ObjectiveThough one of the most common surgeries, there is limited information on variability of practices in cataract surgeries. ‘Eyefficiency’ is a cataract surgical services auditing tool to help global units improve their surgical productivity and reduce their costs, waste generation and carbon footprint. The aim of the present research is to identify variability and efficiency opportunities in cataract surgical practices globally.Methods and Analysis9 global cataract surgical facilities used the Eyefficiency tool to collect facility-level data (staffing, pathway steps, costs of supplies and energy use), and live time-and-motion data. A point person from each site gathered and reported data on 1 week or 30 consecutive cataract surgeries. Environmental life cycle assessment and descriptive statistics were used to quantify productivity, costs and carbon footprint. The main outcomes were estimates of productivity, costs, greenhouse gas emissions, and solid waste generation per-case at each site.ResultsNine participating sites recorded 475 cataract extractions (a mix of phacoemulsification and manual small incision). Cases per hour ranged from 1.7 to 4.48 at single-bed sites and 1.47 to 4.25 at dual-bed sites. Average per-case expenditures ranged between £31.55 and £399.34, with a majority of costs attributable to medical equipment and supplies. Average solid waste ranged between 0.19 kg and 4.27 kg per phacoemulsification, and greenhouse gases ranged from 41 kg carbon dioxide equivalents (CO2e) to 130 kg CO2e per phacoemulsification.ConclusionResults demonstrate the global diversity of cataract surgical services and non-clinical metrics. Eyefficiency supports local decision-making for resource efficiency and could help identify regional or global best practices for optimising productivity, costs and environmental impact of cataract surgery.
Crossland et al. Remote vision testing. Key PointsQuestion: Can a, printed vision chart posted to people with eye disease measure their vision accurately?Findings: In this study of 50 control subjects and 100 ophthalmology outpatients, Bland-Altman analyses showed excellent repeatability of the home acuity test, and good agreement with the last recorded clinic visual acuity.Meaning: These findings suggest a printed chart can be used to measure visual acuity at home by ophthalmology patients
Chromosome segregation in eukaryotes is driven by the kinetochore, a macromolecular complex that connects centromeric DNA to microtubules of the spindle apparatus. Kinetochores in well-studied model eukaryotes consist of a core set of proteins that are broadly conserved among distant eukaryotic phyla. By contrast, unicellular flagellates of the class Kinetoplastida have a unique set of 36 kinetochore components. The evolutionary origin and history of these kinetochores remain unknown. Here, we report evidence of homology between axial element components of the synaptonemal complex and three kinetoplastid kinetochore proteins KKT16-18. The synaptonemal complex is a zipper-like structure that assembles between homologous chromosomes during meiosis to promote recombination. By using sensitive homology detection protocols, we identify divergent orthologues of KKT16-18 in most eukaryotic supergroups, including experimentally established chromosomal axis components, such as Red1 and Rec10 in budding and fission yeast, ASY3-4 in plants and SYCP2-3 in vertebrates. Furthermore, we found 12 recurrent duplications within this ancient eukaryotic SYCP 2–3 gene family, providing opportunities for new functional complexes to arise, including KKT16-18 in the kinetoplastid parasite Trypanosoma brucei . We propose the kinetoplastid kinetochore system evolved by repurposing meiotic components of the chromosome synapsis and homologous recombination machinery that were already present in early eukaryotes.
Chromosome segregation in eukaryotes is driven by a macromolecular protein complex called the kinetochore that connects centromeric DNA to microtubules of the spindle apparatus. Kinetochores in well-studied model eukaryotes consist of a core set of proteins that are broadly conserved among distant eukaryotic phyla. In contrast, unicellular flagellates of the class Kinetoplastida have a unique set of kinetochore components. The evolutionary origin and history of these kinetochores remains unknown. Here, we report evidence of homology between three kinetoplastid kinetochore proteins KKT16-18 and axial element components of the synaptonemal complex, such as the SYCP2:SYCP3 multimers found in vertebrates. The synaptonemal complex is a zipper-like structure that assembles between homologous chromosomes during meiosis to promote recombination. Using a sensitive homology detection protocol, we identify divergent orthologues of SYCP2:SYCP3 in most eukaryotic supergroups including other experimentally established axial element components, such as Red1 and Rec10 in budding and fission yeast, and the ASY3:ASY4 multimers in land plants. These searches also identify KKT16-18 as part of this rapidly evolving protein family. The widespread presence of the SYCP2-3 gene family in extant eukaryotes suggests that the synaptonemal complex was likely present in the last eukaryotic common ancestor. We found at least twelve independent duplications of the SYCP2-3 gene family throughout the eukaryotic tree of life, providing opportunities for new functional complexes to arise, including KKT16-18 in Trypanosoma brucei. We propose that kinetoplastids evolved their unique kinetochore system by repurposing meiotic components of the chromosome synapsis and homologous recombination machinery that were already present in early eukaryotes.
Background Anaemia affects approximately a quarter of the global population. When anaemia occurs during childhood, it can increase susceptibility to infectious diseases and impair cognitive development. This research uses smartphone-based colorimetry to develop a non-invasive technique for screening for anaemia in a previously understudied population of infants and young children in Ghana. Methods We propose a colorimetric algorithm for screening for anaemia which uses a novel combination of three regions of interest: the lower eyelid (palpebral conjunctiva), the sclera, and the mucosal membrane adjacent to the lower lip. These regions are chosen to have minimal skin pigmentation occluding the blood chromaticity. As part of the algorithm development, different methods were compared for (1) accounting for varying ambient lighting, and (2) choosing a chromaticity metric for each region of interest. In comparison to some prior work, no specialist hardware (such as a colour reference card) is required for image acquisition. Results Sixty-two patients under 4 years of age were recruited as a convenience clinical sample in Korle Bu Teaching Hospital, Ghana. Forty-three of these had quality images for all regions of interest. Using a naïve Bayes classifier, this method was capable of screening for anaemia (<11.0g/dL haemoglobin concentration) vs healthy blood haemoglobin concentration (≥11.0g/dL) with a sensitivity of 92.9% (95% CI 66.1% to 99.8%), a specificity of 89.7% (72.7% to 97.8%) when acting on unseen data, using only an affordable smartphone and no additional hardware. Conclusion These results add to the body of evidence suggesting that smartphone colorimetry is likely to be a useful tool for making anaemia screening more widely available. However, there remains no consensus on the optimal method for image preprocessing or feature extraction, especially across diverse patient populations.
Objectives: to develop and validate a simple paper vision test (the Home Acuity Test or HAT) for ophthalmology telemedicine appointments, which can be used by people who are digitally excluded. Design: Bland Altman analysis of the HAT chart, compared to the last measured visual acuity on a standard clinical test. Setting: Routine outpatient ophthalmology telemedicine clinics in a tertiary centre. Participants: 50 control subjects with no eye disease and 100 consecutive adult ophthalmology outpatients from strabismus and low vision telemedicine clinics. Participants were excluded if they reported subjective changes in their vision. Main outcome measures: For control participants, test/retest variability of the HAT and agreement with standard logMAR visual acuity measurement. For ophthalmology outpatients, agreement with the last recorded clinic visual acuity and with ICD11 visual impairment category. Results: For control participants, HAT test/retest variability was -0.012 logMAR (95% CI: -0.25 to 0.11 logMAR). Agreement with standard vision charts was -0.14 logMAR, with a 95% confidence interval of -0.39 to +0.12 logMAR (figure 3). For ophthalmology outpatients, agreement in visual acuity was -0.10 logMAR (one line on a conventional logMAR sight chart), with the HAT indicating poorer vision than the previous clinic test. The 95% confidence interval for difference was -0.44 to +0.24 logMAR. Agreement in visual impairment category was good for patients (Cohen's K test, K = 0.77 (95% CI, 0.74 to 0.81), and control participants (Cohen's K test, K = 0.88 (95% CI, 0.88 to 0.88). Conclusions The HAT can be used to measure vision by telephone for a wide range of ophthalmology outpatients with diverse conditions, including those who are severely visually impaired. Test/retest variability is low and agreement in visual impairment category is good.
The human visual field, on the temporal side, extends to at least 90° from the line of sight. Using a two-alternative forced-choice procedure in which observers are asked to report the direction of motion of a Gabor patch, and taking precautions to exclude unconscious eye movements in the direction of the stimulus, we show that the limiting eccentricity of image-forming vision can be established with precision. There are large, but reliable, individual differences in the limiting eccentricity. The limiting eccentricity exhibits a dependence on log contrast; but it is not reduced when the modulation visible to the rods is attenuated, a result compatible with the histological evidence that the outermost part of the retina exhibits a high density of cones. Our working hypothesis is that only one type of neural channel is present in the far periphery of the retina, a channel that responds to temporally modulated stimuli of low spatial frequency and that is directionally selective.
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