Loss of Vision after Laser Peripheral Iridotomy: A Case Report

Laser Peripheral Iridotomy (LPI) is a common laser procedure carried out in patients with narrow or occluded irido-corneal angles at risk of developing angle closure glaucoma. Nd-YAG and Argon laser are used sequentially in our local population to create an iridotomy. Posterior segment complications are rare after this procedure and generally can occur due to direct laser induced damage. We report a 44-year old patient, who had LPI performed on his both eyes. Post laser patient complained of reduced vision in his left eye and was evaluated in our glaucoma clinic. On examination, his vision was 20/25 unaided in his right eye and 20/60 in his left eye with no further improvement. Optical coherence tomography (OCT) revealed presence of cystoid macular edema (CME) in his left eye responsible for his reduced vision. Key Words: Laser Peripheral Iridotomy, Cystoid Macular Edema, Argon Laser.

THE EFFECT OF ASSISTED HATCHING IN FROZEN-THAWED EMBRYO TRANSFER CYCLES

Background: Laser assisted hatching technique based on the hypothesis to make an artificial hole on zona pellucida (ZP) that can help embryo hatching out of ZP easily. This technique has been shown to increase implantation and pregnancy rates in women of advanced age, in women with recurrent implantation failure and following the transfer of frozen–thawed embryos. This study described the outcome of frozen–thawed embryo transfers with laser assisted hatching (LAH), which is one of the safest method in nowadays. Purpose: To assess the effect of assisted hatching technique on the clinical outcomes in vitrified-warmed transfer cycles. Method: A total of 65 thawed-transfer cycles with 153 thawed-embryos undertaken within a 12-month period were analysed, Assisted hatching with laser zona thinning was performed with one-quarter of the zona pellucida circumference. The overall thawed-embryos (day 3) were kept in culture overnight. Patient were prepared the suitable endometrium and transferred embryos advantageously. Results: In which, having the rate of survival embryos were 143 occupying 94.3%, the percentage of grade 1 and 2 embryos occupied 55.9% and 29,3% respectively, and that were enrolled LAH before transfering of frozen–thawed embryos. The average transferred embryos were 2.4±0.8, The rate of implantation per transferred embryos and per transferred embryos cycles was 19.5% and 43.1% respectively. The rate of clinical pregnancies per embryo transfer cycles occupied 33.8% with percentage of early miscarriages (biochemical pregnancies and early clinical miscarriages) was 12.3%. The rate of ongoing pregnancies was 30.8% and multiple pregnancies was low just 12.3%. This result was equal or higher than other researchs in embryos transfer had or no LAH. Conclusion: LAH contributed to stable frozen–thawed embryos transfer effectiveness. Key words: Laser assisted hatching, frozen–thawed embryos transfer, zona pellucida (ZP)

Laser Hardening Parameters Influencing Component Lifetime and Residual Stresses

Laser surface hardening is an advanced method of surface treatment of structural steels with a great potential for wide industrial applications. The technology is quite new and so, investigations have to be performed in order to gain a comprehensive knowledge about effects on microstructure, hardness, surface properties of treated materials, but also mechanical an particularly fatigue properties. Concerning fatigue resistance of material treated with this technology, results and knowledge recently published in the literature indicate that fatigue resistance can be either reduced or increased, even considerably, depending on numerous parameters of basic material, laser hardening parameters etc. This contribution contains results of a partial study of effect of laser hardening of relatively small specimens on fatigue resistance of 42CrMo4 steel. Two different parameters of the treatment were used, namely two speeds of laser beam on the material surface at constant beam energy. Unlike the lower speed, when fatigue resistance was slightly reduced, higher speed of laser beam resulted in a slight increase of fatigue resistance and fatigue limit. The results are discussed considering an occurrence of residuals stresses. Key words: Laser hardening, residual stress, lifetime, fatigue, fracture, microstructure, surface

Numerical Analysis of Temperature Field of Co-Based Alloy Coatings by Laser Cladding on the Mild Steel

In order to analyze temperature field of Co-based alloys laser cladding, the model of Co-based alloys laser cladding with preset-powder method has been made by finite element method. The temperature field of coatings was analyzed by SYSWELD software, and Experimental verification is done. The results showed that temperature field changed from non-steady-state to steady-state in the laser cladding process. Favorable metallurgy bonding with 8.26% dilution was obtained by scanning velocity was 5 mm/s, the temperature gradient of surface coatings is obviously decreased to 1/20 of bonding interface, the solidification rate of surface is nearly 70 times of bonding interface. Right power with 1.6 kW and 1.87 kW was found when scanning velocity was 3 mm/s and 4 mm/s by SYSWELD software. Based on solidification theory, shape factor of crystallization are analyzed, these are consistent with experimental results. These results provide reference and guide for parametric optimization and control dilution rate of laser cladding. Key words: Laser cladding, Co-based alloy, SYSWELD, Simulation

Stimulasi Laser sebagai Alternatif untuk Induksi Estrus pada Kambing Bligon (Laser Stimulation as an Alternative for Estrus Induction on Bligon Goats)

<p>Reproduction is a very important factor in maintaining livestock productivity. For better reproductivity, estrus induction is one of very important ways to be performed. Estrus induction is usually performed with hormonal method,<br />such as application of PGF2α, but the disadvantage is that it is relatively expensive. For this reason, it is necessary to promote technological breakthrough to lower cost of estrus induction. The aim of this study was to know whether laser<br />stimulation on the points of reproductive acupuncture could be performed for estrus induction on Bligon goats, as it is usually performed with hormonal method. Fourteen female Bligon goats aged 2 years old were randomly divided into two groups, each group consisted of 7 goats. Group I was stimulated with laser and group II was injected with 1.25 mg per head of PGF2α. Laser stimulation was conducted for 10 seconds on each point of acupuncture on day 1, 2, and 3, and was repeated on day 11, 12, and 13. PGF2α injection was performed on day 1 and was repeated on day 11. The observed variables were the percentage of estrus, onset of estrus, estrus duration and progesterone level when estrus occurred after the second estrus induction. The results of the study showed that laser stimulation for estrus induction did not indicate significant difference compared to PGF2α injection, in terms of the percentage of goats undergoing<br />estrus, onset of estrus and the estrus duration. It was concluded that laser stimulation could be used for estrus induction on Bligon goats.</p><p>(Key words: Laser, Estrus induction, Bligon goats)<br /><br /></p>

Coherent control of electrons in molecules

Coherent superposition of electronic states can be achieved by simultaneous laser excitation at different frequencies. As an example, the three-level system is examined in order to demonstrate the possibility of phase control of electron transfer in molecules. Ab initio calculations are used to illustrate the principle in a charge transfer molecule DMBAN, 4-(N,N-dimethylamino)benzonitrile. Key words: laser control, charge transfer electrons.

Effect of methyl substitution on the intramolecular triplet deactivation of p-methoxy-β-phenylpropiophenone

The photochemistry of several methyl-substituted p-methoxy-β-phenylpropiophenones (1–5) has been examined by nanosecond laser flash photolysis using 337-nm laser excitation. The ketone triplets decay by intramolecular β-aryl quenching of the carbonyl in a well-known process that is believed to involve charge transfer. Surprisingly, methyl substitution at the β-methylene group, which is not a participant in the deactiviation mechanism, causes a dramatic decrease in the triplet lifetime; the effect is attributed to different conformational preferences in ketones 1–3 and is rationalized on the basis of MMX calculations. Methyl substitution in the β-aryl ring affects the ease of oxidation of this ring and as a result induces changes in the kinetics for intramolecular charge transfer. This conclusion is further supported by electrochemical studies of ketones 1, 4, and 5. Key words: laser flash photolysis, triplet ketones, intramolecular quenching, charge transfer.

Turbinoplasty by laser

This is a study of 61 cases of turbinoplasty done in 3 hospitals of Bangladesh from August2007 to July 2009 (2 years). This study compares turbinoplasty by laser with that of non-lasertechniques. 60.65% of patients were operated by laser and 39.34% of patients were operatedby non-laser techniques. Majority of the patients were from 21- 40 years of age, (62.16% inlaser group and 54.16% in non-laser group). Male & Female patients ratio was 3:1 in bothgroups. 100% of the patients were presented with nasal obstruction. 98.36% with nasaldischarge, 95.08% with headache and 75.40% with frequent sneezing (p<0.01). Most patientswere operated under local anesthesia in both groups (78.38% and 58.33% respectably).Follow up was satisfactory up to 3 months (Laser group 81.08 % and non-laser group 70.83%). Most of the patient were all symptoms free (86.48 % in laser group and 79.16 % in nonlasergroup). Only 8 patients (21.62%) present with crusting in laser group in respect to 22patients (91.66%) in non-laser group with no incidence of severe post–operative nasal bleedingin laser group. 34 patients (91.89%) of Laser group and 13 patients (35.13%) of non-lasergroup were treated as day care surgery.Most of the cases (70.27%) were operated by diode laser. Recurrences of symptoms werenegligible in laser group (2.70%).Key Words: Laser; Turbinoplasty.DOI: 10.3329/bjo.v16i1.5775Bangladesh J Otorhinolaryngol 2010; 16(1): 9-14