Measurement of ocular transmission in living human eyes with a double-pass system

2019 ◽  
Author(s):  
Roberto F. Sánchez ◽  
Aníbal G. de Paul ◽  
Francisco J. Burgos-Fernández ◽  
Meritxell Vilaseca ◽  
Jaume Pujol ◽  
...  
Keyword(s):  
Optical Quality ◽  
Artificial Eye ◽  
Double Pass ◽  
Pass System ◽  
Linear Behavior ◽  
The Media ◽  
Linear Fit ◽  
Human Eyes

AbstractPurposeTo develop a methodology based on a double-pass system to obtain useful information about the transmission of ocular media, performing noninvasive measures in vivo.MethodsThis noninvasive procedure consists of recording double-pass images at different voltages of a laser diode of 780 nm and the determination of the scattering in an area between 25 and 35 arc minutes of each image.ResultsOcular scattering showed a linear behavior respect to the voltage of the laser and the slope of the linear fit was proportional to the transmittance squared of the media evaluated. The relationship between the ocular light scattering of the images and the transmittance values of several filters located into an artificial eye was used as a calibration function. The measurements performed in a group of ten subjects with ages between 25 and 45 years old presented a mean direct transmittance of the whole eye including retina of 42.7 %, which agrees with the bibliography. No differences between dark eyes and light eyes were found.ConclusionWe have developed a method to determine the transmittance of the human eye in vivo for a wavelength of 780 nm using the double-pass method, commonly used for the determination of the optical quality of an eye.

scholarly journals Transmittance measurement of the in vivo human eye with a double-pass system

2021 ◽  
Vol 51 (1) ◽  
Author(s):  
Roberto Sánchez ◽  
Aníbal De Paul ◽  
Francisco Burgos-Fernández ◽  
Meritxell Vilaseca ◽  
Jaume Pujol ◽  
...  
Keyword(s):  
Artificial Eye ◽  
Double Pass ◽  
Pass System ◽  
Iris Color ◽  
Linear Behavior ◽  
Group A ◽  
The Media ◽  
Ocular Media ◽  
Group B

Purpose: To develop a methodology based on a double-pass system to obtain information about the transmittance of ocular media. Methods: The procedure consists of recording double-pass images at different powers of a laser diode of 780 nm and determining the scattering in an area between 25–35 arcmin of each image. The scattering showed linear behavior in respect to the irradiance of the laser, and the slope of the linear fit was proportional to the transmittance squared of the media evaluated. An artificial eye with different filters was tested first. Then, fifteen subjects with clear ocular media were divided into two groups: ten subjects classified by the iris color were recruited for the measurements of an ocular transmittance index and the estimation of the transmittance (group A), and another five subjects were selected for measurements with neutral filters (group B). Results: The measurements performed in group A presented a mean transmittance of 42.95%. No differences in the transmittance were found between subjects with different iris color (p = 0.154). Measurements in group B showed a good correlation (r = 0.959, p < 0.001) between the expected and the measured value for the transmittance. Conclusion: We proposed and evaluated a method to determine the transmittance of the eye in vivo using the double-pass system.

Optical quality after myopic photorefractive keratectomy and laser in situ keratomileusis: Comparison using a double-pass system

2012 ◽  
Vol 38 (1) ◽  
pp. 16-27 ◽  
Author(s):  
Juan C. Ondategui ◽  
Meritxell Vilaseca ◽  
Montserrat Arjona ◽  
Ana Montasell ◽  
Genís Cardona ◽  
...  
Keyword(s):  
Optical Quality ◽  
Laser In Situ Keratomileusis ◽  
Photorefractive Keratectomy ◽  
Double Pass ◽  
Pass System

Influence of Progressive Lenses in the Retinal Image Quality

Perception ◽  
1997 ◽  
Vol 26 (1_suppl) ◽  
pp. 156-156
Author(s):  
J Gispets ◽  
M Arjona ◽  
J Pujol
Keyword(s):  
Image Quality ◽  
Retinal Image ◽  
Human Subjects ◽  
Optical Quality ◽  
Optical Systems ◽  
Modulation Transfer ◽  
Double Pass ◽  
Progressive Lenses

Progressive lenses (PL) are widely used to correct presbyopia, a visual dysfunction that affects most of the population aged over 40 years. The methods used to evaluate the optical quality of these lenses are mainly based on ray-tracing and optical bench testing. Psychophysical studies based on measurements of the contrast sensitivity function of human subjects also exist. However, all these methods exhibit important limitations because, in general, they do not take into account the optics of the eye. One of the objective techniques that permits evaluation of the retinal image in-vivo is the double pass method (Santamaria et al, 1987 Journal of the Optical Society of America A4 1109 – 1114). It has been possible to study the retinal image quality for different correcting optical systems, such as contact lenses, with this technique (Torrents et al, 1996 Perception25 Supplement, 112 – 113). We studied the retinal image quality of the optical system formed by the eye and a progressive lens. The retinal image quality, characterised by the modulation transfer function (MTF), was measured for different observers as a variety of lines of sight that covered a lens diameter of 50 mm. We show the MTF variation as a function of the lens region and the capacity of this technique to characterise these optical systems.

Biaxial incremental homeostatic elastic moduli of coronary artery: two-layer model

2004 ◽  
Vol 287 (4) ◽  
pp. H1663-H1669 ◽  
Author(s):  
Xiao Lu ◽  
Aditya Pandit ◽  
Ghassan S. Kassab
Keyword(s):  
Coronary Artery ◽  
Axial Direction ◽  
Circumferential Direction ◽  
Small Perturbations ◽  
Porcine Coronary Artery ◽  
Physiological Relevance ◽  
Health And Disease ◽  
The Media

The detailed mechanical properties of various layers of the coronary artery are important for understanding the function of the vessel. The present article is focused on the determination of the incremental modulus in different layers and directions in the neighborhood of the in vivo state. The incremental modulus can be defined for any material subjected to a large deformation if small perturbations in strain lead to small perturbations of stresses in a linear fashion. This analysis was applied to the porcine coronary artery, which was treated as a two-layered structure consisting of an inner intima-media layer and an outer adventitia layer. We adopted a theory based on small-perturbation experiments at homeostatic conditions for determination of incremental moduli in circumferential, axial, and cross directions in the two layers. The experiments were based on inflation and axial stretch. We demonstrate that under homeostatic conditions the incremental moduli are layer- and direction dependent. The incremental modulus is highest in the circumferential direction. Furthermore, in the circumferential direction, the media is stiffer than the whole wall, which is stiffer than the adventitia. In the axial direction, the adventitia is stiffer than the intact wall, which is stiffer than the media. Hence, the coronary artery must be treated as a composite, nonisotropic body. The data acquire physiological relevance in relation to coronary artery health and disease.

Double-Pass System Assessing the Optical Quality of Pseudophakic Eyes

2014 ◽  
Vol 91 (4) ◽  
pp. 437-443 ◽  
Author(s):  
Hun Lee ◽  
Kwanghyun Lee ◽  
Ji Min Ahn ◽  
Eung Kweon Kim ◽  
Bradford Sgrignoli ◽  
...  
Keyword(s):  
Optical Quality ◽  
Double Pass ◽  
Pass System

Optical quality and intraocular scattering assessed with a double-pass system in eyes with contact lens induced corneal swelling

2014 ◽  
Vol 37 (4) ◽  
pp. 278-284 ◽  
Author(s):  
Victoria de Juan ◽  
Mikel Aldaba ◽  
Raul Martin ◽  
Meritxell Vilaseca ◽  
Jose Maria Herreras ◽  
...  
Keyword(s):  
Contact Lens ◽  
Optical Quality ◽  
Double Pass ◽  
Pass System

A Molecular Approach to Immunoscintigraphy: A Study of the T-Antigen Conformation on the Surface of Tumors

1987 ◽  
Vol 26 (01) ◽  
pp. 1-6 ◽  
Author(s):  
S. Selvaraj ◽  
M. R. Suresh ◽  
G. McLean ◽  
D. Willans ◽  
C. Turner ◽  
...  
Keyword(s):  
Monoclonal Antibodies ◽  
Tumor Cell ◽  
T Antigen ◽  
Human Carcinomas ◽  
Animal Tumor ◽  
Synthetic Antigens

The role of glycoconjugates in tumor cell differentiation has been well documented. We have examined the expression of the two anomers of the Thomsen-Friedenreich antigen on the surface of human, canine and murine tumor cell membranes both in vitro and in vivo. This has been accomplished through the synthesis of the disaccharide terminal residues in both a and ß configuration. Both entities were used to generate murine monoclonal antibodies which recognized the carbohydrate determinants. The determination of fine specificities of these antibodies was effected by means of cellular uptake, immunohistopathology and immunoscintigraphy. Examination of pathological specimens of human and canine tumor tissue indicated that the expressed antigen was in the β configuration. More than 89% of all human carcinomas tested expressed the antigen in the above anomeric form. The combination of synthetic antigens and monoclonal antibodies raised specifically against them provide us with invaluable tools for the study of tumor marker expression in humans and their respective animal tumor models.

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