scholarly journals A Geometric Theory Integrating Human Binocular Vision With Eye Movement

2020 ◽  
Vol 14 ◽  
Author(s):  
Jacek Turski
Keyword(s):  
Visual Information ◽  
Ad Hoc ◽  
Geometric Theory ◽  
Crystalline Lens ◽  
Posterior Pole ◽  
Conic Sections ◽  
Primary Position ◽  
Binocular Single Vision ◽  
Meaningful Definition ◽  
Retinal Correspondence

A theory of the binocular system with asymmetric eyes (AEs) is developed in the framework of bicentric perspective projections. The AE accounts for the eyeball's global asymmetry produced by the foveal displacement from the posterior pole, the main source of the eye's optical aberrations, and the crystalline lens' tilt countering some of these aberrations. In this theory, the horopter curves, which specify retinal correspondence of binocular single vision, are conic sections resembling empirical horopters. This advances the classic model of empirical horopters as conic sections introduced in an ad hoc way by Ogle in 1932. In contrast to Ogle's theory, here, anatomically supported horopteric conics vary with the AEs' position in the visual plane of bifoveal fixations and their transformations are visualized in a computer simulation. Integrating horopteric conics with eye movements can help design algorithms for maintaining a stable perceptual world from visual information captured by a mobile robot's camera head. Further, this paper proposes a neurophysiologically meaningful definition for the eyes' primary position, a concept which has remained elusive despite its theoretical importance to oculomotor research. Finally, because the horopteric conic's shape is dependent on the AE's parameters, this theory allows for changes in retinal correspondence, which is usually considered preformed and stable.

scholarly journals A Geometric Theory Integrating Human Binocular Vision with Eye movement

2020 ◽  
Author(s):  
Jacek Turski
Keyword(s):  
Visual Information ◽  
Ad Hoc ◽  
Geometric Theory ◽  
Crystalline Lens ◽  
Posterior Pole ◽  
Conic Sections ◽  
Primary Position ◽  
Binocular Single Vision ◽  
Meaningful Definition ◽  
Retinal Correspondence

AbstractA theory of the binocular system with asymmetric eyes (AEs) is developed in the framework of bicentric perspective projections. The AE accounts for the eyeball’s global asymmetry produced by the foveal displacement from the posterior pole, the main source of the eye’s optical aberrations, and the crystalline lens’ tilt countering some of these aberrations. In this theory, the horopter curves, which specify retinal correspondence of binocular single vision, are conic sections resembling empirical horopters. This advances the classic model of empirical horopters as conic sections introduced in an ad hoc way by Ogle in 1932. In contrast to Ogle’s theory, here, anatomically supported horopteric conics vary with the AEs’ position in the visual plane of bifoveal fixations and their transformations are visualized in a computer simulation. Integrating horopteric conics with eye movements can help design algorithms for maintaining a stable perceptual world from visual information captured by a mobile robot’s camera-head. Further, this paper proposes a neurophysiologically meaningful definition for the eyes’ primary position, a concept which has remained elusive despite its theoretical importance to oculomotor research. Finally, because the horopteric conic’s shape is dependent on the AE’s parameters, this theory allows for changes in retinal correspondence which is usually considered preformed and stable.

Anterior Movement of the Crystalline Lens in the Process of Accommodation in Children

2007 ◽  
Vol 17 (4) ◽  
pp. 515-520 ◽  
Author(s):  
B.J. Kaluzny
Keyword(s):  
Refractive Error ◽  
Axial Length ◽  
Crystalline Lens ◽  
Posterior Pole ◽  
Anterior Pole ◽  
Forward Movement ◽  
Ophthalmic Examination ◽  
Lens Thickness ◽  
Lens Position ◽  
Refractive Status

Purpose To investigate changes of crystalline lens position during accommodation in children with emmetropia, myopia, and hyperopia. Methods A total of 188 children (372 eyes) from 4 to 19 years old (mean age 11.3±4.43) with cycloplegic refractive error within a range +9.00 D to −9.00 D were enrolled. After a general ophthalmic examination, ultrasound biometry was performed, with the eye at a maximal accommodative effort. Cycloplegia was induced by triple installation of 1% tropicamide drops and 30 minutes later the biometric examination was repeated. Results In emmetropic eyes in the process of accommodation, the anterior pole of the crystalline lens moved forward by 0.144±0.14 mm (p ≤ 0.001); the position of the posterior pole did not change. In myopic eyes, the anterior pole moved forward by 0.071±0.13 mm (p≤0.001) and the posterior pole moved backward by 0.039±0.10 mm (p=0.003). In hyperopic eyes, the whole lens translocated anteriorly: anterior pole moved forward by 0.242±0.16 mm (p≤ 0.001) and posterior pole moved forward by 0.036±0.09 mm (p≤0.001). Differences among emmetropia, myopia, and hyperopia were statistically significant. Forward movement of the posterior pole correlated with a low axial length of the eye, and also with plus refractive error and with a smaller accommodative increase of lens thickness. Conclusions In children, accommodative changes of the crystalline lens position depend on refractive status.

Strabismus and oculomotility

2012 ◽  
Author(s):  
Rebecca Ford ◽  
Moneesh Patel
Keyword(s):  
Clinical Skills ◽  
Strabismus Surgery ◽  
Ocular Motility ◽  
Clinical Knowledge ◽  
Ocular Movements ◽  
Single Vision ◽  
Visual Acuity Testing ◽  
Concomitant Strabismus ◽  
Binocular Single Vision ◽  
Retinal Correspondence

The chapter begins by discussing the anatomy and actions of the extraocular muscles and central control of ocular motility, before covering the key clinical skills, namely patient assessment, assessment of ocular movements, visual acuity testing, tests of stereopsis and binocular single vision, tests of retinal correspondence and suppression, and Hess charts. It then covers the key areas of clinical knowledge, including amblyopia, binocular vision and stereopsis, concomitant strabismus, incomitant strabismus, restrictive ocular motility disorders, complex ocular motility syndromes, vertical deviations , and alphabet patterns, and the key practical skills, namely the principles of strabismus surgery and other procedures in strabismus. The chapter concludes with five case-based discussions, on myopic anisometropia, esotropia, infantile esotropia, orbital floor fracture, and consecutive exotropia.

THE ALHACENIAN ACCOUNT OF SPATIAL PERCEPTION AND ITS EPISTEMOLOGICAL IMPLICATIONS

2005 ◽  
Vol 15 (2) ◽  
pp. 219-240 ◽  
Author(s):  
A. MARK SMITH
Keyword(s):  
Seventeenth Century ◽  
Visual Information ◽  
Spatial Perception ◽  
Crystalline Lens ◽  
The Other ◽  
External Objects ◽  
Latin West ◽  
Visual Imaging ◽  
The One ◽  
The Brain

From the late thirteenth to the early seventeenth century, the process of visual imaging was understood in the Latin West as an essentially subjective act initiated by the eye and completed by the brain. The crystalline lens took center stage in this act, its role determined by its peculiar physical and sensitive capacities. As a physical body, on the one hand, it was disposed to accept the physical impressions of light and color radiating to it from external objects. As a sensitive body, on the other hand, it was enabled by the visual spirit flowing to it from the brain to feel those impressions visually. Acting as a sentient selector of visual information, the lens transformed the brute physical impressions of light and color into visual impressions. These, in turn, gave rise to perceptual “depictions” that were passed back along the stream of visual spirits to the brain. Known in Scholastic parlance as “intentional species,” these depictions served as virtual representations of their generating objects. As such, they provided the wherewithal not only for perception, but also for conception and cognition.

Paediatric ophthalmology and strabismus

2016 ◽  
Author(s):  
Lucy Barker ◽  
Kelly MacKenzie ◽  
Joanne Hancox ◽  
Wanda Kozlowska ◽  
Andrew Tatham
Keyword(s):  
Clinical Skills ◽  
Strabismus Surgery ◽  
Ocular Movements ◽  
Single Vision ◽  
Ocular Deviation ◽  
Concomitant Strabismus ◽  
Binocular Single Vision ◽  
Paediatric Ophthalmology ◽  
And Storage ◽  
Retinal Correspondence

This chapter focuses on paediatric ophthalmology and strabismus. It details the embryology, anatomy, and actions of the extraocular muscles, along with clinical skills that include patient assessment and assessment of visual acuity, binocular vision, and stereopsis, assessment of binocular single vision, and retinal correspondence and suppression. It then discusses amblyopia, the measurement and assessment of ocular deviation, the assessment of ocular movements, Hess charts, and the field of binocular single vision. In addition, it discusses concomitant strabismus (the heterophorias, esotropia, and exotropia), incomitant strabismus, the principles of strabismus surgery, general paediatric development, retinopathy of prematurity, retinoblastoma, congenital cataract, paediatric glaucoma, uveitis in children, phacomatoses, and metabolic and storage diseases.

Video Conferencing-based Telehealth

2005 ◽  
Vol 44 (02) ◽  
pp. 334-341 ◽  
Author(s):  
C. R. Anglin ◽  
J. P. Schaafsma ◽  
S. V. Pantazi ◽  
S. Anglin ◽  
N. A. Grimm ◽  
...  
Keyword(s):  
Health Professionals ◽  
Visual Information ◽  
Capital Investment ◽  
Ad Hoc ◽  
Clinical Success ◽  
Video Conferencing ◽  
Variable Cost ◽  
Provider Education ◽  
District Hospitals ◽  
Educational Applications

Summary Purpose: To review the experience with a province-wide telehealth system in Canada, and its implications for health care and health promotion. To explore whether group support systems (GSS) based on networked computers can substitute for video conferencing technology. Methods: Key results of the evaluation of the BC Tele-health Program are summarized. The potential of extending the successful principles through use of GSS is explored based on literature review, demonstrations, and trial use for educational applications. Results: The BC Telehealth Program was designed to support health professionals at secondary care facilities, such as regional and district hospitals in two application domains: children’s and women’s health (C&W) and emergency room and trauma care (ER-Trauma). Successful applications extended beyond health professionals and focused on chronic conditions, the management of which is contingent on visual information, and involves established teams in regular scheduled visits or in sessions scheduled well in advance. Ad hoc applications, in particular applications under emergency conditions proved problematic.Administrative applications in support of telehealth implementation, e.g., through facilitation of management and provider education, are essential for clinical success. Savings from support of administrative applications exceeded the substantial capital investment and made educational and clinical applications available at variable cost. Educational applications were shown to have significant clinical benefits.Exploration of GSS technology showed that it may not be mature enough to substitute for video conferencing technology in support of sophisticated training and education aiming at clinical impact. Conclusion: The substantial clinical and efficiency gains provided by video conferencing-based telehealth may for now continue to depend on mature videoconferencing technology.

scholarly journals Therapeutic results in sixth nerve palsy

2015 ◽  
Vol 22 (1) ◽  
pp. 51-59
Author(s):  
Violeta-Ioana Pruna ◽  
Daniela Cioplean ◽  
Liliana Mary Voinea
Keyword(s):  
Nerve Palsy ◽  
Rectus Muscle ◽  
Lateral Rectus ◽  
Medial Rectus ◽  
Therapeutic Success ◽  
Primary Position ◽  
Sixth Nerve Palsy ◽  
Single Vision ◽  
Binocular Single Vision ◽  
Sixth Nerve

Abstract Authors aim to assess through a retrospective study the efficiency of different therapeutic methods used in VIth nerve palsy. 60 patients with VIth nerve palsy, admitted and treated in Oftapro Clinic, were divided into two groups: a group with partial dysfunction (paresis) of sixth nerve and a group with the complete abolition of neuromuscular function (VIth nerve palsy). Initial examination included assessment of neuromuscular function, binocular vision and existence of medial rectus muscle contracture (ipsi- and contralateral) and contralateral lateral rectus inhibitory palsy. Neuromuscular dysfunction was graded from - 8 (paralysis) to 0 (normal abduction). Therapeutic modalities ranged from conservative treatment (occlusion, prism correction), botulinum toxin chemodenervation and surgical treatment: medial rectus recession + lateral rectus resection, in cases of paresis, and transposition procedures (Hummelscheim and full tendon transfer) in cases of sixth nerve palsy. Functional therapeutic success was defined as absence of diplopia in primary position, with or without prism correction, and surgical success was considered obtaining orthoptic alignment in primary position or a small residual deviation (under 10 PD). 51 patients had unilateral dysfunction, and 9 patients had bilateral VI-th nerve dysfunction. 8 patients had associated fourth or seventh cranial nerves palsy. The most common etiology was traumatic, followed by tumor and vascular causes. There were 18 cases of spontaneous remission, partial or complete (4-8 months after the onset), and 6 cases enhanced by botulinum toxin chemodenervation. 17 paretic eyes underwent surgery, showing a very good outcome, with restoration of binocular single vision. The procedure of choice was recession of medial rectus muscle, combined with resection of lateral rectus muscle. All patients with sixth nerve palsy underwent surgery, except one old female patient, who refused surgery. Hummelscheim procedure was applied in 19 cases, and full tendon transfer in 6 cases. In 13 cases partial results were obtained, who needed further prismatic correction or reintervention. In 12 cases the outcome was very good, with restoration of binocular single vision, without prismatic correction. Therapeutic success in sixth nerve palsy depends on accurate assessment of neuromuscular dysfunction and appropriate choice of therapeutic modality for each case. Interdisciplinary collaboration is mandatory for correct etiologic diagnosis of sixth nerve palsy.

scholarly journals A Power Control Algorithm Based on Outage Probability Awareness in Vehicular Ad Hoc Networks

2018 ◽  
Vol 2018 ◽  
pp. 1-8 ◽  
Author(s):  
Xintong Wu ◽  
Shanlin Sun ◽  
Yun Li ◽  
Zhicheng Tan ◽  
Wentao Huang ◽  
...  
Keyword(s):  
Ad Hoc Networks ◽  
Power Control ◽  
Outage Probability ◽  
Control Algorithm ◽  
Vehicular Ad Hoc Networks ◽  
Ad Hoc ◽  
Geometric Theory ◽  
Maximum Power ◽  
Power Control Algorithm ◽  
Hoc Networks

This paper addresses the problem of adaptive power control based on outage probability minimization in Vehicular Ad Hoc Networks (VANETs), called a Power Control Algorithm Based on Outage Probability Awareness (PC-OPA). Unlike most of the existing works, our power control method aims at minimizing the outage probability and then is subject to the density of nodes in certain area. To fulfill power control, cumulative interference is assumed to be available at the transmitter of each terminal. The transmitters sent data by maximum power and then get the cumulative interference-aware outage probability. Furthermore, we build the interference model by stochastic geometric theory and then derive the expression between outage probability and cumulative interference. According to the expression, we adjust the transmitter power and optimize the outage probability. Simulation results are provided to demonstrate the effectiveness of the proposed power control strategies. It is shown that the PC-OPA can achieve a significant performance gain in terms of the outage probability and throughputs. Comparing MPC (Maximum Power Control algorithm) and WFPC (Water-Filled Power Control algorithm), the proposed PC-OPA decreased by 23% in terms of the outage probability and increased by 25% in terms of throughputs.

Biomechanics of the Posterior Pole During the Remodeling Progression From Normal to Early Experimental Glaucoma

2009 ◽  
Author(s):  
Ian A. Sigal ◽  
Hongli Yang ◽  
Michael D. Roberts ◽  
Claude F. Burgoyne ◽  
J. Crawford Downs
Keyword(s):  
Visual Information ◽  
Lamina Cribrosa ◽  
Posterior Pole ◽  
Glaucomatous Optic Neuropathy ◽  
Retinal Ganglion ◽  
Experimental Glaucoma ◽  
Pass Through ◽  
Mechanical Insult ◽  
The Brain ◽  
Connective Tissue Structure

Glaucoma is one of the leading causes of blindness worldwide. The loss of vision associated with glaucoma is due to damage to the retinal ganglion cell axons, which transmit visual information to the brain. Damage to these axons is believed to occur as the axons pass through the lamina cribrosa (LC), a connective tissue structure in the optic nerve head at the back of the eye. Elevated intraocular pressure (IOP) has been identified as the main risk factor for the development of the neuropathy, but the mechanism(s) by which a mechanical insult (elevated IOP) is translated into a biological effect (glaucomatous optic neuropathy) is not well understood.

scholarly journals OPTO-ACOUSTIC DATA FUSION FOR SUPPORTING THE GUIDANCE OF REMOTELY OPERATED UNDERWATER VEHICLES (ROVs)

2015 ◽  
Vol XL-5/W5 ◽  
pp. 47-53 ◽  
Author(s):  
F. Bruno ◽  
A. Lagudi ◽  
G. Ritacco ◽  
M. Muzzupappa ◽  
R. Guida
Keyword(s):  
Data Fusion ◽  
Optical Sensors ◽  
Visual Information ◽  
Ad Hoc ◽  
Data Extraction ◽  
Underwater Vehicles ◽  
Support Tool ◽  
Acoustic Data ◽  
Mechanical Manipulators ◽  
Application Fields

Remotely Operated underwater Vehicles (ROVs) play an important role in a number of operations conducted in shallow and deep water (e.g.: exploration, survey, intervention, etc.), in several application fields like marine science, offshore construction, and underwater archeology. ROVs are usually equipped with different imaging devices, both optical and acoustic. Optical sensors are able to generate better images in close range and clear water conditions, while acoustic systems are usually employed in long range acquisitions and do not suffer from the presence of turbidity, a well-known cause of coarser resolution and harder data extraction. In this work we describe the preliminary steps in the development of an opto-acoustic camera able to provide an on-line 3D reconstruction of the acquired scene. Taking full advantage of the benefits arising from the opto-acoustic data fusion techniques, the system was conceived as a support tool for ROV operators during the navigation in turbid waters, or in operations conducted by means of mechanical manipulators. <br><br> The paper presents an overview of the device, an <i>ad-hoc</i> methodology for the extrinsic calibration of the system and a custom software developed to control the opto-acoustic camera and supply the operator with visual information.

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