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Pulse Phase Thermography (PPT) has been reported as a novel powerful technique of the thermal NDE. It employs application of the Discrete Fourier Transform (DFT) to thermal images obtained following flash heating of the front surf...
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Pulse Phase Thermography (PPT) has been reported as a novel powerful technique of the thermal NDE. It employs application of the Discrete Fourier Transform (DFT) to thermal images obtained following flash heating of the front surface of a specimen. The computed phasegrams are excellent for defect visualization in a wide range of materials. This is in part due to their low sensitivity to uneven heating. This work is an attempt to analyze advantages and limitations of PPT. Results of application of the DFT to simulated temperature decays are presented. The temperature evolution on a surface has been simulated based on an analytical solution of the one-dimensional heat diffusion problem. A more sophisticated study has been done for different sizes of defects using numerical solution of the three-dimensional mathematical model. Capabilities of PPT for in-depth scanning and for monitoring of the material loss are discussed. The recommendations for the practical application of the PPT are presented. Experimental results obtained following these recommendations are reported.
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The diagnosis, screening, course of illness, efficacy of treatment and prognosis of functional amblyopia was studied. Evidence suggests that functional amblyopia does not have sufficient validating characteristics to be considered...
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The diagnosis, screening, course of illness, efficacy of treatment and prognosis of functional amblyopia was studied. Evidence suggests that functional amblyopia does not have sufficient validating characteristics to be considered a disease. No correlation between the presence of symptoms and social or economic disability was found, nor was organic disease causing the original visual symptoms found. Some psychiatric disease was found in 38% of the patients. Treatment was no more effective than no treatment in eventual outcome and spontaneous remission or improvement occurred on over half the patients.
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This paper presents an overview of anomalous retinal correspondence in strabismus. Definitions, certain testing techniques, and a review of underlying theory are outlined. It is concluded that ARC is not well understood and repres...
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This paper presents an overview of anomalous retinal correspondence in strabismus. Definitions, certain testing techniques, and a review of underlying theory are outlined. It is concluded that ARC is not well understood and represents an area still open for investigation. Reprints. (AW)
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A method and apparatus for electronically performing a visual field test for a patient. A visual field test pattern is displayed to the patient on an electronic display device and the patient's responses to the visual field test p...
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A method and apparatus for electronically performing a visual field test for a patient. A visual field test pattern is displayed to the patient on an electronic display device and the patient's responses to the visual field test pattern are recorded. A visual field representation is generated from the patient's responses. The visual field representation is then used as an input into a variety of automated diagnostic processes. In one process, the visual field representation is used to generate a statistical description of the rapidity of change of a patient's visual field at the boundary of a visual field defect. In another process, the area of a visual field defect is calculated using the visual field representation. In another process, the visual field representation is used to generate a statistical description of the volume of a patient's visual field defect.
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In studies of the 1974-76 accident experience of U.S. general aviation pilots with static physical defects, all the significantly increased rates and ratios were for visual defect categories--blindness, or absence of either eye, d...
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In studies of the 1974-76 accident experience of U.S. general aviation pilots with static physical defects, all the significantly increased rates and ratios were for visual defect categories--blindness, or absence of either eye, deficient distant vision, deficient color vision with no operational limitations, and contact lenses. A 1979 study was limited to accident airmen with 19 visual deficiencies. The 1,140 pilots with aphakia and 173 with artificial lens implants had significantly higher rates, but the monocular pilots and contact lens users did not. The present study examined the 1980-81 accident experience of 4,169 monocular pilots, 1,299 with amblyopia, 969 with aphakia, 285 with lens implants, 118 with a history of diplopia, 1,269 with a tropia, 2,601 with hyperphoria >1 diopter, and 2,711 with esophoria or exophoria >6 diopters by class of medical certificate held. Numbers were too small for statistical treatment, but first and second class medical certificate holders, who often have more accidents per 1,000 airmen, consistently had progressively lower accident rates per 100,000 hours. They fly more. Monocular, aphakic, lens implant, and amblyopic accident airmen had higher accident rates than did the total airman population. Bases were found to question the value and adequacy of phoria and field of vision testing.
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The report compares current methods of testing congenital color deficiencies withtests designed to employ color video display units (VDUs). Twelve persons with congential color vision deficiencies were asked to judge and match col...
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The report compares current methods of testing congenital color deficiencies withtests designed to employ color video display units (VDUs). Twelve persons with congential color vision deficiencies were asked to judge and match colors presented on a full color VDU. Color stimuli were selected from different 'chromaticity-confusion lines' within the CIE 1931 chromaticity diagram; colors were chosen from one tritan, three protan, and three deutan confusion lines. The results show that the ability to discriminate VDU color stimuli is greatly impaired in protanopes and deutranopes, compared with both normal and deuteranomalous observers. When pairs of color stimuli lay on a protan or deutan confusion line, protanopes and deuteranopes frequently accepted them as equivalent even when the stimuli were separated by large distances in the chromaticity diagram. Protanopes performed slightly better on color stimuli from deutan lines than on those from protan lines. Similarly, deuteranopes showed better performance on protan than on deutan pairs. Deutranomalous observers performed better than dichromats but less well than normals. Color confusions shown by dichromats are in agreement with those shown in standard tests of color vision. Since a full color VDU has a larger chromaticity gamut than the pseudo-isochromatic plates or the Farnsworth D-15 test, it can be a powerful tool for screening dichromats from normals and for illustrating the difficulties persons with color deficiency will have in discriminating colors.
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The prospect of a pilot's vision at night being reduced to a less than optimalstate by night myopia has been debated for years in a large body of research. This report casts doubt on the existence of night myopia in young healthy ...
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The prospect of a pilot's vision at night being reduced to a less than optimalstate by night myopia has been debated for years in a large body of research. This report casts doubt on the existence of night myopia in young healthy pilots by presenting evidence that the accommodative reflex may be driven by direct cognitive control inputs. Direct cognitive control, based on an individual's expectation of accommodative range, could bias measures of night myopia if the measuring instruments are placed close to the subject's eyes. Subjects studied for this report demonstrated excellent visual performance in the dark, at a range of 20 ft, despite measured night myopia of up to 7.94 diopters.
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The demonstration project was designed to meet the dual objectives of consumer education and professional/community collaboration on eye/vision care for the elderly. Local level resources were mobilized and professional collaborat...
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The demonstration project was designed to meet the dual objectives of consumer education and professional/community collaboration on eye/vision care for the elderly. Local level resources were mobilized and professional collaboration was encouraged to promote the project's goals. A National Project Advisory Committee (NPAC) was established to serve as advisors to the project and as facilitators for the development of local linkage between the human service professionals and clinicians. With the NPAC as a model for resource sharing and for building collaborative networks, the demonstration program was instituted at five selected area agencies on aging across the country. The Lighthouse project staff prepared training materials and arranged and conducted training sessions at the site. Consumer outreach efforts and media publicity enabled all sites to institute successful consumer education presentations.
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