Factors in visual acuity: I. Neural inhibition and the visual perception of contours

1957 ◽  
Vol 19 (2) ◽  
pp. 147-156 ◽  
Author(s):  
Peter H. Greene
Keyword(s):  
Visual Acuity ◽  
Visual Perception ◽  
Neural Inhibition

scholarly journals Optically correcting visual acuity beyond 20/20 improves visual perception: A cautionary tale for studies of special populations

2016 ◽  
Vol 16 (12) ◽  
pp. 241
Author(s):  
Lisa Cruz ◽  
Brian Keane ◽  
Sabine Kastner ◽  
Thomas Papathomas ◽  
Steven Silverstein
Keyword(s):  
Visual Acuity ◽  
Visual Perception ◽  
Special Populations ◽  
Cautionary Tale

Neuro-ophthalmology: Disorders of Visual Perception, Pupils, and Eyelids

2021 ◽  
pp. 821-833
Author(s):  
Shivram Kumar ◽  
Kelly D. Flemming
Keyword(s):  
Visual Acuity ◽  
Visual Field ◽  
Visual Perception ◽  
Visual Loss ◽  
Visual Field Defects ◽  
Clinical Disorders ◽  
Physical Findings ◽  
Abnormal Visual ◽  
Visual Changes ◽  
Field Defects

Visual loss may develop acutely, subacutely, or insidiously. The course may be transient, static, or progressive. This chapter reviews the causes, diagnosis, and treatment of various disorders resulting in visual loss or abnormal visual perception. In addition, it reviews clinical disorders of the eyelids and pupils. Disorders of visual perception involve visual acuity, color perception, visual field defects, and other visual changes. Historical information and physical findings on examination can help to localize the problem and define the cause.

SYSTEM FOR MEASURING RODENTS' VISUAL FUNCTION: DESIGN AND IMPLEMENTATION

2014 ◽  
Vol 26 (02) ◽  
pp. 1450018 ◽  
Author(s):  
Carlos Perez-Vidal ◽  
Alejandro Garcia ◽  
Nicolas Garcia-Aracil ◽  
Jose M. Sabater ◽  
Eduardo Fernandez
Keyword(s):  
Computer Vision ◽  
Visual Acuity ◽  
Visual Perception ◽  
Contrast Sensitivity ◽  
Visual Function ◽  
Histological Analysis ◽  
Visual Development ◽  
New Drugs ◽  
Design And Implementation ◽  
Function Design

The aim of the work presented in this paper is the design, manufacturing and assembling of a system able to measure rodents' (mice and rats) visual function and to study the evolution of degenerative retina diseases. Measurement of contrast sensitivity and visual acuity is essential to design new drugs and understand mechanisms of visual development to evaluate treatments' effectiveness. Classical methods to study visual perception of animals such as electroretinogram (ERG) or histological analysis are not supplying enough information because connection between eyes and brain is not considered. The system proposed in this work consists of four screens forming a cube with black methacrylate plastic floor and roof. Screens display visual stimulus and the rodent's behaviour (placed over a platform in the middle of the cube) is analized to determine its visual acuity and contrast sensitivity. These visual stimuli are generated from a FPGA board designed in this project. This board has a USB link with a computer and it controls screens via VGA signals. Rodents' behaviour is analized using computer vision algorithms under OpenCV libraries. To test the system, more than 30 mice (C57 and RD10 type) have been used to validate the hardware, the software, the procedure and protocol.

Large-Scale LOD Adaptive Terrain Rendering

2012 ◽  
Vol 220-223 ◽  
pp. 2450-2453 ◽  
Author(s):  
Wen Long Yu ◽  
Li Min Zhang ◽  
Bing Qiang Zhang
Keyword(s):  
Visual Acuity ◽  
Visual Perception ◽  
Large Scale ◽  
Dynamic Error ◽  
Smooth Transition ◽  
Evaluation Function ◽  
Static Error ◽  
Terrain Rendering ◽  
Quad Tree ◽  
Screen Space

The data structure is the form of quad-tree in this paper. The terrain node's LOD evaluation function is given through comprehensive considering the three factors which are the static error of the terrain block ,the screen space dynamic error and visual perception based on the premise of visual acuity. The smooth transition factor is used to eliminate the phenomenon of popping in the GPU vertex shader. The idea to join the skirts is used to eliminate cracks between terrain blocks. The experimental results show that the algorithm can reflect the terrain LOD levels through the fluctuant of terrain and the visual perception intensity so that the terrain has a better adaptability while increasing frame rates and rendering realistic.

Assessing Visual Perception in Heritage Sites with Visual Acuity

2020 ◽  
Vol 14 (1) ◽  
pp. 1-18
Author(s):  
Martina Polig ◽  
Despina G. Papacharalambous ◽  
Nikolas Bakirtzis ◽  
Sorin Hermon
Keyword(s):  
Visual Acuity ◽  
Visual Perception ◽  
Heritage Sites

scholarly journals Stereoscopic Vision and Testing Techniques – Review

2020 ◽  
Vol 4 (2) ◽  
Keyword(s):  
Visual Acuity ◽  
Visual Perception ◽  
Diagnostic Tests ◽  
Early Years ◽  
Stereoscopic Vision ◽  
Risk Of Injury ◽  
Field Of Vision ◽  
Quality Of Vision ◽  
Testing Techniques

Stereoscopic vision or stereopsis is the highest level of binocular vision. It is acquired in the early years of life and requires the “simultaneous perception” of each eye separately, as well as the “matching” of the two images during brain development. First of all, it gives man the visual perception of depth, but it also broadens his field of vision and increases his visual acuity. As anyone can easily understand it is especially useful in everyday life. It is not particularly well known, but the quality of vision at night is based on stereotypes. Finally, people who do not have stereoscopic vision are in a difficult position as they are at immediate risk of injury. For the above reasons, it is clear why constipation should be controlled, with specific diagnostic tests, especially during childhood.

A STUDY ON THE DIFFERENCES IN VISION BETWEEN THE YOUNG AND THE ELDERLY IN SIGNS

2021 ◽  
Author(s):  
M. Ishihara ◽  
K. Suzuki ◽  
J. Heo
Keyword(s):  
Visual Acuity ◽  
Factor Analysis ◽  
Visual Perception ◽  
The Elderly ◽  
Semantic Differential ◽  
Differential Method ◽  
Viewing Distance ◽  
Colour Perception ◽  
Semantic Differential Method ◽  
Visual Characteristics

It has been shown that with aging, cataracts become cloudy and colour perception and visual acuity deteriorate. As the world's population ages, there is a need for signage that considers older people's visual characteristics. This study aimed to clarify the effects of sign components on visual perception and identify differences in the effects of age. We conducted a psychological evaluation using the semantic differential method on 20 young and 10 elderly. The results showed that the younger participants gave higher ratings to many questions than the older participants. The factor analysis results showed that the items of the questionnaire consisted of a "visibility factor" and "harmony factor". The elderly were more likely to be affected by the viewing distance than the young invisibility.

DIRECTED CONTROL OF VERGENCE – EFFECTIVE METHOD OF VISUAL ACUITY IMPROVEMENT IN PATIENTS WITH SPASM OF ACCOMMODATION OR MYOPIA

2020 ◽  
pp. 141-146
Author(s):  
Rabichev I.E. ◽  
Kotov A.V. ◽  
Artyukh A.M.
Keyword(s):  
Visual Acuity ◽  
Eye Movements ◽  
Visual Perception ◽  
Visual Image ◽  
Integral Condition ◽  
Original Method ◽  
Visual Axis ◽  
Precision Control ◽  
Functional Correction ◽  
Strong Motivation

An original method of visual acuity improvement has been developed and tested. Epiphinomenon of visual perception - a virtual visual image (VVI) is used as a base of the proposed method. The VVI emerges in conditions of physiological diplopia and fusion of paired images. The purpose of the research is to show that a directed small-stepped control of the VVI’s parameters including change of vergence of the visual axis is an integral condition of the visual acuity improvement in patients with spam of accommodation or myopia. But such control is possible if only a patient has a binocular vision together with a created on purpose strong motivation to improve the visual acuity. Directed precision control of vergence eye movements leads to the accommodation control and creation of a structural track of adaptation during the training. As a result of trainings a functional correction of visual acuity is possible in patients with spasm of accommodation or myopia (of low and moderate degrees). The proposed method was used for training of 37 school children with spasm of accommodation and 223 patients with myopia of low and moderate degrees. The visual acuity of all the training participants improved by 5-75 per cent. The results of the visual acuity improvement depend on the patient’s visual system flexibility and his/her scrupulous following the instructions given during the training.

The specific nature of difficulties in visual perception resulting from childhood brain tumors

2019 ◽  
Vol LXXX (4) ◽  
pp. 268-277
Author(s):  
Małgorzata Walkiewicz-Krutak ◽  
Małgorzata Paplińska
Keyword(s):  
Visual Acuity ◽  
Brain Tumor ◽  
Visual Perception ◽  
Brain Tumors ◽  
Visual Fields ◽  
Specific Nature ◽  
Vision Assessment ◽  
Visual Problems ◽  
Functional Vision ◽  
Functional Vision Assessment

The analyses presented in the article aim to investigate the specific nature of visual problems in a young child whose visual disability results from a brain tumor. The article presents a case study on difficulties in using vision and visual perception development in an almost 4-year-old boy with a brain tumor. It refers to knowledge concerning visual problems in children with brain tumors that is available in source materials and presents a detailed description of difficulties in visual reception and perception in a boy whose visual problems result from cancer. This description was made based on the results of a functional vision assessment. Decreased visual acuity, reduced visual fields, abnormalities in the development of oculomotor functions, lack of spatial vision, and difficulties in visual perception were found in the boy. Both the analysis of medical literature presented in the paper and the results of the boy's functional vision assessment suggest possible development of visual functioning disorders secondary to a brain tumor, such as decreased visual acuity and reduced visual fields, which determine visual abilities and have an adverse impact on the development of visual perception in early life. Based on the analysis of an individual situation, the description of difficulties in visual functioning suggests there is a risk of similar impairments in children with brain tumors.

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