Observational outcomes in proliferative diabetic retinopathy patients following treatment with ranibizumab, panretinal laser photocoagulation or combination therapy - The non-interventional second year follow-up to the PRIDE study.

PURPOSE: Ranibizumab monotherapy showed stronger effects on area of retinal neovascularization (NV) reduction while offering better visual acuity (VA) results than panretinal laser photocoagulation (PRP) monotherapy during the first 12 months of the PRIDE study. The second year of PRIDE was an observational, non-interventional follow-up, performed to evaluate long-term anatomical and functional outcomes in proliferative diabetic retinopathy (PDR) patients under real-life conditions, prior to the approval of ranibizumab for PDR. METHODS: Seventy-three PDR patients (28 from the ranibizumab group; 20 from the PRP group; 25 from the combination group) were included in the observational follow-up phase and treated at the investigators discretion. Visual acuity (VA) measurements and retinal imaging were performed at Months 12, 18 and 24. RESULTS: Mean (± SD) NV area in the ranibizumab monotherapy and combination follow-up groups increased from 3.16 ± 4.30 mm2 and 1.13 ± 2.78 mm2 at Month 12 to 6.09 ± 10.79 mm2 and 2.14 ± 4.41 mm2 at Month 18 and 10.00 ± 17.63 mm2 and 3.26 ± 7.05 mm2 at Month 24, respectively. In the PRP follow-up group, NV area declined from 5.44 ± 14.55 mm2 at Month 12 to 1.22 ± 1.67 mm2 at Month 18, but increased again to 4.05 ± 11.66 mm2 at Month 24. During the observational phase, only 2 (6;8) patients in the ranibizumab (PRP;combination) follow-up group were treated with anti-VEGF medications, while 17 (6;10) patients received PRP laser therapy. CONCLUSION: Discontinuation of ranibizumab treatment in PDR patients may result in an increase of NV area and VA loss. Tight monitoring of disease activity and continued treatment beyond the first year is needed to maintain disease control.

Diode-side-pumped, intracavity Nd:YLF/KGW/LBO Raman laser at 573 nm for retinal photocoagulation.

Wavelengths in the yellow-orange range are of significant interest for retinal photocoagulation and are especially important in the case of diabetic retinopathy, which can cause blindness and affects 3.3% of all working-age adults. This work presents a highly-efficient, compact, and cost-efficient side-pumped, intracavity Raman configuration to achieve this objective. A side-pumped Nd:YLF/KGW/LBO frequency-doubled Raman laser producing 11.7 W of output power at 1147 nm with 21% of slope efficiency and 6 W of output power at 573.5 nm with 12% slope efficiency is demonstrated.

Prospective evaluation of micropulse transscleral diode cyclophotocoagulation in refractory glaucoma: 1 year results.

PURPOSE: To evaluate the effectiveness in in-traocular pressure reduction and safety of micropulse trans-scleral diode cyclophotocoagulation in refractory glaucoma. METHODS: We prospectively evaluated a case series of 21 eyes of 21 consecutive patients with refractory glaucoma treated with micropulse transscleral diode cyclophotocoagulation at 12-month follow-up. The total treatment time was at the discretion of the surgeon, considering baseline and target intraocular pressure and glaucoma diagnosis. Intraocular pressure, inflammation, visual acuity, and number of medications were monitored. Success was defined as intraocular pressure between 6 and 21 mmHg and/or 30% reduction from baseline intraocular pressure with or without the use of antiglaucoma medications. Visual acuity loss was defined as a loss of ≥2 lines of vision on the Snellen chart or a ≥2-level decrease in visual function in patients with nonmeasurable chart acuity. RESULTS: The mean age was 61.04 ± 12.99 years, and 11 (52.4%) patients were male, with most (95%) patients showing low visual acuity at baseline (count fingers or worse). The mean intraocular pressure was 33.38 ± 15.95 mmHg, and the mean number of medications was 3.5 ± 1.1 at baseline. After 1, 3, 6, and 12 months, 76.19%, 57.14%, 55.56%, and 66.67%, respectively, of the patients were classified as treatment successes. Seven (33.3%) patients required new laser treatment and were considered treatment failures. The mean intraocular pressure reduction was 44.72% ± 29.72% in the first week and 41.59% ± 18.93% at the end of follow-up (p=0.006). The mean number of medications significantly dropped to 2.00 ± 1.7 at the 12-month visit (p=0.044). Complications included hypotony (4.8%), intraocular inflammation after 1 month (19%), and visual acuity loss (4.8%). CONCLUSIONS: Micropulse transscleral diode cyclophotocoagulation was safe and effective for reducing intraocular pressure in eyes with refractory and advanced glaucoma, with reduced need for ocular antihypertensive medication.

Efficacy and Safety of Micropulse® Transscleral Cyclophotocoagulation in Glaucoma. / Eficacia y seguridad de la ciclofotocoagulación transescleral con micropulsos en el tratamiento del glaucoma.

OBJECTIVE: To report the results using Micropulse® transscleral cyclophotocoagulation (Iridex) in the treatment of glaucoma. METHODS: Retrospective study in adult patients with glaucoma with at least 6 months of follow-up, and only one session of Micropulse®. The same surgical technique was used in all cases. The only laser parameter that could vary was the total treatment duration (in seconds). The remaining parameters were fixed at 2 Watts of power and 0.5ms (31.3%) of active cycle. RESULTS: A total of 22 eyes of 17 patients with glaucoma of various types and stages were included (mainly congenital and pseudoexfoliation). The mean follow-up time was 7.9 months. The total treatment duration varied from 100 to 180seconds. Definition of success: 5mmHg

Efficacy of Pattern Scan Laser photocoagulation for superficial conjunctival nevi ablation.

This study reports the efficacy and safety of Pattern Scan Laser (PASCAL) photocoagulation in the removal of superficial conjunctival nevi. Superficial conjunctival nevi were removed from 10 eyes of 10 patients using PASCAL. The laser spots were 200 µm in size, and the power delivered ranged from 250 to 300 mW. The duration of the laser pulse was kept at the minimum needed for adequate lesion removal. The duration of the laser pulse administered to the patients varied from 100 to 200 ms. Complete removal of the conjunctival nevus was observed in all the patients after PASCAL photocoagulation. Six months after treatment, complete re-epithelialization of the overlying conjunctiva was noted. No signs of recurrence or scarring were found in any of the patients during the follow-up period. Pure thermal denaturation is the main mechanism of PASCAL photocoagulation for removal of superficial conjunctival nevi. PASCAL can be considered as an alternative to conventional argon laser treatment or surgery.

Photocoagulation therapy for laryngeal dysplasia using angiolytic lasers.

In the management of laryngeal pre-cancerous lesions such as dysplasia or carcinoma in situ (CIS), it is important that lesion regression occur without any complications. As a minimally invasive treatment option, photocoagulation therapy using angiolytic lasers has been attracting attention. Therapeutic effects have been reported for this type of treatment, however, vocal function after treatment has not been well discussed. In this retrospective case series, we examined the therapeutic effects of photocoagulation therapy on laryngeal dysplasia and the impact on vocal function. Twenty-four patients with laryngeal dysplasia or CIS were treated with photocoagulation therapy using angiolytic lasers. Two patients were treated under general anesthesia, the remaining 22 patients were treated with topical anesthesia. Before and after treatment the extent of the lesion and vocal function was evaluated by endoscopic examination and acoustic and aerodynamic analyses, respectively. More than 50 % disease regression was observed in 20 of 24 patients. Acoustic and aerodynamic analyses revealed improvement in pitch perturbation quotient with no impairment in other parameters. Photocoagulation therapy using angiolytic lasers has proven to be feasible and safe for the treatment of laryngeal dysplasia.

Long-term result of out-patient neodymium-doped yttrium aluminium garnet laser photocoagulation surgery for patients with epistaxis.

OBJECTIVE: To evaluate the long-term efficacy of out-patient neodymium-doped yttrium aluminium garnet laser photocoagulation surgery for patients with epistaxis. METHODS: A retrospective clinical study was conducted. A total of 217 consecutive patients who presented with acute or recurrent epistaxis received neodymium-doped yttrium aluminium garnet laser photocoagulation treatment in an out-patient setting. RESULTS: At three years, 94 per cent of acute epistaxis patients versus 88 per cent of recurrent epistaxis patients reported no bleeding. The outcome scores at 12 weeks and 3 years after treatment showed no significant differences between the 2 groups (p = 0.207 and p = 0.186). However, there was a significant difference in outcome scores at four weeks after treatment (p = 0.034). The median (and mean ± standard deviation) pain levels experienced during the laser operation (performed in an office setting) were 4.0 (3.75 ± 2.09) in the acute epistaxis group and 4.0 (3.83 ± 2.01) in the recurrent epistaxis group. Neither group had any complications. CONCLUSION: Neodymium-doped yttrium aluminium garnet laser photocoagulation is desirable in the treatment of both acute and recurrent epistaxis, and has long-lasting efficacy.

Percutaneous Image-guided Laser Photocoagulation of Spinal Osteoid Osteoma: A Single-Institution Series.

PURPOSE: To retrospectively evaluate the safety and efficacy of percutaneous image-guided laser photocoagulation for the treatment of spinal osteoid osteoma (OO) in proximity to neural structures. MATERIALS AND METHODS: This study was institutional review board-approved with waivers of informed consent. From January 1994 until October 2014, 58 patients with spinal OO (mean age, 25 years; 40 men, 17 women) were treated in one institution by using laser photocoagulation with combined computed tomographic (CT) and fluoroscopic guidance. One patient was excluded because of less than 3 months of follow-up. All patients had typical clinical and imaging findings. Clinical features, radiologic data, and procedure-related data were reviewed, and limitations, complications, and failure rate were evaluated. All data were expressed as means ± standard deviation. P values of less than .05 were indicative of statistical significance. RESULTS: OO was in the vertebral body for 18 of 57 patients, the neural arch for 21 of 57 patients, and the articular process for 18 of 57 patients. Mean nidal diameter was 8 mm, and the mean distance from the closest neural structure was 6.6 mm (minimum distance, ≤5 mm in 35 of 57 patients). In 35 of 57 patients, no cortical coverage was present between the nidus and neural structure in danger. Mean total energy delivered was 1271 J (2-watt continuous power mode). Thermal insulation (carbon dioxide and/or hydrodissection), temperature monitoring, and electrostimulation were used in 42, 24, and one patient, respectively. Primary clinical success at 1 month was 98.2%. Total recurrence rate was 5.3%. All recurrences were addressed percutaneously. Secondary success rate was 100%. One-year follow-up is available in 54 of 57 patients. No major complications were noted. CONCLUSION: Spinal OO can be safely and effectively treated with percutaneous laser photocoagulation. In cases that are less than 8 mm to 10 mm distance and in the absence of cortical coverage, thermal protection techniques of the neural structures should be used.

Spinal cord cavernoma resection using a fiber-optic CO2 laser.

BACKGROUND: Spinal cord cavernomas are rare, and progressive growth can lead to neurologic deterioration. Complete microsurgical resection using the OmniGuide® fiber-optic CO2 laser is safe, precise, and can prevent further neurological deterioration. We describe the process, risks, and benefits associated with this approach. METHODS: Once the cavernoma is isolated, the CO2 laser enables the surgeon to incise and photocoagulate with the same instrument, increasing the accuracy and potentially reducing the procedure's duration. The spinal cord and surrounding tissue are protected from the laser by cerebrospinal fluid and cottonoid pledges. CONCLUSIONS: The fiber-optic CO2 laser is safe and effective when resecting spinal cord cavernomas. Personal experience, coupled with recent literature, brings us to this conclusion.

Rugate filters used in slit-lamp delivery to improve color rendering of illumination for retinal photocoagulation.

Laser filters and color filters used in slit-lamp delivery have been developed by the rugate approach to improve color rendering of illumination for retinal photocoagulation. The double-notch laser filter is designed according to the required laser lines and incident angle. Based on the transmission spectrum of a double-notch laser filter and the spectral power distribution (SPD) of the light source of a slit lamp, a scanning search algorithm is applied to find the optimal transmission spectrum of a multi-notch color filter for the best color rendering index of illumination. Open-source software is used to design the refractive index profile of the rugate filters, which are deposited by the reactive pulse magnetron sputtering. Both the theoretical analysis of SPD of slitlamp delivery with consideration of the deposited rugate filters and the experimental results demonstrate that the color rendering property of illumination can be improved remarkably, thus making fundus observation and retinal laser photocoagulation more reliable and efficient.

Diode laser endoscopic cyclophotocoagulation in the normal equine eye.

OBJECTIVE: To determine the clinical and histologic effects of diode endoscopic cyclophotocoagulation (ECP) in the phakic equine eye. ANIMALS STUDIED: Phase I: 10 equine cadaver eyes. Phase II: four normal adult horses. PROCEDURES: Phase I: ECP probe angle of reach (AR) was determined. Multiple ECP energy levels: 0.75, 0.90, 1.05, 1.20, 1.35, 1.50 J, and the resulting visible and histologic ciliary process changes were evaluated. Phase II: Ocular quadrants were treated with ECP at 0.90, 1.14, 1.38 J, and a control. The contralateral eye underwent a sham operation. Tissue changes (clinical and histologic) were evaluated. RESULTS: Phase I: Mean combined AR was 162 ± 29 degrees. Mean visible tissue scores: 2.60 ± 0.58 (0.75 J) to 5.04 ± 0.30 (1.50 J) from possible total of 6. Tissue 'popping' was observed at 1.50 J. Histologic ciliary tissue damage was present at all settings. Phase II: Mean visible tissue scores: 2.90 ± 0.48 (0.90 J), 3.61 ± 0.57 (1.14 J), and 4.52 ± 0.56 (1.38 J). Tissue 'popping' was observed at 1.38 J. Histologic ciliary tissue damage was present at all settings. Clinical effects included acute inflammation, intraocular pressure reduction, cataract formation, corneal edema, corneal ulceration, and postoperative ocular hypertension. CONCLUSIONS: Diode ECP between 0.90 and 1.14 J is a potential treatment option for glaucoma in horses based on visible tissue effects and target ciliary epithelium damage. Iatrogenic cataract development may limit the use of an anterior chamber approach in phakic horses. Supported in part by an ACVO VAF grant.

Enhanced photocoagulation with catheter-based diffusing optical device.

A novel balloon catheter-based diffusing optical device was designed and evaluated to assist in treating excessive menstrual bleeding. A synthetic fused-silica fiber was micro-machined precisely to create scattering segments on a 25 mm long fiber tip for uniform light distribution. A visible wavelength (λ=532 nm) was used to specifically target the endometrium due to the high vascularity of the uterine wall. Optical simulation presented 30% wider distribution of photons along with approximately 40% higher irradiance induced by addition of a glass cap to the diffuser tip. Incorporation of the optical diffuser with a polyurethane balloon catheter considerably enhanced coagulation depth and area (i.e., 3.5 mm and 18.9 cm2 at 1 min irradiation) in tissue in vitro. The prototype device demonstrated the coagulation necrosis of 2.8±1.2 mm (n=18) and no thermal damage to myometrium in in vivo caprine models. A prototype 5 cm long balloon catheter-assisted optical diffuser was also evaluated with a cadaveric human uterus to confirm the coagulative response of the uterine tissue as well as to identify the further design improvement and clinical applicability. The proposed catheter-based diffusing optical device can be a feasible therapeutic tool to photocoagulate endometrial cell layers in an efficient and safe manner.

Technical characteristics of fractional light devices.

This article deals with the technical characteristics of fractional light devices, fractional lasers, and light sources that cause their biologic effects by increasing the temperature of the target tissues to the point where the target is either killed, or in other cases where the temperature of the target tissue is increased to the point where repair and remodeling systems are turned on but tissue is not killed. Resurfacing devices act by causing ablation and/or coagulation.

Making liver transection even safer: a novel use of microwave technology.

Hepatic surgery has evolved significantly in the past decade. The current article describes the largest series of patients in United States undergoing liver resective therapy with the use of microwave technology for liver precoagulation. Glisson's capsule was incised after securing inflow and outflow control. Two antennae, 2 cm apart, connected to a 915-MHz generator, were inserted 5 cm into liver parenchyma at a 130° angle. Once the parenchyma was firm and changed its color to gray, the antennae were advanced along the line of transection. The parenchyma was divided with electrocautery. Intra- and postoperative data were analyzed. Thirty-five patients (24 men) underwent liver resections. Diseases treated were colorectal metastases (n = 9), hepatic adenoma (n = 3), gallbladder cancer (n = 3), hepatocellular carcinoma (n = 4), neuroendocrine tumor (n = 2), cholangiocarcinoma (n = 5), hemangioma (n = 2), focal nodular hyperplasia (n = 2), metastatic gastrointestinal stromal tumor (n = 1), hydatid cyst (n = 1), hepatoid carcinoma (n = 1), hepatolithiasis (n = 1), and suspected metastatic breast cancer (n = 1). Resections done were right hepatectomy (n = 19), segmental resection (n = 5), left hepatectomy (n = 4), extended right hepatectomy (n = 4), Segment IVb and Segment V resections during radical cholecystectomy (n = 2), and left lateral sectionectomy (n = 1). Median operative time for major resection was 188 and 251 minutes for minor resection. There was one postoperative mortality. Bile leak needing stenting occurred in one patient. Median blood loss for major resection was 500 mL and 265 mL for minor resection. Intraoperative transfusion was required in nine major and one minor resections. Other complications were ileus in four, deep vein thrombosis in two, intra-abdominal abscess in one, and cardiac events in two patients. Liver precoagulation with microwave technology is a novel and efficient technique with minimal morbidity and mortality for liver transection.

Influence of a yellow-tinted intraocular lens on laser beam transmittance.

PURPOSE: To compare the transmittance of laser beams that are used for photocoagulation through a yellow-tinted intraocular lens (IOL) and a clear IOL. METHODS: The transmittance of laser beams of different wavelengths (488 + 514, 514, 521, 568 and 647 nm) through yellow-tinted and clear IOLs of varying dioptric powers [+10, +20 and +30 dioptres (D)] was measured using a laser power meter. The transmittance ratio was defined as the ratio of the transmittance thorough a tinted IOL to that through a clear IOL, assuming that the transmittance value of the latter is 1; this ratio was calculated for each IOL and each wavelength of the laser beam. RESULTS: There were no apparent differences in the transmittance values between the tinted and clear IOLs when the 521, 568 and 647 nm wavelengths were used. In contrast, the transmittance ratio decreased for the tinted IOL when the short wavelengths - 488 + 514 and 514 nm - were used, especially when an IOL of a higher dioptric power was used. This ratio was found to be 91.9% for a +10 D, 86.7% for a +20 D and 82.2% for a +30 D lens when a 488 + 514 nm wavelength beam was used. CONCLUSION: When treating patients using photocoagulation, we must bear in mind the decreased transmittance ratio of short-wavelength laser beams when passed through tinted IOLs and increase the setting power of the beam accordingly.

Semiconductor diode laser transscleral cyclophotocoagulation for the treatment of glaucoma in horses: a retrospective study of 42 eyes.

OBJECTIVE: To evaluate the outcome of diode laser transscleral cyclophotocoagulation (TSCP) for the treatment of glaucoma in horses. PROCEDURE: Medical records at The Ohio State University were reviewed. All horses that underwent diode laser TSCP between the years of 1995 and 2007 were included. Preoperative, procedural and clinical follow-up data were collected, and telephone follow-up was performed. RESULTS: Forty-two eyes of 36 horses were included. Twenty-four hours prior to surgery mean intraocular pressure (IOP) was 37.17 + or - 13.48 mmHg (42 eyes). Forty-one of 42 eyes (98%) were sighted and 39 of 39 (100%) of eyes were receiving topical glaucoma medication. At 3-5 weeks postoperatively the average IOP was 19.36 + or - 12.04 mmHg (22 eyes). IOP remained significantly lower than pretreatment values at all periods of clinical follow-up (P < 0.05). There was no significant difference in vision outcome, or the requirement for topical glaucoma medication relative to pretreatment values at any follow-up period. Hyphema in 5 of 42 eyes was the only complication noted. Of the 27 eyes seen for clinical follow-up, 2 were enucleated because of refractory elevation of IOP. Mean telephone follow-up was 49 months. Twenty-one of 22 owners contacted (95%) reported that the treatment had been of value, 14 of 22 eyes (64%) were receiving topical glaucoma medication, and 13 of 22 eyes (59%) were considered sighted. CONCLUSIONS: Diode laser TSCP aided in the control of IOP and maintenance of vision but did not eliminate the need for topical glaucoma medication during the period of clinical follow-up.

Micropulse transscleral diode laser cyclophotocoagulation in the treatment of refractory glaucoma.

BACKGROUND: Transscleral diode laser cyclophotocoagulation (TSCPC) is an established method of treatment for refractory glaucoma, but is associated with significant complications. This study evaluates the efficacy and safety of a new form of TSCPC using micropulse diode laser and trans-pars plana treatment with a novel contact probe. METHODS: Prospective interventional case series of 40 eyes of 38 consecutive patients with refractory glaucoma treated with micropulse TSCPC with a novel probe. Outcomes measured were success, hypotony and response rates. RESULTS: The mean age of patients was 63.2 +/- 16.0 years. The mean follow-up period was 16.3 +/- 4.5 months. The mean intraocular pressure (IOP) before micropulse TSCPC was 39.3 +/- 12.6 mmHg. Mean IOP decreased to 31.1 +/- 13.4 mmHg at 1 day, 28.0 +/- 12.0 mmHg at 1 week, 27.4 +/- 12.7 mmHg at 1 month, 27.1 +/- 13.6 mmHg at 3 months, 25.8 +/- 14.5 mmHg at 6 months, 26.6 +/- 14.7 mmHg at 12 months and 26.2 +/- 14.3 mmHg at 18 months (P < 0.001 at all time points). No patient had hypotony or loss of best-corrected visual acuity. The overall success rate after a mean of 1.3 treatment sessions was 72.7%. CONCLUSION: Micropulse TSCPC is a safe and effective method of lowering IOP in cases of refractory glaucoma and is comparable with conventional TSCPC.

Effects of conventional argon panretinal laser photocoagulation on retinal nerve fibre layer and driving visual fields in diabetic retinopathy.

AIMS: To determine the effects of argon green panretinal laser photocoagulation on retinal nerve fibre layer thickness, threshold visual fields, and Estermann full-binocular visual fields over time in diabetic retinopathy. METHOD: Prospective, pilot clinical study. Time-domain optical coherence tomography (TD-OCT) of the optic nerve head and 24-2 SITA-Fast Humphrey/Estermann visual fields (HVF, EVFs) recorded at baseline, 10 weeks, and 6 months post laser. Quantitative field analysis of central 10 degrees, 24 degrees, and binocular visual fields. RESULTS: A total of 10 eye samples were subjected to uncomplicated multiple-session 100 ms panretinal laser using 2000 burns, 300-microm spot, and mean power of 136 mW (SD+/-39.3). TD-OCT detected and quantified an increase in mean retinal nerve fibre layer thickness at 10 weeks (+8 microm; P<0.05) and progressive thinning at 6 months (-4 microm; P<0.05) compared with baseline. Mean threshold sensitivities, and 10 degrees and 24 degrees HVF improved at both time points in the majority (9 of 10 and 8 of 10) of patients. EVFs showed no significant change with treatment. CONCLUSIONS: This pilot study shows that conventional argon laser panretinal photocoagulation may increase the retinal nerve fibre layer thickness in the short term, presumably related to laser-induced axonal injury, with progressive thinning of nerve fibre layer over the long term. The 10 degrees and 24 degrees visual fields improved significantly after laser with no adverse effects on the UK standard driving fields.

Micropulse diode laser photocoagulation for central serous chorio-retinopathy.

PURPOSE: Central serous chorioretinopathy (CSC) is usually characterized by a localized detachment of the neurosensory retina that is self-limiting. However, some cases may persist or recur leading to degenerative changes of the retinal pigment epithelium and the neurosensory retina resulting in severe visual loss and requiring intervention. METHODS: This retrospective case series reports the long-term visual outcome of the use of micropulse laser photocoagulation for this condition with a review of literature. RESULTS: The mean follow up was 17.1 months. Four of the five patients had complete resolution of symptoms whereas one patient had recurrent CSC from a new leak that failed to resolve after repeat micropulse treatment despite improvement in symptoms. DISCUSSION: The outcomes in this case series confirm the long-term efficacy of micropulse laser in the management of CSC. It produces therapeutic effects that appear comparable to those of conventional photocoagulation with no detectable signs of laser-induced iatrogenic damage.

A coaxial laser endoscope with arbitrary spots in endoscopic view for fetal surgery.

In this paper, we describe a rigid endoscope that transmits a laser beam coaxially to arbitrary points in the endoscopic view, mainly for treatment of twin-to-twin transfusion syndrome. The endoscope consists of a hotmirror for coaxial transmission of visible light and a Nd:YAG laser beam, and galvanometers for controlling the beam irradiation angle. We evaluated the transmission efficiency of the laser power, the spot size through the endoscope and accuracy in positioning the beam. The maximum laser transmission efficiency was 39% and the spot diameter was 2.2-3.2 mm at a distance of 10-20 mm. The positioning accuracy was mostly within 1.0 mm in the endoscopic view at the distance. The average laser power density on the spot was estimated to be 170-370 W/cm2, and a chicken liver was successfully coagulated by changing the laser beam irradiation angle.