Some Remarks on the Relationship between Depth of Focus of the Human Eye and the Minimal Blur Disc

1978 ◽  
Vol 25 (10) ◽  
pp. 1009-1012 ◽  
Author(s):  
Lucia R. Ronchi
Keyword(s):  
Depth Of Focus ◽  
Human Eye ◽  
The Relationship

scholarly journals The Correlations between Horizontal and Vertical Peripheral Refractions and Human Eye Shape Using Magnetic Resonance Imaging in Highly Myopic Eyes

Healthcare ◽  
2021 ◽  
Vol 9 (8) ◽  
pp. 966
Author(s):  
Hui-Ying Kuo ◽  
John Ching-Jen Hsiao ◽  
Jing-Jie Chen ◽  
Chi-Hung Lee ◽  
Chun-Chao Chuang ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Shape Deformation ◽  
Spherical Equivalent ◽  
Horizontal Meridian ◽  
Resonance Imaging ◽  
Vertical Meridian ◽  
Useful Knowledge ◽  
Human Eye ◽  
The Relationship

The aim of this study was to determine the relationship between relative peripheral refraction and retinal shape by 2-D magnetic resonance imaging in high myopes. Thirty-five young adults aged 20 to 30 years participated in this study with 16 high myopes (spherical equivalent < −6.00 D) and 19 emmetropes (+0.50 to −0.50 D). An open field autorefractor was used to measure refractions from the center out to 60° in the horizontal meridian and out to around 20° in the vertical meridian, with a step of 3 degrees. Axial length was measured by using A-scan ultrasonography. In addition, images of axial, sagittal, and tangential sections were obtained using 2-D magnetic resonance imaging. The highly myopic group had a significantly relative peripheral hyperopic refraction and showed a prolate ocular shape compared to the emmetropic group. The highly myopic group had relative peripheral hyperopic refraction and showed a prolate ocular form. Significant differences in the ratios of height/axial (1.01 ± 0.02 vs. 0.94 ± 0.03) and width/axial (0.99 ± 0.17 vs. 0.93 ± 0.04) were found from the MRI images between the emmetropic and the highly myopic eyes (p < 0.001). There was a negative correlation between the retina’s curvature and relative peripheral refraction for both temporal (Pearson r = −0.459; p < 0.01) and nasal (Pearson r = −0.277; p = 0.011) retina. For the highly myopic eyes, the amount of peripheral hyperopic defocus is correlated to its ocular shape deformation. This could be the first study investigating the relationship between peripheral refraction and ocular dimension in high myopes, and it is hoped to provide useful knowledge of how the development of myopia changes human eye shape.

Depth of Focus of the Human Eye*

1959 ◽  
Vol 49 (3) ◽  
pp. 273 ◽  
Author(s):  
Kenneth N. Ogle ◽  
J. Theodore Schwartz
Keyword(s):  
Depth Of Focus ◽  
Human Eye

Research on the Impact of the Contrast between the White Text and Black Background to Visual Sharpness

2013 ◽  
Vol 469 ◽  
pp. 282-285
Author(s):  
Yu Liu ◽  
Shun Yuan Zhang ◽  
Hua Jun Xin
Keyword(s):  
Linear Relation ◽  
Quality Evaluation ◽  
Basic Research ◽  
Objective Measurement ◽  
Print Quality ◽  
Human Eye ◽  
Black Background ◽  
Measurement Results ◽  
The Impact ◽  
The Relationship

This research is to find out the relationship between objective measurement contrast and clarity to the human eye perception, via the analysis of different tone background and white text, based on the text contrast properties in ISO 13660 standard, to do some basic research for the black background of print quality evaluation. Experimental results show that perceived sharpness and contrast into positive correlation, the greater the contrast, the sharpness perception will increase accordingly， but it is not linear relation, in contrast, under the condition of smaller contrast, small changes of contrast will cause great changes in the perception of the definition, with the increase of contrast, perceived definition changes tend to be gentle, it is important to note that contrast is of the biggest objective measurement results in background of 100% black tone, whereas the human eye subjective sense of clarity is not the best, it turns out that the best sense of clarity in background tone value is around 90%.

scholarly journals Filmic Space and Real Time in Hitchcock’s Rope

2011 ◽  
Author(s):  
Peter J. Dellolio
Keyword(s):  
Real Time ◽  
Spatial Configuration ◽  
Depth Of Focus ◽  
Time And Space ◽  
The Relationship

FILMIC SPACE AND REAL TIME IN HITCHCOCK'S ROPE "Brandon, how did you feel?""When?""During it?"Philip Morgan to Brandon Shaw IntroductionRope explores some of the fundamental characteristics of the cinematic abstraction of time and space by using the mobile camera as an agent that gives plastic reality to subjective material. In Rope, a synthesis of real time and filmic space forces the viewer to absorb narrative information on multiple, often distastefully ironic levels. At the same time, the viewer is given freedom of selection in terms of how, when, and why his/her attention is split, inviting some comparison with similar choices experienced during depth of focus shots, a spatial configuration that Hitchcock characteristically avoided. The movement of the camera throughout the film places the viewer in the ethically, emotionally, and psychologically uncomfortable position of perceiving perversity in the relationship between image and dialogue. For example, during the...

scholarly journals Effect of Phenylephrine on the Accommodative System

2016 ◽  
Vol 2016 ◽  
pp. 1-13 ◽  
Author(s):  
José J. Esteve-Taboada ◽  
Antonio J. Del Águila-Carrasco ◽  
Paula Bernal-Molina ◽  
Teresa Ferrer-Blasco ◽  
Norberto López-Gil ◽  
...  
Keyword(s):  
Image Quality ◽  
Retinal Image ◽  
Ciliary Muscle ◽  
Depth Of Focus ◽  
Pharmacological Agents ◽  
The Real ◽  
Phenylephrine Hydrochloride ◽  
Main Research ◽  
Human Eye ◽  
Real Effects

Accommodation is controlled by the action of the ciliary muscle and mediated primarily by parasympathetic input through postganglionic fibers that originate from neurons in the ciliary and pterygopalatine ganglia. During accommodation the pupil constricts to increase the depth of focus of the eye and improve retinal image quality. Researchers have traditionally faced the challenge of measuring the accommodative properties of the eye through a small pupil and thus have relied on pharmacological agents to dilate the pupil. Achieving pupil dilation (mydriasis) without affecting the accommodative ability of the eye (cycloplegia) could be useful in many clinical and research contexts. Phenylephrine hydrochloride (PHCl) is a sympathomimetic agent that is used clinically to dilate the pupil. Nevertheless, first investigations suggested some loss of functional accommodation in the human eye after PHCl instillation. Subsequent studies, based on different measurement procedures, obtained contradictory conclusions, causing therefore an unexpected controversy that has been spread almost to the present days. This manuscript reviews and summarizes the main research studies that have been performed to analyze the effect of PHCl on the accommodative system and provides clear conclusions that could help clinicians know the real effects of PHCl on the accommodative system of the human eye.

COMPLEXITY-BASED ANALYSIS OF THE RELATION BETWEEN MOVING VISUAL STIMULI AND HUMAN EYE MOVEMENT

Fractals ◽  
2019 ◽  
Vol 27 (03) ◽  
pp. 1950024 ◽  
Author(s):  
HEDIEH ALIPOUR ◽  
HAMIDREZA NAMAZI ◽  
HAMED AZARNOUSH ◽  
SAJAD JAFARI
Keyword(s):  
Eye Movement ◽  
Visual Target ◽  
Fractal Theory ◽  
Complex Structure ◽  
Visual Stimuli ◽  
Vision Science ◽  
Human Eye ◽  
Different Types ◽  
External Stimuli ◽  
The Relationship

Investigating human eye movement is one of the major research topics in vision science. It is known that human eye movement is related to external stimuli. In this way, the analysis of human eye movement due to different types of external stimuli is very important in vision science. Beside all reported analysis, no one has discovered any relation between the complex structure of moving visual stimuli and the complex structure of human eye movement. This study reveals the relationship between the complexity of human eye movement signal and the applied visual stimuli. For this purpose, we employ fractal theory. We demonstrated that the fractal dynamics of human eye movement in both horizontal and vertical directions shifts toward the fractal dynamics of moving visual target as stimulus. The capability observed in this research opens new doors to scientists to study the relation between the human eye movement and the applied stimuli.

scholarly journals Depth-of-focus of the human eye in the near retinal periphery

2004 ◽  
Vol 44 (11) ◽  
pp. 1115-1125 ◽  
Author(s):  
Bin Wang ◽  
Kenneth J Ciuffreda
Keyword(s):  
Depth Of Focus ◽  
Human Eye ◽  
Retinal Periphery

scholarly journals Cornea donation process and tissue quality for transplantation

PLoS ONE ◽  
2021 ◽  
Vol 16 (4) ◽  
pp. e0249927
Author(s):  
Giovanna Karinny Pereira Cruz ◽  
Marcos Antonio Ferreira Júnior ◽  
Oleci Pereira Frota ◽  
Elen Ferraz Teston ◽  
Viviane Euzébia Pereira Santos ◽  
...  
Keyword(s):  
Epidemiologic Study ◽  
Tissue Bank ◽  
Corneal Tissue ◽  
Tissue Quality ◽  
Sociodemographic Variables ◽  
Human Eye ◽  
Donation Process ◽  
The Relationship ◽  
Cornea Donation

Introduction The quality of the corneal tissue can be influenced by several factors inherent to the recipient, donor, and to the donation and transplantation process. The donated corneal tissue can be classified by its quality as excellent, good, regular, bad, or unacceptable for transplantation, evaluating it in a slit lamp. Objective To analyze the relationship between the clinical and sociodemographic variables of the donors and the donation process and the classification of the quality of the corneal tissue collected for transplantation. Methods This is an epidemiologic study, retrospective cohort type, which addressed the process of cornea donation by the Human Eye Tissue Bank in a reference service in Northeast Brazil. The sample consisted of corneas processed by the Human Eye Tissue Bank of Rio Grande do Norte (n = 419). For descriptive and inferential analysis, the study used the Statistical Package for the Social Sciences (SPSS) software, version 25.0, and considered a significance level of 0.05. Logistic regression analysis was used for the adjustment of the final model. Results It was verified that the epidemiological profile showed a prevalence of individuals with a mean age of 42.54 years old, male (73.99%), and living in the metropolitan region of the state capital (75.66%). When analyzing the relationship between the clinical and sociodemographic variables of the donors, it was identified that those aged 45 years old or less had better quality corneas (excellent and good), while the chronological variables were predictive factors for corneas of regular and bad qualities. Conclusion The identification of the factors inherent to the donation process and predictors of corneal tissue quality contribute to minimizing the risk of transplantation and to a better ocular prognosis.

scholarly journals Errors in the Vickers diagonal length measurement caused by different designs of microscopes

ACTA IMEKO ◽  
2020 ◽  
Vol 9 (5) ◽  
pp. 261
Author(s):  
S. Takagi ◽  
Y. Tanaka ◽  
Y. Seino
Keyword(s):  
Numerical Aperture ◽  
Image Resolution ◽  
Point Of View ◽  
Length Measurement ◽  
Resolving Power ◽  
Measuring System ◽  
Objective Lens ◽  
Depth Of Focus ◽  
The Relationship ◽  
Diagonal Length

The errors in the Vickers diagonal length measurement are discussed from the point of view of the design of microscope. Effects of the numerical aperture (NA) of an objective lens are evaluated through the experiment. With smaller NA, the resolving power of the microscope gets worse and the depth of focus gets deeper as predicted Rayleigh’s criterion. The relationship between the repeatability of diagonal length and the objective NA follows the theory. In addition, the variation of NA relates the measured diagonal length. Those effects are much significant than the image resolution or the minimum count of a measuring system.

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