Eye Perspective Research Articles

Acknowledgments

The ideas in this book began as a few notes on the back of a napkin, scribbled together with Alison Phipps, whom I must thank first for our rich and rewarding years of friendship, for her collegiality and support, for her sharp mind, brilliant ideas, and deep humanity, for helping to draw the occasional bright idea out of me, for the inspiration and motivation to think beyond the narrow confines of the language classroom in order to help recognize the potential of language teaching and learning, for showing me that understanding the complexities of language and learning is useless unless it serves the larger purpose of fostering human capabilities, creativity, and compassion. I also want to offer Heidi Byrnes tausend Dank, for encouraging the writing of this monograph beyond the confines of an academic article. Her feedback and guidance early in the project were essential for seeing the big picture of what the book should be about. Thank you to Wander Lowie for his encouragement and support throughout the writing process, and his patience with my delays and many questions. I am also very grateful to David Block and Rick Kern for their rich and detailed feedback and instructions for revising the first draft; I did my best to address all of their concerns and wishes. Thanks, too, to Kate Miller for her skillful editing of the manuscript, and to Shalini Chawla for her patience and attention to detail in the production phase. I am inexpressibly grateful to Bridget Swanson for her keen and brutally honest reading and editing of drafts of this monograph, for what I call her bird's-eye perspective of issues of language teaching, and for her unwavering encouragement throughout! I want to thank Monika Böhme for the many insightful and inspiring conversations we had about language teaching and language learners, which were helpful in focusing many of the discussions in these chapters, as well as keeping them grounded in what teachers actually do, or can do, with their students. Likewise, the many discussions I had on the topics in these chapters were invaluable, and so I am very grateful to Claire Kramsch, Christina Frei, Hiram Maxim, Cori Crane, Chantelle Warner, Steve Thorne, David Gramling, Susanne Rott, Barbara Schmenk, Thor Sawin, Julio Torres, Lisa Parkes, Jerry Won Lee, Bettina Matthias, Carl Blyth, Dave Malinowski, Heather Willis Allen, Friederike Tebben, Per Urlaub, Rosemarie Tracy, Stephan Breidbach, Tessa Wegener, and Sébastien Dubreil. I am forever grateful to all of the graduate students I have had the pleasure to work with over many years, who provided both inspiration and insights through our many interactions about language teaching and my many visits to their classes. Thanks to Eric Blankenship, Kristin Brehm, Patrick Carlson, Matt Cooper, Natalie Eppelsheimer, Jonathan Fine, Friederike Kaufel, Rose Jones, Erin Kelly, Franz Kuzay, David Lamme, Alex Lotz, Susan Morse, Simona Moti, Steven Nave, Yao Pei, Mohammed Rafi, Jaime Roots, Rebecca Schuman, Henrik Sponsel, Jacob Schaubs, Xuxu Song, Magda Tarnawska Senel, Jessica Wood, and Jason Wilby. Also, without the amazing friendship, hospitality, and support of Gail Hart and Dennis Perchak, I am certain I would not have had the peace and quiet I needed at crucial stages of the work. Finally, I want to thank Ursula Levine for the support and encouragement through the years I worked on this book. While writing is a solitary activity, her belief in me was crucial. Just as much, I am grateful to my children, Hanna, Annika, and Sam, especially for their understanding for the many days I was gone in order to research and write. To all of those who gave feedback and comments on parts or all of the book, the usual disclaimer applies: Any shortcomings of the work are entirely on me. Glenn Levine Irvine, California, October 26, 2019

Optimized but Not Maximized Cue Integration for 3D Visual Perception.

Reconstructing three-dimensional (3D) scenes from two-dimensional (2D) retinal images is an ill-posed problem. Despite this, 3D perception of the world based on 2D retinal images is seemingly accurate and precise. The integration of distinct visual cues is essential for robust 3D perception in humans, but it is unclear whether this is true for non-human primates (NHPs). Here, we assessed 3D perception in macaque monkeys using a planar surface orientation discrimination task. Perception was accurate across a wide range of spatial poses (orientations and distances), but precision was highly dependent on the plane's pose. The monkeys achieved robust 3D perception by dynamically reweighting the integration of stereoscopic and perspective cues according to their pose-dependent reliabilities. Errors in performance could be explained by a prior resembling the 3D orientation statistics of natural scenes. We used neural network simulations based on 3D orientation-selective neurons recorded from the same monkeys to assess how neural computation might constrain perception. The perceptual data were consistent with a model in which the responses of two independent neuronal populations representing stereoscopic cues and perspective cues (with perspective signals from the two eyes combined using nonlinear canonical computations) were optimally integrated through linear summation. Perception of combined-cue stimuli was optimal given this architecture. However, an alternative architecture in which stereoscopic cues, left eye perspective cues, and right eye perspective cues were represented by three independent populations yielded two times greater precision than the monkeys. This result suggests that, due to canonical computations, cue integration for 3D perception is optimized but not maximized.

Talent Management:A Bird’s-Eye Perspective

Human capital is considered as one of the most vital source of competitive advantage. This reality compels organisations to approach talent as a precious resource that must be handled effectively and efficiently in order to achieve high performance. Organisations are gradually appreciating that effective talent management is the key success factor to achieve organisational goals with high performance. A number of organisations are implementing talent management but still there are abundant unknown areas that need to be explored. This paper contributes to a better understanding of talent management by adopting a bird’s eye perspective of the available scholarly literature ranging from 1997 to 2019 to explore the conceptual boundaries of talent management. Findings reveal that the term talent management has become the most debated topics of 21 st century among HR professionals and academicians which leads toward high performance with successful achievement of personal and organisational ambitions.

Correlations and How to Interpret Them

Correlations between observed data are at the heart of all empirical research that strives for establishing lawful regularities. However, there are numerous ways to assess these correlations, and there are numerous ways to make sense of them. This essay presents a bird’s eye perspective on different interpretive schemes to understand correlations. It is designed as a comparative survey of the basic concepts. Many important details to back it up can be found in the relevant technical literature. Correlations can (1) extend over time (diachronic correlations) or they can (2) relate data in an atemporal way (synchronic correlations). Within class (1), the standard interpretive accounts are based on causal models or on predictive models that are not necessarily causal. Examples within class (2) are (mainly unsupervised) data mining approaches, relations between domains (multiscale systems), nonlocal quantum correlations, and eventually correlations between the mental and the physical.

Deconstructing landscape pattern: applications of remote sensing to physiognomic landscape mapping

In 1939, Carl Troll pointed out that “air photo interpretation is to a large extent landscape ecology”. From that time forward, remote sensing has been applied across different disciplines to comprehend the holistic and dynamic spatial layout of the visual Earth environment. However, its applicability in the domain of landscape character assessment, landscape design and planning is still questionable. The purpose of this paper was to synthesise some historical and current applications of remote sensing for the decomposition of the continual visual landscape from a bird’s eye perspective and to explore the potential for bridging geographic processes with visual perception and an appreciation of the landscape pattern. From the point of view of landscape ecology, the organisation of the landscape pattern [namely, the size, shape (form), number, density and diversity, the complexity of landscape elements, and colours and textures of the land cover] is crucial for the cognition of both the visual landscape experience and the geographic processes. There are numerous pieces of evidence from the literature that remote sensing data are widely implemented in the modelling of physiognomic landscape. The synthesis of the literature concludes with perspective directions of remote sensing applications, such as mapping the status of the ecosystem (landscape) services provision, the delineation of the boundaries of the protected areas based on the quality of the visual environment, and the assessment of the sustainability of the land use practices, regarding their impact on landscape aesthetics extent.

Soil Degradation Mapping in Drylands Using Unmanned Aerial Vehicle (UAV) Data

Arid and semi-arid landscapes often show a patchwork of bare and vegetated spaces. Their heterogeneous patterns can be of natural origin, but may also indicate soil degradation. This study investigates the use of unmanned aerial vehicle (UAV) imagery to identify the degradation status of soils, based on the hypothesis that vegetation cover can be used as a proxy for estimating the soils’ health status. To assess the quality of the UAV-derived products, we compare a conventional field-derived map (FM) with two modelled maps based on (i) vegetation cover (RGB map), and (ii) vegetation cover, topographic information, and a flow accumulation analysis (RGB+DEM map). All methods were able to identify areas of soil degradation but differed in the extent of classified soil degradation, with the RGB map classifying the least amount as degraded. The RGB+DEM map classified 12% more as degraded than the FM, due to the wider perspective of the UAV compared to conventional field mapping. Overall, conventional UAVs provide a valuable tool for soil mapping in heterogeneous landscapes where manual field sampling is very time consuming. Additionally, the UAVs’ planform view from a bird’s-eye perspective can overcome the limited view from the surveyors’ (ground-based) vantage point.

Additive manufacturing – digitally changing the global business landscape

Purpose Additive manufacturing, that is, layer-based manufacturing technologies, is thought to change supply chain operations from global to local, while also affecting design processes and product structures. As this transformation happens, a power struggle among various actors relating themselves to additive manufacturing has emerged. The purpose of this paper is to discuss and explain the development of additive manufacturing from a power dependence point of view. Design/methodology/approach The paper is based on data collected from a number of seminars hosting a total of 620 industry experts representing 102 companies in the area, and reflecting every step of the supply chain. Findings The paper points out how measures to deal and create power imbalances occur also related to indirect parties, and how the disruptive character of the supply chain leads to exercised power. Originality/value The power struggle provides new insights into how an emerging technology is realised and the effect of protectionism on such attempts. Specifically related to additive manufacturing, the paper illustrates the business side from various actors’ point of view, which adds to technological perspectives on additive manufacturing, as well as studies viewing the supply chain from a bird’s-eye perspective.

Interpreting the EU Internal Market

At the occasion of honoring the career of prof. Laurence W. Gormley - celebrated mentor and friend - this chapter asks one simple question: what does it mean to interpret the free movement of goods, persons, services or capital under EU law reasonably? Reasonableness takes center stage – both explicitly and implicitly – in the European Court of Justice (ECJ)’s jurisprudence on the four freedoms of the EU internal market. For all doctrinal attempts to find a grand unified theory of EU internal market law, deducing ever more principles from the expanding body of case law, the ECJ has never succumbed to calls for settling these questions once and for all, stoically persisting in pragmatism and judicial minimalism. Taking a bird’s eye perspective, perhaps the case law can be roughly summarized as follows. First, reasonable measures of the Member States are compatible with EU internal market law. Second, direct and indirect discrimination is usually unreasonable. Third, truly non-discriminatory barriers to free movement are usually reasonable, but sometimes they are not. Fourth, what is ‘reasonable’ and ‘unreasonable’ is ultimately for the Court to decide. If reasonableness is central to EU internal market law, the Court’s seminal Dassonville judgment seems to contain right about everything one needs to know. However, since reasonableness is in the eye of the beholder, and it is unclear what a ‘reasonable’ approach to the legal rules entails, the guiding function of EU law would benefit from some further clarification. At the same time, the EU legal system’s relative youth entails that the substantive content of EU law is at an early stage of development, and the meaning of autonomous EU concepts is only developing as appropriate cases arise. Consequently, it is up to the ECJ to exercise good judgement in individual judgments. Four possible sources of reasonableness are identified: the notion of ‘regulatory autonomy’ (II), the definition of a trade barrier (III), the burden and standard of proof (IV) and the notion of ‘holistic interpretation’ (V).

Integrating Drone Technology in STEM Education: A Case Study to Assess Teachers’ Readiness and Training Needs

Aim/Purpose: Drone technology has been increasingly used in education. This paper reports a study of assessing teachers’ readiness and training needs for using drone technology in their teaching. Background: New technology promotes new ways of practices. With the sophisticated design and the affordance to explore our world from a bird’s eye perspective, a drone has been increasingly used to support science, technology, engineering, and mathematics education. However, it also brings challenges to teachers to integrate drone technology in their teaching. It is therefore important to obtain a better understanding of various aspects of integrating drone technology in education. Methodology: A group of pre-service teachers was engaged in a case study conducted using a designed-based approach. The participants were randomly assigned into three groups. They were required to develop lesson plans with the application of drone technology in teaching. The lesson plans were subsequently analyzed using the TPCK framework to identify teachers’ readiness and training needs. Findings: The participants, to a large extent, have sufficient competence to master the skills and knowledge of drone technology and to integrate it into their teaching. However, they were required to strengthen the pedagogical knowledge, subject content knowledge, and technological content knowledge in order to maximize the potential benefits of drone technology in education. Contribution: This paper reports the level of readiness and training needs of teachers regarding the use of drone technology in their teaching. Recommendations for Practitioners: To conduct teacher training regarding the use of drone technology in education, a particular focus should be put on enhancing teachers’ pedagogical knowledge, subject content knowledge, and technological content knowledge. Recommendations for Researchers: Researcher may further explore the strategies to integrate drone technology in teaching. Impact on Society: This paper suggests the area of teacher training regarding the use of drone technology in education. The teaching and learning effectiveness could be improved. Future Research: Future research may study the safety issue and ethical issue of using a drone in education.

A Probabilistic Steering Parameter Model for Deterministic Motion Planning Algorithms

AbstractThe simulation of two‐dimensional human locomotion in a bird's eye perspective is a key technology for various domains to realistically predict walk paths. The generated trajectories, however, are frequently deviating from reality due to the usage of simplifying assumptions. For instance, common deterministic motion planning algorithms predominantly utilize a set of static steering parameters (e.g. maximum acceleration or velocity of the agent) to simulate the walking behaviour of a person. This procedure neglects important influence factors, which have a significant impact on the spatio‐temporal characteristics of the finally resulting motion—such as the operator's physical conditions or the probabilistic nature of the human locomotor system. In overcome this drawback, this paper presents an approach to derive probabilistic motion models from a database of captured human motions. Although being initially designed for industrial purposes, this method can be applied to a wide range of use cases while considering an arbitrary number of dependencies (input) and steering parameters (output). To underline its applicability, a probabilistic steering parameter model is implemented, which models velocity, angular velocity and acceleration as a function of the travel distances, path curvature and height of a respective person. Finally, the technical performance and advantages of this model are demonstrated within an evaluation.

Characterizing projective geometry of binocular visual space by Möbius transformation

Binocular vision involves the projection of objects in the 3-D visual space onto the two retinae and the comparison of spatial layout of objects in these retinal half-images. Here we characterize the unitary representation of the binocular space as a complex half-plane from the perspective of the cyclopean eye. We then investigate its automorphism group, namely the Möbius transformation group, and the associated invariants when the two eye positions are treated as fixed points of the automorphism. A three-point simple ratio from an object point to both eyes is constructed; as a complex number, its angle measures the difference in azimuth of the projected rays from the object point to each eye (i.e., horizontal disparity) while its modulus measures the ratio of the distances of the object point to the two eyes (i.e., relative vertical magnification or vertical size ratio). The four-point cross-ratio of two such simple ratios, as the only four-point invariant under Möbius transforms, reflects the fact that the relative disparity between any two object points remains unchanged when the eyes change fixation. Since the complex half-plane is biholomorphically equivalent to an open unit disk, both Poincaré model and Klein–Beltrami model give rise to a hyperbolic geometry, consistent with the empirically supported Luneburg’s (1947; 1950) model of binocular geometry (for the depth plane). Finally, the hyperbolic tangent function f(z)=tanh(z), with inverse f−1(z)=12log1+z1−z, is shown to act as the psychophysical function relating the physical representation of the binocular space to its cyclopean representation.

Bioethics After the Death of God

In After God: Morality & Bioethics in a Secular Age, Professor H. Tristram Engelhardt, Jr. argues that the now dominant intellectual culture of the West actively shuns any transcendent point of orientation, such as an appeal to God or to a God’s eye perspective on reality. Instead, it seeks to frame its understanding of reality and morality, and thus its bioethics, without reference to any foundation outside of particular human concerns. This article explores the implications of living in a secular culture that eschews any appeal to a fully objective perspective on reality. Drawing on Engelhardt’s analysis, it argues that absent access to a binding moral standpoint that is not already conditioned by a particular society, culture, or place in history, all moral and bioethical commitments are merely contingent, subject to particular human interests, aesthetic inclinations, personal intuitions, idiosyncratic choices, and political objectives.

Opposition to Inbreeding Between Close Kin Reflects Inclusive Fitness Costs.

Due to the intense selection pressure against inbreeding, humans are expected to possess psychological adaptations that regulate mate choice and avoid inbreeding. From a gene’s-eye perspective, there is little difference in the evolutionary costs between situations where an individual him/herself is participating in inbreeding and inbreeding among other close relatives. The difference is merely quantitative, as fitness can be compromised via both routes. The question is whether humans are sensitive to the direct as well as indirect costs of inbreeding. Using responses from a large population-based sample (27,364 responses from 2,353 participants), we found that human motivations to avoid inbreeding closely track the theoretical costs of inbreeding as predicted by inclusive fitness theory. Participants were asked to select in a forced choice paradigm, which of two acts of inbreeding with actual family members they would want to avoid most. We found that the estimated fitness costs explained 83.6% of participant choices. Importantly, fitness costs explained choices also when the self was not involved. We conclude that humans intuit the indirect fitness costs of mating decisions made by close family members and that psychological inbreeding avoidance mechanisms extend beyond self-regulation.

@Alabedbana: Twitter, the child, and the war diary

ABSTRACT On 3 October 2016 The Guardian ran a story titled, ‘“I need peace”: Seven-Year-Old Bana Tweets Her Life in Besieged Aleppo’. @AlabedBana’s Twitter feed recounts Bana’s everyday experiences in Aleppo. The posts emphasise a child’s-eye perspective: simple language and pleas for peace amid violence and trauma. Sometimes her mother tweets from the account and signs off with her name. After The Guardian’s story Bana’s Twitter followers grew by tens of thousands. I encountered this article through The Guardian’s Facebook page and amongst the many engaged and supportive comments was a smaller selection of comments that doubted the veracity of the Twitter account (suggesting manipulation, or worse propaganda). Further, a series of fake, troll accounts emerged to spoof al-Abed– again doubting the possibility that a seven-year-old could author such a narrative. This article considers the new variables, complexities, and mediations that new media diaries bring to a discussion of childhood diaries by considering the circulation and reception of @AlabedBana’s Twitter. How might Twitter ‘work’ as a diary mode for representing trauma, particularly childhood experiences of war and conflict? What issues might @AlabedBana’s Twitter diary raise for scholars thinking about the trajectories of global life narratives emerging from new media diary modes?

Focusing on individual species reveals the specific nature of assembly mechanisms in a tropical dry-forest

We employed an individual-species approach based on the plant’s eye perspective to disentangle the effects of individual species on community assembly in a dry tropical forest of southern Ecuador. We completely mapped a forest plot of 9 ha, and measured several functional traits (leaf area, specific leaf area, wood density, seed mass and maximum height) for tree and shrub species. To account for stochastic and habitat filtering effects, we fitted spatial point processes for the 23 more abundant species in the plot, which confirmed that all species responded to plot scale habitat filtering and 14 were dispersal-limited. We tested the hypothesis that facilitative interactions would be prevalent in this dry forest. For this, we compared the distribution of taxonomic (TD), functional (FD) and phylogenetic (PD) diversity in the neighborhood of the studied species with the diversity expected under a null model combining habitat filtering and stochastic assembly. We found that in the fine spatial scales where species interactions are expected to occur (i.e., neighborhoods of 1–20 m) eight species did not show any significant pattern for TD, FD or PD. Eleven species showed evidences of facilitation (i.e., accumulated more TD than expected) but in some cases the facilitated neighborhoods had more FD or PD than expected, suggesting the joint effect of facilitation and competition based on niche differences. One species showed less TD than expected, accompanied by lower FD and higher PD, suggesting competition based on fitness differences.Our study shows that in this dry tropical forest, where abiotic stress is prevalent, the assembly of diversity is controlled by environmental heterogeneity and both facilitative and competitive biotic processes, all of them acting simultaneously and at the same scale in the same neighborhoods.

Integrating Drone Technology with GPS Data Collection to Enhance Forestry Students Interactive Hands-On Field Experiences

Undergraduate students pursuing a Bachelor of Science in Forestry (BSF) at Stephen F. Austin State University (SFA) within the Arthur Temple College of Forestry and Agriculture (ATCOFA) attend an intensive 6-week hands-on instruction in applied field methods. The second week of field station is focused on land measurement activities to introduce students to practical, hands-on, and technology based ways to survey forest boundaries. On Monday of the second week students are introduced to the concepts of how to use a handheld compass to navigate from point to point, use a consumer-grade handheld Global Positioning System (GPS) unit for collecting the geographic coordinates of given locations, use a GPS unit to calculate the area of a forest opening, use a GPS unit to walk and record a forest hiking trail, and evaluate the accuracy of their GPS derived locations via a Root Mean Square Error (RMSE) analysis. RMSE analysis between a students collected geographic coordinates and the instructors collected geographic coordinates indicated that the students were sufficient in correctly recording the geographic coordinates of point, line, and polygon features identified in the field. Grades on the student submitted reports summarizing Monday’s activities resulted in 33 of 56 students (59.0%) receiving a high A, 14 of 56 students (25.0%) receiving a low A, and 9 of 56 students (16.0%) receiving a high B indicating that the interactive hands-on nature of ATCOFA’s field station is effective at providing students with real-world applications whereby they will be ready to make a difference the day after graduation. Interactive drone imagery and video integrated into the daily activities in the field to enhance a student’s understanding of their specific objectives provided the students in the field with a bird’s eye perspective of the landscape to aid their understanding and planning of the field tasks assigned. In conclusion, employers can have confidence that when hiring recent BSF graduates from ATCOFA that the students have been introduced to geospatial technologies within a proven one-on-one instruction methodology designed to increase cognitive retention and can traverse from location to location accurately and record the geographic coordinates of earth surface features correctly.

Jan Van Eyck and the Ghent Altarpiece

The painter Jan Van Eyck is one of the most significant representatives of Northern Renaissance art. The brothers Van Eyck painted the large almost 600-year-old Ghent Altarpiece. This polyptych with 26 paintings is an impressive rendering of Catholic mysticism. Jan Van Eyck used new techniques of handling both oil paint and transparent glazes. He was an early light designer and painted realistic lighting and shadows. Jan Van Eyck used central perspective, eye-level perspective and worm's-eye perspective in his paintings. He was the first to use aerial perspective. Jan Van Eyck included numerous verbal messages and symbols in his paintings, designed in every detail.

Most borrowable construction ever! A large-scale approach to contact-induced pragmatic change

The construction Beste boek ooit (‘Best book ever!’) comes in different forms in Dutch. Variation is not only attested in the absence or presence of determiners and postmodifiers, but also in code choice: English, Dutch and hybrid (Beste boek ever!) variants occur.This article investigates differentiation between instances with ooit and instances with ever. To ensure sufficient signal, we adopt a bird's eye perspective, analyzing over 100,000 observations from a Twitter corpus from the Low Countries (period 2011–2016). Our results reveal that (1) the two constructional variants increase in frequency in the time period under study, (2) this increase is more pronounced for the ooit-variant; (3) the ever-variant undergoes specialization towards a pragmatically marked form.Overall, our account complements anglicism research (Andersen 2014) in four ways. First, we foreground constructional borrowing instead of single-word borrowing. Second, in working with Twitter data, we break with the tradition of print media corpora. Third, we explore NLP based methods for large datasets sampled from big data collections in a field of research that has mainly relied on manual coding of small-scale datasets. Finally, we illustrate how matter and pattern replication can go hand in hand in contact-induced change.

The bird’s-eye perspective: how do district health managers experience the impact of family physicians within the South African district health system? A qualitative study

Background: Health policy-makers in Africa are looking for local solutions to strengthen primary care teams. A South African national position paper (2015) described six aspirational roles of family physicians (FPs) working within the district health system. However, the actual contributions of FPs are unclear at present, and evidence is required as to how this cadre may be able to strengthen health systems.
 
 Methods: Using semi-structured interviews, this study sought to obtain the views of South African district health managers regarding the impact made by FPs within their districts on health system performance, clinical processes and health outcomes. 
 
 Results: A number of benefits of FPs to the health system in South Africa were confirmed, including: their ability to enhance the functionality of the local health system by increasing access to a more comprehensive and coordinated health service, and by improving clinical services delivered through clinical care, capacitating the local health team and facilitating clinical governance activities.
 
 Conclusions: District managers confirmed the importance of all six roles of the FP and expressed both direct and indirect ways in which FPs contribute to strengthening health systems’ performance and clinical outcomes. FPs were seen as important clinical leaders within the district healthcare team. Managers recognised the need to support newly appointed FPs to clarify their roles within the healthcare team and to mature across all their roles. This study supports the employment of FPs at scale within the South African district health system according to the national position paper on family medicine.
 
 (Full text of the research articles are available online at www.medpharm.tandfonline.com/ojfp)
 
 S Afr Fam Pract 2018; DOI: 10.1080/20786190.2017.1348047

Retractor endoscopic techniques in the treatment of entrapment peripheral neuropathies

With increasing awareness for minimally invasive approaches, endoscopic techniques for peripheral nerve decompression are becoming increasingly popular. The first endoscopic approach to release a pinched nerve was for carpal tunnel release through a single entry port, whereby the compressed canal was dilated with bougies and an endoscope introduced into this canal to transect the transverse carpal ligament. Since most of the manipulations with the blunt bougie in this technique were done in a blind fashion, there was a lurking potential for iatrogenic nerve injury using the bougie technique. Thus the retractor-integrated endoscopic technique was developed. In this technique, the retractor bearing the endoscope is introduced into a plane above the compressing ligaments and the nerve proper and a bird’s eye perspective of the anatomical site is gained. Owing to the simplicity of the technique, the retractor-endoscope was used to decompress any nerve at any site in the body: furthermore it was employed for harvesting nerves, vessels and tendons for transplantation. In this paper, we describe the various endoscopic techniques used for decompression in peripheral nerve entrapment syndromes and provide a comprehensive and comparative metaanalysis of the techniques.