Purpose: To investigate the relation between the quantitative iris parameters and iridotrabecular contact (ITC) in patients with primary angle-closure (PAC) and PAC glaucoma (PACG). Materials and methods: PAC and PACG with laser peripheral iridotomy were recruited pro- spectively. Anterior-segment optical coherence tomography (ASOCT) was performed under light and dark conditions, and scans were taken along the vertical and horizontal axes. Iris thickness at 500 μm (IT500) and 750 μm (IT750) from the scleral spur, maximal iris thickness (MIT), and cross sections of the iris area (I-Area) were measured by using software. ITC was defined by the ASOCT as the contact between the peripheral iris and angle wall anterior to the scleral spur. The ITC + and ITC − groups were defined as eyes that had ITC in two or more quadrants
Background: China has the largest burden of primary angle-closure glaucoma (PACG) worldwide. The mechanism of the angle closure is complex and includes pupillary block and non-pupillary block. Currently, opinion is that laser peripheral iridotomy (LPI) alone is not sufficient to prevent disease progression. Laser peripheral iridoplasty (LPIP) is an alternative and effective way of widening the angle recess in eyes that are affected by primary angle closure (PAC). However, it is not known if greater benefit would be achieved using LPI plus LPIP for PAC with multiple mechanisms (MAC). Thus, the aim of this study is to demonstrate if LPI plus LPIP would be more effective than single LPI in controlling the progression of PAC with multiple mechanisms, based on ultrasound biomicroscopy (UBM) classification. A secondary aim is to determine whether or not this would result in the use of less medication and/or prolong the time to antiglaucoma surgery. Methods: This multiple-mechanism angle-closure study will comprise a 3-year, multicenter, randomized, parallel-group, open-label, superiority trial, the aim of which will be to evaluate the safety and efficacy of LPI plus LPIP versus LPI for PAC. It is anticipated that 240 adults, diagnosed with PAC (the mechanism of angle closure will be assessed by UBM and it will be determined whether or not it involves multiple mechanisms) will be recruited from ten ophthalmic centers in China. Participants will be randomly allocated to receive either single LPI or LPI plus LPIP. Participant assessment will be designed to test the rate of disease progression and who will be followed up for 3 years. The primary outcome will be the disease progression rate and a comparison will be made between the LPI and LPI plus LPIP groups using Pearson ’ s χ 2 test. Logistic regression analysis will be performed to account for the central effect.
difficult cases may not have been evenly distributed across all resident classes. More junior residents may preferentially get assigned LPI procedures that are perceived as more straightforward, leaving the more difficult cases for the senior residents. The decrease in mean power usage across resident classes may perhaps be even more pronounced among patients randomized to residents of varying experi- ence. The decreasing total power use among residents of increasing seniority suggests that a learning curve is present, though whether this learning curve is sufficiently aggressive remains to be seen. With proper supervision and standard- ized training, it might be reasonable to expect residents to be performing LPIs using total powers comparable to mean powers reported in the literature for Caucasian and non-Caucasian eyes at a much earlier stage in training. The learning curve might be shortened with standardization of power per shot depending on the thickness of the iris (based on color or ethnicity) or with a lower threshold to increase power per shot if the laser setting is not effective. Increased observation of junior residents may help them to improve laser aim and focusing to decrease rate of ineffective laser shots. Standardizing iridotomy size might also be beneficial to prevent early closure of the iridotomy or an unnecessarily large iridotomy.
capsule rupture was seen after two clear-lens extractions (1%). No severe complications were reported as a direct consequence of laser iridotomy. Irreversible loss of vision of more than ten ETDRS letters was seen in one participant in the clear-lens extraction group and three in the standard care group. Intolerance of medications was reported less frequently in the clear-lens extraction group than in the standard group (three vs ten participants, diﬀ erence 3·3%, 95% CI 0·004–6·6, p=0·049). Further intraocular surgery was needed to manage complications of the primary or additional interventions in three patients (zonulo- hyaloido-vitrectomy for malignant glaucoma, repositioning of a subluxated intraocular lens, and injection of antibody against VEGF for macular oedema) in the clear-lens extraction group and one participant (pars plana vitrectomy for dislocated lens) in the standard care group. Also in the latter group, 12 (6%) patients underwent surgery for clinically relevant cataracts. One patient in the clear-lens extraction group developed transient corneal oedema and another suﬀ ered malignant glaucoma. Central corneal thickness did not diﬀ er between groups. One patient in the clear-lens extraction group developed an acute angle- closure attack before the operation and was treated with laser peripheral iridotomy (crossover).
review of 27 patients who underwent ALPI for persistent occludable angles after laser peripheral iridotomy. The most common underlying mechanisms were plateau iris (56%) followed by lens-induced angle closure (34%). Considering the entire population, IOP was signifi- cantly reduced from 17.9±4.9 mm Hg to 14.5±4.2 mm Hg (p<0.01) at the end of follow-up, with no significant differences between patients with PIS and lens-induced angle closure (p=0.34). Approximately 90% of the eyes had a non-occludable angle defined as a posterior trabec- ular meshwork visible on 180° without indentation on gonioscopic examination following ALPI. The number of medications was not evaluated in this study.
ing BK after ALI remain unclear. For these reasons, laser iridotomy using yttrium aluminum garnet (YAG) lasers is currently used in Japan instead of ALI. Most recently, clear- lens extraction has proven to be more cost-effective than laser peripheral iridotomy, and should be considered as an option for first-line treatment of angle-closure glaucoma. 25
PAC and PACG are highly prevalent in Asians, especially in East Asians . In China, 38.3% of PACG patients suf- fer from unilateral or bilateral blindness . When the de- gree of PAS is limited, laser peripheral iridotomy (LPI) alone, or combined with laser iridoplasty is the preferred method of treatment for PAC/PACG patients, while trabe- culectomy is traditionally employed to treat patients with extensive PAS. Complications such as shallow anterior chamber, cataract progression, filtering bleb scarring, en- dophthalmitis and other risks, exist for trabeculectomy . Phacoemulsification plus Phaco-GSL, a surgical pro- cedure in which the shallow anterior chamber is deepened and the adhered angle is re-opened in an attempt to re- store trabecular function, is an alternative procedure which has been shown to successfully lower the IOP in PAC/PACG patients with coexisting cataract. In addition to having a very similar IOP lowering effect, Phaco-GSL has certain advantages over trabeculectomy, especially when considering the possibility of complications [4 – 8].
years and above. They were counseled and those willing to be included signed a written consent to undergo MP3 laser procedure. Ethical approval was obtained prior to the study. All patients who had a history of ocular infection, inflammation or ocular surgery 2 months prior to the laser procedure were excluded from the study. MP3 laser was done under peribulbar anaesthesia (2% Xylocaine and Adrenaline) with laser settings at 2000mW, 90 secs in each quadrant using a sliding motion, and avoiding the 3 and 9 o’clock positions. Baseline visual acuity (VA) and Intraocular pressure (IOP) were obtained prior to use of Micropulse laser treatment. Following the laser treatment, IOP and VA were assessed at day 1, one week, one month and 6 months post treatment.
Diabetic peripheral neuropathy (DPN) is the most com- mon complication of diabetes mellitus with significant clinical sequelae and impact on patients ’ quality of life [1, 2]. DPN manifests itself on the toes and progresses in a stocking distribution . Nerve damage is related to hyperglycemia. However, various other mechanisms play a role in the pathogenesis of DPN . These include ele- vated polyol pathway activity, advanced glycation end products (AGEs), oxidative stress, growth factors, im- paired insulin/C-peptide action, and elevated protein kinase C activity. These may directly affect neuronal tis- sues as well as vascular structures, thus compromising nerve vascular supply [4, 5].
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993; McKenzie, 1990). The current nature of the problem is determined by the direct relationship between therapeutic efficacy and biological factors such as total body reactivity, regenerative and reprocessing processes, oxidative and reductive potentials, regional and general blood flow, the presence of pathogenic associations of microorganisms and the neuromuscular regulation of the Miserendino et al., 1995). Particularly relevant is the topic of laser energy therapy with coherent monochromatic laser radiation and programmable output power in the mean range of infrared electromagnetic radiation Coluzzi, 2008). A key clinical parameter for assessing therapeutic efficacy is the amount and ied laser light power (Coluzzi, 2008). The next goal is to master new frequency bands, which is related to the development of new measurement methods. Particularly relevant is the topic of the resonant phenomenon of tissue response under the influence of electromagnetic radiation combining frequencies with a specific therapeutic effect. A qualitatively different approach is needed to confirm the healing effect of known frequencies and to recommend new frequency ranges. The scientific research in the field of medical knowledge of the physical parameters of the laser devices is the most recent one for their flexible combination for optimal dosing of the working power and energy and precise dosing of
ers from erythroplakia on his lower lip. The study stated that the erythroplakia completely disappea- red and there was no repetition of them was obser- ved. In (Hatzis, 2000), the authors compared the results of different laser treatments for thirty pati- ents suffering from congenital melanocytic nevi (CMN). They were divided into three groups. The first group were treated by Nd: YAG laser (Q- switched, 1064nm and 30 ns pulse-width). The second group were treated by using of both Nd: YAG and CO2 laser (10600 nm, CW mode with duty cycle 50% with power 8-14 Watt) and third group were treated by using of both Q-switched Nd:YAG and Er: YAG laser (2940nm, 350µs pul- se-width with energy fluence 10-15J/cm 2 ). Accor-
Two studies compared phacoemulsi ﬁ cation with iridot- omy for the prevention of further increases in intraocular pressure and reported increases in ocular pressure of 46.7% and 38.6% after laser iridotomy. 3,15 This result may be due to a residual angle closure produced as a result of an anteriorly placed ciliary process. 3 Other possible alternatives include direct damage to the trabecular mesh- work and development of peripheral anterior synechiae. 3 In the present study, a persistent increase in intraocular pressure of 42.85% was observed after completion of sequential iridotomy, and this percentage was within the ranges described in the literature.
Conventional laser photocoagulation has limited use in many retinal diseases involving the macular such as age-related macular degeneration (AMD), DME, and CSCR due to collateral thermal damage which can cause severe loss of vi- sion. These diseases are considered to be associated with the dysfunction of RPE. Selective retinal therapy (SRT) with microsecond pulses has been developed to selectively induce changes in the RPE so that the laser-induced thermal damage to surrounding tissue can be avoided, particularly to the neurosensory retina . With microsecond pulses, produced heat is confined to the absorber site, predominantly the melanosomes within RPE cells. Formation of intracellular microbubbles around melanosomes results in destruction of RPE cells while avoiding damage to surrounding tissue. Subsequently, RPE cells proliferate and migrate into the lesion site to restore RPE continuity. The clinical potential of microsecond pulses in selectively destroying RPE cells was first demonstrated in rabbit eyes  . It used 5-microsecond argon laser pulses at 514 nm and a repetition rate of 500 Hz. Histologic analysis revealed that the damage in SRT le- sions is primarily limited to the RPE while the surrounding retinal temperature remains at sublethal levels. Preliminary clinical trials performed with a Nd:YLF laser using a pulse duration of 1.7 μs have demonstrated no visual loss after the treatment, as confirmed by microperimetry .
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cantly correlates with the contrast value, whereas no significant correlation is detected between the readability and the contrast value. Laser energy and marking time have positive correlations with read- ability of the code, while laser power gives no corre- lation. Accordingly, readability is more dependent on the laser energy and marking time than on the laser power. Marking at low laser energy for a short time tends to produce relatively low readability due to less contrast. However, applying low laser ener- gy for a longer time will produce better readability. This behaviour was similarly described by Sood et al. (2008), namely that higher exposure time at a low laser energy level (0.000752 W/dot) creates darker labels without significantly increasing peel disruption on tangerines. By contrast, using high energy may potentially damage outer cell layers of bananas and promote unsuccessful readability of the codes. Once the laser beam has irradiated on the outer cells, photons penetrate into the epider- mis layer and convert into thermal energy. Thus, the heat is distributed within the cells. According to Blanaru et al. (2003), the heat distribution is in- fluenced by thermal properties, conductivity, heat capacity, convective coefficients and emissivity of the plant material.
Laser-induced breakdown spectroscopy – laser-induced fluorescence (LIBS- LIF) is a hyphenated technique that uses a high-energy laser as a source for a laser- induced plasma and a second resonant excitation laser to specifically populate an upper energy level of an atom or ion in the plasma. LIBS-LIF is typically used for trace element detection in samples such as trace metal in biospecimens [1-4]. The resonant excitation laser, in our case an OPO (discussed in Chapter 3), is tuned to a specific wavelength of a transition from an upper energy level of interest. At a desired time after plasma formation (interpulse delay) the resonant excitation laser is incident on the plasma. Assuming there is a non-zero population in the lower energy level of the transition (which there is in a thermally populated distribution), the upper energy level is resonantly excited (pumped) which then increases the population of atoms in the upper energy level. This increases the spontaneous emission on all transitions exiting the energy level. Increasing the emission will result in larger observed emission lines in our spectra that may be brought above the background and noise levels. This is advantageous when the limiting factor in trace elemental detection is a small signal that is below the noise and/or background.
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energy of the protons decreased. However, this reduction was smaller for a given intensity than that demonstrated when the target was kept at best focus and the laser energy reduced. This measurement of the maximum proton energy is consistent with the data found by Brenner et al. [4,5] for shorter pulse laser conditions. Measurements of the divergence of the electrons were also conducted by Coury et al. using the K-alpha x-rays from the rear surface. This found no significant trend for the angular divergence of the electrons as a function of intensity for variation of energy or focus. The primary observable for both of these studies, and others, is the effect that the laser spot size has on the accelerated protons. No studies have examined in detail the escaping electron population as a function of focal spot size.
To study the role of laser influence and laser irradiation time in the ablation procedure we have prepared PtNPs with different average laser powers and laser irradiation times. The absorption spectra of PtNPs prepared in 0.01M PVP solution using 1064 nm wavelength with different average laser powers ranging from 200mW to 550mW and laser irradiation time of 15 minutes are plotted in Fig.5.
Differential AO-EB staining of PBMC and thymocytes after treatment with various apoptosis-inducing agents. Radiation- induced apoptosis in PBMC is a useful but limited model in which to study differential DNA staining during processes of cell death. To test whether differential AO-EB staining of live and apoptotic cells results from cellular changes associated with apoptosis in general or is associated exclusively with ra- diation-induced DNA damage, we examined the fluorescence of AO-EB-stained human PBMC and mouse thymocytes fol- lowing exposure to various conditions reported to induce ap- optosis. Peripheral lymphocytes show significant apoptosis in culture following exposure to HIV in vivo or in vitro or when activated in vitro with polyclonal mitogens (23, 31, 43). As shown in Fig. 5, these two treatments generate green versus red fluorescence profiles following AO-EB staining that are similar to those seen following irradiation. PBMC from an asymptom- atic HIV-seropositive donor show significant cell death by FS and SS (Fig. 5A). In this example, cells were grown in culture in the absence of fetal bovine serum, which further induces apoptosis. Correspondingly, both AO high and AO low popula-
Other material discontinuities have been observed in laser-PBF man- ufacture; Attar et al. reported on elongated porosities as well as un- melted particles in the manufacture of commercially pure titanium powder . It was shown that the processing parameters, such as in- suf ﬁ cient laser power and hence unbalanced viscosity of the liquid pool, were the main reasons for the formation of these discontinuities. ‘ Balling up ’ of the powder has been observed in a high laser power envi- ronment, where the powdered material forms spheres that exceed the layer thickness, due to a presence of oxygen ( N 0.1%) in the build cham- ber leading to oxidation. Subsequent layers amplify this discontinuity due to the resulting powder layers being non-uniform. This behaviour has been seen in stainless steel, iron and nickel based powders, shown in Table 3 [38,39]. Li et al. have shown that an increase of the oxygen content in the laser-PBF apparatus to 10% resulted in oxidation of the powder upon solidifying . Gu et al. showed that similar balling of stainless steel powders can be observed in a low power environment, where the laser power is insuf ﬁ cient to melt the powder fully . Par- tial re-melting of the surface has successfully been used in combating balling of the laser-PBF processed components. Residual stresses have also been observed in laser-PBF components; the chosen hatching re- gime plays a major role in the residual stress development of a part, with resulting stresses concentrated perpendicular to the scan direction . A method to reduce residual stress in parts produced is to compen- sate for the stark temperature gradient by heating the build platform . Furthermore, it has been shown that a change in scan strategy af- fects the cracking behaviour arising from these stresses, by altering the cooling rate behaviour . The material discontinuities discussed above are summarised in Table 3.
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In this study, we demonstrate the integrated use of Optos 200Tx widefield imaging with the Navilas Panretinal laser to treat peripheral retinal ischemia and subsequently, to break the cycle of rebound edema, while preserving most periph- eral vision. This case study shows that in order to prevent rebound edema, both the nonreversible and reversible areas of peripheral nonperfusion need to be treated. To define these areas for targeted treatment, the timing of widefield angiography with respect to anti-VEGF therapy must be carefully considered. In particular, it is crucial to map the areas of nonperfusion when the edema (and presumably the