Intraocular Lens Opacification After Descemet's Membrane Endothelial Keratoplasty-Risk Factors and Outcomes After Intraocular Lens Exchange.

PURPOSE: To determine risk factors for intraocular lens opacification (IOLop) after Descemet membrane endothelial keratoplasty (DMEK) and to analyze clinical outcomes after IOL exchange. METHODS: Cross-Sectional Study: Analysis of all cases of IOL exchange because of post-DMEK IOLop with a minimum of 6-month postoperative follow-up observed in clinic between November 2021 and April 2022. Main outcomes analyzed at the study visit were change in logarithm of the minimum angle of resolution (logMAR) best-corrected visual acuity after IOL exchange, endothelial cell loss (ECL), and graft survival. An historical cohort of 232 pseudophakic DMEK eyes was retrospectively analyzed to determine risk factors for post-DMEK IOLop. RESULTS: Cross-Sectional Study: Four eyes were observed (median follow-up = 45 (35.5-86.8) months). IOL materials were hydrophilic acrylic IOLs in 2 eyes and hydrophobic-hydrophilic in the other 2. At the study visit, improvement in median best-corrected visual acuity after IOL exchange was statistically significant (0.25 (0.19-0.41) logMAR to 0.00 (0-0.10) logMAR; P = 0.041). ECL ranged between 57.7% and 85.3%, without cases of graft failure. In the historical cohort, 21 eyes (9.05%) had some IOLop. In multivariate logistic regression model (105 eyes where IOL material data was available), IOLs with high water content material (odds ratio = 65.5, P = 0.0005) and rebubbling (odds ratio = 9.51, P = 0.0138) were independent risk factors for post-DMEK IOLop. CONCLUSIONS: Post-DMEK IOLop is infrequent, but a non-neglectable proportion of cases may require IOL explantation. IOL exchange is safe and effective in these eyes but may pose a risk for increased ECL. This study confirms that IOL material and number of rebubblings are major risk factors for post-DMEK IOLop.

Ultrathin DSAEK versus DMEK - Review of systematic reviews.

The efficacy and safety of Descemet's membrane endothelial keratoplasty (DMEK) and ultrathin Descemet stripping automated endothelial keratoplasty (UT-DSAEK) have been recently compared in several systematic reviews (SRs). The aim of this study was to assess the evidence quality of such SRs, in order to obtain a scientifically rigorous comparison between the two techniques. We performed a systematic review of SRs and meta-analyses comparing the efficacy and safety between UT-DSAEK and DMEK up to 24th March 2023, using 3 electronic databases (PubMed, Cochrane Library, Google Scholar) plus manual reference search. Specific outcomes analyzed included best-corrected visual acuity (BCVA), endothelial cell density (ECD), rebubbling rate, and other postoperative complications. Of 90 titles/abstracts screened, four SRs met the inclusion criteria. All SRs adequately analyzed potential bias of the included studies. One SR raised concern for potential literature search bias and two SRs have heterogeneity in some outcomes analyzed. All SRs found higher BCVA after DMEK, but one SR reported significant heterogeneity. All SRs found significant heterogeneity in ECD analysis, with one SR providing inconsistent analysis of this outcome. Three SRs analyzed rebubbling rates, favoring UT-DSAEK over DMEK. Three SRs concluded a higher overall complication rate after DMEK, although rebubbling may be a confounding factor. This systematic review clarifies the strengths and weaknesses of published SRs and reinforces the conclusion that DMEK leads to superior visual outcomes compared to UT-DSAEK, with the trade-off of higher rebubbling rates and possibly other postoperative complications. Studies with longer follow-up are needed to ascertain these differences between procedures.

Investigation of Plasticity Effects on Growing Fatigue Cracks Using the CJP Model of Crack Tip Fields.

A growing fatigue crack gives rise to a plastic enclave that envelops the crack and can exert a shielding effect on the crack from the global elastic stress field driving fatigue propagation. This work presents the potential of the CJP model of crack tip fields to investigate the plasticity-induced shielding effects on growing fatigue cracks as well as its ability to characterise the size and shape of the plastic zone generated at the tip of a growing fatigue crack. The model was specifically developed to consider the influence of the plastic enclave generated around a fatigue crack on the surrounding elastic material. Different aspects related to fracture mechanics and its implications for fatigue crack growth have been investigated, namely plasticity-induced crack shielding, the retardation effect induced on fatigue crack growth due to the application of an overload and the estimate of the size and shape of the crack tip plastic zone. The model has been successfully applied by analysing displacement fields experimentally measured by DIC in different CT specimens made of 2024-T3 aluminium alloy and commercially pure titanium. Results presented in this work intend to contribute to a better understanding of the shielding effects during fatigue crack growth.

Study of Effective Stress Intensity Factor through the CJP Model Using Full-Field Experimental Data.

In this work, the Christopher-James-Patterson crack tip field model is used to infer and assess the effective stress intensity factor ranges measured from thermoelastic and digital image correlation data. The effective stress intensity factor range obtained via the Christopher-James-Patterson model, which provides an effective rationalization of fatigue crack growth rates, is separated into two components representing the elastic and retardation components to assess shielding phenomena on growing fatigue cracks. For this analysis, fatigue crack growth tests were performed on Compact-Tension specimens manufactured in pure grade 2 titanium for different stress ratio levels, and digital image correlation and thermoelastic measurements were made for different crack lengths. A good agreement (~2% average deviation) was found between the results obtained via thermoelastic stress analysis and digital image correlation indicating the validity of the Christopher-James-Patterson model to investigate phenomena in fracture mechanics where plasticity plays an important role. The results show the importance of considering crack-shielding effects using the Christopher-James-Patterson model beyond considering an exclusive crack closure influence.

Evaluation of planktonic cyanobacteria in Peruvian freshwater lentic water bodies: prevalence and regulatory framework to aid policy making.

Increasing reports of cyanobacteria or cyanotoxins around the world expose a major threat for the environment, animal, and human health. Current water treatment processes are ineffective at eliminating cyanotoxins; hence, risk management relies mostly on early detection and on the development of specific regulatory frameworks. In developed countries, well-documented monitoring activities offer a good assessment of the cyanobacterial and/or cyanotoxin status and are used to prevent intoxications. In developing countries such as Peru, despite their potential threat to the environment and public health, cyanobacteria and cyanotoxins are still poorly studied. We found that the regulatory measures regarding cyanobacteria and/or cyanotoxin are almost non-existent. We also present and discuss some examples of recent monitoring efforts underwent by isolated local authorities and scientific reports that, whereas limited, may provide some important insights to be considered nationally. A revision of the available information of planktonic cyanobacteria or cyanotoxins in Peruvian freshwater lentic water bodies revealed a total of 50 documented reports of 15 different genera across 19 water bodies, including the reported highly toxic Dolichospermum and Microcystis. A unique case of microcystin-LR has been documented. We propose some recommendations to be implemented to improve potential toxic cyanobacteria risk management that include incorporating a widespread monitoring of cyanobacterial communities in lakes and reservoirs used for human consumption via specific guidelines. Aligning Peruvian regulations on cyanobacteria and cyanotoxins to international standards may also support law enforcement and ensure compliance.

Virus-to-prokaryote ratio in the Salar de Huasco and different ecosystems of the Southern hemisphere and its relationship with physicochemical and biological parameters.

The virus-to-prokaryote ratio (VPR) has been used in many ecosystems to study the relationship between viruses and their hosts. While high VPR values indicate a high rate of prokaryotes' cell lysis, low values are interpreted as a decrease in or absence of viral activity. Salar de Huasco is a high-altitude wetland characterized by a rich microbial diversity associated with aquatic sites like springs, ponds, streams and a lagoon with variable physicochemical conditions. Samples from two ponds, Poza Rosada (PR) and Poza Verde (PV), were analyzed by epifluorescence microscopy to determine variability of viral and prokaryotic abundance and to calculate the VPR in a dry season. In addition, to put Salar de Huasco results into perspective, a compilation of research articles on viral and prokaryotic abundance, VPR, and metadata from various Southern hemisphere ecosystems was revised. The ecosystems were grouped into six categories: high-altitude wetlands, Pacific, Atlantic, Indian, and Southern Oceans and Antarctic lakes. Salar de Huasco ponds recorded similar VPR values (an average of 7.4 and 1.7 at PR and PV, respectively), ranging from 3.22 to 15.99 in PR. The VPR variability was associated with VA and chlorophyll a, when considering all data available for this ecosystem. In general, high-altitude wetlands recorded the highest VPR average (53.22 ± 95.09), followed by the Oceans, Southern (21.91 ± 25.72), Atlantic (19.57 ± 15.77) and Indian (13.43 ± 16.12), then Antarctic lakes (11.37 ± 15.82) and the Pacific Ocean (6.34 ± 3.79). Physicochemical variables, i.e., temperature, conductivity, nutrients (nitrate, ammonium, and phosphate) and chlorophyll a as a biological variable, were found to drive the VPR in the ecosystems analyzed. Thus, the viral activity in the Wetland followed similar trends of previous reports based on larger sets of metadata analyses. In total, this study highlights the importance of including viruses as a biological variable to study microbial temporal dynamics in wetlands considering their crucial role in the carbon budgets of these understudied ecosystems in the southern hemisphere.

Improving Cognitive Visual-Motor Abilities in Individuals with Down Syndrome.

Down syndrome causes a reduction in cognitive abilities, with visual-motor skills being particularly affected. In this work, we have focused on this skill in order to stimulate better learning. The proposal relies on stimulating the cognitive visual-motor skills of individuals with Down Syndrome (DS) using exercises with a gestural interaction platform based on the KINECT sensor named TANGO:H, the goal being to improve them. To validate the proposal, an experimental single-case study method was designed using two groups: a control group and an experimental one, with similar cognitive ages. Didactic exercises were provided to the experimental group using visual cognitive stimulation. These exercises were created on the TANGO:H Designer, a platform that was designed for gestural interaction using the KINECT sensor. As a result, TANGO:H allows for visual-motor cognitive stimulation through the movement of hands, arms, feet and head. The "Illinois Test of Psycholinguistic Abilities (ITPA)" was applied to both groups as a pre-test and post-test in its four reference sections: visual comprehension, visual-motor sequential memory, visual association, and visual integration. Two checks were made, one using the longitudinal comparison of the pre-test/post-test of the experimental group, and another that relied on comparing the difference of the means of the pre-test/post-test. We also used an observational methodology for the working sessions from the experimental group. Although the statistical results do not show significant differences between the two groups, the results of the observations exhibited an improvement in visual-motor cognitive skills.