laser remote sensing from satellites require efficient, long lifetime, maintenance-free tunable lasers and new solid state laser technology is emerging to meet these requirements. This new technology will provide lasers for the medical community capable of tunable operation over a broad wavelength range with factors of ten reductions in size, power and cooling requirements and maintenance costs while remaining competitive in cost with present laser technology.

Developing refractive surgery techniques usually requires pre-clinical trials with animals before human clinicals are performed. In order to assess the results of the surgery, an accurate and repeatable measurement of the resultant refraction must be made. Normal techniques such as retinoscopy, subjective examinations, and conventional autorefractions all run into problems when animals are involved. The authors have modified a conventional autorefractor and have made measurements on rabbits and monkeys both before and after refractive surgery treatments with an excimer laser. The results showed refractive changes with degrees of myopic correction.

A thorough planning process prior to a medical laser purchase can ease its transition into the patient care environment. From a user perspective safety is the most important issue, but several other issues exist. Use a process that fits the needs of your institution and follow it through.

We analyze the potential of an optical fiber based remote thermography system. Achievable accuracy, resolution, range, and response time are examined. Experimental results concerning each of these parameters will be presented and compared with theoretical predictions. Results obtained utilizing both silica and fluoride fibers are compared and the benefits and limitations of each are discussed. Two main application areas of this measurement technique are addressed. The use of this technique in the invitro and invivo study of laser induced temperature rise in biological tissue will lead to a better understanding of laser-tissue interaction. Tissue temperature information can be used as a feedback element in a medical laser energy delivery system. Simultaneous laser energy delivery and thernographic sensing through a single fiber will provide "automatic dosing" in many laser coagulative treatments.

The Technicon H*1 system^TM is a clinical laboratory flow cytometer which performs a complete hematology profile, providing quantitative information on the various types of cells in a blood sample. A light-scattering method, using a HeNe laser, determines in a single flow channel the red cell count, platelet count, and the distributions of red cell volume, red cell hemoglobin concentration, and platelet volume. To accomplish this the scattered light from each red cell in the sample is measured in real time at two angular intervals. The cell volume and the hemoglobin concentration within the cell are derived from these two measurements. Severe accuracy and precision specifications are placed on the medically important red cell count (RBC) and the mean red cell volume (MCV). From the point of view of optical system design, the dominant factor is the requirement that RBC and MCV have precision and accuracy of the order of 2%. Signal-to-noise and scattering-angle definition requirements dictated the choice of a HeNe laser light source. The optics includes an illumination system for producing a sharply defined, uniformly illuminated scattering region and a detection system which must accurately define the accepted scattering angles. In previous cytometric methods for determining MCV only a single quantity was measured for each cell. Such methods cannot disentangle the independent effects of cell size and hemoglobin concentration on the measurement, thus compromising MCV accuracy. The present double-angle scattering method overcomes this accuracy problem. The H*1 red cell method, the supporting optical design and data demonstrating that the use of this technique eliminates interference between the observed red cell indices are presented.

Neonates with jaundice require monitoring of serum bilirubin which should be repeated at frequent intervals. However, taking blood samples from neonates is not always an easy job, plus being an invasive and traumatising procedure with the additional risk of blood loss. In this paper the authors present the theory and design of a new noninvasive device for transcutaneous bilirubinometry, using a differential absorption laser system. The new technique depends upon illuminating the skin of the neonate with radiation from a two wave-length oscillation laser. The choice of the wavelengths follows the principles of optical bilirubinometry. For obtaining more accurate measurements, different pairs of two wave-lengths are incorporated in the design. The presence of hemoglobin is corrected for by appropriate selection of the laser wavelengths. The new design was tested for accuracy and precision using an argon ion laser. Correlation study between serum bilirubin determination by laser transcutaneous bilirubinometry and by American optical bilirubinometer was highly significant.

Tumors can be detected by their increased fluorescence compared to surrounding tissue, several hours after injection of a fluorescent, tumor-localizing compound such as dihematoporphyrin ether. The fluorescence is observed by either a nonimaging photodetector, with appropriate filters, or by an imaging optical system (usually employing an image intensifier because the fluorescence is weak). Excitation is best carried out with a laser, but a filtered arc lamp may be suitable. Instruments differ in the methods of excitation, detection, reduction of background from native fluorescence of tissues, and provision for a whitelight - illuminated reflectance image or other means for guiding and identification of anatomical landmarks. Carcinoma in situ has been detected by a number of these instruments.

Alexandrite laser properties are discussed in light of applications foreseen in medical instrumentation. Attention is given to apparent clinical alternatives to be made possible by this technology, and to some directions now being pursued in medical research.