Microwave Ablation versus Laser Ablation in Occluding Lateral Veins in Goats

Increasing number of endovenous techniques are available for the treatment of saphenous vein reflux and endovenous laser ablation（EVLA） is a frequently used method. A newly developed alternative, based on thermal therapy, is endovenous microwave ablation（EMA）. This study evaluated the effect of the two procedures, in terms of coagulation and histological changes, in occluding lateral veins in goats. Twelve animals were randomized into two group, with 6 treated with EMA（EMA group）, and the rest 6 with EVLA（EVLA group）. Results of coagulation, including coagulation, fibrinolysis and platelet activation, were assessed at three or four different time points： before, immediately after, 24 h（and 48 h） after ablation. The diameter change, a measure of efficacy, was ultrasonographically measured before and 1 month after the ablation. Histological changes were grossly and microscopically evaluated immediately, 1 and 3 month（s） after the ablation. The length of the ablated vein and preoperative average diameter were comparable between the two groups. In both EMA and EVLA groups, several coagulation parameters, fibrinolysis and platelet activation parameters only underwent slight changes. Ultrasound imaging displayed that the diameter reduction of the veins treated by EMA was significantly larger than by EVLA, in consistent with the results of macroscopic examination. Microscopic examination revealed necrosis and thickening of the vein wall, and occlusion of the lumen within 3 months after ablation in both EMA and EVLA groups. It is concluded that EMA is a minimally invasive therapy, which appears to be safe and effective for treatment of lateral veins in goats.

Corneal damage effects induced by infrared optical parametric oscillator radiation at 3743 nm

The main aim of this paper is to investigate the corneal damage effects induced by mid-infrared optical parametric oscillator(OPO)radiation.Experiments were performed to determine the corneal damage thresholds of New Zealand white rabbit at the wavelength of 3743 nm for ex-posurédurations of 0.1 s,1.0 s and 10.0 s.Through slit-lamp biomicroscope and histopathology,corneal injury characteristics were revealed.The damage thresholds were 3.73 J/cm^(2),7.91 J/cm^(2)and 31.1 J/cm^(2),respectively,for exposure durations of 0.1 s,1.0 s and 10.0 s.The damage data was correlated by an empirical equation:Radiant exposure at the threshold=9.72×exposure duration,^(0.46)where the units of radiant exposure and exposure duration were J/cm^(2)and second.At near-threshold level,corneal injuries at 1 h post-exposure mainly involved the epithelium,and the epithelium damages repaired at 24-h post-exposure.There are sufficient safety margins be-tween the damage thresholds and the maximum permitted exposures from current international laser safety standard IEC 60825-1.

Online determination of the source of stray light in the SG-Ⅲ high-power laser facility

Stray light in high-power laser facilities not only decreases the gain capacity of the main amplifier, but can also cause permanent damage to optical components, greatly threatening the safety operation of the SG-III. This Letter reports a technique for quickly pinpointing the source of stray light in the main amplification optical path of the SG-III. The achieved results indicate that the accuracy of our method is up to 1 m in an optical path of 100 m. The judging method is effective for examining and removing harmful stray light in the SG-III laser facility and it can be promoted in huge laser facilities of this kind.