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eye anatomy

Jorge Otero-Millan, Lance M Optican, Stephen L Macknik, Susana Martinez-Conde
When we explore a static visual scene, our eyes move in a sequence of fast eye movements called saccades, which are separated by fixation periods of relative eye stability. Based on uncertain sensory and cognitive inputs, the oculomotor system must decide, at every moment, whether to initiate a saccade or to remain in the fixation state. Even when we attempt to maintain our gaze on a small spot, small saccades, called microsaccades, intrude on fixation once or twice per second. Because microsaccades occur at the boundary of the decision to maintain fixation versus starting a saccade, they offer a unique opportunity to study the mechanisms that control saccadic triggering...
2018: Frontiers in Neurology
Benjamin A Palmer, Dvir Gur, Steve Weiner, Lia Addadi, Dan Oron
Vision mechanisms in animals, especially those living in water, are diverse. Many eyes have reflective elements that consist of multilayers of nanometer-sized crystalline plates, composed of organic molecules. The crystal multilayer assemblies owe their enhanced reflectivity to the high refractive indices of the crystals in preferred crystallographic directions. The high refractive indices are due to the molecular arrangements in their crystal structures. Herein, data regarding these difficult-to-characterize crystals are reviewed...
June 10, 2018: Advanced Materials
Jianchun Yu, Xing Chen, Danying Zhou, Jian Shen, Yanbing Wu, Qingzhu Sun
BACKGROUND Currently, safe and effective surgical treatment of malignant glaucoma is still under investigation. This study evaluated the clinical efficacy of ciliary ring incision combined with modified partial pars plana vitrectomy in the treatment of malignant glaucoma. The technique is particularly useful in the treatment of "phakic" patients with malignant glaucoma, especially those who wish to preserve the natural lens. MATERIAL AND METHODS We retrospectively analyzed 13 cases (16 eyes) of malignant glaucoma in which patients underwent ciliary ring incision combined with modified partial pars plana vitrectomy based on follow-up data collected from May 2004 to March 2017...
June 10, 2018: Medical Science Monitor: International Medical Journal of Experimental and Clinical Research
C Fernández, A A de Salles, M E Sears, R D Morris, D L Davis
Children's brains are more susceptible to hazardous exposures, and are thought to absorb higher doses of radiation from cell phones in some regions of the brain. Globally the numbers and applications of wireless devices are increasing rapidly, but since 1997 safety testing has relied on a large, homogenous, adult male head phantom to simulate exposures; the "Standard Anthropomorphic Mannequin" (SAM) is used to estimate only whether tissue temperature will be increased by more than 1 Celsius degree in the periphery...
May 22, 2018: Environmental Research
Y Kate Hong, Eliza F Burr, Joshua R Sanes, Chinfei Chen
The retinogeniculate synapse transmits information from retinal ganglion cells (RGC) in the eye to thalamocortical relay neurons in the visual thalamus, the dorsal lateral geniculate nucleus (dLGN). Studies in mice have identified genetic markers for distinct classes of RGCs encoding different features of the visual space, facilitating the dissection of RGC subtype-specific physiology and anatomy. In this study, we examine the morphological properties of axon arbors of the BD-RGC class of ON-OFF direction selective cells that, by definition, exhibit a stereotypic dendritic arbor and termination pattern in the retina...
June 8, 2018: European Journal of Neuroscience
Jonathan J Dutton
PURPOSE: To review and summarize the clinical findings in thyroid eye disease (TED) related to the unique anatomical structures of the eyelids and orbit. METHODS: A PubMed search was performed searching for anatomical relationships between eyelid and orbital anatomy and the clinical findings of TED. RESULTS: The major clinical findings associated with TED are varied. They typically involve both the eyelid and the orbit. In the eyelid, usual findings include upper eyelid retraction, contour abnormalities, eyelid edema, prolapsed orbital fat, conjunctival injection and chemosis, caruncular edema, and meibomian gland dysfunction...
May 10, 2018: Ophthalmic Plastic and Reconstructive Surgery
Maren Stropahl, Anna-Katharina R Bauer, Stefan Debener, Martin G Bleichner
Electroencephalography (EEG) source localization approaches are often used to disentangle the spatial patterns mixed up in scalp EEG recordings. However, approaches differ substantially between experiments, may be strongly parameter-dependent, and results are not necessarily meaningful. In this paper we provide a pipeline for EEG source estimation, from raw EEG data pre-processing using EEGLAB functions up to source-level analysis as implemented in Brainstorm. The pipeline is tested using a data set of 10 individuals performing an auditory attention task...
2018: Frontiers in Neuroscience
Kayla R Ficarrotta, Simon A Bello, Youssef H Mohamed, Christopher L Passaglia
Purpose: The study aimed to provide a quantitative description of aqueous humor dynamics in healthy rat eyes. Methods: One eye of 26 anesthetized adult Brown-Norway rats was cannulated with a needle connected to a perfusion pump and pressure transducer. Pressure-flow data were measured in live and dead eyes by varying pump rate (constant-flow technique) or by modulating pump duty cycle to hold intraocular pressure (IOP) at set levels (modified constant-pressure technique)...
May 1, 2018: Investigative Ophthalmology & Visual Science
Sajad Mir, Douglas A Andres
PURPOSE: Ras-like without CAAX 1 (RIT1/Rit) is a member of the Ras subfamily of small GTP-binding proteins with documented roles in regulating neuronal function, including contributions to neurotrophin signaling, neuronal survival and neurogenesis. The aim of the study was to (1) examine the expression of RIT1 protein in mouse retina and retinal cell types and (2) determine whether RIT1 contributes to retinal ganglion cell survival and synaptic stability following excitotoxic stress. MATERIALS AND METHODS: Gene expression and immunohistochemical analysis were used to examine RIT1 expression in the mouse retina...
May 29, 2018: Current Eye Research
Daniel L Adams, Brittany C Rapone, John R Economides, Jonathan C Horton
PURPOSE: To assess the outcome of free tenotomy of the medial rectus muscle in post-natal monkeys. METHODS: The medial rectus muscle was disinserted in both eyes of 6 macaques at age 4 weeks to induce an alternating exotropia. After the impact on the visual cortex and superior colliculus was investigated, the animals were examined post-mortem to assess the anatomy of the medial rectus muscles. RESULTS: After tenotomy, the monkeys eventually recovered partial adduction...
May 29, 2018: Journal of Pediatric Ophthalmology and Strabismus
Filiz Onat, Medine Gülçebi İdriz Oğlu, Safiye Çavdar
Ray (Rainner) Guillery was a perfect scientist role model for the young generation. He was very generous in sharing his scientific knowledge and had an enormous sense of humor which showed his brilliant sharp intelligence. We had the privilege to work with him for four years (2006-2010) in Marmara University, Istanbul and kept in contact until he passed away in 2017. As neuroscientists, we were not the only ones to greatly benefit from his experience during his stay in the Departments of Anatomy and Pharmacology, he was also in contactwith the other departments (Public Health, Histology, Internal Medicine, etc) of the medical faculty...
May 28, 2018: European Journal of Neuroscience
Irem Maro Kiris
Architectural production has been influenced by a variety of sources. Forms derived from nature, biology and live organisms, had often been utilised in art and architecture. Certain features of the human anatomy had been reflected in design process in various ways, as imitations, abstractions, interpretations of the reality. The correlation of ideal proportions had been investigated throughout centuries. Scholars, art historians starting with Vitruvius from the world of ancient Roman architecture, described the human figure as being the principal source of proportion among the classical orders of architecture...
May 4, 2018: Turkish Neurosurgery
Ivailo Zhekov, Shahina Pardhan, Rupert Ra Bourne
IMPORTANCE: The change in the anatomical dimensions over time and the effect on diurnal intraocular pressure (DIOP) following laser peripheral iridotomy is poorly understood. BACKGROUND: To evaluate change over time in anterior chamber angle anatomy following laser peripheral iridotomy (LPI) in patients with primary angle closure compared to control eyes. Additionally, the effect of LPI on DIOP fluctuation was investigated. DESIGN: Longitudinal, prospective, double-randomized research study...
May 16, 2018: Clinical & Experimental Ophthalmology
Yiwen Li Hegner, Justus Marquetand, Adham Elshahabi, Silke Klamer, Holger Lerche, Christoph Braun, Niels K Focke
Epilepsy is one of the most prevalent neurological diseases with a high morbidity. Accumulating evidence has shown that epilepsy is an archetypical neural network disorder. Here we developed a non-invasive cortical functional connectivity analysis based on magnetoencephalography (MEG) to assess commonalities and differences in the network phenotype in different epilepsy syndromes (non-lesional/cryptogenic focal and idiopathic/genetic generalized epilepsy). Thirty-seven epilepsy patients with normal structural brain anatomy underwent a 30-min resting state MEG measurement with eyes closed...
May 15, 2018: Brain Topography
Jacob G Sivak, Jeremy M Sivak
It has been speculated that the unitary eyes of vertebrates and molluscs, and the compound eyes of insects and crustaceans, evolved separately. On the other hand, the common use of rhodopsin as a photoreceptor molecule, and the conservation of Pax6 as a master control gene for eye development, suggest instead that the eye evolved once. Yet, recently the molecular genetics that had seemed to suggest a definitive answer to this evolutionary point has once again become cloudy. Here we propose an alternative approach to addressing the question of eye evolution through comparative analyses of physiological optics...
May 11, 2018: Experimental Eye Research
S Terrell Jinson, Jan Liebich, Stephen L Senft, Lydia M Mäthger
Investigating retinal specializations offers insights into eye functionality. Using retinal wholemount techniques, we investigated the distribution of retinal ganglion cells in the Little skate Leucoraja erinacea by (1) dye-backfilling into the optic nerve prior to retinal wholemounting; (2) Nissl-staining of retinal wholemounts. Retinas were examined for regional specializations (higher numbers) of ganglion cells that would indicate higher visual acuity in those areas. Total ganglion cell number were low compared to other elasmobranchs (backfilled: average 49,713 total ganglion cells, average peak cell density 1,315 ganglion cells mm-2 ; Nissl-stained: average 47,791 total ganglion cells, average peak cell density 1,319 ganglion cells mm-2 )...
May 14, 2018: Journal of Comparative Neurology
Ilse M Daly, Martin J How, Julian C Partridge, Nicholas W Roberts
Almost all animals, regardless of the anatomy of the eyes, require some level of gaze stabilization in order to see the world clearly and without blur. For the mantis shrimp, achieving gaze stabilization is unusually challenging as their eyes have an unprecedented scope for movement in all three rotational degrees of freedom: yaw, pitch and torsion. We demonstrate that the species Odontodactylus scyllarus performs stereotypical gaze stabilization in the yaw degree of rotational freedom, which is accompanied by simultaneous changes in the pitch and torsion rotation of the eye...
May 16, 2018: Proceedings. Biological Sciences
Christopher A Emerling
Regressive evolution involves the degradation of formerly useful traits as organisms invade novel ecological niches. In animals, committing to a strict subterranean habit can lead to regression of the eyes, likely due to a limited exposure to light. Several lineages of subterranean mammals show evidence of such degeneration, which can include decreased organization of the retina, malformation of the lens and subcutaneous positioning of the eye. Advances in DNA sequencing have revealed that this regression co-occurs with a degradation of genomic loci encoding visual functions, including protein-coding genes...
April 25, 2018: Integrative and Comparative Biology
Wing Li, Thao N Yeh, Tiana Leung, Tiffany Yuen, Mariel Lerma, Meng C Lin
Purpose: There has been interest in determining whether lid wiper epitheliopathy (LWE) plays a key role in causing ocular discomfort. Conflicting reports have made it difficult to discern whether LWE is more prevalent in certain populations, what characteristics are associated with its severity, and what its role is in symptomology. This cross-sectional study on a large and diverse population attempts to answer these questions. Methods: Subjects were asked to complete questionnaires related to dry eye and to ocular discomfort...
April 1, 2018: Investigative Ophthalmology & Visual Science
James R Wright
Bodysnatching was an illegal way to procure cadavers for anatomical dissection before the existence of effective anatomy legislation. As knowledge of anatomy was fundamental to medical practice, many famous 19th century physicians turned a blind eye to this activity or even participated. Sir William Osler, perhaps the most revered physician of all time, received his medical degree from McGill University in 1872 and then served as pathologist at Montreal General Hospital from 1874 to 1884, where he began a career which culminated in him becoming both the first Professor of Medicine at Johns Hopkins and then Regius Professor at Oxford...
April 17, 2018: Clinical Anatomy
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