Mechanisms of Action and Targets of Nitric Oxide in the Oculomotor System

Nitric oxide (NO) production by neurons in the prepositus hypoglossi (PH) nucleus is necessary for the normal performance of eye movements in alert animals. In this study, the mechanism(s) of action of NO in the oculomotor system has been investigated. Spontaneous and vestibularly induced eye movements were recorded in alert cats before and after microinjections in the PH nucleus of drugs affecting the NO–cGMP pathway. The cellular sources and targets of NO were also studied by immunohistochemical detection of neuronal NO synthase (NOS) and NO-sensitive guanylyl cyclase, respectively. Injections of NOS inhibitors produced alterations of eye velocity, but not of eye position, for both spontaneous and vestibularly induced eye movements, suggesting that NO produced by PH neurons is involved in the processing of velocity signals but not in the eye position generation. The effect of neuronal NO is probably exerted on a rich cGMP-producing neuropil dorsal to the nitrergic somas in the PH nucleus. On the other hand, local injections of NO donors or 8-Br-cGMP produced alterations of eye velocity during both spontaneous eye movements and vestibulo-ocular reflex (VOR), as well as changes in eye position generation exclusively during spontaneous eye movements. The target of this additional effect of exogenous NO is probably a well defined group of NO-sensitive cGMP-producing neurons located between the PH and the medial vestibular nuclei. These cells could be involved in the generation of eye position signals during spontaneous eye movements but not during the VOR.Fondo de Investigación Sanitaria Grants 94/0388 and 97/2054Comunidad Autónoma de Madrid Grant 08.5/0019/1997Dirección General de Investigación Científica y Technológica Grant PB 93–117

Characteristic and Correlation Between TIME and Complication After Destructive Eye Procedure Patient at Plastic and Reconstruction Division Sanglah Hospital\u27s Eye Clinic Bali-Indonesia

Destructive eye procedure can be carried out by enucleation, evisceration and excenteration. Some efforts have been developed to reduce the complications, but it still occur within several years after the operation. This research aims to find out the characteristic and correlation between time and complications in patient after destructive eye procedure at Plastic and Reconstruction Division Sanglah Hospital\u27s Eye Clinic. For addition, characteristic of other patients in plastic and reconstruction also provided. This report is an analytical cross sectional study. Data were collected retrospectively from medical report of patients with history of destructive eye procedure in Sanglah Hospital\u27s eye clinic from January 1st until December 31st 2010. Patient\u27s characteristics were presented as frequency, percentage, mean, and standard deviation. Correlations between variables were statistically analyzed with Correlation of Lambda. Eye trauma, anophthalmic socket and nasolacrimal duct obstruction were the most common diagnosis at plastic and reconstruction division Sanglah Hospital\u27s eye clinic. There were 17 patients with history of destructive eye procedure in this report, including 76.5% male and 23.5% female. There is 58.8% destructive eye procedure held in age 13-50 year, mean 30.75 (SD 19.81). Infection (35.3%), trauma (23.5%) and tumor (11.8%) were the most common cause of destructive eye procedure in this study. Complications of destructive eye procedure occur in 70.6% of patient with contracted socket was the most common complication (58.3%). There was medium correlation between time and complication after the procedure, but the correlation was not statistically significant (r = 0.40; p > 0.05). In conclusion, from this study we obtained that there was medium correlation between time and complication after the procedure, but the correlation was not statistically significant

A Low-Dimensional Model of Coordinated Eye and Head Movements

Eye and head movement data, were recorded under head fixed and head-free conditions, and compared with theoretical results obtained using a nonlinear model of eye-head coordination. The model explains slow, or pursuit movement correlated closely to target movement, and saccades, or quick phases of eye movement. Eye movement under head-fixed conditions was modeled by an externally forced Duffing equation, whilst properties of head movement are described by a second externally forced Duffing equation with lower eigen frequency. In the more natural, head-free conditions where both eye and head movements are used synergetically to pursue a visual target, the vestibulocular reflex (VOR) is represented by coefficients defining the mutual coupling between these two oscillatory systems. In the present model, the oscillator that models eye movement has an inhibitory influence on head movement; head to eye coupling coefficients are included to model the influence of the VOR mechanism. Individual eye and head movement patterns in different subjects can be adequately modeled by altering the coupling coefficients. In order to adequatcly simulate those changes introduced by microgravity conditions, the coefficients defining eye-head coordination (mutual coupling) must be changed. It may be hypothesized tlmt such changes in the neurovestibular system could introduce the instability in eye-head coordination, which is known to lead to space sickness.Whitehall Foundation (S93-24

Input Sources and Properties of Position-Sensitive Oculomotor Fibres in the Rock Lobster, Panulirus Interruptus (Randall)

Sets of head-up, head-down, eye-up and eye-down motor fibres were studied in the oculomotor nerve of the rock lobster. An eye-withdrawal fibre was also investigated. Apart from the statocyst input, light distribution on the eyes has the strongest influence on the position-sensitive fibres. Weaker optokinetic input from moving targets is also present. Strongly habituating input is obtained from the antennal joints. This input causes orientation of the eye toward the direction in which the antenna points. The same antennule movement in the vertical plane can result in either excitation or inhibition of the head-down fibre, suggesting the presence of two opposing inputs, presumably from the statocysts and basal joint receptors of the antennule. The inputs on to the position-sensitive fibres which indicate body position are such as to stabilize the eye position in space during body movement. The optokinetic and antennal joint inputs are probably involved in tracking and antennal pointing reactions. The eye-withdrawal fibre is stimulated by touch of the head and around the eye, but is inhibited by the excited state

Reflections about the creative process of the architectural project and its teaching

This paper aims to reflect on the importance of the eye in the creative process of architectural projects. All creation is based on a watchful eye, which acts as an instrument of knowledge and reflection; an active and creative eye that contains a thought. But creation is also in the hands of those who put these thoughts down onto paper and materialise them. In this sense, teaching architectural design should fundamentally consider educating the eye, so that students develop a perceptual ability allowing them to address all kinds of architectural projects creatively. Educating the eye therefore becomes the main goal of teaching architectural design. Learning how to see is essential. This learning calls on the eye as an instrument of knowledge and analysis of the reality to be transformed. An eye with a purpose not just of looking at something for the sake of it, but of seeing it, of seeing it to learn and to become aware of the world surrounding us, whether physically, emotionally or intellectually. An eye that focusses on the reality around them in a conscious and attentive way in order to provide the information to work with when it comes to designing, both from an objective and rational outside world and an intimate and personal world. A creative eye, capable of creating and transforming reality. An eye that involves the action of thinking. But above all, an eye that acts in coordination with hands that work as instruments of knowledge, that move between the world of matter and thought, and that allow this world of ideas to be unearthed, spilling thoughts onto paper, specifying them and fixing them until turning them into something that can be built. In the teaching of architectural design, it would be necessary to foster this action as a way of doing and thinking.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tec

Circulating markers of arterial thrombosis and late-stage age-related macular degeneration: a case-control study.

PURPOSE: The aim of this study was to examine the relation of late-stage age-related macular degeneration (AMD) with markers of systemic atherothrombosis. METHODS: A hospital-based case-control study of AMD was undertaken in London, UK. Cases of AMD (n=81) and controls (n=77) were group matched for age and sex. Standard protocols were used for colour fundus photography and to classify AMD; physical examination included height, weight, history of or treatment for vascular-related diseases and smoking status. Blood samples were taken for measurement of fibrinogen, factor VIIc (FVIIc), factor VIIIc, prothrombin fragment F1.2 (F1.2), tissue plasminogen activator, and von Willebrand factor. Odds ratios from logistic regression analyses of each atherothrombotic marker with AMD were adjusted for age, sex, and established cardiovascular disease risk factors, including smoking, blood pressure, body mass index, and total cholesterol. RESULTS: After adjustment FVIIc and possibly F1.2 were inversely associated with the risk of AMD; per 1 standard deviation increase in these markers the odds ratio were, respectively, 0.62 (95% confidence interval 0.40, 0.95) and 0.71 (0.46, 1.09). None of the other atherothrombotic risk factors appeared to be related to AMD status. There was weak evidence that aspirin is associated with a lower risk of AMD. CONCLUSIONS: This study does not provide strong evidence of associations between AMD and systematic markers of arterial thrombosis, but the potential effects of FVIIc, and F1.2 are worthy of further investigation

An Improved Algorithm for Eye Corner Detection

In this paper, a modified algorithm for the detection of nasal and temporal eye corners is presented. The algorithm is a modification of the Santos and Proenka Method. In the first step, we detect the face and the eyes using classifiers based on Haar-like features. We then segment out the sclera, from the detected eye region. From the segmented sclera, we segment out an approximate eyelid contour. Eye corner candidates are obtained using Harris and Stephens corner detector. We introduce a post-pruning of the Eye corner candidates to locate the eye corners, finally. The algorithm has been tested on Yale, JAFFE databases as well as our created database

Recent Saccadic Eye Movement Research Uncovers Patterns of Cognitive Dysfunction in Schizophrenia.

The frontal cortex and the subcortical areas of the brain play a major role in the control of thought and action. Eye movements are increasingly used in neuropsychological research to explore the executive and sensorimotor functions of such neural networks. This interface links the control of action, at the fundamental levels of neurophysiological and neurochemical processes, with the high-level cognitive operations that underlie visual orienting. Patients with schizophrenia have neurocognitive impairments that can be readily investigated with novel saccadic eye movement paradigms. Animal, human lesion, and neuroimaging studies have identified the cerebral centers that underlie saccadic eye movements. The areas of the prefrontal cortex include the dorsolateral prefrontal cortex, the frontal eye fields, the supplementary eye fields, and the anterior cingulate gyrus. Pathology of saccadic eye movements therefore provides information on the functional status of the underlying neural circuitry in brain disorders such as schizophrenia