Ophthalmic surgeries on post mortem porcine eyes with picosecond ultrashort laser pulses.

Purpose: This work demonstrates significant advantages in ophthalmic surgeries through the use of picosecond ultrashort laser pulses instead of state-of-the-art nanosecond laser pulses. These ultrashort lasers shall serve as universal tools more effectively combining advantages of high precision, low impact and economic advantages compared to existing instruments. Methods: As samples, we used post-mortem porcine eyes on which we performed the experiments with both picosecond and nanosecond lasers. Performed surgeries were laser iridotomy, (post-) cataract treatment/capsulotomy and selective laser-trabeculoplasty. Pulse widths were between 12 ps and 220 ns with pulse energies between 30 µJ and 10 mJ at 532 nm and 1,064 nm. Additionally, we investigated accompanying shock waves, cavitation bubbles, and heat effects during the ablation processes. Results: For all surgeries, significant differences were observed between picosecond and nanosecond pulses: It was possible to scale the pulse energy down to 10 of microjoules rather than requiring millijoules, and resulting tissue ablations are much more precise, more deterministic and less frayed. The shock wave and cavitation bubble investigation revealed major differences in pressure between picosecond pulses (0.25 MPa, 50 µJ) and nanosecond pulses (37 MPa, 5 mJ). The heat input during ablation could be lowered by two orders of magnitude. Conclusion: Picosecond ultrashort laser pulses show substantial benefits for several ophthalmic surgeries, with regard to ablation precision, shock wave generation and heat input. They are better than state-of-the-art ophthalmic nanosecond lasers in all aspects tested.

Sub-20-ps pulses from a passively Q-switched microchip laser at 1 MHz repetition rate.

We present a 50 µm Nd3+:YVO4 microchip laser that is passively Q-switched by a semiconductor saturable absorber mirror. To reduce handling problems caused by the small crystal dimensions, the 50 µm Nd3+:YVO4 crystal is optically bonded to an undoped YVO4 crystal of a length of about 500 µm. By using a saturable absorber mirror with an effective modulation depth of >10% the system is able to deliver 16 ps pulses at a repetition rate of up to 1.0 MHz. The average laser power is 16 mW at 1064 nm. To our knowledge these are the shortest Q-switched pulses ever reported from a solid-state laser. The limits in terms of pulse width, repetition rate, output power, and system stability are discussed. Additionally, continuous-wave behavior is analyzed. Experimental data is compared with the simulation results of the coupled rate equations.

Risk-adapted primary HPV cervical cancer screening project in Wolfsburg, Germany--experience over 3 years.

BACKGROUND: Currently, the German cervical cancer screening program encompasses an annual cytological Papanicolaou (Pap) smear. However, primary screening for cervical cancer using human papillomavirus (HPV) DNA testing detects cervical pre-cancerous lesions with a significantly higher sensitivity than the Pap smear-based cytology. OBJECTIVES: In order to develop viable modalities for primary cervical screening incorporating DNA testing for high-risk (HR) types of HPV, we started a pilot project in the city of Wolfsburg, Germany, in February 2006. This program provided a risk-adapted HPV testing-based strategy with defined patient pathways and extended screening intervals for women of 30 years or older. We report here the data of a 3-year follow-up. STUDY DESIGN: In the context of the usual routine screening at their office-based gynecologists, women were offered conventional cytology plus the Hybrid Capture 2 (HC2) HPV DNA test. Women with inconspicuous cytological findings (Pap I/II) and negative HC2 test were re-tested after 5 years but continued their annual gynecological examinations. When cytology and HC2 were positive, women were immediately referred to colposcopy. In women with a negative cytology but positive HC2 test, Pap smear was repeated after 6 mo and HC2 testing after 12 mo, and women were called for colposcopy if the HC2 test was persistently positive. RESULTS: From February 2006 to December 2008, 16,724 women agreed to participate in the project. Overall, 906 (5.41%) had positive HC2 results and 338 (2.02%) showed atypical Pap smears at recruitment. There were 417 (2.48%) women referred for colposcopy, 104 of whom were diagnosed with cervical intraepithelial neoplasia (CIN) 3 or worse, including 8 invasive cancers and 8 adenocarcinoma in situ (ACIS). No case of CIN 3 or worse occurred in HC2 negative women. CONCLUSIONS: The presented risk-adapted Wolfsburg Cervical Cancer Prevention Project ("Wolfsburg Model") has been shown to be effective and feasible in identifying women at risk and for avoiding unnecessary procedures for those who are double negative, thus allowing longer screening intervals and cost savings. Acceptance rates for the program were high for both participating women and gynecologists.

Compact multi-Watt picosecond coherent white light sources using multiple-taper fibers.

The combination of a diode-pumped Nd:YVO4 picosecond laser source with tapered fibers allows the realization of a compact white light source with an average output power of up to 5.65 W. We generated supercontinua with a throughput of ~50% over a spectral range of up to 1140 nm by using a series of tapered fibers that were spliced together.

How safe is percutaneous ethanol injection for treatment of thyroid nodule? Report of a case of severe toxic necrosis of the larynx and adjacent skin.

OBJECTIVE: Since 1990, percutaneous ethanol injection therapy (PEIT) has been clinically applied as a treatment for autonomous functioning nodules of the thyroid as well as for cystic lesions. Some additional indications are currently under consideration, e.g. inoperable advanced cancer of the thyroid. Since its inception, PEIT has generally been regarded as an effective, low-risk, inexpensive procedure which can be performed on an ambulatory basis. MATERIAL AND METHODS: We report the first case of severe ethyl toxic necrosis of the larynx combined with necrotic dermatitis in a patient treated with PEIT by a radiologist. RESULTS: The patient was admitted to hospital, where the necrosis and dermatitis were treated conservatively. A cyst which developed in the right false vocal fold was removed by microsurgery 10 months later. Voice was restored almost to normal but a significant reduction in nodular volume was not seen, probably due to the inexperience of the operator. CONCLUSION: PEIT for functional thyroid gland autonomy is an inexpensive method of treating hyperthyroidism with focal autonomy on an ambulatory basis if surgical intervention and radioiodine therapy are not feasible either for medical reasons or because of refusal by the patient. Severe complications must be taken into consideration and discussed with the patient. To avoid complications, substantial experience and a precise ultrasound-guided injection are required. In the case of complications the opinion of a specialist should be sought at anearly stage.