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Sample records for acuity color vision

  1. Color vision test

    MedlinePlus

    ... from birth) color vision problems: Achromatopsia -- complete color blindness , seeing only shades of gray Deuteranopia -- difficulty telling ... test -- color; Ishihara color vision test Images Color blindness tests References Adams AJ, Verdon WA, Spivey BE. ...

  2. Color improves "visual" acuity via sound.

    PubMed

    Levy-Tzedek, Shelly; Riemer, Dar; Amedi, Amir

    2014-01-01

    Visual-to-auditory sensory substitution devices (SSDs) convey visual information via sound, with the primary goal of making visual information accessible to blind and visually impaired individuals. We developed the EyeMusic SSD, which transforms shape, location, and color information into musical notes. We tested the "visual" acuity of 23 individuals (13 blind and 10 blindfolded sighted) on the Snellen tumbling-E test, with the EyeMusic. Participants were asked to determine the orientation of the letter "E." The test was repeated twice: in one test, the letter "E" was drawn with a single color (white), and in the other test, with two colors (red and white). In the latter case, the vertical line in the letter, when upright, was drawn in red, with the three horizontal lines drawn in white. We found no significant differences in performance between the blind and the sighted groups. We found a significant effect of the added color on the "visual" acuity. The highest acuity participants reached in the monochromatic test was 20/800, whereas with the added color, acuity doubled to 20/400. We conclude that color improves "visual" acuity via sound. PMID:25426015

  3. Color vision deficiencies

    NASA Astrophysics Data System (ADS)

    Vannorren, D.

    1982-04-01

    Congenital and acquired color vision defects are described in the context of physiological data. Light sources, photometry, color systems and test methods are described. A list of medicines is also presented. The practical social consequences of color vision deficiencies are discussed.

  4. 49 CFR 242.117 - Vision and hearing acuity.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... required in 29 CFR 1910.95(h) (OSHA); (2) As required in § 227.111 of this chapter; or (3) Conducted using... 49 Transportation 4 2013-10-01 2013-10-01 false Vision and hearing acuity. 242.117 Section 242.117... Requirements § 242.117 Vision and hearing acuity. (a) Each railroad shall adopt and comply with a program...

  5. 49 CFR 242.117 - Vision and hearing acuity.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... required in 29 CFR 1910.95(h) (OSHA); (2) As required in § 227.111 of this chapter; or (3) Conducted using... 49 Transportation 4 2014-10-01 2014-10-01 false Vision and hearing acuity. 242.117 Section 242.117... Requirements § 242.117 Vision and hearing acuity. (a) Each railroad shall adopt and comply with a program...

  6. 49 CFR 242.117 - Vision and hearing acuity.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... required in 29 CFR 1910.95(h) (OSHA); (2) As required in § 227.111 of this chapter; or (3) Conducted using... 49 Transportation 4 2012-10-01 2012-10-01 false Vision and hearing acuity. 242.117 Section 242.117... Requirements § 242.117 Vision and hearing acuity. (a) Each railroad shall adopt and comply with a program...

  7. Evaluation of visual acuity with Gen 3 night vision goggles

    NASA Technical Reports Server (NTRS)

    Bradley, Arthur; Kaiser, Mary K.

    1994-01-01

    Using laboratory simulations, visual performance was measured at luminance and night vision imaging system (NVIS) radiance levels typically encountered in the natural nocturnal environment. Comparisons were made between visual performance with unaided vision and that observed with subjects using image intensification. An Amplified Night Vision Imaging System (ANVIS6) binocular image intensifier was used. Light levels available in the experiments (using video display technology and filters) were matched to those of reflecting objects illuminated by representative night-sky conditions (e.g., full moon, starlight). Results show that as expected, the precipitous decline in foveal acuity experienced with decreasing mesopic luminance levels is effectively shifted to much lower light levels by use of an image intensification system. The benefits of intensification are most pronounced foveally, but still observable at 20 deg eccentricity. Binocularity provides a small improvement in visual acuity under both intensified and unintensified conditions.

  8. Light Vision Color

    NASA Astrophysics Data System (ADS)

    Valberg, Arne

    2005-04-01

    Light Vision Color takes a well-balanced, interdisciplinary approach to our most important sensory system. The book successfully combines basics in vision sciences with recent developments from different areas such as neuroscience, biophysics, sensory psychology and philosophy. Originally published in 1998 this edition has been extensively revised and updated to include new chapters on clinical problems and eye diseases, low vision rehabilitation and the basic molecular biology and genetics of colour vision. Takes a broad interdisciplinary approach combining basics in vision sciences with the most recent developments in the area Includes an extensive list of technical terms and explanations to encourage student understanding Successfully brings together the most important areas of the subject in to one volume

  9. 49 CFR 240.121 - Criteria for vision and hearing acuity data.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 4 2014-10-01 2014-10-01 false Criteria for vision and hearing acuity data. 240... ENGINEERS Component Elements of the Certification Process § 240.121 Criteria for vision and hearing acuity... paragraph (e) of this section, a person's vision and hearing shall meet or exceed the standards...

  10. 49 CFR 240.121 - Criteria for vision and hearing acuity data.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 4 2011-10-01 2011-10-01 false Criteria for vision and hearing acuity data. 240... ENGINEERS Component Elements of the Certification Process § 240.121 Criteria for vision and hearing acuity... paragraph (e) of this section, a person's vision and hearing shall meet or exceed the standards...

  11. 49 CFR 240.121 - Criteria for vision and hearing acuity data.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 4 2013-10-01 2013-10-01 false Criteria for vision and hearing acuity data. 240... ENGINEERS Component Elements of the Certification Process § 240.121 Criteria for vision and hearing acuity... paragraph (e) of this section, a person's vision and hearing shall meet or exceed the standards...

  12. 49 CFR 240.121 - Criteria for vision and hearing acuity data.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 4 2012-10-01 2012-10-01 false Criteria for vision and hearing acuity data. 240... ENGINEERS Component Elements of the Certification Process § 240.121 Criteria for vision and hearing acuity... paragraph (e) of this section, a person's vision and hearing shall meet or exceed the standards...

  13. 49 CFR 240.121 - Criteria for vision and hearing acuity data.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Criteria for vision and hearing acuity data. 240... ENGINEERS Component Elements of the Certification Process § 240.121 Criteria for vision and hearing acuity... paragraph (e) of this section, a person's vision and hearing shall meet or exceed the standards...

  14. Genetics Home Reference: color vision deficiency

    MedlinePlus

    ... represents a group of conditions that affect the perception of color. Red-green color vision defects are ... two forms of color vision deficiency disrupt color perception but do not affect the sharpness of vision ( ...

  15. 49 CFR 240.207 - Procedures for making the determination on vision and hearing acuity.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 4 2013-10-01 2013-10-01 false Procedures for making the determination on vision and hearing acuity. 240.207 Section 240.207 Transportation Other Regulations Relating to... making the determination on vision and hearing acuity. (a) Each railroad, prior to initially...

  16. 49 CFR 240.207 - Procedures for making the determination on vision and hearing acuity.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 4 2012-10-01 2012-10-01 false Procedures for making the determination on vision and hearing acuity. 240.207 Section 240.207 Transportation Other Regulations Relating to... making the determination on vision and hearing acuity. (a) Each railroad, prior to initially...

  17. 49 CFR 240.207 - Procedures for making the determination on vision and hearing acuity.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 4 2014-10-01 2014-10-01 false Procedures for making the determination on vision and hearing acuity. 240.207 Section 240.207 Transportation Other Regulations Relating to... making the determination on vision and hearing acuity. (a) Each railroad, prior to initially...

  18. 49 CFR 240.207 - Procedures for making the determination on vision and hearing acuity.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 4 2011-10-01 2011-10-01 false Procedures for making the determination on vision and hearing acuity. 240.207 Section 240.207 Transportation Other Regulations Relating to... making the determination on vision and hearing acuity. (a) Each railroad, prior to initially...

  19. 49 CFR 240.207 - Procedures for making the determination on vision and hearing acuity.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Procedures for making the determination on vision and hearing acuity. 240.207 Section 240.207 Transportation Other Regulations Relating to... making the determination on vision and hearing acuity. (a) Each railroad, prior to initially...

  20. Color vision characteristics of visually impaired children.

    PubMed

    Kalloniatis, M; Johnston, A W

    1990-03-01

    A classroom assessment of color vision characteristics of children with low vision was conducted using a battery of tests. The results showed 75% of the children failed one or more tests, although only 24% had a moderate or severe color vision defect. Comparisons with the low vision clinic color vision assessment showed that many of the children were not identified as being color vision defective. Considering the use of color-coded information in education, greater emphasis on color vision evaluations in routine low vision examinations is recommended. PMID:2320360

  1. Progress in color night vision

    NASA Astrophysics Data System (ADS)

    Toet, Alexander; Hogervorst, Maarten A.

    2012-01-01

    We present an overview of our recent progress and the current state-of-the-art techniques of color image fusion for night vision applications. Inspired by previously developed color opponent fusing schemes, we initially developed a simple pixel-based false color-mapping scheme that yielded fused false color images with large color contrast and preserved the identity of the input signals. This method has been successfully deployed in different areas of research. However, since this color mapping did not produce realistic colors, we continued to develop a statistical color-mapping procedure that would transfer the color distribution of a given example image to a multiband nighttime image. This procedure yields a realistic color rendering. However, it is computationally expensive and achieves no color constancy since the mapping depends on the relative amounts of the different materials in the scene. By applying the statistical mapping approach in a color look-up-table framework, we finally achieved both color constancy and computational simplicity. This sample-based color transfer method is specific for different types of materials in a scene and can be easily adapted for the intended operating theatre and the task at hand. The method can be implemented as a look-up-table transform and is highly suitable for real-time implementations.

  2. Molecular basis for color vision.

    PubMed

    Yoshizawa, T

    1994-05-01

    Amino acid sequences of four kinds of chicken cone pigments and two kinds of nocturnal gecko visual pigment were determined. Calculations of amino acid identities indicate that gecko pigments should be cone pigments. A phylogenetic tree of visual pigments constructed demonstrated that cone pigments evolved earlier than rod pigments (rhodopsins), indicating that daylight vision including color vision appeared earlier than twilight vision. The divergence of cone pigments to rhodopsins would be caused by replacing basic amino acid residues to acidic ones according to net charge calculations. A comparison between chicken rhodopsin and cone pigments (chicken green and red) displayed that the cone pigments are faster in regeneration from 11-cis retinal and opsin, faster in formation of meta II-intermediate and shorter in lifetime of meta II-intermediate than rhodopsin. These facts would partly explain the rapid dark adaptation, the rapid light response and the low photosensitivity of cones compared with rods. In comparison with di- and tri-chromatic color visions, chicken tetra-chromatic vision was discussed on the basis of both absorption spectra of cone pigments and filtering effect of oil droplets. PMID:8011932

  3. Vision Screening by Color Photography

    NASA Technical Reports Server (NTRS)

    Jayroe, R.; Richardson, J. R.; Kerr, J.; Hay, S.; Mcbride, R.

    1985-01-01

    Screening test developed for detecting a range of vision defects in eye, including common precursors to amblyopia. Test noninvasive, safe, and administered easily in field by operator with no medical training. Only minimal momentary cooperation of subject required: Thus, test shows promise for use with very young children. Test produces color-slide images of retinas of eyes under specially-controlled lighting conditions. Trained observer screens five children per minute.

  4. Resource Letter CCV-1: Color and Color Vision.

    ERIC Educational Resources Information Center

    Stuewer, Roger H., Ed.; Pease, Paul L.

    1980-01-01

    Listed are selected resource materials on color vision and the measurement and specification of the stimulus for vision, photometry, and colorimetry. The author's purpose is to equip teachers and students with an understanding of normal and abnormal color vision. References are categorized relative to content level. (Author/DS)

  5. Night vision goggle visual acuity assessment: results of an interagency test

    NASA Astrophysics Data System (ADS)

    Task, H. Lee

    2001-08-01

    There are several parameters that are used to characterize the quality of a night vision goggle (NVG) such as resolution, gain, field-of-view, visual acuity, etc. One of the primary parameters is visual acuity or resolution of the NVG. These two terms are often used interchangeably primarily because of the measurement methods employed. The objectives of this paper are to present: (1) an argument as to why NVG visual acuity and resolution should be considered as distinctly different parameters, (2) descriptions of different methods of measuring visual acuity and resolution, and (3) the results of a blind test by several agencies to measure the resolution of the same two NVGs (four oculars).

  6. Color Vision Deficiencies in Children. United States.

    ERIC Educational Resources Information Center

    National Center for Health Statistics (DHEW/PHS), Hyattsville, MD.

    Presented are prevalence data on color vision deficiencies (color blindness) in noninstitutionalized children, aged 6-11, in the United States, as estimated from the Health Examination Survey findings on a representative sample of over 7,400 children. Described are the two color vision tests used in the survey, the Ishihara Test for Color…

  7. Color Vision Deficits and Literacy Acquisition.

    ERIC Educational Resources Information Center

    Hurley, Sandra Rollins

    1994-01-01

    Shows that color blindness, whether partial or total, inhibits literacy acquisition. Offers a case study of a third grader with impaired color vision. Presents a review of literature on the topic. Notes that people with color vision deficits are often unaware of the handicap. (RS)

  8. Transfer color to night vision images

    NASA Astrophysics Data System (ADS)

    Sun, Shaoyuan; Jing, Zhongliang; Liu, Gang; Li, Zhenhua

    2005-08-01

    Natural color appearance is the key problem of color night vision field. In this paper, the color mood of daytime color image is transferred to the monochromic night vision image. This method gives the night image a natural color appearance. For each pixel in the night vision image, the best matching pixel in the color image is found based on texture similarity measure. Entropy, energy, contrast, homogeneity, and correlation features based on co-occurrence matrix are combined as texture similarity measure to find the corresponding pixels between the two images. We use a genetic algorithm (GA) to find the optimistic weighting factors assigned to the five different features. GA is also employed in searching the matching pixels to make the color transfer algorithm faster. When the best matching pixel in the color image is found, the chromaticity values are transferred to the corresponding pixel of the night vision image. The experiment results demonstrate the efficiency of this natural color transfer technique.

  9. Color Vision Defects: What Teachers Should Know.

    ERIC Educational Resources Information Center

    Lewis, Barbara A.; And Others

    1990-01-01

    Discusses the nature of color vision defects as they relate to reading instruction. Suggests ways that teachers can adapt instruction to help provide maximal learning opportunities for the color deficient child. (RS)

  10. Visual acuity test

    MedlinePlus

    Eye test -- acuity; Vision test -- acuity; Snellen test ... from your face. This will test your near vision. ... examination, particularly if there is a change in vision or a problem with vision. In children, the ...

  11. Schopenhauer on vision and the colors.

    PubMed

    Crone, R A

    1997-01-01

    Arthur Schopenhauer (1788-1860) published his book, On Vision and the Colors in 1816. He started from Aristotle's linear color system and Goethe's three pairs of contrast colors. His work preceded Hering's theory of opponent colors but his path to insight was blocked by his anti-Newtonianism and his neo-Hellenistic attitude toward science. Because of his theory of the subjectivity of colors he was a forerunner of the psycho-physiological variant of neo-Kantianism. PMID:9476605

  12. The Nursing Home Minimum Data Set for Vision and Its Association with Visual Acuity and Contrast Sensitivity

    PubMed Central

    Swanson, Mark W.; McGwin, Gerald; Elliott, Amanda F.; Owsley, Cynthia

    2009-01-01

    Objectives To evaluate the association between the Minimum Data Set's (MDS) Vision Patterns section and near and distance visual acuity and contrast sensitivity in nursing home residents. Design Cross-sectional study Setting Seventeen nursing homes in the Birmingham, Alabama area. Participants 371 nursing home residents ≥ 55 years old with Mini-mental State Exams of ≥ 13. Measurements The MDS 2.0 assessment for vision from the date closest to acuity and contrast sensitivity assessment was obtained from the resident's medical record. Acuity and contrast sensitivity were measured by the ETDRS chart and Pelli-Robson chart, respectively. Results The MDS rating of visual status was associated with both distance and near visual acuity and contrast sensitivity. The MDS performed poorly in distinguishing residents with mild versus moderate visual impairment. For residents who were rated on the MDS as having adequate vision, 45.9% had distance acuity worse than 20/40 in the better eye, 72.8% had near acuity worse than 20/40 in the better eye, and 85.8% had contrast sensitivity < 1.50. Conclusion The MDS 2.0 assessment for vision in nursing home residents is positively associated with visual acuity and contrast sensitivity, but does not adequately distinguish between individuals with mild versus moderate visual impairment and classifies many as having adequate vision who have visual impairment. The validity of the MDS 2.0 as a mechanism for triggering comprehensive eye care for nursing home residents is questionable. PMID:19187419

  13. Color universal design: analysis of color category dependency on color vision type (3)

    NASA Astrophysics Data System (ADS)

    Kojima, Natsuki; Ichihara, Yasuyo G.; Ikeda, Tomohiro; Kamachi, Miyuki G.; Ito, Kei

    2012-01-01

    We report on the results of a study investigating the color perception characteristics of people with red-green color confusion. We believe that this is an important step towards achieving Color Universal Design. In Japan, approximately 5% of men and 0.2% of women have red-green confusion. The percentage for men is higher in Europe and the United States; up to 8% in some countries. Red-green confusion involves a perception of colors different from normal color vision. Colors are used as a means of disseminating clear information to people; however, it may be difficult to convey the correct information to people who have red-green confusion. Consequently, colors should be chosen that minimize accidents and that promote more effective communication. In a previous survey, we investigated color categories common to each color vision type, trichromat (C-type color vision), protan (P-type color vision) and deuteran (D-type color vision). In the present study, first, we conducted experiments in order to verify a previous survey of C-type color vision and P-type color vision. Next, we investigated color difference levels within "CIE 1976 L*a*b*" (the CIELAB uniform color space), where neither C-type nor P-type color vision causes accidents under certain conditions (rain maps/contour line levels and graph color legend levels). As a result, we propose a common chromaticity of colors that the two color vision types are able to categorize by means of color names common to C-type color vision. We also offer a proposal to explain perception characteristics of color differences with normal color vision and red-green confusion using the CIELAB uniform color space. This report is a follow-up to SPIE-IS & T / Vol. 7528 7528051-8 and SPIE-IS & T /vol. 7866 78660J-1-8.

  14. Theoretical aspects of color vision

    NASA Technical Reports Server (NTRS)

    Wolbarsht, M. L.

    1972-01-01

    The three color receptors of Young-Helmholtz and the opponent colors type of information processing postulated by Hering are both present in the human visual system. This mixture accounts for both the phenomena of color matching or hue discrimination and such perceptual qualities of color as the division of the spectrum into color bands. The functioning of the cells in the visual system, especially within the retina, and the relation of this function to color perception are discussed.

  15. A quantitative analysis of head movement behaviour during visual acuity assessment under prosthetic vision simulation

    NASA Astrophysics Data System (ADS)

    Chen, S. C.; Hallum, L. E.; Suaning, G. J.; Lovell, N. H.

    2007-03-01

    In most current vision prosthesis designs, head movement is the sole director of visual gaze and scanning due to the head-mounted nature of the camera. Study of this unnatural behaviour may provide insight into improved prosthesis designs and rehabilitation procedures. In this paper, we conducted a psychophysical study to investigate the characteristics of head movements of normally sighted subjects undergoing a visual acuity task in simulated prosthetic vision (SPV). In 12 naïve, untrained subjects, we recorded spontaneous changes in the amount of head movements during SPV sessions compared to control (normal vision) sessions. The observed behaviour continued to be refined until five or six sessions of practice. Increased head movement velocity was shown to be correlated to improved visual acuity performance, up to 0.3 logMAR, an equivalent of detecting details at half the physical size compared to complete deprivation of head movements. We postulate that visual scanning can as much as double the spatial frequency information in prosthetic vision. Increased head movement velocity observed when subjects were attempting smaller test items and for low-pass filtering schemes with higher cut-off frequencies may be further evidence that higher frequency content may be available through visual scanning, unconsciously driving subjects to increase head movement velocity.

  16. Theoretical and applied aspects of night vision goggle resolution and visual acuity assessment

    NASA Astrophysics Data System (ADS)

    Task, H. Lee; Pinkus, Alan R.

    2007-04-01

    The image quality of night vision goggles is often expressed in terms of visual acuity, resolution or modulation transfer function. The primary reason for providing a measure of image quality is the underlying assumption that the image quality metric correlates with the level of visual performance that one could expect when using the device, for example, target detection or target recognition performance. This paper provides a theoretical analysis of the relationships between these three image quality metrics: visual acuity, resolution and modulation transfer function. Results from laboratory and field studies were used to relate these metrics to visual performance. These results can also be applied to non-image intensifier based imaging systems such as a helmet-mounted display coupled to an imaging sensor.

  17. Vision-guided ocular growth in a mutant chicken model with diminished visual acuity

    PubMed Central

    Ritchey, Eric R.; Zelinka, Christopher; Tang, Junhua; Liu, Jun; Code, Kimberly A.; Petersen-Jones, Simon; Fischer, Andy J.

    2012-01-01

    Visual experience is known to guide ocular growth. We tested the hypothesis that vision-guided ocular growth is disrupted in a model system with diminished visual acuity. We examine whether ocular elongation is influenced by form-deprivation (FD) and lens-imposed defocus in the Retinopathy, Globe Enlarged (RGE) chicken. Young RGE chicks have poor visual acuity, without significant retinal pathology, resulting from a mutation in guanine nucleotide-binding protein β3 (GNB3), also known as transducin β3 or Gβ3. The mutation in GNB3 destabilizes the protein and causes a loss of Gβ3 from photoreceptors and ON-bipolar cells. (Ritchey et al. 2010)FD increased ocular elongation in RGE eyes in a manner similar to that seen in wild-type (WT) eyes. By comparison, the excessive ocular elongation that results from hyperopic defocus was increased, whereas myopic defocus failed to significantly decrease ocular elongation in RGE eyes. Brief daily periods of unrestricted vision interrupting FD prevented ocular elongation in RGE chicks in a manner similar to that seen in WT chicks. Glucagonergic amacrine cells differentially expressed the immediate early gene Egr1 in response to growth-guiding stimuli in RGE retinas, but the defocus-dependent up-regulation of Egr1 was lesser in RGE retinas compared to that of WT retinas. We conclude that high visual acuity, and the retinal signaling mediated by Gβ3, is not required for emmetropization and the excessive ocular elongation caused by FD and hyperopic defocus. However, the loss of acuity and Gβ3 from RGE retinas causes enhanced responses to hyperopic defocus and diminished responses to myopic defocus. PMID:22824538

  18. Resource letter CCV-1: Color and color vision

    NASA Astrophysics Data System (ADS)

    Pease, Paul L.

    1980-11-01

    The author has selected resource material that focusses on color vision and the measurement and specification of the stimulus for vision, that is, photometry and colorimetry. References are marked E (elementary), I (intermediate), and A (advanced). Those references to be included in a Reprint Book are marked with an ().

  19. 21 CFR 886.1170 - Color vision tester.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Color vision tester. 886.1170 Section 886.1170...) MEDICAL DEVICES OPHTHALMIC DEVICES Diagnostic Devices § 886.1170 Color vision tester. (a) Identification. A color vision tester is a device that consists of various colored materials, such as colored...

  20. 21 CFR 886.1170 - Color vision tester.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Color vision tester. 886.1170 Section 886.1170...) MEDICAL DEVICES OPHTHALMIC DEVICES Diagnostic Devices § 886.1170 Color vision tester. (a) Identification. A color vision tester is a device that consists of various colored materials, such as colored...

  1. 21 CFR 886.1170 - Color vision tester.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Color vision tester. 886.1170 Section 886.1170...) MEDICAL DEVICES OPHTHALMIC DEVICES Diagnostic Devices § 886.1170 Color vision tester. (a) Identification. A color vision tester is a device that consists of various colored materials, such as colored...

  2. 21 CFR 886.1170 - Color vision tester.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Color vision tester. 886.1170 Section 886.1170...) MEDICAL DEVICES OPHTHALMIC DEVICES Diagnostic Devices § 886.1170 Color vision tester. (a) Identification. A color vision tester is a device that consists of various colored materials, such as colored...

  3. 21 CFR 886.1170 - Color vision tester.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Color vision tester. 886.1170 Section 886.1170...) MEDICAL DEVICES OPHTHALMIC DEVICES Diagnostic Devices § 886.1170 Color vision tester. (a) Identification. A color vision tester is a device that consists of various colored materials, such as colored...

  4. Color and polarization vision in foraging Papilio.

    PubMed

    Kinoshita, Michiyo; Arikawa, Kentaro

    2014-06-01

    This paper gives an overview of behavioral studies on the color and polarization vision of the Japanese yellow swallowtail butterfly, Papilio xuthus. We focus on indoor experiments on foraging individuals. Butterflies trained to visit a disk of certain color correctly select that color among various other colors and/or shades of gray. Correct selection persists under colored illumination, but is systematically shifted by background colors, indicating color constancy and simultaneous color contrast. While their eyes contain six classes of spectral receptors, their wavelength discrimination performance indicates that their color vision is tetrachromatic. P. xuthus innately prefers brighter targets, but can be trained to select dimmer ones under certain conditions. Butterflies trained to a dark red stimulus select an orange disk presented on a bright gray background over one on dark gray. The former probably appears darker to them, indicating brightness contrast. P. xuthus has a strong innate preference for vertically polarized light, but the selection of polarized light changes depending on the intensity of simultaneously presented unpolarized light. Discrimination of polarization also depends on background intensity. Similarities between brightness and polarization vision suggest that P. xuthus perceive polarization angle as brightness, such that vertical polarization appears brighter than horizontal polarization. PMID:24722674

  5. Color universal design: analysis of color category dependency on color vision type (4)

    NASA Astrophysics Data System (ADS)

    Ikeda, Tomohiro; Ichihara, Yasuyo G.; Kojima, Natsuki; Tanaka, Hisaya; Ito, Kei

    2013-02-01

    This report is af ollow-up to SPIE-IS+T / Vol. 7528 7528051-8, SPIE-IS+T / Vol. 7866 78660J-1-8 and SPIE-IS+T / Vol. 8292 829206-1-8. Colors are used to communicate information in various situations, not just for design and apparel. However, visual information given only by color may be perceived differently by individuals with different color vision types. Human color vision is non-uniform and the variation in most cases is genetically linked to L-cones and M-cones. Therefore, color appearance is not the same for all color vision types. Color Universal Design is an easy-to-understand system that was created to convey color-coded information accurately to most people, taking color vision types into consideration. In the present research, we studied trichromat (C-type), prolan (P-type), and deutan (D-type) forms of color vision. We here report the result of two experiments. The first was the validation of the confusion colors using the color chart on CIELAB uniform color space. We made an experimental color chart (total of color cells is 622, the color difference between color cells is 2.5) for fhis experiment, and subjects have P-type or D-type color vision. From the data we were able to determine "the limits with high probability of confusion" and "the limits with possible confusion" around various basing points. The direction of the former matched with the theoretical confusion locus, but the range did not extend across the entire a* range. The latter formed a belt-like zone above and below the theoretical confusion locus. This way we re-analyzed a part of the theoretical confusion locus suggested by Pitt-Judd. The second was an experiment in color classification of the subjects with C-type, P-type, or D-type color vision. The color caps of fhe 100 Hue Test were classified into seven categories for each color vision type. The common and different points of color sensation were compared for each color vision type, and we were able to find a group of color caps

  6. Visual acuity, self-reported vision and falls in the EPIC-Norfolk Eye study

    PubMed Central

    Yip, Jennifer L Y; Khawaja, Anthony P; Broadway, David; Luben, Robert; Hayat, Shabina; Dalzell, Nichola; Bhaniani, Amit; Wareham, Nicholas; Khaw, Kay-Tee; Foster, Paul J

    2014-01-01

    Purpose To examine the relationship between visual acuity (VA) and self-reported vision (SRV) in relation to falls in 8317 participants of the European Prospective Investigation into Cancer-Norfolk Eye study. Methods All participants completed a health questionnaire that included a question regarding SRV and questions regarding the number of falls in the past year. Distance VA was measured using a logMAR chart for each eye. Poor SRV was defined as those reporting fair or poor distance vision. The relationship between VA and SRV and self-rated falls was analysed by logistic regression, adjusting for age, sex, physical activity, body mass index, chronic disease, medication use and grip strength. Results Of 8317 participants, 26.7% (95% CI 25.7% to 27.7%) had fallen in the past 12 months. Worse VA and poorer SRV were associated with one or more falls in multivariable analysis (OR for falls=1.31, 95% CI 1.04 to 1.66 and OR=1.32, 95% CI 1.09 to 1.61, respectively). Poorer SRV was significantly associated with falls even after adjusting for VA (OR=1.28, 95% CI 1.05 to 1.57). Conclusions SRV was associated with falls independently of VA and could be used as a simple proxy measure for other aspects of visual function to detect people requiring vision-related falls interventions. PMID:24338086

  7. Binocular depth acuity research to support the modular multi-spectral stereoscopic night vision goggle

    NASA Astrophysics Data System (ADS)

    Merritt, John O.; CuQlock-Knopp, V. Grayson; Paicopolis, Peter; Smoot, Jennifer; Kregel, Mark; Corona, Bernard

    2006-05-01

    This paper discusses the depth acuity research conducted in support of the development of a Modular Multi-Spectral Stereoscopic (M2S2) night vision goggle (NVG), a customizable goggle that lets the user select one of five goggle configurations: monocular thermal, monocular image intensifier (I2), binocular I2, binocular thermal, and binocular dual-waveband (thermal imagery to one eye and I2 imagery to the other eye). The motives for the development of this type of customizable goggle were (1) the need for an NVG that allows the simultaneous use of two wavebands, (2) the need for an alternative sensor fusion method to avoid the potential image degradation that may accompany digitally fused images, (3) a requirement to provide the observer with stereoscopic, dual spectrum views of a scene, and (4) the need to handle individual user preferences for sensor types and ocular configurations employed in various military operations. Among the increases in functionality that the user will have with this system is the ability to convert from a binocular I2 device (needed for detailed terrain analysis during off-road mobility) to a monocular thermal device (for increased situational awareness in the unaided eye during nights with full moon illumination). Results of the present research revealed potential depth acuity advantages that may apply to off-road terrain hazard detection for the binocular thermal configuration. The results also indicated that additional studies are needed to address ways to minimize binocular incompatibility for the dual waveband configuration.

  8. Simulation of thalamic prosthetic vision: reading accuracy, speed, and acuity in sighted humans

    PubMed Central

    Vurro, Milena; Crowell, Anne Marie; Pezaris, John S.

    2014-01-01

    The psychophysics of reading with artificial sight has received increasing attention as visual prostheses are becoming a real possibility to restore useful function to the blind through the coarse, pseudo-pixelized vision they generate. Studies to date have focused on simulating retinal and cortical prostheses; here we extend that work to report on thalamic designs. This study examined the reading performance of normally sighted human subjects using a simulation of three thalamic visual prostheses that varied in phosphene count, to help understand the level of functional ability afforded by thalamic designs in a task of daily living. Reading accuracy, reading speed, and reading acuity of 20 subjects were measured as a function of letter size, using a task based on the MNREAD chart. Results showed that fluid reading was feasible with appropriate combinations of letter size and phosphene count, and performance degraded smoothly as font size was decreased, with an approximate doubling of phosphene count resulting in an increase of 0.2 logMAR in acuity. Results here were consistent with previous results from our laboratory. Results were also consistent with those from the literature, despite using naive subjects who were not trained on the simulator, in contrast to other reports. PMID:25408641

  9. Color vision in the peripheral retina.

    PubMed

    Johnson, M A

    1986-02-01

    Until recently, color vision in the peripheral field has been thought to be substantially less developed than color vision in the central field. Although the exact dimensions vary from study to study, most estimates of peripheral chromatic perception place the limit of trichromatic vision at no more than 30 degrees from fixation; the visual field is thought to be completely color blind at about 50 degrees of eccentricity. Within the last 10 years, an increased understanding of the changing spatial scale in the peripheral field has led researchers to reevaluate what is believed about peripheral function. We now know that virtually every measure of peripheral color perception can be improved by using a suitably large stimulus in the peripheral field. This paper examines current and past perspectives on peripheral color function, and describes two studies which demonstrate that peripheral and central chromatic processing are the same to the first order if the changes in spatial scale and photopic sensitivity with eccentricity are considered. PMID:3953765

  10. 21 CFR 886.1160 - Color vision plate illuminator.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Color vision plate illuminator. 886.1160 Section... (CONTINUED) MEDICAL DEVICES OPHTHALMIC DEVICES Diagnostic Devices § 886.1160 Color vision plate illuminator. (a) Identification. A color vision plate illuminator is an AC-powered device that is a lamp...

  11. 21 CFR 886.1160 - Color vision plate illuminator.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Color vision plate illuminator. 886.1160 Section... (CONTINUED) MEDICAL DEVICES OPHTHALMIC DEVICES Diagnostic Devices § 886.1160 Color vision plate illuminator. (a) Identification. A color vision plate illuminator is an AC-powered device that is a lamp...

  12. 21 CFR 886.1160 - Color vision plate illuminator.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Color vision plate illuminator. 886.1160 Section... (CONTINUED) MEDICAL DEVICES OPHTHALMIC DEVICES Diagnostic Devices § 886.1160 Color vision plate illuminator. (a) Identification. A color vision plate illuminator is an AC-powered device that is a lamp...

  13. 21 CFR 886.1160 - Color vision plate illuminator.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Color vision plate illuminator. 886.1160 Section... (CONTINUED) MEDICAL DEVICES OPHTHALMIC DEVICES Diagnostic Devices § 886.1160 Color vision plate illuminator. (a) Identification. A color vision plate illuminator is an AC-powered device that is a lamp...

  14. 21 CFR 886.1160 - Color vision plate illuminator.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Color vision plate illuminator. 886.1160 Section... (CONTINUED) MEDICAL DEVICES OPHTHALMIC DEVICES Diagnostic Devices § 886.1160 Color vision plate illuminator. (a) Identification. A color vision plate illuminator is an AC-powered device that is a lamp...

  15. LITE, Optics, Color and Vision

    NASA Astrophysics Data System (ADS)

    Brecher, Kenneth

    2006-12-01

    Over the past several years, as part of Project LITE Light Inquiry Through Experiments, we have developed hands-on (and eyes-on) resources for use in introductory undergraduate astronomy courses. These center on light, optics, color and visual perception. Many of the materials can also be used in K through 12 and informal science education settings, particularly our kit of inexpensive optical materials that is integrated with a set of Java applets. The combined kit and software gives students the chance to do actual experiments concerning geometrical and physical optics, fluorescence, phosphorescence, polarization and other topics by making use of the light emitted from computer screens. We have also developed over 200 Flash applets that allow students to directly explore many aspects of visual perception. In this presentation, we will demonstrate a variety of these physical and perceptual interactive experiences. All of the software can be found at http://lite.bu.edu. Project LITE is supported by Grant #DUE-0125992 from the NSF Division of Undergraduate Education.

  16. Comparison on testability of visual acuity, stereo acuity and colour vision tests between children with learning disabilities and children without learning disabilities in government primary schools

    PubMed Central

    Abu Bakar, Nurul Farhana; Chen, Ai-Hong

    2014-01-01

    Context: Children with learning disabilities might have difficulties to communicate effectively and give reliable responses as required in various visual function testing procedures. Aims: The purpose of this study was to compare the testability of visual acuity using the modified Early Treatment Diabetic Retinopathy Study (ETDRS) and Cambridge Crowding Cards, stereo acuity using Lang Stereo test II and Butterfly stereo tests and colour perception using Colour Vision Test Made Easy (CVTME) and Ishihara's Test for Colour Deficiency (Ishihara Test) between children in mainstream classes and children with learning disabilities in special education classes in government primary schools. Materials and Methods: A total of 100 primary school children (50 children from mainstream classes and 50 children from special education classes) matched in age were recruited in this cross-sectional comparative study. The testability was determined by the percentage of children who were able to give reliable respond as required by the respective tests. ‘Unable to test’ was defined as inappropriate response or uncooperative despite best efforts of the screener. Results: The testability of the modified ETDRS, Butterfly stereo test and Ishihara test for respective visual function tests were found lower among children in special education classes (P < 0.001) but not in Cambridge Crowding Cards, Lang Stereo test II and CVTME. Conclusion: Non verbal or “matching” approaches were found to be more superior in testing visual functions in children with learning disabilities. Modifications of vision testing procedures are essential for children with learning disabilities. PMID:24008790

  17. The photochemical determinants of color vision

    PubMed Central

    Wang, Wenjing; Geiger, James H; Borhan, Babak

    2014-01-01

    The evolution of a variety of important chromophore-dependent biological processes, including microbial light sensing and mammalian color vision, relies on protein modifications that alter the spectral characteristics of a bound chromophore. Three different color opsins share the same chromophore, but have three distinct absorptions that together cover the entire visible spectrum, giving rise to trichromatic vision. The influence of opsins on the absorbance of the chromophore has been studied through methods such as model compounds, opsin mutagenesis, and computational modeling. The recent development of rhodopsin mimic that uses small soluble proteins to recapitulate the binding and wavelength tuning of the native opsins provides a new platform for studying protein-regulated spectral tuning. The ability to achieve far-red shifted absorption in the rhodopsin mimic system was attributed to a combination of the lack of a counteranion proximal to the iminium, and a uniformly neutral electrostatic environment surrounding the chromophore. PMID:24323922

  18. Aircrew visual acuity viewing with different night vision goggle eyepiece diopter settings

    NASA Astrophysics Data System (ADS)

    Angel, Share-Dawn P.; Baldwin, J. Bruce

    2004-09-01

    The AN/AVS-9 night vision goggle (NVG) has an eyepiece lens that can be adjusted from +2 to -6 diopters (D). We have shown previously1,2,3 that on average NVG users tend to select about -1D, with a range of +0.5D to -4D3. This study was designed to evaluate NVG visual acuity (NVG VA) and subjective ratings for a range of diopter settings including user-selected and three fixed settings of -0.25D, -1D and -2D. Twenty-one experienced USAF Special Operations aircrew members, including 15 pilots, served as subjects. The median user-selected setting was -1.25D and ranged from +0.5D to -3.5D. Only 2 of the 21 subjects had user-selected NVG VA significantly better than a fixed setting of -1D. Of those two, one was not wearing prescribed glasses and the other was 49 years old, presbyopic, and could not focus through the -1D lenses. Subjective ratings and NVG VA indicated that most people could fly with a fixed setting of -1D for each eye, although two individuals needed different diopter settings for the right and left eyes. The new Panoramic NVG (PNVG) has a fixed eyepiece focus of -1D. Results suggest the PNVG should have a limited set of accessory lenses available.

  19. Is 20/20 vision good enough? Visual acuity differences within the normal range predict contour element detection and integration

    PubMed Central

    Keane, Brian P.; Kastner, Sabine; Paterno, Danielle; Silverstein, Steven M.

    2014-01-01

    Contour integration (CI) combines appropriately aligned and oriented elements into continuous boundaries. Collinear facilitation (CF) occurs when a low-contrast oriented element becomes more visible when flanked by collinear high-contrast elements. Both processes rely at least partly on long-range horizontal connections in early visual cortex, and thus both have been extensively studied to understand visual cortical functioning in aging, development, and clinical disorders. Here, we ask: Can acuity differences within the normal range predict CI or CF? To consider this question, we measured binocular visual acuity and compared subjects with 20/20 vision to those with better-than-20/20 vision (SharpPerceivers) on two tasks. In the CI task, subjects located an integrated shape embedded in varying amounts of noise; in the CF task, subjects detected a low-contrast element flanked by collinear or orthogonal high-contrast elements. In each case, displays were scaled in size to modulate element visibility and spatial frequency (4-12 cycles/deg). SharpPerceivers could integrate contours under noisier conditions than the 20/20 group (p=.0002) especially for high spatial frequency displays. Moreover, although the two groups exhibited similar collinear facilitation, SharpPerceivers could detect the central target with lower contrast at high spatial frequencies (p<.05). These results suggest that small acuity differences within the normal range—corresponding to about a one line difference on a vision chart—strongly predict element detection and integration. Furthermore, simply ensuring that subjects have normal or corrected-to-normal vision is not sufficient when comparing groups on contour tasks; visual acuity confounds also need to be ruled out. PMID:24845876

  20. Testing vision testing: quantifying the effect of movement on visual acuity measurement

    PubMed Central

    Tidbury, L P; O'Connor, A R

    2015-01-01

    Purpose Assessment of visual acuity (VA) has been shown to vary between tests, which may be attributable in part to test inaccuracies, such as a change in the distance between the chart and subject. Therefore, the study aim was to quantify changes in chart/patient separation during near and distance VA testing, and to analyse the relationship between VA and movement observed. Methods Volunteer orthoptists and subjects were filmed during near and distance VA testing, with the amount of movement determined from the recording. Controlling for movement using chin rests and chart stands, VA was retested. Actual changes in VA due to a change in subject or chart movement were compared with theoretical predictions. Results Fifty-one subjects (18–73 years) were assessed. Median (interquartile) movements of 0.06 m (0.07) towards and 0.11 m (0.08) away from the chart were measured (maximum 0.17 m towards and 0.24 m away). Significant differences in VA score were measured when movement was restricted, at near and distance (P<0.05). VA score change agreed with predicted values in 67% of the cases, however, reduced test distance during near vision testing resulted in a degradation of VA, opposite to the improvement expected. Conclusion There were significant variations in subject/chart separation during testing, which could have affected VA values. While this movement is associated with a change in VA, additional factors to movement appear to influence the score achieved during near testing. Procedures to minimise variation, by eliminating movement of test chart or subject, will improve VA test accuracy. PMID:25341437

  1. Color matches in diseased eyes with good acuity: detection of deficits in cone optical density and in chromatic discrimination

    NASA Astrophysics Data System (ADS)

    Swanson, William H.; Fish, Gary E.

    1995-10-01

    Reduced foveal cone optical density in diseased eyes with normal acuity can affect color matches. Using field diameters of 1 deg, 2 deg, 4 deg, and 8 deg, we measured mean color-match midpoints and match widths in patients who had good acuity and who hereditary macular degeneration ( n=12 ), retinitis pigmentosa ( n=19 ), and glaucoma ( n=18 ). Results were compared with those for normal observers of comparable ages. Mean color-match midpoints were abnormal only for the population with hereditary macular degeneration, indicating a reduction in cone optical density in the central 4 deg. Mean color-match widths were enlarged for both hereditary macular degeneration and retinitis pigmentosa, a result consistent with a reduction in the number of foveal cones. chromatic discrimination, macular degeneration, retinitis pigmentosa, glaucoma.

  2. The genetics of normal and defective color vision

    PubMed Central

    Neitz, Jay; Neitz, Maureen

    2011-01-01

    The contributions of genetics research to the science of normal and defective color vision over the previous few decades are reviewed emphasizing the developments in the 25 years since the last anniversary issue of Vision Research. Understanding of the biology underlying color vision has been vaulted forward through the application of the tools of molecular genetics. For all their complexity, the biological processes responsible for color vision are more accessible than for many other neural systems. This is partly because of the wealth of genetic variations that affect color perception, both within and across species, and because components of the color vision system lend themselves to genetic manipulation. Mutations and rearrangements in the genes encoding the long, middle, and short wavelength sensitive cone pigments are responsible for color vision deficiencies and mutations have been identified that affect the number of cone types, the absorption spectrum of the pigments, the functionality and viability of the cones, and the topography of the cone mosaic. The addition of an opsin gene, as occurred in the evolution of primate color vision, and has been done in experimental animals can produce expanded color vision capacities and this has provided insight into the underlying neural circuitry. PMID:21167193

  3. Associations among Visual Acuity and Vision- and Health-Related Quality of Life among Patients in the Multicenter Uveitis Steroid Treatment Trial

    PubMed Central

    Drye, Lea T.; Kempen, John H.; Dunn, James P.; Holland, Gary N.; Latkany, Paul; Rao, Narsing A.; Sen, H. Nida; Sugar, Elizabeth A.; Thorne, Jennifer E.; Wang, Robert C.; Holbrook, Janet T.

    2012-01-01

    Purpose. To evaluate the associations between visual acuity and self-reported visual function; visual acuity and health-related quality of life (QoL) metrics; a summary measure of self-reported visual function and health-related QoL; and individual domains of self-reported visual function and health-related QoL in patients with uveitis. Methods. Best-corrected visual acuity, vision-related functioning as assessed by the NEI VFQ-25, and health-related QoL as assessed by the SF-36 and EuroQoL EQ-5D questionnaires were obtained at enrollment in a clinical trial of uveitis treatments. Multivariate regression and Spearman correlations were used to evaluate associations between visual acuity, vision-related function, and health-related QoL. Results. Among the 255 patients, median visual acuity in the better-seeing eyes was 20/25, the vision-related function score indicated impairment (median, 60), and health-related QoL scores were within the normal population range. Better visual acuity was predictive of higher visual function scores (P ≤ 0.001), a higher SF-36 physical component score, and a higher EQ-5D health utility score (P < 0.001). The vision-specific function score was predictive of all general health-related QoL (P < 0.001). The correlations between visual function score and general quality of life measures were moderate (ρ = 0.29–0.52). Conclusions. The vision-related function score correlated positively with visual acuity and moderately positively with general QoL measures. Cost–utility analyses relying on changes in generic healthy utility measures will be more likely to detect changes when there are clinically meaningful changes in vision-related function, rather than when there are only changes in visual acuity. (ClinicalTrials.gov number, NCT00132691.) PMID:22247489

  4. Color vision and neuroretinal function in diabetes

    PubMed Central

    Bearse, M. A.; Schneck, M. E.; Dhamdhere, K.; Harrison, W. W.; Barez, S.; Adams, A. J.

    2015-01-01

    Purpose We investigate how type 2 diabetes (T2DM) and diabetic retinopathy (DR) affect color vision (CV) and mfERG implicit time (IT), whether CV and IT are correlated, and whether CV and IT abnormality classifications agree. Methods Adams desaturated D-15 color test, mfERG, and fundus photographs were examined in 37 controls, 22 T2DM patients without DR (NoRet group), and 25 T2DM patients with DR (Ret group). Color confusion score (CCS) was calculated. ITs were averaged within the central 7 hexagons (central IT; ≥4.5°) and outside this area (peripheral IT; ≤4.5°). DR was within (DRIN) or outside (DROUT) of the central 7 hexagons. Group differences, percentages of abnormalities, correlations, and agreement were determined. Results CCS was greater in the NoRet (P = 0.002) and Ret (P < 0.0001) groups than in control group. CCS was abnormal in 3, 41, and 48 % of eyes in the control, NoRet, and Ret groups, respectively. Ret group CV abnormalities were more frequent in DRIN than in DROUT subgroups (71 vs. 18 %, respectively; P < 0.0001). CCS and IT were correlated only in the Ret group, in both retinal zones (P ≥ 0.028). Only in the Ret group did CCS and peripheral IT abnormality classifications agree (72 %; P < 0.05). Conclusion CV is affected in patients with T2DM, even without DR. Central DR increases the likelihood of a CV deficit compared with non-central DR. mfERG IT averaged across central or peripheral retinal locations is less frequently abnormal than CV in the absence of DR, and these two measures are correlated only when DR is present. PMID:25516428

  5. Epistatic Adaptive Evolution of Human Color Vision

    PubMed Central

    Yokoyama, Shozo; Xing, Jinyi; Liu, Yang; Faggionato, Davide; Altun, Ahmet; Starmer, William T.

    2014-01-01

    Establishing genotype-phenotype relationship is the key to understand the molecular mechanism of phenotypic adaptation. This initial step may be untangled by analyzing appropriate ancestral molecules, but it is a daunting task to recapitulate the evolution of non-additive (epistatic) interactions of amino acids and function of a protein separately. To adapt to the ultraviolet (UV)-free retinal environment, the short wavelength-sensitive (SWS1) visual pigment in human (human S1) switched from detecting UV to absorbing blue light during the last 90 million years. Mutagenesis experiments of the UV-sensitive pigment in the Boreoeutherian ancestor show that the blue-sensitivity was achieved by seven mutations. The experimental and quantum chemical analyses show that 4,008 of all 5,040 possible evolutionary trajectories are terminated prematurely by containing a dehydrated nonfunctional pigment. Phylogenetic analysis further suggests that human ancestors achieved the blue-sensitivity gradually and almost exclusively by epistasis. When the final stage of spectral tuning of human S1 was underway 45–30 million years ago, the middle and long wavelength-sensitive (MWS/LWS) pigments appeared and so-called trichromatic color vision was established by interprotein epistasis. The adaptive evolution of human S1 differs dramatically from orthologous pigments with a major mutational effect used in achieving blue-sensitivity in a fish and several mammalian species and in regaining UV vision in birds. These observations imply that the mechanisms of epistatic interactions must be understood by studying various orthologues in different species that have adapted to various ecological and physiological environments. PMID:25522367

  6. The Role of Color Vision Anomalies in Elementary School Achievement

    ERIC Educational Resources Information Center

    Mandola, John

    1969-01-01

    Results of a study involving 13 color-deficient and 15 color-normal pupils in grades three through six, show no evidence of relationship between color vision and achievement. Supports findings of previous studies by Lorenz and McClure (1935), and Shearron (1965). (CJ)

  7. Color night vision method based on the correlation between natural color and dual band night image

    NASA Astrophysics Data System (ADS)

    Zhang, Yi; Bai, Lian-fa; Zhang, Chuang; Chen, Qian; Gu, Guo-hua

    2009-07-01

    Color night vision technology can effectively improve the detection and identification probability. Current color night vision method based on gray scale modulation fusion, spectrum field fusion, special component fusion and world famous NRL method, TNO method will bring about serious color distortion, and the observers will be visual tired after long time observation. Alexander Toet of TNO Human Factors presents a method to fuse multiband night image a natural day time color appearance, but it need the true color image of the scene to be observed. In this paper we put forward a color night vision method based on the correlation between natural color image and dual band night image. Color display is attained through dual-band low light level images and their fusion image. Actual color image of the similar scene is needed to obtain color night vision image, the actual color image is decomposed to three gray-scale images of RGB color module, and the short wave LLL image, long wave LLL image and their fusion image are compared to them through gray-scale spatial correlation method, and the color space mapping scheme is confirmed by correlation. Gray-scale LLL images and their fusion image are adjusted through the variation of HSI color space coefficient, and the coefficient matrix is built. Color display coefficient matrix of LLL night vision system is obtained by multiplying the above coefficient matrix and RGB color space mapping matrix. Emulation experiments on general scene dual-band color night vision indicate that the color display effect is approving. This method was experimented on dual channel dual spectrum LLL color night vision experimental apparatus based on Texas Instruments digital video processing device DM642.

  8. Change of Color Appearance in Photopic, Mesopic and Scotopic Vision

    NASA Astrophysics Data System (ADS)

    Shin, Jae Chul; Yaguchi, Hirohisa; Shioiri, Satoshi

    2004-07-01

    Mesopic vision describes a range of light levels where vision is mediated by both cones and rods. The appearance of color in mesopic vision differs drastically from that in photopic vision, where only cones mediate visual information. We used a haploscopic color matching technique to investigate the color appearance under various illuminance levels, ranging from photopic to scotopic via mesopic levels. The observers did color matching between a test color chip under various illuminance levels and a matching color stimulus presented on the Cathode-Ray Tube (CRT) display under the photopic illuminance condition. The results showed that not only chroma and lightness but hue of most color chips changed with illuminance. The manner of the hue changed depended on the color of the test chip, while matching points approached a neutral gray with decrease in illuminance level for all test chips. Chroma reduced continuously with decrease of the illuminance level until 0.1 lx for reddish and yellowish color chips or until 1 lx for greenish and bluish ones. Beyond those illuminance levels, chroma was approximately constant. Lightness decreased with decreasing illuminance level for all test chips except bluish color chips, for which lightness did not decrease much in general and even increased in some cases as predicted by the Purkinje shift. The experimental results obtained in the present study provide critical features that should be considered in predicting the appearance of color at low light levels.

  9. Considering the Influence of Nonadaptive Evolution on Primate Color Vision.

    PubMed

    Jacobs, Rachel L; Bradley, Brenda J

    2016-01-01

    Color vision in primates is variable across species, and it represents a rare trait in which the genetic mechanisms underlying phenotypic variation are fairly well-understood. Research on primate color vision has largely focused on adaptive explanations for observed variation, but it remains unclear why some species have trichromatic or polymorphic color vision while others are red-green color blind. Lemurs, in particular, are highly variable. While some species are polymorphic, many closely-related species are strictly dichromatic. We provide the first characterization of color vision in a wild population of red-bellied lemurs (Eulemur rubriventer, Ranomafana National Park, Madagascar) with a sample size (87 individuals; NX chromosomes = 134) large enough to detect even rare variants (0.95 probability of detection at ≥ 3% frequency). By sequencing exon 5 of the X-linked opsin gene we identified opsin spectral sensitivity based on known diagnostic sites and found this population to be dichromatic and monomorphic for a long wavelength allele. Apparent fixation of this long allele is in contrast to previously published accounts of Eulemur species, which exhibit either polymorphic color vision or only the medium wavelength opsin. This unexpected result may represent loss of color vision variation, which could occur through selective processes and/or genetic drift (e.g., genetic bottleneck). To indirectly assess the latter scenario, we genotyped 55 adult red-bellied lemurs at seven variable microsatellite loci and used heterozygosity excess and M-ratio tests to assess if this population may have experienced a recent genetic bottleneck. Results of heterozygosity excess but not M-ratio tests suggest a bottleneck might have occurred in this red-bellied lemur population. Therefore, while selection may also play a role, the unique color vision observed in this population might have been influenced by a recent genetic bottleneck. These results emphasize the need to

  10. Considering the Influence of Nonadaptive Evolution on Primate Color Vision

    PubMed Central

    Jacobs, Rachel L.; Bradley, Brenda J.

    2016-01-01

    Color vision in primates is variable across species, and it represents a rare trait in which the genetic mechanisms underlying phenotypic variation are fairly well-understood. Research on primate color vision has largely focused on adaptive explanations for observed variation, but it remains unclear why some species have trichromatic or polymorphic color vision while others are red-green color blind. Lemurs, in particular, are highly variable. While some species are polymorphic, many closely-related species are strictly dichromatic. We provide the first characterization of color vision in a wild population of red-bellied lemurs (Eulemur rubriventer, Ranomafana National Park, Madagascar) with a sample size (87 individuals; NX chromosomes = 134) large enough to detect even rare variants (0.95 probability of detection at ≥ 3% frequency). By sequencing exon 5 of the X-linked opsin gene we identified opsin spectral sensitivity based on known diagnostic sites and found this population to be dichromatic and monomorphic for a long wavelength allele. Apparent fixation of this long allele is in contrast to previously published accounts of Eulemur species, which exhibit either polymorphic color vision or only the medium wavelength opsin. This unexpected result may represent loss of color vision variation, which could occur through selective processes and/or genetic drift (e.g., genetic bottleneck). To indirectly assess the latter scenario, we genotyped 55 adult red-bellied lemurs at seven variable microsatellite loci and used heterozygosity excess and M-ratio tests to assess if this population may have experienced a recent genetic bottleneck. Results of heterozygosity excess but not M-ratio tests suggest a bottleneck might have occurred in this red-bellied lemur population. Therefore, while selection may also play a role, the unique color vision observed in this population might have been influenced by a recent genetic bottleneck. These results emphasize the need to

  11. Color Vision and Hue Categorization in Young Human Infants

    ERIC Educational Resources Information Center

    Bornstein, Marc H.; And Others

    1976-01-01

    The main objective of the present investigations was to determine whether or not young human infants see the physical spectrum in a categorical fashion as human adults and animals who possess color vision regularly do. (Author)

  12. Modeling, Measuring, and Compensating Color Weak Vision

    NASA Astrophysics Data System (ADS)

    Oshima, Satoshi; Mochizuki, Rika; Lenz, Reiner; Chao, Jinhui

    2016-06-01

    We use methods from Riemann geometry to investigate transformations between the color spaces of color-normal and color weak observers. The two main applications are the simulation of the perception of a color weak observer for a color normal observer and the compensation of color images in a way that a color weak observer has approximately the same perception as a color normal observer. The metrics in the color spaces of interest are characterized with the help of ellipsoids defined by the just-noticable-differences between color which are measured with the help of color-matching experiments. The constructed mappings are isometries of Riemann spaces that preserve the perceived color-differences for both observers. Among the two approaches to build such an isometry, we introduce normal coordinates in Riemann spaces as a tool to construct a global color-weak compensation map. Compared to previously used methods this method is free from approximation errors due to local linearizations and it avoids the problem of shifting locations of the origin of the local coordinate system. We analyse the variations of the Riemann metrics for different observers obtained from new color matching experiments and describe three variations of the basic method. The performance of the methods is evaluated with the help of semantic differential (SD) tests.

  13. RGB calibration for color image analysis in machine vision.

    PubMed

    Chang, Y C; Reid, J F

    1996-01-01

    A color calibration method for correcting the variations in RGB color values caused by vision system components was developed and tested in this study. The calibration scheme concentrated on comprehensively estimating and removing the RGB errors without specifying error sources and their effects. The algorithm for color calibration was based upon the use of a standardized color chart and developed as a preprocessing tool for color image analysis. According to the theory of image formation, RGB errors in color images were categorized into multiplicative and additive errors. Multiplicative and additive errors contained various error sources-gray-level shift, a variation in amplification and quantization in camera electronics or frame grabber, the change of color temperature of illumination with time, and related factors. The RGB errors of arbitrary colors in an image were estimated from the RGB errors of standard colors contained in the image. The color calibration method also contained an algorithm for correcting the nonuniformity of illumination in the scene. The algorithm was tested under two different conditions-uniform and nonuniform illumination in the scene. The RGB errors of arbitrary colors in test images were almost completely removed after color calibration. The maximum residual error was seven gray levels under uniform illumination and 12 gray levels under nonuniform illumination. Most residual RGB errors were caused by residual nonuniformity of illumination in images, The test results showed that the developed method was effective in correcting the variations in RGB color values caused by vision system components. PMID:18290059

  14. A color-coded vision scheme for robotics

    NASA Technical Reports Server (NTRS)

    Johnson, Kelley Tina

    1991-01-01

    Most vision systems for robotic applications rely entirely on the extraction of information from gray-level images. Humans, however, regularly depend on color to discriminate between objects. Therefore, the inclusion of color in a robot vision system seems a natural extension of the existing gray-level capabilities. A method for robot object recognition using a color-coding classification scheme is discussed. The scheme is based on an algebraic system in which a two-dimensional color image is represented as a polynomial of two variables. The system is then used to find the color contour of objects. In a controlled environment, such as that of the in-orbit space station, a particular class of objects can thus be quickly recognized by its color.

  15. Color vision in the ring-tailed lemur (Lemur catta).

    PubMed

    Blakeslee, B; Jacobs, G H

    1985-01-01

    Behavioral discrimination tests were used to examine spectral sensitivity and color vision in a pair of ring-tailed lemurs (Lemur catta). Sensitivity tests revealed the presence of a Purkinje shift and a photopic visual system. As measured at increment-threshold, the photopic spectral sensitivity function for the lemur has multiple peaks (at ca. 440-460, 540, and 620 nm). In color vision tests lemurs behave trichromatically in that (a) they show no evidence for a neutral point in the spectral range of 470-510 nm, and (b) they set a unique Rayleigh match (540 nm + 645 nm = 570 nm). Tests of wavelength and colorimetric purity discrimination reveal that although this prosimian has color vision, it is not an acute capacity--thresholds for these color discriminations were consistently much higher for lemurs than for normal human trichromats tested in the same situation. PMID:4084762

  16. Multiple redundant medulla projection neurons mediate color vision in Drosophila.

    PubMed

    Melnattur, Krishna V; Pursley, Randall; Lin, Tzu-Yang; Ting, Chun-Yuan; Smith, Paul D; Pohida, Thomas; Lee, Chi-Hon

    2014-01-01

    The receptor mechanism for color vision has been extensively studied. In contrast, the circuit(s) that transform(s) photoreceptor signals into color percepts to guide behavior remain(s) poorly characterized. Using intersectional genetics to inactivate identified subsets of neurons, we have uncovered the first-order interneurons that are functionally required for hue discrimination in Drosophila. We developed a novel aversive operant conditioning assay for intensity-independent color discrimination (true color vision) in Drosophila. Single flying flies are magnetically tethered in an arena surrounded by blue and green LEDs (light-emitting diodes). The flies' optomotor response is used to determine the blue-green isoluminant intensity. Flies are then conditioned to discriminate between equiluminant blue or green stimuli. Wild-type flies are successfully trained in this paradigm when conditioned to avoid either blue or green. Functional color entrainment requires the function of the narrow-spectrum photoreceptors R8 and/or R7, and is within a limited range, intensity independent, suggesting that it is mediated by a color vision system. The medulla projection neurons, Tm5a/b/c and Tm20, receive direct inputs from R7 or R8 photoreceptors and indirect input from the broad-spectrum photoreceptors R1-R6 via the lamina neuron L3. Genetically inactivating these four classes of medulla projection neurons abolished color learning. However, inactivation of subsets of these neurons is insufficient to block color learning, suggesting that true color vision is mediated by multiple redundant pathways. We hypothesize that flies represent color along multiple axes at the first synapse in the fly visual system. The apparent redundancy in learned color discrimination sharply contrasts with innate ultraviolet (UV) spectral preference, which is dominated by a single pathway from the amacrine neuron Dm8 to the Tm5c projection neurons. PMID:24766346

  17. The evolution of concepts of color vision

    PubMed Central

    Lee, Barry. B.

    2010-01-01

    The evolution of ideas about the way we see color was closely linked to physical theories of light. Proponents of both corpuscular and wave theories viewed light as a continuous spectrum. This was not easily reconciled with the fact that, for the human eye, all colors can be matched by mixture of three primaries. Physicists such as Mayer who described trichromatic color matching often assumed that there were just three types of rays in the spectrum. This argument was finally resolved by Thomas Young, who noted that trichromatic color matching was consistent with a continuous spectrum if there were just three receptors in the eye. This kind of conceptual mistake, in this case the confusion of the properties of the visual system with physical properties of light, has been common in the history of color science. As another example, the idea of trichromacy was disputed by those who viewed color sensations as opponent processes, red-green, blue-yellow and black-white. The discovery of color-opponent neurons in the visual pathway has partly resolved this dilemma. Much of the physiological substrate of the way we detect and distinguish colors is now established, but the link between the signals leaving the retina and the way we name and order colors is still poorly defined. PMID:21593994

  18. Adaptation of the Central Retina for High Acuity Vision: Cones, the Fovea and the Avascular Zone

    PubMed Central

    Provis, Jan M; Dubis, Adam M; Maddess, Ted; Carroll, Joseph

    2013-01-01

    Presence of a fovea centralis is directly linked to molecular specification of an avascular area in central retina, before the fovea (or `pit') begins to form. Modeling suggests that mechanical forces, generated within the eye, initiate formation of a pit within the avascular area, and its later remodeling in the postnatal period. Within the avascular area the retina is dominated by `midget' circuitry, in which signals are transferred from a single cone to a single bipolar cell, then a single ganglion cell. Thus in inner, central retina there are relatively few lateral connections between neurons. This renders the region adaptable to tangential forces, that translocate of ganglion cells laterally / centrifugally, to form the fovea. Optical coherence tomography enables live imaging of the retina, and shows that there is greater variation in the morphology of foveae in humans than previously thought. This variation is associated with differences in size of the avascular area and appears to be genetically based, but can be modified by environmental factors, including prematurity. Even when the fovea is absent (foveal hypoplasia), cones in central retina adopt an elongated and narrow morphology, enabling them to pack more densely to increase the sampling rate, and to act as more effective waveguides. Given these findings, what then is the adaptive advantage of a fovea? We suggest that the advantages of having a pit in central retina are relatively few, and minor, but together work to enhance acuity. PMID:23500068

  19. Human vision based color edge detection

    NASA Astrophysics Data System (ADS)

    Kim, Ari; Kim, Hong-suk; Park, Seung-ok

    2011-01-01

    Edge detection can be of great importance to image processing in various digital imaging applications such as digital television and camera. Therefore, extracting more accurate edge properties are significantly demanded for achieving a better image understanding. In vector gradient edge detection, absolute difference of RGB values between a center pixel value, and its neighborhood values are usually used, although such a device-dependent color space does not account for human visual characteristics well. The goal of this study is to test a variety of color difference equations and propose the most effective model that can be used for the purpose of color edge detection. Three of synthetic images generated using perceptibility threshold of the human visual system were used for objectively evaluate to 5 color difference equations studied in this paper. A set of 6 complex color images was also used to testing the 5 color difference equations psychophysically. The equations include ΔRGB, ΔE* ab, ΔECMC, CIEDE2000 (ΔE00) and CIECAM02-UCS delta E (ΔECAM-UCS). Consequently, there were not significant performance variations observed between those 5 color difference equations for the purpose of edge detection. However, ΔE00 and ΔECAM-UCS showed slightly higher mean opinion score (MOS) in detected edge information.

  20. High e-vector acuity in the polarisation vision system of the fiddler crab Uca vomeris.

    PubMed

    How, Martin J; Pignatelli, Vincenzo; Temple, Shelby E; Marshall, N Justin; Hemmi, Jan M

    2012-06-15

    Polarisation vision is used by a variety of species in many important tasks, including navigation and orientation (e.g. desert ant), communication and signalling (e.g. stomatopod crustaceans), and as a possible substitute for colour vision (e.g. cephalopod molluscs). Fiddler crabs are thought to possess the anatomical structures necessary to detect polarised light, and occupy environments rich in polarisation cues. Yet little is known about the capabilities of their polarisation sense. A modified polarisation-only liquid crystal display and a spherical rotating treadmill were combined to test the responses of fiddler crabs to moving polarisation stimuli. The species Uca vomeris was found to be highly sensitive to polarised light and detected stimuli differing in e-vector angle by as little as 3.2 deg. This represents the most acute behavioural sensitivity to polarised light yet measured for a crustacean. The occurrence of null points in their discrimination curve indicates that this species employs an orthogonal (horizontal/vertical) receptor array for the detection of polarised light. PMID:22623201

  1. Red-Green Color Vision Impairment in Duchenne Muscular Dystrophy

    PubMed Central

    Costa, Marcelo Fernandes ; Oliveira, Andre Gustavo Fernandes ; Feitosa-Santana, Claudia ; Zatz, Mayana ; Ventura, Dora Fix 

    2007-01-01

    The present study evaluated the color vision of 44 patients with Duchenne muscular dystrophy (DMD) (mean age 14.8 years; SD 4.9) who were submitted to a battery of four different color tests: Cambridge Colour Test (CCT), Neitz Anomaloscope, Ishihara, and American Optical Hardy-Rand-Rittler (AO H-R-R). Patients were divided into two groups according to the region of deletion in the dystrophin gene: upstream of exon 30 (n=12) and downstream of exon 30 (n=32). The control group was composed of 70 age-matched healthy male subjects with no ophthalmological complaints. Of the patients with DMD, 47% (21/44) had a red-green color vision defect in the CCT, confirmed by the Neitz Anomaloscope with statistical agreement (P<.001). The Ishihara and the AO H-R-R had a lower capacity to detect color defects—5% and 7%, respectively, with no statistical similarity between the results of these two tests nor between CCT and Anomaloscope results (P>.05). Of the patients with deletion downstream of exon 30, 66% had a red-green color defect. No color defect was found in the patients with deletion upstream of exon 30. A negative correlation between the color thresholds and age was found for the controls and patients with DMD, suggesting a nonprogressive color defect. The percentage (66%) of patients with a red-green defect was significantly higher than the expected <10% for the normal male population (P<.001). In contrast, patients with DMD with deletion upstream of exon 30 had normal color vision. This color defect might be partially explained by a retina impairment related to dystrophin isoform Dp260. PMID:17503325

  2. Cognitive control predicted by color vision, and vice versa.

    PubMed

    Colzato, Lorenza S; Sellaro, Roberta; Hulka, Lea M; Quednow, Boris B; Hommel, Bernhard

    2014-09-01

    One of the most important functions of cognitive control is to continuously adapt cognitive processes to changing and often conflicting demands of the environment. Dopamine (DA) has been suggested to play a key role in the signaling and resolution of such response conflict. Given that DA is found in high concentration in the retina, color vision discrimination has been suggested as an index of DA functioning and in particular blue-yellow color vision impairment (CVI) has been used to indicate a central hypodopaminergic state. We used color discrimination (indexed by the total color distance score; TCDS) to predict individual differences in the cognitive control of response conflict, as reflected by conflict-resolution efficiency in an auditory Simon task. As expected, participants showing better color discrimination were more efficient in resolving response conflict. Interestingly, participants showing a blue-yellow CVI were associated with less efficiency in handling response conflict. Our findings indicate that color vision discrimination might represent a promising predictor of cognitive controlability in healthy individuals. PMID:25058057

  3. Adaptive color rendering of maps for users with color vision deficiencies

    NASA Astrophysics Data System (ADS)

    Kvitle, Anne Kristin; Green, Phil; Nussbaum, Peter

    2015-01-01

    A map is an information design object for which canonical colors for the most common elements are well established. For a CVD observer, it may be difficult to discriminate between such elements - for example, it may be hard to distinguish a red road from a green landscape on the basis of color alone. We address this problem through an adaptive color schema in which the conspicuity of elements in a map to the individual user is maximized. This paper outlines a method to perform adaptive color rendering of map information for users with color vision deficiencies. The palette selection method is based on a pseudo-color palette generation technique which constrains colors to those which lie on the boundary of a reference object color gamut. A user performs a color vision discrimination task, and based on the results of the test, a palette of colors is selected using the pseudo-color palette generation method. This ensures that the perceived difference between palette elements is high but which retains the canonical color of well-known elements as far as possible. We show examples of color palettes computed for a selection of normal and CVD observers, together with maps rendered using these palettes.

  4. The Organization of Shape and Color in Vision and Art

    PubMed Central

    Pinna, Baingio

    2011-01-01

    The aim of this work is to study the phenomenal organization of shape and color in vision and art in terms of microgenesis of the object perception and creation. The idea of “microgenesis” is that the object perception and creation takes time to develop. Our hypothesis is that the roles of shape and color are extracted in sequential order and in the same order these roles are also used by artists to paint objects. Boundary contours are coded before color contours. The microgenesis of the object formation was demonstrated (i) by introducing new conditions derived from the watercolor illusion, where the juxtaposed contours are displaced horizontally or vertically, and based on variations of Matisse’s Woman, (ii) by studying descriptions and replications of visual objects in adults and children of different ages, and (iii) by analyzing the linguistic sequence and organization in a free naming task of the attributes related to shape and color. The results supported the idea of the microgenesis of the object perception, namely the temporal order in the formation of the roles of the object properties (shape before color). Some general principles were extracted from the experimental results. They can be a starting point to explore a new domain focused on the microgenesis of shape and color within the more general problem of object organization, where integrated and multidisciplinary studies based on art and vision science can be very useful. PMID:22065954

  5. The organization of shape and color in vision and art.

    PubMed

    Pinna, Baingio

    2011-01-01

    The aim of this work is to study the phenomenal organization of shape and color in vision and art in terms of microgenesis of the object perception and creation. The idea of "microgenesis" is that the object perception and creation takes time to develop. Our hypothesis is that the roles of shape and color are extracted in sequential order and in the same order these roles are also used by artists to paint objects. Boundary contours are coded before color contours. The microgenesis of the object formation was demonstrated (i) by introducing new conditions derived from the watercolor illusion, where the juxtaposed contours are displaced horizontally or vertically, and based on variations of Matisse's Woman, (ii) by studying descriptions and replications of visual objects in adults and children of different ages, and (iii) by analyzing the linguistic sequence and organization in a free naming task of the attributes related to shape and color. The results supported the idea of the microgenesis of the object perception, namely the temporal order in the formation of the roles of the object properties (shape before color). Some general principles were extracted from the experimental results. They can be a starting point to explore a new domain focused on the microgenesis of shape and color within the more general problem of object organization, where integrated and multidisciplinary studies based on art and vision science can be very useful. PMID:22065954

  6. Color vision for road scene interpretation

    NASA Astrophysics Data System (ADS)

    Sandt, Frederic; Aubert, Didier; Festas, Laurence

    1993-12-01

    For ten years, unstructured road following has been the subject of many studies. Road following must support the automatic navigation, at reasonable speed, of mobile robots on irregular paths and roads, with heterogeneous surfaces and under variable lighting conditions. Civil and military applications of this technology include transportation, logistics, security and engineering. The definition of our lane following system requires an evaluation of the existing technologies. Although the various operational systems converge on a color perception and a region segmentation optimizing discrimination and stability respectively, the treatments and performances vary. In this paper, the robustness of four operational systems and two connected techniques are compared according to common evaluation criteria. We present the identification of typical situations that have been used to create the image data base, the experimental protocol designs to compare the performances of the techniques and the analysis of the experimental results.

  7. The Ability of Color-Vision Defective and Color-Normal Early Elementary and Junior High Students to Utilize Color. Final Report.

    ERIC Educational Resources Information Center

    Cook, Ann C. N.; Hannaford, Alonzo E.

    The investigation was undertaken to obtain data on the number of kindergarten, second, and seventh grade Ss classified as having color vision defects by the American Optical-Hardy, Rand, Rittler Test (AO-HRR) and two tests by S. Ishihara. Also studied was the ability of color vision defective and color normal Ss to utilize color as measured by the…

  8. Red-green color vision in three catarrhine primates

    PubMed Central

    Fornalé, Francesca; Vaglio, Stefano; Spiezio, Caterina; Previde, Emanuela Prato

    2012-01-01

    The evolution of the red-green visual subsystem in trichromatic primates has been linked to foraging advantages, specifically the detection of either ripe fruits or young leaves amid mature foliage, and to the intraspecific socio-sexual communication, namely the signal of the male rank, the mate choice and the reproductive strategies in females. New data should be added to the debate regarding the evolution of trichromatic color vision. Three catarrhine primates were observed to achieve this goal. The research was performed on captive groups of vervet monkeys (Chlorocebus aethiops), pig-tailed macaques (Macaca nemestrina) and chimpanzees (Pan troglodytes) housed at Parco Natura Viva - Garda Zoological Park (Italy). Using pairs of red-green bags containing the same hidden reward in comparable outdoor enclosures, we recorded the choices by observed individuals (n = 25) to investigate the role of color cues in choosing an object. The results indicate that chimpanzees used red color as cue to choose an object that contains food by showing a preference toward red objects; in contrast, vervet monkeys and pig-tailed macaques do not demonstrate a clear choice based on the color of the object. Our findings highlight the importance of the foraging hypothesis but not rule out the potential role of the intraspecific socio-sexual communication and may serve to add useful information to the debate regarding the adaptive value of the evolution of color vision in order to fill a phylogenetic gap from Old World monkeys to humans. Future studies should address the role of socio-sexual communication, such as the selection of the reproductive partner of both high genetic quality and with compatible genes, to determine how this influenced the evolution of color vision in non-human primates. PMID:23336029

  9. Motion vision is independent of color in Drosophila

    PubMed Central

    Yamaguchi, Satoko; Wolf, Reinhard; Desplan, Claude; Heisenberg, Martin

    2008-01-01

    Whether motion vision uses color contrast is a controversial issue that has been investigated in several species, from insects to humans. We used Drosophila to answer this question, monitoring the optomotor response to moving color stimuli in WT and genetic variants. In the fly eye, a motion channel (outer photoreceptors R1–R6) and a color channel (inner photoreceptors R7 and R8) have been distinguished. With moving bars of alternating colors and high color contrast, a brightness ratio of the two colors can be found, at which the optomotor response is largely missing (point of equiluminance). Under these conditions, mutant flies lacking functional rhodopsin in R1–R6 cells do not respond at all. Furthermore, genetically eliminating the function of photoreceptors R7 and R8 neither alters the strength of the optomotor response nor shifts the point of equiluminance. We conclude that the color channel (R7/R8) does not contribute to motion detection as monitored by the optomotor response. PMID:18353989

  10. Motion vision is independent of color in Drosophila.

    PubMed

    Yamaguchi, Satoko; Wolf, Reinhard; Desplan, Claude; Heisenberg, Martin

    2008-03-25

    Whether motion vision uses color contrast is a controversial issue that has been investigated in several species, from insects to humans. We used Drosophila to answer this question, monitoring the optomotor response to moving color stimuli in WT and genetic variants. In the fly eye, a motion channel (outer photoreceptors R1-R6) and a color channel (inner photoreceptors R7 and R8) have been distinguished. With moving bars of alternating colors and high color contrast, a brightness ratio of the two colors can be found, at which the optomotor response is largely missing (point of equiluminance). Under these conditions, mutant flies lacking functional rhodopsin in R1-R6 cells do not respond at all. Furthermore, genetically eliminating the function of photoreceptors R7 and R8 neither alters the strength of the optomotor response nor shifts the point of equiluminance. We conclude that the color channel (R7/R8) does not contribute to motion detection as monitored by the optomotor response. PMID:18353989

  11. Diversity of Color Vision: Not All Australian Marsupials Are Trichromatic

    PubMed Central

    Ebeling, Wiebke; Natoli, Riccardo C.; Hemmi, Jan M.

    2010-01-01

    Color vision in marsupials has recently emerged as a particularly interesting case among mammals. It appears that there are both dichromats and trichromats among closely related species. In contrast to primates, marsupials seem to have evolved a different type of trichromacy that is not linked to the X-chromosome. Based on microspectrophotometry and retinal whole-mount immunohistochemistry, four trichromatic marsupial species have been described: quokka, quenda, honey possum, and fat-tailed dunnart. It has, however, been impossible to identify the photopigment of the third cone type, and genetically, all evidence so far suggests that all marsupials are dichromatic. The tammar wallaby is the only Australian marsupial to date for which there is no evidence of a third cone type. To clarify whether the wallaby is indeed a dichromat or trichromatic like other Australian marsupials, we analyzed the number of cone types in the “dichromatic” wallaby and the “trichromatic” dunnart. Employing identical immunohistochemical protocols, we confirmed that the wallaby has only two cone types, whereas 20–25% of cones remained unlabeled by S- and LM-opsin antibodies in the dunnart retina. In addition, we found no evidence to support the hypothesis that the rod photopigment (rod opsin) is expressed in cones which would have explained the absence of a third cone opsin gene. Our study is the first comprehensive and quantitative account of color vision in Australian marsupials where we now know that an unexpected diversity of different color vision systems appears to have evolved. PMID:21151905

  12. Diversity of color vision: not all Australian marsupials are trichromatic.

    PubMed

    Ebeling, Wiebke; Natoli, Riccardo C; Hemmi, Jan M

    2010-01-01

    Color vision in marsupials has recently emerged as a particularly interesting case among mammals. It appears that there are both dichromats and trichromats among closely related species. In contrast to primates, marsupials seem to have evolved a different type of trichromacy that is not linked to the X-chromosome. Based on microspectrophotometry and retinal whole-mount immunohistochemistry, four trichromatic marsupial species have been described: quokka, quenda, honey possum, and fat-tailed dunnart. It has, however, been impossible to identify the photopigment of the third cone type, and genetically, all evidence so far suggests that all marsupials are dichromatic. The tammar wallaby is the only Australian marsupial to date for which there is no evidence of a third cone type. To clarify whether the wallaby is indeed a dichromat or trichromatic like other Australian marsupials, we analyzed the number of cone types in the "dichromatic" wallaby and the "trichromatic" dunnart. Employing identical immunohistochemical protocols, we confirmed that the wallaby has only two cone types, whereas 20-25% of cones remained unlabeled by S- and LM-opsin antibodies in the dunnart retina. In addition, we found no evidence to support the hypothesis that the rod photopigment (rod opsin) is expressed in cones which would have explained the absence of a third cone opsin gene. Our study is the first comprehensive and quantitative account of color vision in Australian marsupials where we now know that an unexpected diversity of different color vision systems appears to have evolved. PMID:21151905

  13. Sex and vision II: color appearance of monochromatic lights

    PubMed Central

    2012-01-01

    Background Because cerebral cortex has a very large number of testosterone receptors, we examined the possible sex differences in color appearance of monochromatic lights across the visible spectrum. There is a history of men and women perceiving color differently. However, all of these studies deal with higher cognitive functions which may be culture-biased. We study basic visual functions, such as color appearance, without reference to any objects. We present here a detailed analysis of sex differences in primary chromatic sensations. Methods We tested large groups of young adults with normal vision, including spatial and temporal resolution, and stereopsis. Based on standard color-screening and anomaloscope data, we excluded all color-deficient observers. Stimuli were equi-luminant monochromatic lights across the spectrum. They were foveally-viewed flashes presented against a dark background. The elicited sensations were measured using magnitude estimation of hue and saturation. When the only permitted hue terms are red (R) yellow (Y), green (G), blue (B), alone or in combination, such hue descriptions are language-independent and the hue and saturation values can be used to derive a wide range of color-discrimination functions. Results There were relatively small but clear and significant, differences between males and females in the hue sensations elicited by almost the entire spectrum. Generally, males required a slightly longer wavelength to experience the same hue as did females. The spectral loci of the unique hues are not correlated with anomaloscope matches; these matches are directly determined by the spectral sensitivities of L- and M-cones (genes for these cones are on the X-chromosomes). Nor are there correlations between loci of pairs of unique hues (R, Y, G, B). Wavelength-discrimination functions derived from the scaling data show that males have a broader range of poorer discrimination in the middle of the spectrum. The precise values for all the

  14. Measurement of meat color using a computer vision system.

    PubMed

    Girolami, Antonio; Napolitano, Fabio; Faraone, Daniela; Braghieri, Ada

    2013-01-01

    The limits of the colorimeter and a technique of image analysis in evaluating the color of beef, pork, and chicken were investigated. The Minolta CR-400 colorimeter and a computer vision system (CVS) were employed to measure colorimetric characteristics. To evaluate the chromatic fidelity of the image of the sample displayed on the monitor, a similarity test was carried out using a trained panel. The panelists found the digital images of the samples visualized on the monitor very similar to the actual ones (P<0.001). During the first similarity test the panelists observed at the same time both the actual meat sample and the sample image on the monitor in order to evaluate the similarity between them (test A). Moreover, the panelists were asked to evaluate the similarity between two colors, both generated by the software Adobe Photoshop CS3 one using the L, a and b values read by the colorimeter and the other obtained using the CVS (test B); which of the two colors was more similar to the sample visualized on the monitor was also assessed (test C). The panelists found the digital images very similar to the actual samples (P<0.001). As to the similarity (test B) between the CVS- and colorimeter-based colors the panelists found significant differences between them (P<0.001). Test C showed that the color of the sample on the monitor was more similar to the CVS generated color than to the colorimeter generated color. The differences between the values of the L, a, b, hue angle and chroma obtained with the CVS and the colorimeter were statistically significant (P<0.05-0.001). These results showed that the colorimeter did not generate coordinates corresponding to the true color of meat. Instead, the CVS method seemed to give valid measurements that reproduced a color very similar to the real one. PMID:22981646

  15. Color Vision Deficiency and Color Blindness: An Introduction to the Problem.

    ERIC Educational Resources Information Center

    Olsen, Mary Margaret; Harris, Kenneth R.

    The paper examines issues concerned with the education and employment of individuals, primarily males, with color vision deficiency. After a brief introduction, the first chapter looks at adult problems such as employment areas in which the disability presents problems. The next chapter considers problems of children, noting the heavy use of color…

  16. An Evaluative Study of Color-Vision Tests for Kindergarten and First Grade Pupils.

    ERIC Educational Resources Information Center

    Lampe, John M.

    Because of the increasing use of color in instructional materials at the level of the primary grades, the Health Service Department of the Denver Public Schools became interested in investigating the color vision of 5- and 6-year-olds. A project was established to create color-vision testing methods and to use those methods to ascertain incidence…

  17. Intelligent control of robotic paint stripping using color vision feedback

    NASA Astrophysics Data System (ADS)

    Harvey, D. N.; Rogers, T. W.

    1993-08-01

    The paper describes a color-based machine vision system which is capable of functioning as a real-time process control system for a robotic work cell currently being developed for stripping paint from both large and small aircraft. The system is based on hue, saturation, and intensity representation of the image data and on rapid analysis techniques and is capable of differentiating between painted, primed, stripped, and roughened aircraft surfaces. These techniques were tested on a large number of aircraft paint schemes under actual stripping conditions, and were found to be fast and robust enough for real-time process control.

  18. 38 CFR 4.76 - Visual acuity.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... distance and near vision using Snellen's test type or its equivalent. (b) Evaluation of visual acuity. (1) Evaluate central visual acuity on the basis of corrected distance vision with central fixation, even if a central scotoma is present. However, when the lens required to correct distance vision in the poorer...

  19. 38 CFR 4.76 - Visual acuity.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... distance and near vision using Snellen's test type or its equivalent. (b) Evaluation of visual acuity. (1) Evaluate central visual acuity on the basis of corrected distance vision with central fixation, even if a central scotoma is present. However, when the lens required to correct distance vision in the poorer...

  20. 38 CFR 4.76 - Visual acuity.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... distance and near vision using Snellen's test type or its equivalent. (b) Evaluation of visual acuity. (1) Evaluate central visual acuity on the basis of corrected distance vision with central fixation, even if a central scotoma is present. However, when the lens required to correct distance vision in the poorer...

  1. 38 CFR 4.76 - Visual acuity.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... distance and near vision using Snellen's test type or its equivalent. (b) Evaluation of visual acuity. (1) Evaluate central visual acuity on the basis of corrected distance vision with central fixation, even if a central scotoma is present. However, when the lens required to correct distance vision in the poorer...

  2. 38 CFR 4.76 - Visual acuity.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... distance and near vision using Snellen's test type or its equivalent. (b) Evaluation of visual acuity. (1) Evaluate central visual acuity on the basis of corrected distance vision with central fixation, even if a central scotoma is present. However, when the lens required to correct distance vision in the poorer...

  3. Vision - night blindness

    MedlinePlus

    ... symptoms do you have? Do you have unusual stress, anxiety, or a fear of the dark? The eye exam will include: Color vision testing Pupil light reflex Refraction Retinal exam Slit lamp examination Visual acuity Other tests may be done: Electroretinogram ( ...

  4. Molecular patterns of X chromosome-linked color vision genes among 134 men of European ancestry.

    PubMed

    Drummond-Borg, M; Deeb, S S; Motulsky, A G

    1989-02-01

    We used Southern blot hybridization to study X chromosome-linked color vision genes encoding the apoproteins of red and green visual pigments in 134 unselected Caucasian men. One hundred and thirteen individuals (84.3%) had a normal arrangement of their color vision pigment genes. All had one red pigment gene; the number of green pigment genes ranged from one to five with a mode of two. The frequency of molecular genotypes indicative of normal color vision (84.3%) was significantly lower than had been observed in previous studies of color vision phenotypes. Color vision defects can be due to deletions of red or green pigment genes or due to formation of hybrid genes comprising portions of both red and green pigment genes [Nathans, J., Piantanida, T.P., Eddy, R.L., Shows, T.B., Jr., & Hogness, D.S. (1986) Science 232, 203-210]. Characteristic anomalous patterns were seen in 15 (11.2%) individuals: 7 (5.2%) had patterns characteristic of deuteranomaly (mild defect in green color perception), 2 (1.5%) had patterns characteristic of deuteranopia (severe defect in green color perception), and 6 (4.5%) had protan patterns (the red perception defects protanomaly and protanopia cannot be differentiated by current molecular methods). Previously undescribed hybrid gene patterns consisting of both green and red pigment gene fragments in addition to normal red and green genes were observed in another 6 individuals (4.5%). Only 2 of these patterns were considered as deuteranomalous. Thus, DNA testing detected anomalous color vision pigment genes at a higher frequency than expected from phenotypic color vision tests. Some color vision gene arrays associated with hybrid genes are likely to mediate normal color vision. PMID:2915991

  5. Quantifying nonhomogeneous colors in agricultural materials. Part II: comparison of machine vision and sensory panel evaluations.

    PubMed

    Balaban, M O; Aparicio, J; Zotarelli, M; Sims, C

    2008-11-01

    The average colors of mangos and apples were measured using machine vision. A method to quantify the perception of nonhomogeneous colors by sensory panelists was developed. Three colors out of several reference colors and their perceived percentage of the total sample area were selected by untrained panelists. Differences between the average colors perceived by panelists and those from the machine vision were reported as DeltaE values (color difference error). Effects of nonhomogeneity of color, and using real samples or their images in the sensory panels on DeltaE were evaluated. In general, samples with more nonuniform colors had higher DeltaE values, suggesting that panelists had more difficulty in evaluating more nonhomogeneous colors. There was no significant difference in DeltaE values between the real fruits and their screen image, therefore images can be used to evaluate color instead of the real samples. PMID:19021818

  6. Field trials of three tests for color vision and color aptitude

    NASA Astrophysics Data System (ADS)

    Hirschler, Robert; Gay, Jennifer; Ferreira de Oliveira, Danielle

    2002-06-01

    253 visual observers, at the average level of between 'unselected' (inexperienced) and 'in-plant applicants' have been tested under controlled industrial conditions using the Ishihara or T.M.C. (Murakami) pseudoisochromatic plates, the Farnworth-Munsell 100 Hue Test (FM), the HVC Color Vision Skill Test (HVC) and the Japanese Color Aptitude Test (JCAT). There is only loose correlation between the FM and the HVC tests. The FM scores do not improve significantly by retesting, while the HVC scores can be improved through training, e.g. by using the JCAT. We found practically no correlation between the performance in visual pass/fail decisions and the FM or the HVC scores. Three different editions (3 copies from 1991, 3 from 1997 and two from 1998) of the HVC test were measured and analyzed. They showed good, in the latest edition very good, intra-edition repeatability and good inter-edition reproducibility.

  7. Color Vision Deficiency and Functional Disorders Among Israeli Male Adolescents Between 2007 and 2013.

    PubMed

    Berger, Assaf; Findler, Michael; Maymon, Dror; Korach, Tzfanya; Yativ, Oshrat Fono; Gronovich, Yoav; Hassidim, Ayal

    2016-09-01

    Color vision deficiency has been associated with educational difficulties among male children, as well as attention-deficit hyperactivity disorder (ADHD). We examined the association of color vision deficiency with functional conditions, including ADHD, irritable bowel syndrome, enuresis and somatoform disorders, in a large population of male adolescents. We included all Israeli male adolescents that underwent medical and cognitive examinations during conscription between the years 2007 and 2013. The prevalence of ADHD, irritable bowel syndrome, enuresis, and somatoform disorders among color vision deficiency patients was compared to a control group. The study included 305 964 males aging 17 ± 0.6, of which 7584 (2.5%) had color vision deficiency. Using a multivariable analysis, the probability for irritable bowel syndrome, enuresis, and somatoform disorders among color vision deficiency patients was increased by 1.41, 1.94, and 3.87, respectively (P < .05). No significant association was found between ADHD and color vision deficiency. Color vision abnormalities are associated with functional disorders in male adolescents, including irritable bowel syndrome, enuresis, and somatoform disorders. PMID:27280722

  8. Numbers and Ratios of Visual Pigment Genes for Normal Red-Green Color Vision

    NASA Astrophysics Data System (ADS)

    Neitz, Maureen; Neitz, Jay

    1995-02-01

    Red-green color vision is based on middle-wavelength- and long-wavelength-sensitive visual pigments encoded by an array of genes on the X chromosome. The numbers and ratios of genes in this cluster were reexamined in men with normal color vision by means of newly refined methods. These methods revealed that many men had more pigment genes on the X chromosome than had previously been suggested and that many had more than one long-wave pigment gene. These discoveries challenge accepted ideas that are the foundation for theories of normal and anomalous color vision.

  9. Improved colorization for night vision system based on image splitting

    NASA Astrophysics Data System (ADS)

    Ali, E.; Kozaitis, S. P.

    2015-03-01

    The success of a color night navigation system often depends on the accuracy of the colors in the resulting image. Often, small regions can incorrectly adopt the color of large regions simply due to size of the regions. We presented a method to improve the color accuracy of a night navigation system by initially splitting a fused image into two distinct sections before colorization. We split a fused image into two sections, generally road and sky regions, before colorization and processed them separately to obtain improved color accuracy of each region. Using this approach, small regions were colored correctly when compared to not separating regions.

  10. A review of color blindness for microscopists: guidelines and tools for accommodating and coping with color vision deficiency.

    PubMed

    Keene, Douglas R

    2015-04-01

    "Color blindness" is a variable trait, including individuals with just slight color vision deficiency to those rare individuals with a complete lack of color perception. Approximately 75% of those with color impairment are green diminished; most of those remaining are red diminished. Red-Green color impairment is sex linked with the vast majority being male. The deficiency results in reds and greens being perceived as shades of yellow; therefore red-green images presented to the public will not illustrate regions of distinction to these individuals. Tools are available to authors wishing to accommodate those with color vision deficiency; most notable are components in FIJI (an extension of ImageJ) and Adobe Photoshop. Using these tools, hues of magenta may be substituted for red in red-green images resulting in striking definition for both the color sighted and color impaired. Web-based tools may be used (importantly) by color challenged individuals to convert red-green images archived in web-accessible journal articles into two-color images, which they may then discern. PMID:25739321

  11. Acquired Color Vision Defects and Hexane Exposure: A Study of San Francisco Bay Area Automotive Mechanics.

    PubMed

    Beckman, Stella; Eisen, Ellen A; Bates, Michael N; Liu, Sa; Haegerstrom-Portnoy, Gunilla; Hammond, S Katharine

    2016-06-01

    Occupational exposure to solvents, including n-hexane, has been associated with acquired color vision defects. Blue-yellow defects are most common and may be due to neurotoxicity or retinal damage. Acetone may potentiate the neurotoxicity of n-hexane. We present results on nonhexane solvent and hexane exposure and color vision from a cross-sectional study of 835 automotive repair workers in the San Francisco Bay Area, California (2007-2013). Cumulative exposure was estimated from self-reported work history, and color vision was assessed using the Lanthony desaturated D-15 panel test. Log-binomial regression was used to estimate prevalence ratios for color vision defects. Acquired color vision defects were present in 29% of participants, of which 70% were blue-yellow. Elevated prevalence ratios were found for nonhexane solvent exposure, with a maximum of 1.31 (95% confidence interval (CI): 0.86, 2.00) for blue-yellow. Among participants aged ≤50 years, the prevalence ratio for blue-yellow defects was 2.17 (95% CI: 1.03, 4.56) in the highest quartile of nonhexane solvent exposure and 1.62 (95% CI: 0.97, 2.72) in the highest category of exposure to hexane with acetone coexposure. Cumulative exposures to hexane and nonhexane solvents in the highest exposure categories were associated with elevated prevalence ratios for color vision defects in younger participants. PMID:27188942

  12. Does Assessing Eye Alignment along with Refractive Error or Visual Acuity Increase Sensitivity for Detection of Strabismus in Preschool Vision Screening?

    PubMed Central

    2007-01-01

    Purpose Preschool vision screenings often include refractive error or visual acuity (VA) testing to detect amblyopia, as well as alignment testing to detect strabismus. The purpose of this study was to determine the effect of combining screening for eye alignment with screening for refractive error or reduced VA on sensitivity for detection of strabismus, with specificity set at 90% and 94%. Methods Over 3 years, 4040 preschool children were screened in the Vision in Preschoolers (VIP) Study, with different screening tests administered each year. Examinations were performed to identify children with strabismus. The best screening tests for detecting children with any targeted condition were noncycloplegic retinoscopy (NCR), Retinomax autorefractor (Right Manufacturing, Virginia Beach, VA), SureSight Vision Screener (Welch-Allyn, Inc., Skaneateles, NY), and Lea Symbols (Precision Vision, LaSalle, IL and Good-Lite Co., Elgin, IL) and HOTV optotypes VA tests. Analyses were conducted with these tests of refractive error or VA paired with the best tests for detecting strabismus (unilateral cover testing, Random Dot “E” [RDE] and Stereo Smile Test II [Stereo Optical, Inc., Chicago, IL]; and MTI PhotoScreener [PhotoScreener, Inc., Palm Beach, FL]). The change in sensitivity that resulted from combining a test of eye alignment with a test of refractive error or VA was determined with specificity set at 90% and 94%. Results Among the 4040 children, 157 were identified as having strabismus. For screening tests conducted by eye care professionals, the addition of a unilateral cover test to a test of refraction generally resulted in a statistically significant increase (range, 15%–25%) in detection of strabismus. For screening tests administered by trained lay screeners, the addition of Stereo Smile II to SureSight resulted in a statistically significant increase (21%) in sensitivity for detection of strabismus. Conclusions The most efficient and low-cost ways to achieve

  13. Addressing the Needs of Students with Color Vision Deficiencies in the Elementary School Library

    ERIC Educational Resources Information Center

    Collins, Karla Bame

    2013-01-01

    Color vision deficiencies affect approximately eight percent of the male population (Birch & Chisholm, 2008; Cole, 2007; Jenny & Kelso, 2007; Neitz & Neitz, 2000), yet the condition is often overlooked in the educational setting despite the pervasiveness of color in the school (Suero et al., 2004). The purpose of this study was to…

  14. Analysis of the retinex theory of color vision

    NASA Technical Reports Server (NTRS)

    Brainard, D. H.; Wandell, B. A.

    1986-01-01

    Land's (1983) retinex algorithm is a model of human color constancy. The retinex algorithm is analyzed and its general properties are discussed. It is shown that the algorithm is too sensitive to changes in the color of nearby objects to serve as an adequate model of human color constancy.

  15. Genetic Testing as a New Standard for Clinical Diagnosis of Color Vision Deficiencies

    PubMed Central

    Davidoff, Candice; Neitz, Maureen; Neitz, Jay

    2016-01-01

    Purpose The genetics underlying inherited color vision deficiencies is well understood: causative mutations change the copy number or sequence of the long (L), middle (M), or short (S) wavelength sensitive cone opsin genes. This study evaluated the potential of opsin gene analyses for use in clinical diagnosis of color vision defects. Methods We tested 1872 human subjects using direct sequencing of opsin genes and a novel genetic assay that characterizes single nucleotide polymorphisms (SNPs) using the MassArray system. Of the subjects, 1074 also were given standard psychophysical color vision tests for a direct comparison with current clinical methods. Results Protan and deutan deficiencies were classified correctly in all subjects identified by MassArray as having red–green defects. Estimates of defect severity based on SNPs that control photopigment spectral tuning correlated with estimates derived from Nagel anomaloscopy. Conclusions The MassArray assay provides genetic information that can be useful in the diagnosis of inherited color vision deficiency including presence versus absence, type, and severity, and it provides information to patients about the underlying pathobiology of their disease. Translational Relevance The MassArray assay provides a method that directly analyzes the molecular substrates of color vision that could be used in combination with, or as an alternative to current clinical diagnosis of color defects. PMID:27622081

  16. Visual Search in the Real World: Color Vision Deficiency Affects Peripheral Guidance, but Leaves Foveal Verification Largely Unaffected

    PubMed Central

    Kugler, Günter; 't Hart, Bernard M.; Kohlbecher, Stefan; Bartl, Klaus; Schumann, Frank; Einhäuser, Wolfgang; Schneider, Erich

    2015-01-01

    Background: People with color vision deficiencies report numerous limitations in daily life, restricting, for example, their access to some professions. However, they use basic color terms systematically and in a similar manner as people with normal color vision. We hypothesize that a possible explanation for this discrepancy between color perception and behavioral consequences might be found in the gaze behavior of people with color vision deficiency. Methods: A group of participants with color vision deficiencies and a control group performed several search tasks in a naturalistic setting on a lawn. All participants wore a mobile eye-tracking-driven camera with a high foveal image resolution (EyeSeeCam). Search performance as well as fixations of objects of different colors were examined. Results: Search performance was similar in both groups in a color-unrelated search task as well as in a search for yellow targets. While searching for red targets, participants with color vision deficiencies exhibited a strongly degraded performance. This was closely matched by the number of fixations on red objects shown by the two groups. Importantly, once they fixated a target, participants with color vision deficiencies exhibited only few identification errors. Conclusions: In contrast to controls, participants with color vision deficiencies are not able to enhance their search for red targets on a (green) lawn by an efficient guiding mechanism. The data indicate that the impaired guiding is the main influence on search performance, while foveal identification (verification) is largely unaffected by the color vision deficiency. PMID:26733851

  17. Keeping Older Adults with Vision Loss Safe: Chronic Conditions and Comorbidities that Influence Functional Mobility

    ERIC Educational Resources Information Center

    Riddering, Anne T.

    2008-01-01

    Age-related macular degeneration (AMD) is a leading cause of vision loss in Americans aged 60 and older. The loss of central vision from AMD can decrease visual acuity, contrast sensitivity, glare sensitivity, color discrimination, and the ability to adapt to changes in lighting conditions. Older adults with vision loss often have other chronic,…

  18. Color vision deficiencies in youths 12-17 years of age, United States.

    PubMed

    Slaby, D; Roberts, J

    1974-01-01

    Presented in this report are data on the prevalence of color vision deficiencies in American youths 12-17 years of age as estimated from the Health Examination Survey of 1966-70. The data are stratified by age, sex, race, geographic region, size of place of residence, and annual family income. Comparisons are also made with the findings from the 1963-65 Health Examination Survey among children 6-11 years of age. Color vision deficiency, commonly called color blindness, manifests itself in everyday life in the confusion of, or blindness to, one or more primary colors, and its origins may be congenital or acquired. Congenital defects occur in two chief forms, total and partial. The former is very rare and is generally associated with nystagmus and a central scotoma. All colors appear as grays of differing brightness. The partial form is the most common type of color vision defect and is primarily an inherited condition transmitted through the mother, who is usually unaffected. It is probably due to the absence of one of the photopigments normally found in the foveal cones. In most cases reds and greens are confused. Acquired defects of color vision may often develop in, the course of ocular, mainly retinal, disease. Red-green defects are frequently characteristic of lesions of the optic nerve and optic pathways, while blue-yellow defects are more likely to result from lesions of the outer layers of the retina. PMID:25208588

  19. Efficient Halogen Lamp Daylight Simulator for Color Vision Examination

    NASA Astrophysics Data System (ADS)

    Samu, K.; Szakaly-Molnar, A.

    2011-01-01

    Recently there has been a growing interest in the selection of product colors for design engineering purposes and for quality control. The selection is generally based on color samples and the quality control is carried out with specific measurement instruments. In low quantity production it is common to avoid instrumental color measurement using human control personnel instead. For such subjective color judgment it is necessary to have standardized illumination that is usually produced by high cost daylight simulator lamps. Our aim was to build a cost effective daylight simulator with halogen incandescent light sources that can match the parameters (CCT, CRI, MIvis and Illumination) of the similar but more expensive products.

  20. Introduction to light: the physics of light, vision and color

    SciTech Connect

    Waldman, G.

    1983-01-01

    This book designed as a text for a one-semester undergraduate course presents a nonmathematical treatment of optics. The material is divided into 11 chapters entitled: Early Ideas of Light, the Classical Theories, Modern Theories, Geometrical Optics, Polarization, Lasers, Holography, the Eye, Seeing, Light and Color in Nature, and Color Science. Additional mathematical details are included in the three appendixes. (BLM)

  1. 75 FR 9480 - Qualification of Drivers; Exemption Applications; Vision

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-03-02

    ... this Notice. Note that DOT posts all comments received without change to http://www.regulations.gov..., 2000 (65 FR 19476). This information is also available at http://www.regulations.gov . FOR FURTHER... medical opinion, Mr. Williford has sufficient visual acuity, color vision and peripheral vision to...

  2. Color changes in the red-green plates of the 50-year-old AO HRR color vision test.

    PubMed

    Lee, David Y

    2006-01-01

    The original AO HRR color vision test has been considered by many as one of the best plate tests. It is still accepted by many governmental agencies for color vision certification. In their 1954 publication, Hardy, Rand, and Rittler stated that specially compounded inks were used for printing to avoid color changes with time. Fifty years later, it is both important and interesting to determine whether the wear and tear cause significant color changes. The chance finding of a never-used second edition offers an opportunity to evaluate the color changes. A GretagMacbeth Spectrolino spectrophotometer was used to measure the chromaticities of the never-used book, and an extensively used book. Four plates (#4, 7, 13, 16), selected randomly from the four red-green sections, were analyzed. The colored dots from each of the eight plates were plotted on a CIE chromaticity diagram. Isocolor lines were drawn to evaluate chromatic alignment. Chromaticities for plates #4 and 7 are significantly different between the two books. With regard to alignment with isocolor lines, the extensively used book is better than the never-used book for plate #4. There is significant misalignment on plate #7 for both books. Chromaticities for plates #13 and 16 are essentially identical between books, all with good alignment with isocolor lines. The overall comparison shows that the chromatic alignment characteristics of the extensively used book are not worse than the never-used book. Since colors in these plates have to be aligned with both the protan and deutan axes, any significant color changes would have disturbed this delicate requirement. The findings of many plates with good alignment, and the lack of differences on plates #13 and 16 between books, suggest that there are no significant color changes over time. Differences between books on plates #4 and 7 were likely the result of the original printing process. PMID:16962013

  3. Visual Acuity and the Eye.

    ERIC Educational Resources Information Center

    Beynon, J.

    1985-01-01

    Shows that visual acuity is a function of the structure of the eye and that its limit is set by the structure of the retina, emphasizing the role of lens aberrations and difraction on image quality. Also compares human vision with that of other vertebrates and insects. (JN)

  4. Massively parallel neural circuits for stereoscopic color vision: encoding, decoding and identification.

    PubMed

    Lazar, Aurel A; Slutskiy, Yevgeniy B; Zhou, Yiyin

    2015-03-01

    Past work demonstrated how monochromatic visual stimuli could be faithfully encoded and decoded under Nyquist-type rate conditions. Color visual stimuli were then traditionally encoded and decoded in multiple separate monochromatic channels. The brain, however, appears to mix information about color channels at the earliest stages of the visual system, including the retina itself. If information about color is mixed and encoded by a common pool of neurons, how can colors be demixed and perceived? We present Color Video Time Encoding Machines (Color Video TEMs) for encoding color visual stimuli that take into account a variety of color representations within a single neural circuit. We then derive a Color Video Time Decoding Machine (Color Video TDM) algorithm for color demixing and reconstruction of color visual scenes from spikes produced by a population of visual neurons. In addition, we formulate Color Video Channel Identification Machines (Color Video CIMs) for functionally identifying color visual processing performed by a spiking neural circuit. Furthermore, we derive a duality between TDMs and CIMs that unifies the two and leads to a general theory of neural information representation for stereoscopic color vision. We provide examples demonstrating that a massively parallel color visual neural circuit can be first identified with arbitrary precision and its spike trains can be subsequently used to reconstruct the encoded stimuli. We argue that evaluation of the functional identification methodology can be effectively and intuitively performed in the stimulus space. In this space, a signal reconstructed from spike trains generated by the identified neural circuit can be compared to the original stimulus. PMID:25594573

  5. True RGB line scan camera for color machine vision applications

    NASA Astrophysics Data System (ADS)

    Lemstrom, Guy F.

    1994-11-01

    In this paper a true RGB 3-chip color line scan camera is described. The camera was mainly developed for accurate color measuring in industrial applications. Due to the camera's modularity it's also possible to use it as a B/W-camera. The color separation is made with a RGB-beam splitter. The CCD linear arrays are fixed with a high accuracy to the beam splitters output in order to match the pixels of the three different CCDs on each other. This makes the color analyses simple compared to color line arrays where line or pixel matching has to be done. The beam splitter can be custom made to separate spectral components other than standard RGB. The spectral range is from 200 to 1000 nm for most CCDs and two or three spectral areas can be separately measured with the beam splitter. The camera is totally digital and has a 16-bit parallel computer interface to communicate with a signal processing board. Because of the open architecture of the camera it's possible for the customer to design a board with some special functions handling the preprocessing of the data (for example RGB - HSI conversion). The camera can also be equipped with a high speed CPU-board with enough local memory to do some image processing inside the camera before sending the data forward. The camera has been used in real industrial applications and has proven that its high resolution and high dynamic range can be used to measure color differences of small amounts to separate or grade objects such as minerals, food or other materials that can't be measured with a black and white camera.

  6. Color vision and learning in the monarch butterfly, Danaus plexippus (Nymphalidae).

    PubMed

    Blackiston, Douglas; Briscoe, Adriana D; Weiss, Martha R

    2011-02-01

    The monarch butterfly, Danaus plexippus, is well known for its intimate association with milkweed plants and its incredible multi-generational trans-continental migrations. However, little is known about monarch butterflies' color perception or learning ability, despite the importance of visual information to butterfly behavior in the contexts of nectar foraging, host-plant location and mate recognition. We used both theoretical and experimental approaches to address basic questions about monarch color vision and learning ability. Color space modeling based on the three known spectral classes of photoreceptors present in the eye suggests that monarchs should not be able to discriminate between long wavelength colors without making use of a dark orange lateral filtering pigment distributed heterogeneously in the eye. In the context of nectar foraging, monarchs show strong innate preferences, rapidly learn to associate colors with sugar rewards and learn non-innately preferred colors as quickly and proficiently as they do innately preferred colors. Butterflies also demonstrate asymmetric confusion between specific pairs of colors, which is likely a function of stimulus brightness. Monarchs readily learn to associate a second color with reward, and in general, learning parameters do not vary with temporal sequence of training. In addition, monarchs have true color vision; that is, they can discriminate colors on the basis of wavelength, independent of intensity. Finally, behavioral trials confirm that monarchs do make use of lateral filtering pigments to enhance long-wavelength discrimination. Our results demonstrate that monarchs are proficient and flexible color learners; these capabilities should allow them to respond rapidly to changing nectar availabilities as they travel over migratory routes, across both space and time. PMID:21228210

  7. Suitable digital color palette (DPC) for individual human color vision sensitivity

    NASA Astrophysics Data System (ADS)

    Ichihara, Yasuyo G.

    1999-12-01

    In this study, 34 students and teachers form a college of fine arts selected suitable colors for their artistic work on CRT display. From the results, several fundamental colors selected by artists can be seen on CIE-xy color spaces. The result of our experiment clearly showed that the 34 subjects could be divided into three groups based on differences in the level of red light or green light in their color palette.

  8. Color Blindness

    MedlinePlus

    ... rose in full bloom. If you have a color vision defect, you may see these colors differently than most people. There are three main kinds of color vision defects. Red-green color vision defects are the most ...

  9. Color Blindness

    MedlinePlus

    ... rose in full bloom. If you have a color vision defect, you may see these colors differently than most people. There are three main kinds of color vision defects. Red-green color vision defects are the ...

  10. [Colors and their meaning in culture and psychology--a historical outline and contemporary status of color vision theories].

    PubMed

    Grzybowski, Andrzej; Lewicka, Romana; Torlińska, Teresa; Stelcer, Bogusław

    2008-01-01

    The mechanism of color perception has intrigued scholars from antiquity. However, the understanding of this phenomena only came with the recognition of the nature of light and visual perception. Ancient concepts, present in science until the Renaissance, were based more on philosophical considerations and theoretical speculations than on anatomical studies and a matter-of-fact assessment of physiological functions of the visual system. From antiquity to 17th century scientific approach to the concept of vision was dominated by two theories: intromission and extramission (emanation). Intromission theory, propagated by Alhazen (lbn al.-Haythama), Vitello, John Peckham, Roger Bacon and Leonardo da Vinci, assumed that the light was transmitted from the observed object perpendicularly to the transparent eye structures. Johannes Kepler was the first scholar to propose that the retina was the receptive part of the eye. In the first half of the 17th century, Kepler's groundbreaking optical achievements and anatomical discoveries of many other scientists cast new light on the understanding of the role of different eye structures, finally wiping out the intromission theory. A further major achievement contributing to the recognition of the true nature of colors was a theory presented by Newton in 1688. He argued that they were colored rays, and not white light, that were composed of homogenous and pure light. It was, however, not until the 19th century when two modern theories of color appeared, i.e. a trichromatic theory mostly associated with the names of Young and Hemlholtz, and an opponent colors theory of Hering. In the 20th century, the two theories--previously assumed as contradictory--were joined into the zone theories of color vision. Colors have their cultural and social meanings, as far as a very individual and personal interpretation. In the former function they are used to illustrate some cultural and sociological phenomena; in the latter, they are helpful in

  11. Effects of Background Lighting Color and Movement Distance on Reaching Times Among Participants With Low Vision, Myopia, and Normal Vision.

    PubMed

    Chen, Chun-Fu; Huang, Kuo-Chen

    2016-04-01

    This study investigated the effects of target distance (30, 35, and 40 cm) and the color of background lighting (red, green, blue, and yellow) on the duration of movements made by participants with low vision, myopia, and normal vision while performing a reaching task; 48 students (21 women, 27 men; M age = 21.8 year, SD = 2.4) participated in the study. Participants reached for a target (a white LED light) whose vertical position varied randomly across trials, ranging in distance from 30 to 40 cm. Movement time was analyzed using a 3 (participant group) × [4 (color of background lighting) × 3 (movement distance)] mixed-design ANOVA model. Results indicated longer times for completing a reaching movement when: participants belonged to the low vision group; the target distance between the starting position and the target position was longer (40 cm); and the reaching movement occurred in the red-background lighting condition. These results are particularly relevant for situations in which a user is required to respond to a signal by reaching toward a button or an icon. PMID:27166331

  12. Qualitative evaluations and comparisons of six night-vision colorization methods

    NASA Astrophysics Data System (ADS)

    Zheng, Yufeng; Reese, Kristopher; Blasch, Erik; McManamon, Paul

    2013-05-01

    Current multispectral night vision (NV) colorization techniques can manipulate images to produce colorized images that closely resemble natural scenes. The colorized NV images can enhance human perception by improving observer object classification and reaction times especially for low light conditions. This paper focuses on the qualitative (subjective) evaluations and comparisons of six NV colorization methods. The multispectral images include visible (Red-Green- Blue), near infrared (NIR), and long wave infrared (LWIR) images. The six colorization methods are channel-based color fusion (CBCF), statistic matching (SM), histogram matching (HM), joint-histogram matching (JHM), statistic matching then joint-histogram matching (SM-JHM), and the lookup table (LUT). Four categries of quality measurements are used for the qualitative evaluations, which are contrast, detail, colorfulness, and overall quality. The score of each measurement is rated from 1 to 3 scale to represent low, average, and high quality, respectively. Specifically, high contrast (of rated score 3) means an adequate level of brightness and contrast. The high detail represents high clarity of detailed contents while maintaining low artifacts. The high colorfulness preserves more natural colors (i.e., closely resembles the daylight image). Overall quality is determined from the NV image compared to the reference image. Nine sets of multispectral NV images were used in our experiments. For each set, the six colorized NV images (produced from NIR and LWIR images) are concurrently presented to users along with the reference color (RGB) image (taken at daytime). A total of 67 subjects passed a screening test ("Ishihara Color Blindness Test") and were asked to evaluate the 9-set colorized images. The experimental results showed the quality order of colorization methods from the best to the worst: CBCF < SM < SM-JHM < LUT < JHM < HM. It is anticipated that this work will provide a benchmark for NV

  13. 76 FR 49707 - CooperVision, Inc.; Filing of Color Additive Petitions

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-08-11

    ... From the Federal Register Online via the Government Publishing Office ] DEPARTMENT OF HEALTH AND HUMAN SERVICES Food and Drug Administration 21 CFR Part 73 CooperVision, Inc.; Filing of Color Additive Petitions Correction In proposed rule document 2011-16089 appearing on page 37690 in the issue of...

  14. Color Vision Deficiencies in Youths 12-17 Years of Age United States.

    ERIC Educational Resources Information Center

    Slaby, David; Roberts, Jean

    The prevalence of color vision deficiencies among youths 12 to 17 years of age in the United States was evaluated during a 1966-1970 survey of 6,768 youths selected as representative of noninstitutionalized adolescents with respect to age, sex, race, geographic region, income, population size of place of residence, and rate of population change in…

  15. 76 FR 55321 - CooperVision, Inc.; Filing of Color Additive Petitions

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-09-07

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF HEALTH AND HUMAN SERVICES Food and Drug Administration 21 CFR Part 73 CooperVision, Inc.; Filing of Color Additive Petitions Correction In proposed rule document C1-2011-16089 appearing on page 49707 in the issue...

  16. Low light level color night vision technology study on triple-band

    NASA Astrophysics Data System (ADS)

    Chen, Yichao; Hu, Wengang

    2015-08-01

    Single-channel triple-band color night vision system is able to gain low-light color imagery. The core design idea of one-channel triple-band color night vision system is increasing a scanner than traditional low-light night vision system in the front of the image intensifier. The scanner is consisted of several filters which is used for dividing the emitted light or reflected light of the aim into three parts, R, G and B. Each part is taken a frame image respectively and then fused three frames into color imagery by Color Mapping Guidelines. The addition of filters makes the SNR of each frame image decreases, it means that images detail loss and gray value is low. To overcome this difficult, on the basis of three frame images fusion, a frame image of all band is added to fusion. Experimental results show that fused image which is fused by R, G, B and all band improve image brightness and detail information obviously through calculating the variance and entropy. This fused method is more conducive to the human eye.

  17. FDA regulation of labeling and promotional claims in therapeutic color vision devices: a tutorial.

    PubMed

    Drum, Bruce

    2004-01-01

    The Food and Drug Administration (FDA) is responsible for determining whether medical device manufacturers have provided reasonable assurance, based on valid scientific evidence, that new devices are safe and effective for their intended use before they are introduced into the U.S. market. Most existing color vision devices pose so little risk that their manufacturers are not required to submit a premarket notification [510(k)] to FDA prior to market. However, even low-risk devices may not be acceptable if they are marketed on the basis of misleading or excessive claims. Although most color vision devices are diagnostic, two types that are therapeutic rather than diagnostic are colored lenses intended to improve deficient color vision and colored lenses intended to improve reading performance. Both of these devices have presented special regulatory challenges to FDA because the intended uses and effectiveness claims initially proposed by the manufacturers were not supported by valid scientific evidence. In each instance, however, FDA worked with the manufacturer to restrict labeling and promotional claims in ways that were consistent with the available device performance data and that allowed for the legal marketing of the device. PMID:15518230

  18. Applications of color machine vision in the agricultural and food industries

    NASA Astrophysics Data System (ADS)

    Zhang, Min; Ludas, Laszlo I.; Morgan, Mark T.; Krutz, Gary W.; Precetti, Cyrille J.

    1999-01-01

    Color is an important factor in Agricultural and the Food Industry. Agricultural or prepared food products are often grade by producers and consumers using color parameters. Color is used to estimate maturity, sort produce for defects, but also perform genetic screenings or make an aesthetic judgement. The task of sorting produce following a color scale is very complex, requires special illumination and training. Also, this task cannot be performed for long durations without fatigue and loss of accuracy. This paper describes a machine vision system designed to perform color classification in real-time. Applications for sorting a variety of agricultural products are included: e.g. seeds, meat, baked goods, plant and wood.FIrst the theory of color classification of agricultural and biological materials is introduced. Then, some tools for classifier development are presented. Finally, the implementation of the algorithm on real-time image processing hardware and example applications for industry is described. This paper also presented an image analysis algorithm and a prototype machine vision system which was developed for industry. This system will automatically locate the surface of some plants using digital camera and predict information such as size, potential value and type of this plant. The algorithm developed will be feasible for real-time identification in an industrial environment.

  19. Rod-cone based color vision in seals under photopic conditions.

    PubMed

    Oppermann, Daniela; Schramme, Jürgen; Neumeyer, Christa

    2016-08-01

    Marine mammals have lost the ability to express S-cone opsin, and possess only one type of M/L-cone in addition to numerous rods. As they are cone monochromats they should be color blind. However, early behavioral experiments with fur seals and sea lions indicated discrimination ability between many shades of grey and blue or green. On the other hand, most recent training experiments with harbor seals under "mesopic" conditions demonstrated rod based color blindness (Scholtyssek et al., 2015). In our experiments we trained two harbor seals (Phoca vitulina) and two South African fur seals (Arctocephalus pusillus) with surface colors under photopic conditions. The seals had to detect a triangle on grey background shown on one of three test fields while the other two test fields were homogeneously grey. In a first series of experiments we determined brightness detection. We found a luminance contrast of >3% sufficient for correctly choosing the triangle. In the tests for color vision the triangle was blue, green or yellow in grey surround. The results show that the animals could see the colored triangle despite minimal or zero brightness contrast. Thus, seals have color vision based on the contribution of cones and rods even in bright daylight. PMID:27245870

  20. Preferred memory color difference between the deuteranomalous and normal color vision

    NASA Astrophysics Data System (ADS)

    Baek, YeSeul; Kwak, Youngshin; Woo, Sungjoo; Park, Chongwook

    2015-01-01

    The goal of this study is to evaluate the difference of the preferred hues of familiar objects between the color deficient observer and the normal observer. Thirteen test color images were chosen covering fruit colors, natural scene and human faces. It contained red, yellow, green, blue, purple and skin color. Two color deficient observer (deuteranomal) and two normal observers were participated in this experiment. They controlled the YCC hue of the objects in the images to obtain the most preferred and the most natural image. The selected images were analyzed using CIELAB values of each pixel. Data analysis results showed that in the case of naturalness, both groups selected the similar hues for the most of image, while, in the case of preference, the color deficient observer preferred more reddish or more greenish images. Since the deuteranomalous observer has relatively week perception for red and green region, they may prefer more reddish or greenish color. The color difference between natural hue and preferred hue of deuteranomal observer is bigger than those of normal observer.

  1. Eye guidance during real-world scene search: The role color plays in central and peripheral vision.

    PubMed

    Nuthmann, Antje; Malcolm, George L

    2016-01-01

    The visual system utilizes environmental features to direct gaze efficiently when locating objects. While previous research has isolated various features' contributions to gaze guidance, these studies generally used sparse displays and did not investigate how features facilitated search as a function of their location on the visual field. The current study investigated how features across the visual field--particularly color--facilitate gaze guidance during real-world search. A gaze-contingent window followed participants' eye movements, restricting color information to specified regions. Scene images were presented in full color, with color in the periphery and gray in central vision or gray in the periphery and color in central vision, or in grayscale. Color conditions were crossed with a search cue manipulation, with the target cued either with a word label or an exact picture. Search times increased as color information in the scene decreased. A gaze-data based decomposition of search time revealed color-mediated effects on specific subprocesses of search. Color in peripheral vision facilitated target localization, whereas color in central vision facilitated target verification. Picture cues facilitated search, with the effects of cue specificity and scene color combining additively. When available, the visual system utilizes the environment's color information to facilitate different real-world visual search behaviors based on the location within the visual field. PMID:26824640

  2. Exploring visual plasticity: dietary carotenoids can change color vision in guppies (Poecilia reticulata).

    PubMed

    Sandkam, Benjamin A; Deere-Machemer, Kerry A; Johnson, Ashley M; Grether, Gregory F; Helen Rodd, F; Fuller, Rebecca C

    2016-07-01

    Differences in color vision can play a key role in an organism's ability to perceive and interact with the environment across a broad range of taxa. Recently, species have been shown to vary in color vision across populations as a result of differences in regulatory sequence and/or plasticity of opsin gene expression. For decades, biologists have been intrigued by among-population variation in color-based mate preferences of female Trinidadian guppies. We proposed that some of this variation results from variation in color vision caused by plasticity in opsin expression. Specifically, we asked about the role of dietary carotenoid availability, because carotenoids (1) are the precursors for vitamin A, which is essential for the creation of photopigments and (2) have been linked to variation in female mate choice. We raised guppies on different carotenoid-level diets and measured opsin expression. Guppies raised on high-carotenoid diets expressed higher levels of long wavelength sensitive opsin (LWS) opsins than those raised on lower levels of carotenoids. These results suggest that dietary effects on opsin expression represent a previously unaccounted for mechanism by which ecological differences across populations could lead to mate choice differences. PMID:27283858

  3. Vision-based reading system for color-coded bar codes

    NASA Astrophysics Data System (ADS)

    Schubert, Erhard; Schroeder, Axel

    1996-02-01

    Barcode systems are used to mark commodities, articles and products with price and article numbers. The advantage of the barcode systems is the safe and rapid availability of the information about the product. The size of the barcode depends on the used barcode system and the resolution of the barcode scanner. Nevertheless, there is a strong correlation between the information content and the length of the barcode. To increase the information content, new 2D-barcode systems like CodaBlock or PDF-417 are introduced. In this paper we present a different way to increase the information content of a barcode and we would like to introduce the color coded barcode. The new color coded barcode is created by offset printing of the three colored barcodes, each barcode with different information. Therefore, three times more information content can be accommodated in the area of a black printed barcode. This kind of color coding is usable in case of the standard 1D- and 2D-barcodes. We developed two reading devices for the color coded barcodes. First, there is a vision based system, consisting of a standard color camera and a PC-based color frame grabber. Omnidirectional barcode decoding is possible with this reading device. Second, a bi-directional handscanner was developed. Both systems use a color separation process to separate the color image of the barcodes into three independent grayscale images. In the case of the handscanner the image consists of one line only. After the color separation the three grayscale barcodes can be decoded with standard image processing methods. In principle, the color coded barcode can be used everywhere instead of the standard barcode. Typical applications with the color coded barcodes are found in the medicine technique, stock running and identification of electronic modules.

  4. Effects of saturation contrast on color recognition in night vision goggles

    NASA Astrophysics Data System (ADS)

    Havig, Paul R.; Marasco, Peter L.; Post, David L.; Ellwanger, Harold L.; Reis, George A.

    2004-09-01

    In the past we have examined the luminance contrast ratios required to maintain color recognition in helmet-mounted displays (HMDs). Using typical daytime viewing conditions as simulated backgrounds we were able to determine 95% correct color recognition thresholds resulting in luminance contrast ratios averaging 1.17:1. Last year we adapted this research to determine the best colors to maintain color recognition of symbology that is on a night vision goggle (NVG) image. We simulated NVG P43 green phosphor and determined 95% correct color recognition thresholds. Results indicated that, on average, a luminance contrast ratio of nearly 1.5:1 was required to maintain color recognition. Review of the studies indicated that our simulated P43 phosphor was a much more saturated background, so saturation contrast may play as important a role as luminance contrast. A P45 white phosphor NVG may therefore be less problematic. Here we investigate the effects of both luminance and saturation contrast by manipulating color mixtures of green, yellow, and red symbology against two different backgrounds, P43 green and P45 white. We discuss our results in terms of both luminance and saturation contrast required for the maintenance of color recognition in NVGs.

  5. Advances in understanding the molecular basis of the first steps in color vision.

    PubMed

    Hofmann, Lukas; Palczewski, Krzysztof

    2015-11-01

    Serving as one of our primary environmental inputs, vision is the most sophisticated sensory system in humans. Here, we present recent findings derived from energetics, genetics and physiology that provide a more advanced understanding of color perception in mammals. Energetics of cis-trans isomerization of 11-cis-retinal accounts for color perception in the narrow region of the electromagnetic spectrum and how human eyes can absorb light in the near infrared (IR) range. Structural homology models of visual pigments reveal complex interactions of the protein moieties with the light sensitive chromophore 11-cis-retinal and that certain color blinding mutations impair secondary structural elements of these G protein-coupled receptors (GPCRs). Finally, we identify unsolved critical aspects of color tuning that require future investigation. PMID:26187035

  6. Advances in understanding the molecular basis of the first steps in color vision

    PubMed Central

    Hofmann, Lukas; Palczewski, Krzysztof

    2015-01-01

    Serving as one of our primary environmental inputs, vision is the most sophisticated sensory system in humans. Here, we present recent findings derived from energetics, genetics and physiology that provide a more advanced understanding of color perception in mammals. Energetics of cis–trans isomerization of 11-cis-retinal accounts for color perception in the narrow region of the electromagnetic spectrum and how human eyes can absorb light in the near infrared (IR) range. Structural homology models of visual pigments reveal complex interactions of the protein moieties with the light sensitive chromophore 11-cis-retinal and that certain color blinding mutations impair secondary structural elements of these G protein-coupled receptors (GPCRs). Finally, we identify unsolved critical aspects of color tuning that require future investigation. PMID:26187035

  7. Quantitative computerized color vision testing in diabetic retinopathy: A possible screening tool?

    PubMed Central

    Al Saeidi, Rashid; Kernt, Marcus; Kreutzer, Thomas C; Rudolph, Guenther; Neubauer, Aljoscha S; Haritoglou, Christos

    2013-01-01

    Purpose: To evaluate the efficacy of a computerized color vision testing (Arden color contrast test) as a screening test for detection of diabetic macular edema (DME). Materials and Methods: A consecutive, prospective case series of 83 eyes of 42 diabetic patients with and without macular edema was enrolled. Macular edema was assessed clinically by stereoscopic grading and by central retinal thickness measurement with optical coherence tomography (OCT). Additionally, a computerized chromatest for the protan- and tritan-axis was performed. Analysis of test characteristics included receiver operating characteristic (ROC) curves and calculated sensitivity and specificity. Results: Sixty-one eyes had clinically significant macular edema (CSME). OCT yielded an area under the ROC curve (AUC) of 0.92. Color vision testing yielded an AUC of 0.82 for the tritan- and 0.80 for the protan-axis. Using a cut off of 199 microns OCT resulted in a 100% sensitivity at 39% specificity. With a cut-off of 4.85, color testing yielded a sensitivity of 100% at a specificity of 8% on the tritan-axis, respectively. Considering OCT instead of clinical examination as a reference standard resulted in a comparable high sensitivity, but low specificity for color vision testing. Disturbance of the tritan axis was more pronounced than for the protan axis in present macular edema and also better correlated (r = 0.46) with retinal thickness measured with OCT. Conclusions: Computerized, quantitative color testing using the chromatest allows detection of diabetic maculopathy with high sensitivity. However, only a low specificity exists for retinal macular edema, as in diabetic retinopathy (DR) frequently abnormalities of the tritan axis exist before any retinal thickening occurs. PMID:24391371

  8. Prevalence of Red-Green Color Vision Defects among Muslim Males and Females of Manipur, India

    PubMed Central

    SHAH, Ahsana; HUSSAIN, Ruqaiya; FAREED, Mohd; AFZAL, Mohammad

    2013-01-01

    Background: Color blindness is a common X-linked genetic disorder. However, most of color blinds remain undetected due to absence of proper screening. Our study was to determine the prevalence of red-green color vision defects among Manipuri Muslim males and females. The study could help in decreasing birth of children with this disorder as Muslims commonly perform consanguineous marriage among themselves. Methods: Unrelated individuals of both sexes (Male-1352, Female-1302) belonging to six different populations were randomly selected and screened for red-green color vision defects using the Ishihara (pseudo-isochromatic plates) test from the area of Imphal East and Imphal west districts of Manipur, which is a small hilly state, situated in the north eastern extreme corner of India sharing an international boundary with Myanmar (Burma). Results: About 8.73% of males and 1.69% of females were found to be color blind. Among six different populations studied the males of Meitei population shows the highest frequency i.e. 14.93% while Naga population shows the least frequency of 3.75%. Among females, Meitei population again shows the highest frequency of 2.5% and least frequency is shown by Mughal and Naga populations 0.00% as not a single female color blind was found. Conclusion: Present study shows higher prevalence rate of color blindness as compared to other reported rates of India. Deuteranomaly cases occur in higher percentage than other types of color blindness. The higher prevalence rate observed in Muslims may be due to the hidden effect of consanguineous marriages. PMID:23515069

  9. A general zone theory of color and brightness vision. II. The space-time field.

    PubMed

    Bird, J F; Massof, R W

    1978-11-01

    The elements of vision are brightness and color varying in time and space, constituting a vector space-time function: the visual sensation field. The sensory-field generated from the light-field variations on the retina is analyzed here in terms of elemental space-time responses (Green's functions). Both chromaticity and intensity variations in either time or space are included in a unified theory, to bridge the existing gap between color theory and analyses of spatial and temporal brightness. Sensory Green's functions are here related to standard color models and to familiar responses for special stimuli, and are shown to be advantageous for nonhomogeneous and/or nonstationary visual conditions. The theory is first applied for intensity space-time variations, to elucidate existing intensity-contrast analyses. Then the general theory including chromatic contrast is illustrated by deriving color vision generalizations of the Bloch and Ricco laws and a general space-time reciprocity law, by analyses of wavelength-pulse and color-flicker experiments, and by derivation of Abney's law of luminance additivity for heterochromoatic flicker and minimally distinct borders. PMID:755855

  10. The color-vision approach to emotional space: cortical evoked potential data.

    PubMed

    Boucsein, W; Schaefer, F; Sokolov, E N; Schröder, C; Furedy, J J

    2001-01-01

    A framework for accounting for emotional phenomena proposed by Sokolov and Boucsein (2000) employs conceptual dimensions that parallel those of hue, brightness, and saturation in color vision. The approach that employs the concepts of emotional quality. intensity, and saturation has been supported by psychophysical emotional scaling data gathered from a few trained observers. We report cortical evoked potential data obtained during the change between different emotions expressed in schematic faces. Twenty-five subjects (13 male, 12 female) were presented with a positive, a negative, and a neutral computer-generated face with random interstimulus intervals in a within-subjects design, together with four meaningful and four meaningless control stimuli made up from the same elements. Frontal, central, parietal, and temporal ERPs were recorded from each hemisphere. Statistically significant outcomes in the P300 and N200 range support the potential fruitfulness of the proposed color-vision-model-based approach to human emotional space. PMID:11666042

  11. Nocturnal light environments and species ecology: implications for nocturnal color vision in forests.

    PubMed

    Veilleux, Carrie C; Cummings, Molly E

    2012-12-01

    Although variation in the color of light in terrestrial diurnal and twilight environments has been well documented, relatively little work has examined the color of light in nocturnal habitats. Understanding the range and sources of variation in nocturnal light environments has important implications for nocturnal vision, particularly following recent discoveries of nocturnal color vision. In this study, we measured nocturnal irradiance in a dry forest/woodland and a rainforest in Madagascar over 34 nights. We found that a simple linear model including the additive effects of lunar altitude, lunar phase and canopy openness successfully predicted total irradiance flux measurements across 242 clear sky measurements (r=0.85, P<0.0001). However, the relationship between these variables and spectral irradiance was more complex, as interactions between lunar altitude, lunar phase and canopy openness were also important predictors of spectral variation. Further, in contrast to diurnal conditions, nocturnal forests and woodlands share a yellow-green-dominant light environment with peak flux at 560 nm. To explore how nocturnal light environments influence nocturnal vision, we compared photoreceptor spectral tuning, habitat preference and diet in 32 nocturnal mammals. In many species, long-wavelength-sensitive cone spectral sensitivity matched the peak flux present in nocturnal forests and woodlands, suggesting a possible adaptation to maximize photon absorption at night. Further, controlling for phylogeny, we found that fruit/flower consumption significantly predicted short-wavelength-sensitive cone spectral tuning in nocturnal mammals (P=0.002). These results suggest that variation in nocturnal light environments and species ecology together influence cone spectral tuning and color vision in nocturnal mammals. PMID:22899522

  12. Signatures of Selection and Gene Conversion Associated with Human Color Vision Variation

    PubMed Central

    Verrelli, Brian C.; Tishkoff, Sarah A.

    2004-01-01

    Trichromatic color vision in humans results from the combination of red, green, and blue photopigment opsins. Although color vision genes have been the targets of active molecular and psychophysical research on color vision abnormalities, little is known about patterns of normal genetic variation in these genes among global human populations. The current study presents nucleotide sequence analyses and tests of neutrality for a 5.5-kb region of the X-linked long-wave “red” opsin gene (OPN1LW) in 236 individuals from ethnically diverse human populations. Our analysis of the recombination landscape across OPN1LW reveals an unusual haplotype structure associated with amino acid replacement variation in exon 3 that is consistent with gene conversion. Compared with the absence of OPN1LW amino acid replacement fixation since divergence from chimpanzee, the human population exhibits a significant excess of high-frequency OPN1LW replacements. Our results suggest that subtle changes in L-cone opsin wavelength absorption may have been adaptive during human evolution. PMID:15252758

  13. Visual function and color vision in adults with Attention-Deficit/Hyperactivity Disorder

    PubMed Central

    Kim, Soyeon; Chen, Samantha; Tannock, Rosemary

    2013-01-01

    Purpose Color vision and self-reported visual function in everyday life in young adults with Attention-Deficit/Hyperactivity Disorder (ADHD) were investigated. Method Participants were 30 young adults with ADHD and 30 controls matched for age and gender. They were tested individually and completed the Visual Activities Questionnaire (VAQ), Farnsworth-Munsell 100 Hue Test (FMT) and A Quick Test of Cognitive Speed (AQT). Results The ADHD group reported significantly more problems in 4 of 8 areas on the VAQ: depth perception, peripheral vision, visual search and visual processing speed. Further analyses of VAQ items revealed that the ADHD group endorsed more visual problems associated with driving than controls. Color perception difficulties on the FMT were restricted to the blue spectrum in the ADHD group. FMT and AQT results revealed slower processing of visual stimuli in the ADHD group. Conclusion A comprehensive investigation of mechanisms underlying visual function and color vision in adults with ADHD is warranted, along with the potential impact of these visual problems on driving performance. PMID:24646898

  14. Signatures of selection and gene conversion associated with human color vision variation.

    PubMed

    Verrelli, Brian C; Tishkoff, Sarah A

    2004-09-01

    Trichromatic color vision in humans results from the combination of red, green, and blue photopigment opsins. Although color vision genes have been the targets of active molecular and psychophysical research on color vision abnormalities, little is known about patterns of normal genetic variation in these genes among global human populations. The current study presents nucleotide sequence analyses and tests of neutrality for a 5.5-kb region of the X-linked long-wave "red" opsin gene (OPN1LW) in 236 individuals from ethnically diverse human populations. Our analysis of the recombination landscape across OPN1LW reveals an unusual haplotype structure associated with amino acid replacement variation in exon 3 that is consistent with gene conversion. Compared with the absence of OPN1LW amino acid replacement fixation since divergence from chimpanzee, the human population exhibits a significant excess of high-frequency OPN1LW replacements. Our results suggest that subtle changes in L-cone opsin wavelength absorption may have been adaptive during human evolution. PMID:15252758

  15. Phylogenetic analysis and experimental approaches to study color vision in vertebrates.

    PubMed

    Yokoyama, S

    2000-01-01

    To elucidate the molecular mechanisms of vertebrate color vision, it is essential to establish associations between amino acid substitutions and the directions of lambda max shifts of visual pigments. In this way, we can identify critical amino acid changes that may be responsible for lambda max shifts of visual pigments. In this process, we may consider only highly conserved residues, simply because the evolutionary conservation often implies functional importance. Using such an "evolutionary model" as a convenient tool in designing mutagenesis experiments, we can test specific hypotheses on the molecular mechanisms that are responsible for color vision in vertebrates. Virtually any vertebrate opsin cDNA can be expressed in COS cells, reconstituted with 11-cis-retinal, and the lambda max values of the regenerated pigments can be measured rather easily. By constructing mutant pigments with desired amino acid changes and conducting the in vitro assay and comparing their lambda max values with those of corresponding wild-type pigments, we can elucidate the molecular mechanisms of lambda max shifts--and color vision--of vertebrates rigorously. PMID:10736710

  16. A Call for Considering Color Vision Deficiency When Creating Graphics for Psychology Reports.

    PubMed

    Frane, Andrew

    2015-01-01

    Although color vision deficiency (CVD) is fairly common, it is often not adequately considered when data is presented in color graphics. This study found that CVD tends to be mentioned neither in the author guidelines of psychology journals nor in the standard publication manuals of the field (e.g., the publication manuals of the American Psychological Association and the American Medical Association). To illustrate the relevance of this problem, a panel of scholars with CVD was used to evaluate the color figures in three respected psychological science journals. Results suggested that a substantial proportion of those figures were needlessly confusing for viewers with CVD and could have been easily improved through simple adjustments. Based on prior literature and on feedback from the panelists, recommendations are made for improving the accessibility of graphics in psychology reports. PMID:26273941

  17. Diagnosis of Normal and Abnormal Color Vision with Cone-Specific VEPs

    PubMed Central

    Rabin, Jeff C.; Kryder, Andrew C.; Lam, Dan

    2016-01-01

    Purpose Normal color vision depends on normal long wavelength (L), middle wavelength (M), and short wavelength sensitive (S) cones. Hereditary “red-green” color vision deficiency (CVD) is due to a shift in peak sensitivity or lack of L or M cones. Hereditary S cone CVD is rare but can be acquired as an early sign of disease. Current tests detect CVD but few diagnose type or severity, critical for linking performance to real-world demands. The anomaloscope and newer subjective tests quantify CVD but are not applicable to infants or cognitively impaired patients. Our purpose was to develop an objective test of CVD with sensitivity and specificity comparable to current tests. Methods A calibrated visual-evoked potential (VEP) display and Food and Drug Administration-approved system was used to record L, M, and S cone-specific pattern-onset VEPs from 18 color vision normals (CVNs) and 13 hereditary CVDs. VEP amplitudes and latencies were compared between groups to establish VEP sensitivity and specificity. Results Cone VEPs show 100% sensitivity for diagnosis of CVD and 94% specificity for confirming CVN. L cone (protan) CVDs showed a significant increase in L cone latency (53.1 msec, P < 0.003) and decreased amplitude (10.8 uV, P < 0.0000005) but normal M and S cone VEPs (P > 0.31). M cone (deutan) CVDs showed a significant increase in M cone latency (31.0 msec, P < 0.000004) and decreased amplitude (8.4 uV, P < 0.006) but normal L and S cone VEPs (P > 0.29). Conclusions Cone-specific VEPs offer a rapid, objective test to diagnose hereditary CVD and show potential for detecting acquired CVD in various diseases. Translational Relevance This paper describes the efficacy of cone-specific color VEPs for quantification of normal and abnormal color vision. The rapid, objective nature of this approach makes it suitable for detecting color sensitivity loss in infants and the cognitively impaired. PMID:27226932

  18. Acquired color vision and visual field defects in patients with ocular hypertension and early glaucoma

    PubMed Central

    Papaconstantinou, Dimitris; Georgalas, Ilias; Kalantzis, George; Karmiris, Efthimios; Koutsandrea, Chrysanthi; Diagourtas, Andreas; Ladas, Ioannis; Georgopoulos, Gerasimos

    2009-01-01

    Purpose: To study acquired color vision and visual field defects in patients with ocular hypertension (OH) and early glaucoma. Methods: In a prospective study we evaluated 99 eyes of 56 patients with OH without visual field defects and no hereditary color deficiencies, followed up for 4 to 6 years (mean = 4.7 ± 0.6 years). Color vision defects were studied using a special computer program for Farnsworth–Munsell 100 hue test and visual field tests were performed with Humphrey analyzer using program 30–2. Both tests were repeated every six months. Results: In fifty-six eyes, glaucomatous defects were observed during the follow-up period. There was a statistically significant difference in total error score (TES) between eyes that eventually developed glaucoma (157.89 ± 31.79) and OH eyes (75.51 ± 31.57) at the first examination (t value 12.816, p < 0.001). At the same time visual field indices were within normal limits in both groups. In the glaucomatous eyes the earliest statistical significant change in TES was identified at the first year of follow-up and was −20.62 ± 2.75 (t value 9.08, p < 0.001) while in OH eyes was −2.11 ± 4.36 (t value 1.1, p = 0.276). Pearson’s coefficient was high in all examinations and showed a direct correlation between TES and mean deviation and corrected pattern standard deviation in both groups. Conclusion: Quantitative analysis of color vision defects provides the possibility of follow-up and can prove a useful means for detecting early glaucomatous changes in patients with normal visual fields. PMID:19668575

  19. New mobile technologies and visual acuity.

    PubMed

    Livingstone, I A T; Lok, A S L; Tarbert, C

    2014-01-01

    Mobile devices have shown promise in visual assessment. Traditional acuity measurement involves retro-illuminated charts or card-based modalities. Mobile platforms bring potential to improve on both portability and objectivity. The present research activity relates to design and validation of a novel tablet-based infant acuity test. Early results in an adult cohort, with various levels of artificially degraded vision, suggest improved test-retest reliability compared with current standards for infant acuity. Future pragmatic trials will assess the value of this emerging technology in pediatric visual screening. PMID:25570420

  20. Postoperative Vision-Related Quality of Life in Macula-Off Rhegmatogenous Retinal Detachment Patients and Its Relation to Visual Function

    PubMed Central

    van de Put, Mathijs A. J.; Hoeksema, Lisette; Wanders, Wouter; Nolte, Ilja M.; Hooymans, Johanna M. M.; Los, Leonoor I.

    2014-01-01

    Objective To determine the vision-related quality of life (VR-QOL) after surgery for macula-off rhegmatogenous retinal detachment (RRD) in relation to visual acuity, contrast acuity, and color vision. Methods In a prospective observational study, we included 55 patients with a macula-off RRD. Best corrected visual acuity (BCVA), color vision (saturated and desaturated color confusion indices (CCI)) and contrast acuity were measured at 12 months postoperatively in both the RRD eye and the fellow control eye, and the 25-item National Eye Institute Visual Function Questionnaire (NEI VFQ-25) was filled out. Results Operated and fellow control eyes differed significantly in mean LogMAR BCVA (P<0.0001), median Log contrast acuity (P<0.0001), saturated CCI (P = 0.009), and desaturated CCI (P = 0.016). Significant correlations were observed between the NEI VFQ-25 overall composite score and postoperative LogMAR BCVA (R = −0.551, P<0.0001), contrast acuity (R = 0.472, P<0.0001), saturated CCI (R = −0.315, P = 0.023), and desaturated CCI (R = −0.283, P = 0.044). Conclusions A lower VR-QOL was highly correlated to a worse postoperative BCVA and contrast acuity and to a lesser extent to color vision disturbances. PMID:25460011

  1. Effect of elimination of nitrogen and/or hypoxia or restricted visual environment on color vision and range of accommodation

    NASA Technical Reports Server (NTRS)

    Wolbarsht, M. L.; White, C. W.; Anderson, W. B., Jr.

    1973-01-01

    The effects upon range of accommodation and color vision of reduced atmospheric pressure, at partial and complete elimination of nitrogen, of hypoxia, and of exposure for varying periods of time to restricted visual environment, have been studied alone or in various combinations. Measurements were made on the electroretinogram, the electrooculogram, and the diameter of the retinal vessels as an indicator of blood flow to the retina at the time of total elimination of nitrogen. An objective method was used to test range of accommodation. In the color vision test the flicker colors of a Benham's top were matched with a colorimeter.

  2. What studies of macaque monkeys have told us about human color vision

    PubMed Central

    Horwitz, Gregory D.

    2014-01-01

    Animal models are a necessary component of systems neuroscience research. Determining which animal model to use for a given study involves a complicated calculus. Some experimental manipulations are easily made in some animal models but impossible in others. Some animal models are similar to humans with respect to particular scientific questions, and others are less so. In this review, I discuss work done in my laboratory to investigate the neural mechanisms of color vision in the rhesus macaque. The emphasis is on the strengths of the macaque model, but shortcomings are also discussed. PMID:25445192

  3. The molecular genetics of red and green color vision in mammals.

    PubMed

    Yokoyama, S; Radlwimmer, F B

    1999-10-01

    To elucidate the molecular mechanisms of red-green color vision in mammals, we have cloned and sequenced the red and green opsin cDNAs of cat (Felis catus), horse (Equus caballus), gray squirrel (Sciurus carolinensis), white-tailed deer (Odocoileus virginianus), and guinea pig (Cavia porcellus). These opsins were expressed in COS1 cells and reconstituted with 11-cis-retinal. The purified visual pigments of the cat, horse, squirrel, deer, and guinea pig have lambdamax values at 553, 545, 532, 531, and 516 nm, respectively, which are precise to within +/-1 nm. We also regenerated the "true" red pigment of goldfish (Carassius auratus), which has a lambdamax value at 559 +/- 4 nm. Multiple linear regression analyses show that S180A, H197Y, Y277F, T285A, and A308S shift the lambdamax values of the red and green pigments in mammals toward blue by 7, 28, 7, 15, and 16 nm, respectively, and the reverse amino acid changes toward red by the same extents. The additive effects of these amino acid changes fully explain the red-green color vision in a wide range of mammalian species, goldfish, American chameleon (Anolis carolinensis), and pigeon (Columba livia). PMID:10511567

  4. Development of computerized color vision testing as a replacement for Martin Lantern

    PubMed Central

    Kapoor, Gaurav; Vats, D.P.; Parihar, J.K.S.

    2012-01-01

    Background Development and standardization of computerized color vision testing as a replacement for Martin Lantern test. Non-randomized comparative trial. Methods All candidates of SSB, Allahabad, reporting for SMB underwent color vision testing at the eye dept by computerized eye test and currently available tests. Results All candidates were subjected to Ishihara chart testing and those found to be CP III were subjected to the confirmatory test on Martin Lantern and the Software. Candidates requiring CP I standards for eligibility were tested on the same on Martin Lantern and on the new software method. On comparison between the Standard Martin Lantern and the Software, the results were consistent and comparable with 82 patients testing CP I on the Martin Lantern and 81 on the software. Of the CP III patients, 253 tested positive on the Standard lantern test as compared to 251 on the software and of the CP IV group, 147 tested positive on the Standard lantern and 149 by the software method. Conclusion It was found that the software replicated the existing Martin Lantern accurately and consistently. The Martin Lantern Software can be used as a replacement for existing old Lanterns which are not in production since the early 20th century. PMID:24532927

  5. Response variability of the red-green color vision system using reaction times

    NASA Astrophysics Data System (ADS)

    Medina, José M.; Díaz, José A.

    2011-05-01

    We have studied the intrinsic variability of color coding by examining the temporal fluctuations of chromatic-opponent neurons at the large scale. Simple reaction times were measured for stimuli selected along the red-green direction in the isoluminant plane of the human color space (S-cone constant or L-M axis). Stimulus size also changed from 8 minutes of arc to 10 degrees. Fluctuations increased as the mean reaction time increased and showed a bi-linear scaling function. The coefficient of variation was always lower than predicted by a Poisson process. The variability decreased as a function of the chromatic contrast and as a function of the stimulus size. The analysis of the hazard functions was consistent with power-law dominant random processes at low stimulus size and low contrasts and log-normal dominant processes at high contrasts. Our results conclude that response variability is signal-dependent and evidence for a random multiplicative process in human color vision. We suggest that multiplicative internal noise modulates red-green spatial summation and chromatic contrast processing and may represent a fundamental limit in spatially disordered networks.

  6. Acquired color vision loss and a possible mechanism of ganglion cell death in glaucoma.

    PubMed Central

    Nork, T M

    2000-01-01

    PURPOSE: First, to study the cellular mechanisms of acquired color vision loss in retinal detachment and diabetic retinopathy. Second, to learn why, in glaucoma, the type of color vision deficit that is observed is more characteristic of a retinal injury than it is of an optic neuropathy. Third, to test a hypothesis of photoreceptor-induced, ganglion cell death in glaucoma. METHODS: Various histologic techniques were employed to distinguish the L/M-cones (long/medium wavelength-sensitive cones, or red/green sensitive cones) from the S-cones (short wavelength-sensitive cones, or blue sensitive cones) in humans and monkeys with retinal detachment, humans with diabetic retinopathy, and both humans and monkeys with glaucoma. To test if the photoreceptors were contributing to ganglion cell death, laser photocoagulation was used in a experimental model of glaucoma to focally eliminate the photoreceptors. As a control, optic nerve transection was done following retinal laser photocoagulation in one animal. RESULTS: Selective and widespread loss of the S-cones was found in retinal detachment as well as diabetic retinopathy. By contrast, in human as well as experimental glaucoma, marked swelling of the L/M-cones was the predominant histopathologic feature. Retinal laser photocoagulation followed by experimental glaucoma resulted in selective protection of ganglion cells overlying the laser spots. This was not seen with retinal laser photocoagulation by optic nerve transection. CONCLUSIONS: In retinal detachment and diabetic retinopathy, acquired tritan-like color vision loss could be caused, or contributed to, by selective loss of the S-cones. Both L- and M-cones are affected in glaucoma, which is also consistent with a tritan-like deficit. Although not a therapeutic option, protection of ganglion cells by retinal laser in experimental glaucoma is consistent with an hypothesis of anterograde, photoreceptor-induced, ganglion cell death. Images FIGURE 1 FIGURE 2 FIGURE 3

  7. Color blindness

    MedlinePlus

    ... care provider or eye specialist can check your color vision in several ways. Testing for color blindness is ... Adams AJ, Verdon WA, Spivey BE. Color vision. In: Tasman W, Jaeger EA, eds. ... PA: Lippincott Williams & Wilkins; 2013:vol. 2, chap ...

  8. Color machine vision system for process control in the ceramics industry

    NASA Astrophysics Data System (ADS)

    Penaranda Marques, Jose A.; Briones, Leoncio; Florez, Julian

    1997-08-01

    This paper is focused on the design of a machine vision system to solve a problem found in the manufacturing process of high quality polished porcelain tiles. This consists of sorting the tiles according to the criteria 'same appearance to the human eye' or in other words, by color and visual texture. In 1994 this problem was tackled and led to a prototype which became fully operational at production scale in a manufacturing plant, named Porcelanatto, S.A. The system has evolved and has been adapted to meet the particular needs of this manufacturing company. Among the main issues that have been improved, it is worth pointing out: (1) improvement to discern subtle variations in color or texture, which are the main features of the visual appearance; (2) inspection time reduction, as a result of algorithm optimization and the increasing computing power. Thus, 100 percent of the production can be inspected, reaching a maximum of 120 tiles/sec.; (3) adaptation to the different types and models of tiles manufactured. The tiles vary not only in their visible patterns but also in dimensions, formats, thickness and allowances. In this sense, one major problem has been reaching an optimal compromise: The system must be sensitive enough to discern subtle variations in color, but at the same time insensitive thickness variations in the tiles. The following parts have been used to build the system: RGB color line scan camera, 12 bits per channel, PCI frame grabber, PC, fiber optic based illumination and the algorithm which will be explained in section 4.

  9. Wavelength Discrimination in Drosophila Suggests a Role of Rhodopsin 1 in Color Vision

    PubMed Central

    Garbers, Christian; Wachtler, Thomas

    2016-01-01

    Among the five photoreceptor opsins in the eye of Drosophila, Rhodopsin 1 (Rh1) is expressed in the six outer photoreceptors. In a previous study that combined behavioral genetics with computational modeling, we demonstrated that flies can use the signals from Rh1 for color vision. Here, we provide an in-depth computational analysis of wildtype Drosophila wavelength discrimination specifically considering the consequences of different choices of computations in the preprocessing of the behavioral data. The results support the conclusion that Drosophila wavelength discrimination behavior can best be explained by a contribution of Rh1. These findings are corroborated by results of an information-theoretical analysis that shows that Rh1 provides information for discrimination of natural reflectance spectra. PMID:27258000

  10. Adaptive optics retinal imaging reveals S-cone dystrophy in tritan color-vision deficiency

    NASA Astrophysics Data System (ADS)

    Baraas, Rigmor C.; Carroll, Joseph; Gunther, Karen L.; Chung, Mina; Williams, David R.; Foster, David H.; Neitz, Maureen

    2007-05-01

    Tritan color-vision deficiency is an autosomal dominant disorder associated with mutations in the short-wavelength-sensitive- (S-) cone-pigment gene. An unexplained feature of the disorder is that individuals with the same mutation manifest different degrees of deficiency. To date, it has not been possible to examine whether any loss of S-cone function is accompanied by physical disruption in the cone mosaic. Two related tritan subjects with the same novel mutation in their S-cone-opsin gene, but different degrees of deficiency, were examined. Adaptive optics was used to obtain high-resolution retinal images, which revealed distinctly different S-cone mosaics consistent with their discrepant phenotypes. In addition, a significant disruption in the regularity of the overall cone mosaic was observed in the subject completely lacking S-cone function. These results taken together with other recent findings from molecular genetics indicate that, with rare exceptions, tritan deficiency is progressive in nature.

  11. On-line determination of pork color and intramuscular fat by computer vision

    NASA Astrophysics Data System (ADS)

    Liao, Yi-Tao; Fan, Yu-Xia; Wu, Xue-Qian; Xie, Li-juan; Cheng, Fang

    2010-04-01

    In this study, the application potential of computer vision in on-line determination of CIE L*a*b* and content of intramuscular fat (IMF) of pork was evaluated. Images of pork chop from 211 pig carcasses were captured while samples were on a conveyor belt at the speed of 0.25 m•s-1 to simulate the on-line environment. CIE L*a*b* and IMF content were measured with colorimeter and chemical extractor as reference. The KSW algorithm combined with region selection was employed in eliminating the surrounding fat of longissimus dorsi muscle (MLD). RGB values of the pork were counted and five methods were applied for transforming RGB values to CIE L*a*b* values. The region growing algorithm with multiple seed points was applied to mask out the IMF pixels within the intensity corrected images. The performances of the proposed algorithms were verified by comparing the measured reference values and the quality characteristics obtained by image processing. MLD region of six samples could not be identified using the KSW algorithm. Intensity nonuniformity of pork surface in the image can be eliminated efficiently, and IMF region of three corrected images failed to be extracted. Given considerable variety of color and complexity of the pork surface, CIE L*, a* and b* color of MLD could be predicted with correlation coefficients of 0.84, 0.54 and 0.47 respectively, and IMF content could be determined with a correlation coefficient more than 0.70. The study demonstrated that it is feasible to evaluate CIE L*a*b* values and IMF content on-line using computer vision.

  12. An alternative technique for the computation of the designator in the retinex theory of color vision.

    PubMed

    Land, E H

    1986-05-01

    Accepting the first postulate of the retinex theory of color vision that there are three independent lightness-determining mechanisms (one for long waves, one for middle waves, and one for short waves), each operative with less than a millisecond exposure and each served by its own retinal pigment, a basic task of retinex theory becomes the determination of the nature of these mechanisms. Earlier references proposed several workable algorithms. [Land, E. H. (1959) Proc. Natl. Acad. Sci. USA 45, 115-129; Land, E. H. (1959) Proc. Natl. Acad. Sci. USA 45, 636-644; Land, E. H. (1983) Proc. Natl. Acad. Sci. USA 80, 5163-5169; Land, E. H. & McCann, J. J. (1971) J. Opt. Soc. Am. 61, 1-11; Land, E. H. (1986) Vision Res. 26, 7-21.] The present paper describes a relatively simple alternative technique for the computation of the designator in retinex theory and reports the general operational effectiveness of the new technique, including the competence, not possessed by earlier algorithms, for generating Mach bands. PMID:3458165

  13. A low-cost color vision system for automatic estimation of apple fruit orientation and maximum equatorial diameter

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The overall objective of this research was to develop an in-field presorting and grading system to separate undersized and defective fruit from fresh market-grade apples. To achieve this goal, a cost-effective machine vision inspection prototype was built, which consisted of a low-cost color camera,...

  14. Individual Differences in Scotopic Visual Acuity and Contrast Sensitivity: Genetic and Non-Genetic Influences

    PubMed Central

    Bartholomew, Alex J.; Lad, Eleonora M.; Cao, Dingcai; Bach, Michael; Cirulli, Elizabeth T.

    2016-01-01

    Despite the large amount of variation found in the night (scotopic) vision capabilities of healthy volunteers, little effort has been made to characterize this variation and factors, genetic and non-genetic, that influence it. In the largest population of healthy observers measured for scotopic visual acuity (VA) and contrast sensitivity (CS) to date, we quantified the effect of a range of variables on visual performance. We found that young volunteers with excellent photopic vision exhibit great variation in their scotopic VA and CS, and this variation is reliable from one testing session to the next. We additionally identified that factors such as Circadian preference, iris color, astigmatism, depression, sex and education have no significant impact on scotopic visual function. We confirmed previous work showing that the amount of time spent on the vision test influences performance and that laser eye surgery results in worse scotopic vision. We also showed a significant effect of intelligence and photopic visual performance on scotopic VA and CS, but all of these variables collectively explain <30% of the variation in scotopic vision. The wide variation seen in young healthy volunteers with excellent photopic vision, the high test-retest agreement, and the vast majority of the variation in scotopic vision remaining unexplained by obvious non-genetic factors suggests a strong genetic component. Our preliminary genome-wide association study (GWAS) of 106 participants ruled out any common genetic variants of very large effect and paves the way for future, larger genetic studies of scotopic vision. PMID:26886100

  15. Individual Differences in Scotopic Visual Acuity and Contrast Sensitivity: Genetic and Non-Genetic Influences.

    PubMed

    Bartholomew, Alex J; Lad, Eleonora M; Cao, Dingcai; Bach, Michael; Cirulli, Elizabeth T

    2016-01-01

    Despite the large amount of variation found in the night (scotopic) vision capabilities of healthy volunteers, little effort has been made to characterize this variation and factors, genetic and non-genetic, that influence it. In the largest population of healthy observers measured for scotopic visual acuity (VA) and contrast sensitivity (CS) to date, we quantified the effect of a range of variables on visual performance. We found that young volunteers with excellent photopic vision exhibit great variation in their scotopic VA and CS, and this variation is reliable from one testing session to the next. We additionally identified that factors such as Circadian preference, iris color, astigmatism, depression, sex and education have no significant impact on scotopic visual function. We confirmed previous work showing that the amount of time spent on the vision test influences performance and that laser eye surgery results in worse scotopic vision. We also showed a significant effect of intelligence and photopic visual performance on scotopic VA and CS, but all of these variables collectively explain <30% of the variation in scotopic vision. The wide variation seen in young healthy volunteers with excellent photopic vision, the high test-retest agreement, and the vast majority of the variation in scotopic vision remaining unexplained by obvious non-genetic factors suggests a strong genetic component. Our preliminary genome-wide association study (GWAS) of 106 participants ruled out any common genetic variants of very large effect and paves the way for future, larger genetic studies of scotopic vision. PMID:26886100

  16. Vision in albinism.

    PubMed Central

    Summers, C G

    1996-01-01

    PURPOSE: The purpose of this investigation was to study vision in albinism from 3 perspectives: first, to determine the characteristics of grating acuity development in children with albinism; second, to study the effect of illumination on grating acuity; and third, to define the effect of melanin pigment in the macula on visual acuity. METHODS: I. Binocular and monocular grating acuity was measured with the acuity card procedure in 40 children with albinism during the first 3 years of life. Recognition acuity was eventually measured in 27 of these patients. Ocular pigment was documented by a previously established method of grading iris transillumination and macular transparency. II. Grating acuity under standard and increased illumination levels was measured in 20 adults with albinism (group I) compared with that in 20 adults with nystagmus due to conditions other than albinism (group II) and 20 adults without ocular abnormalities (group III). Recognition acuity measured with the ETDRS charts was also recorded for each group. III. Best-corrected binocular acuity was measured in 29 patients with albinism who were identified with melanin pigment in their maculas by direct ophthalmoscopy. RESULTS: I. Both binocular and monocular grating acuity was reduced 2 to 3 octaves below the norm for ages 6 months to 3 years. Limited data available in the first 6 months of life did not show failure of vision to develop. Grating acuity measurements overestimated eventual recognition acuity. Mean recognition acuity was 20/111. A relationship between grating acuity development and presence or absence of ocular pigment was not found. II. Grating acuity was significantly better for groups I and II under the condition of increased illumination (P < .03). For patients with albinism, grating acuity under standard illumination was significantly better than recognition acuity (P < .001). For all groups, grating acuity under increased illumination was significantly better than recognition

  17. Intelligent Color Vision System for Ripeness Classification of Oil Palm Fresh Fruit Bunch

    PubMed Central

    Fadilah, Norasyikin; Mohamad-Saleh, Junita; Halim, Zaini Abdul; Ibrahim, Haidi; Ali, Syed Salim Syed

    2012-01-01

    Ripeness classification of oil palm fresh fruit bunches (FFBs) during harvesting is important to ensure that they are harvested during optimum stage for maximum oil production. This paper presents the application of color vision for automated ripeness classification of oil palm FFB. Images of oil palm FFBs of type DxP Yangambi were collected and analyzed using digital image processing techniques. Then the color features were extracted from those images and used as the inputs for Artificial Neural Network (ANN) learning. The performance of the ANN for ripeness classification of oil palm FFB was investigated using two methods: training ANN with full features and training ANN with reduced features based on the Principal Component Analysis (PCA) data reduction technique. Results showed that compared with using full features in ANN, using the ANN trained with reduced features can improve the classification accuracy by 1.66% and is more effective in developing an automated ripeness classifier for oil palm FFB. The developed ripeness classifier can act as a sensor in determining the correct oil palm FFB ripeness category. PMID:23202043

  18. Intelligent color vision system for ripeness classification of oil palm fresh fruit bunch.

    PubMed

    Fadilah, Norasyikin; Mohamad-Saleh, Junita; Abdul Halim, Zaini; Ibrahim, Haidi; Syed Ali, Syed Salim

    2012-01-01

    Ripeness classification of oil palm fresh fruit bunches (FFBs) during harvesting is important to ensure that they are harvested during optimum stage for maximum oil production. This paper presents the application of color vision for automated ripeness classification of oil palm FFB. Images of oil palm FFBs of type DxP Yangambi were collected and analyzed using digital image processing techniques. Then the color features were extracted from those images and used as the inputs for Artificial Neural Network (ANN) learning. The performance of the ANN for ripeness classification of oil palm FFB was investigated using two methods: training ANN with full features and training ANN with reduced features based on the Principal Component Analysis (PCA) data reduction technique. Results showed that compared with using full features in ANN, using the ANN trained with reduced features can improve the classification accuracy by 1.66% and is more effective in developing an automated ripeness classifier for oil palm FFB. The developed ripeness classifier can act as a sensor in determining the correct oil palm FFB ripeness category. PMID:23202043

  19. Multi-capability color night vision HD camera for defense, surveillance, and security

    NASA Astrophysics Data System (ADS)

    Pang, Francis; Powell, Gareth; Fereyre, Pierre

    2015-05-01

    e2v has developed a family of high performance cameras based on our next generation CMOS imagers that provide multiple features and capabilities to meet the range of challenging imaging applications in defense, surveillance, and security markets. Two resolution sizes are available: 1920x1080 with 5.3 μm pixels, and an ultra-low light level version at 1280x1024 with 10μm pixels. Each type is available in either monochrome or e2v's unique bayer pattern color version. The camera is well suited to accommodate many of the high demands for defense, surveillance, and security applications: compact form factor (SWAP+C), color night vision performance (down to 10-2 lux), ruggedized housing, Global Shutter, low read noise (<6e- in Global shutter mode and <2.5e- in Rolling shutter mode), 60 Hz frame rate, high QE especially in the enhanced NIR range (up to 1100nm). Other capabilities include active illumination and range gating. This paper will describe all the features of the sensor and the camera. It will be followed with a presentation of the latest test data with the current developments. Then, it will conclude with a description of how these features can be easily configured to meet many different applications. With this development, we can tune rather than create a full customization, making it more beneficial for many of our customers and their custom applications.

  20. Set shot shooting performance and visual acuity in basketball.

    PubMed

    Applegate, R A; Applegate, R A

    1992-10-01

    Common sense suggests that decreasing visual acuity will have a negative effect on basketball shooting performance. To test the hypothesis that basketball shooting performance monotonically decreases with decreasing acuity, 19 subjects attempted 25 set shots from a fixed location at each of 5 different acuity levels: 6/6 or better and vision blurred (by optical defocus) to visual acuities of 6/12, 6/24, 6/48, and 6/75. Our results revealed a small but statistically nonsignificant decrease in shooting performance between the 6/6+ and 6/12 conditions. For visual acuities between 6/12 and 6/75, the number of baskets made remained constant. We conclude that decreases in visual acuity over the range of 6/6+ to 6/75 resulting from defocus do not significantly reduce set shot shooting performance. PMID:1436997

  1. Long-Term Occupational Exposure to Organic Solvents Affects Color Vision, Contrast Sensitivity and Visual Fields

    PubMed Central

    Costa, Thiago Leiros; Barboni, Mirella Telles Salgueiro; Moura, Ana Laura de Araújo; Bonci, Daniela Maria Oliveira; Gualtieri, Mirella; de Lima Silveira, Luiz Carlos; Ventura, Dora Fix

    2012-01-01

    The purpose of this study was to evaluate the visual outcome of chronic occupational exposure to a mixture of organic solvents by measuring color discrimination, achromatic contrast sensitivity and visual fields in a group of gas station workers. We tested 25 workers (20 males) and 25 controls with no history of chronic exposure to solvents (10 males). All participants had normal ophthalmologic exams. Subjects had worked in gas stations on an average of 9.6±6.2 years. Color vision was evaluated with the Lanthony D15d and Cambridge Colour Test (CCT). Visual field assessment consisted of white-on-white 24–2 automatic perimetry (Humphrey II-750i). Contrast sensitivity was measured for sinusoidal gratings of 0.2, 0.5, 1.0, 2.0, 5.0, 10.0 and 20.0 cycles per degree (cpd). Results from both groups were compared using the Mann–Whitney U test. The number of errors in the D15d was higher for workers relative to controls (p<0.01). Their CCT color discrimination thresholds were elevated compared to the control group along the protan, deutan and tritan confusion axes (p<0.01), and their ellipse area and ellipticity were higher (p<0.01). Genetic analysis of subjects with very elevated color discrimination thresholds excluded congenital causes for the visual losses. Automated perimetry thresholds showed elevation in the 9°, 15° and 21° of eccentricity (p<0.01) and in MD and PSD indexes (p<0.01). Contrast sensitivity losses were found for all spatial frequencies measured (p<0.01) except for 0.5 cpd. Significant correlation was found between previous working years and deutan axis thresholds (rho = 0.59; p<0.05), indexes of the Lanthony D15d (rho = 0.52; p<0.05), perimetry results in the fovea (rho = −0.51; p<0.05) and at 3, 9 and 15 degrees of eccentricity (rho = −0.46; p<0.05). Extensive and diffuse visual changes were found, suggesting that specific occupational limits should be created. PMID:22916187

  2. Visual modelling suggests a weak relationship between the evolution of ultraviolet vision and plumage coloration in birds.

    PubMed

    Lind, O; Delhey, K

    2015-03-01

    Birds have sophisticated colour vision mediated by four cone types that cover a wide visual spectrum including ultraviolet (UV) wavelengths. Many birds have modest UV sensitivity provided by violet-sensitive (VS) cones with sensitivity maxima between 400 and 425 nm. However, some birds have evolved higher UV sensitivity and a larger visual spectrum given by UV-sensitive (UVS) cones maximally sensitive at 360-370 nm. The reasons for VS-UVS transitions and their relationship to visual ecology remain unclear. It has been hypothesized that the evolution of UVS-cone vision is linked to plumage colours so that visual sensitivity and feather coloration are 'matched'. This leads to the specific prediction that UVS-cone vision enhances the discrimination of plumage colours of UVS birds while such an advantage is absent or less pronounced for VS-bird coloration. We test this hypothesis using knowledge of the complex distribution of UVS cones among birds combined with mathematical modelling of colour discrimination during different viewing conditions. We find no support for the hypothesis, which, combined with previous studies, suggests only a weak relationship between UVS-cone vision and plumage colour evolution. Instead, we suggest that UVS-cone vision generally favours colour discrimination, which creates a nonspecific selection pressure for the evolution of UVS cones. PMID:25664902

  3. Allelic variation in the squirrel monkey x-linked color vision gene: biogeographical and behavioral correlates.

    PubMed

    Cropp, Susan; Boinski, Sue; Li, Wen-Hsiung

    2002-06-01

    Most Neotropical primate species possess a polymorphic X-linked and a monomorphic autosomal color vision gene. Consequently, populations are composed of both dichromatics and trichromatics. Most theories on the maintenance of this genetic system revolve around possible advantages for foraging ecology. To examine the issue from a different angle, we compared the numbers and relative frequencies of alleles at the X-linked locus among three species of Saimiri representing a wide range of geographical and behavioral variation in the genus. Exons 3, 4, and 5 of the X-linked opsin gene were sequenced for a large number of X chromosomes for all three species. Several synonymous mutations were detected in exons 4 and 5 for the originally reported alleles but only a single nonsynonymous change was detected. Two alleles were found that appeared to be the result of recombination events. The low occurrence of recombinant alleles and absence of mutations in the amino acids critical for spectral tuning indicates that stabilizing selection acts to maintain the combinations of critical sites specific to each allele. Allele frequencies were approximately the same for all Saimiri species, with a slight but significant difference between S. boliviensis and S. oerstedii. No apparent correlation exists between allele frequencies and behavioral or biogeographical differences between species, casting doubt on the speculation that the spectral sensitivities of the alleles have been maintained because they are specifically well-tuned to Saimiri visual ecology. Rather, the spectral tuning peaks might have been maintained because they are as widely spaced as possible within the limited range of middlewave to longwave spectra useful to all primates. This arrangement creates a balance between maximizing the distance between spectral tuning peaks (allowing the color opponency of the visual system to distinguish between peaks) and maximizing the number of alleles within a limited range (yielding

  4. A Comparison of Patched HOTV Visual Acuity and Photoscreening

    ERIC Educational Resources Information Center

    Leman, Rachel; Clausen, Michelle M.; Bates, Janice; Stark, Lee; Arnold, Koni K.; Arnold, Robert W.

    2006-01-01

    Early detection of significant vision problems in children is a high priority for pediatricians and school nurses. Routine vision screening is a necessary part of that detection and has traditionally involved acuity charts. However, photoscreening in which "red eye" is elicited to show whether each eye is focusing may outperform routine acuity…

  5. Food search through the eyes of a monkey: a functional substitution approach for assessing the ecology of primate color vision.

    PubMed

    Melin, A D; Kline, D W; Hickey, C M; Fedigan, L M

    2013-06-28

    Efficient detection and selection of reddish fruits against green foliage has long been thought to be a major selective pressure favoring the evolution of primate trichromatic color vision. This has recently been questioned by studies of free-ranging primates that fail to show predicted differences in foraging efficiency between dichromats and trichromats. In the present study, we use a unique approach to evaluate the adaptive significance of trichromacy for fruit detection by undertaking a functional substitution model. The color vision phenotypes of neotropical monkeys are simulated for human observers, who use a touch-sensitive computer interface to search for monkey food items in digital images taken under natural conditions. We find an advantage to trichromatic phenotypes - especially the variant with the most spectrally separated visual pigments - for red, yellow and greenish fruits, but not for dark (purple or black) fruits. These results indicate that trichromat advantage is task-specific, and that shape, size and achromatic contrast variation between ripe and unripe fruits cannot completely mitigate the advantage of color vision. Similarities in fruit foraging performance between primates with different phenotypes in the wild likely reflect the behavioral flexibility of dichromats in overcoming a chromatic disadvantage. PMID:23643907

  6. Nocturnal light environments influence color vision and signatures of selection on the OPN1SW opsin gene in nocturnal lemurs.

    PubMed

    Veilleux, Carrie C; Louis, Edward E; Bolnick, Deborah A

    2013-06-01

    Although loss of short-wavelength-sensitive (SWS) cones and dichromatic color vision in mammals has traditionally been linked to a nocturnal lifestyle, recent studies have identified variation in selective pressure for the maintenance of the OPN1SW opsin gene (and thus, potentially dichromacy) among nocturnal mammalian lineages. These studies hypothesize that purifying selection to retain SWS cones may be associated with a selective advantage for nocturnal color vision under certain ecological conditions. In this study, we explore the effect of nocturnal light environment on OPN1SW opsin gene evolution in a diverse sample of nocturnal lemurs (106 individuals, 19 species, and 5 genera). Using both phylogenetic and population genetic approaches, we test whether species from closed canopy rainforests, which are impoverished in short-wavelength light, have experienced relaxed selection compared with species from open canopy forests. We identify clear signatures of differential selection on OPN1SW by habitat type. Our results suggest that open canopy species generally experience strong purifying selection to maintain SWS cones. In contrast, closed canopy species experience weaker purifying selection or a relaxation of selection on OPN1SW. We also found evidence of nonfunctional OPN1SW genes in all Phaner species and in Cheirogaleus medius, implying at least three independent losses of SWS cones in cheirogaleids. Our results suggest that the evolution of color vision in nocturnal lemurs has been influenced by nocturnal light environment. PMID:23519316

  7. Retinal Glial Cells Enhance Human Vision Acuity

    NASA Astrophysics Data System (ADS)

    Labin, A. M.; Ribak, E. N.

    2010-04-01

    We construct a light-guiding model of the retina outside the fovea, in which an array of glial (Muller) cells permeates the depth of the retina down to the photoreceptors. Based on measured refractive indices, we propagate light to obtain a significant increase of the intensity at the photoreceptors. For pupils up to 6 mm width, the coupling between neighboring cells is only a few percent. Low cross talk over the whole visible spectrum also explains the insensitivity to chromatic aberrations of the eye. The retina is revealed as an optimal structure designed for improving the sharpness of images.

  8. Relation between uncorrected astigmatism and visual acuity in pseudophakia.

    PubMed

    Singh, Archana; Pesala, Veerendranath; Garg, Prashant; Bharadwaj, Shrikant R

    2013-04-01

    PURPOSE.: The end point of astigmatic correction after cataract surgery will depend on how uncorrected astigmatism impacts distance and near vision of pseudophakic eyes. This study determined the impact of induced astigmatism and pupil size on the distance and near acuity of otherwise emmetropic pseudophakic eyes implanted with monofocal intraocular lenses. METHODS.: Monocular high-contrast distance (4 m) and near (40 cm) logMAR acuity was determined in 15 subjects (mean ± 1 SD, 57.9 ± 9.0 years) without astigmatism and with 2.5 diopters (D) myopic to 2.0 D hyperopic astigmatic lenses induced in 0.5-D steps at 0-, 45-, 90-, and 135-degree axes. This experiment was repeated for the same range of induced astigmatism with 1.5-, 3-, and 6-mm artificial pupil diameters placed before one eye of 10 subjects dilated with 10% phenylephrine HCl. RESULTS.: Distance acuity deteriorated with astigmatism for all axes tested (p < 0.01). Near acuity deteriorated with hyperopic astigmatism (p < 0.1), whereas it improved with up to 1 D of myopic astigmatism before saturating for all axes tested (p < 0.01). Distance and near acuity improved with a reduction in pupil diameter (p < 0.01). The change in distance and near acuity with induced astigmatism was smaller for 1.5-mm than for 3-mm and 6-mm pupil diameters (p < 0.01). CONCLUSIONS.: Partial restoration of near acuity with uncorrected myopic astigmatism comes with a proportional loss of distance acuity in pseudophakic eyes. Uncorrected myopic astigmatism more than 1 D results in a large loss of distance acuity at no additional benefit to near acuity. Both distance and near acuities with and without astigmatism are benefited with a reduction in pupil diameter. Uncorrected hyperopic astigmatism results in deterioration of both distance and near acuities of pseudophakic eyes. PMID:23458979

  9. Etiology of reduced visual acuity in congenital nystagmus.

    PubMed

    Spierer, A

    1991-10-01

    A study was undertaken to identify the etiologic factor of reduced visual acuity in congenital nystagmus. Fourteen children with congenital nystagmus and reduced visual acuity were examined, using a modified "E" game test. Their success rate in identifying vertical lines was compared with their success rate in identifying horizontal lines. The children identified both vertical and horizontal lines with a similar rate of success. These results may indicate that poor vision in congenital nystagmus patients is partly the result of amblyopia. PMID:1755616

  10. Malingering or simulation in ophthalmology-visual acuity.

    PubMed

    Incesu, Ali Ihsan; Sobacı, Güngör

    2011-01-01

    Simulation can be defined as malingering, or sometimes functional visual loss (FVL). It manifests as either simulating an ophthalmic disease (positive simulation), or denial of ophthalmic disease (negative simulation). Conscious behavior and compensation or indemnity claims are prominent features of simulation. Since some authors suggest that this is a manifestation of underlying psychopathology, even conversion is included in this context. In today's world, every ophthalmologist can face with simulation of ophthalmic disease or disorder. In case of simulation suspect, the physician's responsibility is to prove the simulation considering the disease/disorder first, and simulation as an exclusion. In simulation examinations, the physician should be firm and smart to select appropriate test(s) to convince not only the subject, but also the judge in case of indemnity or compensation trials. Almost all ophthalmic sensory and motor functions including visual acuity, visual field, color vision and night vision can be the subject of simulation. Examiner must be skillful in selecting the most appropriate test. Apart from those in the literature, we included all kinds of simulation in ophthalmology. In addition, simulation examination techniques, such as, use of OCT (optical coherence tomography), frequency doubling perimetry (FDP), and modified polarization tests were also included. In this review, we made a thorough literature search, and added our experiences to give the readers up-to-date information on malingering or simulation in ophthalmology. PMID:22553721

  11. Malingering or simulation in ophthalmology-visual acuity

    PubMed Central

    Incesu, Ali Ihsan; Sobacı, Güngör

    2011-01-01

    Simulation can be defined as malingering, or sometimes functional visual loss (FVL). It manifests as either simulating an ophthalmic disease (positive simulation), or denial of ophthalmic disease (negative simulation). Conscious behavior and compensation or indemnity claims are prominent features of simulation. Since some authors suggest that this is a manifestation of underlying psychopathology, even conversion is included in this context. In today's world, every ophthalmologist can face with simulation of ophthalmic disease or disorder. In case of simulation suspect, the physician's responsibility is to prove the simulation considering the disease/disorder first, and simulation as an exclusion. In simulation examinations, the physician should be firm and smart to select appropriate test(s) to convince not only the subject, but also the judge in case of indemnity or compensation trials. Almost all ophthalmic sensory and motor functions including visual acuity, visual field, color vision and night vision can be the subject of simulation. Examiner must be skillful in selecting the most appropriate test. Apart from those in the literature, we included all kinds of simulation in ophthalmology. In addition, simulation examination techniques, such as, use of OCT (optical coherence tomography), frequency doubling perimetry (FDP), and modified polarization tests were also included. In this review, we made a thorough literature search, and added our experiences to give the readers up-to-date information on malingering or simulation in ophthalmology. PMID:22553721

  12. Characterization of Opsin Gene Alleles Affecting Color Vision in a Wild Population of Titi Monkeys (Callicebus brunneus)

    PubMed Central

    Bunce, John A.; Isbell, Lynne A.; Neitz, Maureen; Bonci, Daniela; Surridge, Alison K.; Jacobs, Gerald H.; Smith, David Glenn

    2011-01-01

    The color vision of most platyrrhine primates is determined by alleles at the polymorphic X-linked locus coding for the opsin responsible for the middle- to long-wavelength (M/L) cone photopigment. Females who are heterozygous at the locus have trichromatic vision while homozygous females and all males are dichromatic. This study characterized the opsin alleles in a wild population of the socially monogamous platyrrhine monkey Callicebus brunneus (the brown titi monkey), a primate that an earlier study suggests may possess an unusual number of alleles at this locus and thus may be a subject of special interest in the study of primate color vision. Direct sequencing of regions of the M/L opsin gene using feces-, blood-, and saliva-derived DNA obtained from 14 individuals yielded evidence for the presence of three functionally distinct alleles, corresponding to the most common M/L photopigment variants inferred from a physiological study of cone spectral sensitivity in captive Callicebus. PMID:20938927

  13. Characterization of opsin gene alleles affecting color vision in a wild population of titi monkeys (Callicebus brunneus).

    PubMed

    Bunce, John A; Isbell, Lynne A; Neitz, Maureen; Bonci, Daniela; Surridge, Alison K; Jacobs, Gerald H; Smith, David Glenn

    2011-02-01

    The color vision of most platyrrhine primates is determined by alleles at the polymorphic X-linked locus coding for the opsin responsible for the middle- to long-wavelength (M/L) cone photopigment. Females who are heterozygous at the locus have trichromatic vision, whereas homozygous females and all males are dichromatic. This study characterized the opsin alleles in a wild population of the socially monogamous platyrrhine monkey Callicebus brunneus (the brown titi monkey), a primate that an earlier study suggests may possess an unusual number of alleles at this locus and thus may be a subject of special interest in the study of primate color vision. Direct sequencing of regions of the M/L opsin gene using feces-, blood-, and saliva-derived DNA obtained from 14 individuals yielded evidence for the presence of three functionally distinct alleles, corresponding to the most common M/L photopigment variants inferred from a physiological study of cone spectral sensitivity in captive Callicebus. PMID:20938927

  14. Motion and color analysis for animat perception

    SciTech Connect

    Rabie, T.F.; Terzopoulos, D.

    1996-12-31

    We propose novel gaze control algorithms for active perception in mobile autonomous agents with directable, foveated vision sensors. Our agents are realistic artificial animals, or animals, situated in physics-based virtual worlds. Their active perception systems continuously analyze photorealistic retinal image streams to glean information useful for controlling the animal`s eyes and body. The vision system computes optical flow and segments moving targets in the low-resolution visual periphery. It then matches segmented targets against mental models of colored objects of interest. The eyes saccade to increase acuity by foveating objects, The resulting sensorimotor control loop supports complex behaviors, such as predation.

  15. Visual acuity and pupillary reactions after peribulbar anaesthesia.

    PubMed Central

    Talks, S J; Chong, N H; Gibson, J M; Francis, I R

    1994-01-01

    The effect of peribulbar anaesthesia on optic nerve function in 20 patients, before and after cataract surgery, was measured. All the patients had decreased visual acuity. Five (25%) had no perception of light. Seventeen (85%) developed a relative afferent pupil defect (RAPD). No patients saw the operating instruments. Seven (35%) had improved visual acuity immediately postoperatively. Patients should be warned that they may lose vision completely on being given a peribulbar anaesthetic; however their vision will improve, but not necessarily immediately, postoperatively. Examination for an RAPD is a good method of providing reassurance that the operating instruments will not be seen. PMID:8110698

  16. Incorporating ecology and social system into formal hypotheses to guide field studies of color vision in primates.

    PubMed

    Bunce, John A

    2015-05-01

    The X-linked gene polymorphism responsible for the variable color vision of most Neotropical monkeys and some lemurs is thought to be maintained by balancing selection, such that trichromats have an advantage over dichromats for some ecologically important task(s). However, evidence for such an advantage in wild primate populations is equivocal. The purpose of this study is to refine a hypothesis for a trichromat advantage by tailoring it to the ecology of territorial primates with female natal dispersal, such that dispersing trichromatic females have a foraging and, by extension, survival advantage over dichromats. I then examine the most practical way to test this hypothesis using field data. Indirect evidence in support of the hypothesis may take the form of differences in genotype frequencies among life stages and differences in disperser food item encounter rates. A deterministic evolutionary matrix population model and a stochastic model of food patch encounter rates are constructed to investigate the magnitude of such differences and the likelihood of statistical detection using field data. Results suggest that, although the sampling effort required to detect the hypothesized genotype frequency differences is impractical, a field study of reasonable scope may be able to detect differences in disperser foraging rates. This study demonstrates the utility of incorporating socioecological details into formal hypotheses during the planning stages of field studies of primate color vision. PMID:25690845

  17. Assessing the utility of visual acuity measures in visual prostheses.

    PubMed

    Caspi, Avi; Zivotofsky, Ari Z

    2015-03-01

    There are presently several ongoing clinical trials to provide usable sight to profoundly visually impaired patients by means of electrical stimulation of the retina. Some of the blind patients implanted with retinal prosthesis reported un-patterned perception and yet benefit from the device in many activities of daily living, seemingly because they adopt active scanning strategies. The aim of the present work is to evaluate if and under what conditions a measured visual acuity level is truly an indication that the brain perceived a patterned image from the electrical stimulation of the visual prosthesis. Sighted subjects used a pixelized simulator in which they perceived either a low resolution sub-sampling of the original image ("normal mode"--patterned vision) or an image that was solely a function of the brightness and size of the original image ("brightness mode"--no patterned vision). Results show that subjects were able to adopt a head scanning strategy that enabled acuity beyond the resolution set by a static view of the stimulus. In brightness mode, i.e. without patterned vision, most subjects achieved a measurable acuity level better than the limit set by the geometrical resolution of the entire array but worse than the limit set by the distance between neighboring simulated pixels. In normal mode all subject achieved acuity level that is better than the geometrical resolution of the simulated pixels. Thus, visual acuity levels comparable with the electrodes/pixels resolution implies that the patient perceives an image with spatial patterns. PMID:25637855

  18. Tactile Acuity Charts: A Reliable Measure of Spatial Acuity

    PubMed Central

    Bruns, Patrick; Camargo, Carlos J.; Campanella, Humberto; Esteve, Jaume; Dinse, Hubert R.; Röder, Brigitte

    2014-01-01

    For assessing tactile spatial resolution it has recently been recommended to use tactile acuity charts which follow the design principles of the Snellen letter charts for visual acuity and involve active touch. However, it is currently unknown whether acuity thresholds obtained with this newly developed psychophysical procedure are in accordance with established measures of tactile acuity that involve passive contact with fixed duration and control of contact force. Here we directly compared tactile acuity thresholds obtained with the acuity charts to traditional two-point and grating orientation thresholds in a group of young healthy adults. For this purpose, two types of charts, using either Braille-like dot patterns or embossed Landolt rings with different orientations, were adapted from previous studies. Measurements with the two types of charts were equivalent, but generally more reliable with the dot pattern chart. A comparison with the two-point and grating orientation task data showed that the test-retest reliability of the acuity chart measurements after one week was superior to that of the passive methods. Individual thresholds obtained with the acuity charts agreed reasonably with the grating orientation threshold, but less so with the two-point threshold that yielded relatively distinct acuity estimates compared to the other methods. This potentially considerable amount of mismatch between different measures of tactile acuity suggests that tactile spatial resolution is a complex entity that should ideally be measured with different methods in parallel. The simple test procedure and high reliability of the acuity charts makes them a promising complement and alternative to the traditional two-point and grating orientation thresholds. PMID:24504346

  19. Influence of loupes and age on the near visual acuity of practicing dentists

    NASA Astrophysics Data System (ADS)

    Eichenberger, Martina; Perrin, Philippe; Neuhaus, Klaus W.; Bringolf, Ueli; Lussi, Adrian

    2011-03-01

    We evaluated the near visual acuity of 40 dentists and its improvement by using different magnification devices. The acuity was tested with miniaturized E-optotype tests on a negatoscope under the following conditions: 1. natural visual acuity, 300 mm; 2. single lens loupe, 2×, 250 mm; 3. Galilean loupe, 2.5×, 380 mm; and 4. Keplerian loupe, 4.3×, 400 mm. In part 1, the influence of the magnification devices was investigated for all dentists. The Keplerian loupe obtained the highest visual acuity (4.64), followed by the Galilean loupe (2.43), the single lens loupe (1.42), and natural visual acuity (1.19). For part 2, the dentists were classified according to their age (=40 years). The younger dentists' group achieved a significantly higher visual acuity with all magnification devices (p<0.001). For part 3, the dentists were grouped according to their natural visual acuity. The group with the higher natural visual acuity achieved significantly higher visual acuity with all magnification devices than did the group of dentists with the lower natural visual acuity (p<0.01). It can be concluded that near visual acuity varies highly between individuals and decreases during the lifetime. Independent of age or natural vision, visual acuity can be significantly improved by using magnification devices.

  20. Color vision in attention-deficit/hyperactivity disorder: A pilot visual evoked potential study

    PubMed Central

    Kim, Soyeon; Banaschewski, Tobias; Tannock, Rosemary

    2014-01-01

    Background Individuals with attention-deficit/hyperactivity disorder (ADHD) are reported to manifest visual problems (including ophthalmological and color perception, particularly for blue–yellow stimuli), but findings are inconsistent. Accordingly, this study investigated visual function and color perception in adolescents with ADHD using color Visual Evoked Potentials (cVEP), which provides an objective measure of color perception. Method Thirty-one adolescents (aged 13–18), 16 with a confirmed diagnosis of ADHD, and 15 healthy peers, matched for age, gender, and IQ participated in the study. All underwent an ophthalmological exam, as well as electrophysiological testing color Visual Evoked Potentials (cVEP), which measured the latency and amplitude of the neural P1 response to chromatic (blue–yellow, red–green) and achromatic stimuli. Result No intergroup differences were found in the ophthalmological exam. However, significantly larger P1 amplitude was found for blue and yellow stimuli, but not red/green or achromatic stimuli, in the ADHD group (particularly in the medicated group) compared to controls. Conclusion Larger amplitude in the P1 component for blue–yellow in the ADHD group compared to controls may account for the lack of difference in color perception tasks. We speculate that the larger amplitude for blue–yellow stimuli in early sensory processing (P1) might reflect a compensatory strategy for underlying problems including compromised retinal input of s-cones due to hypo-dopaminergic tone. PMID:25435188

  1. [The role of rotary prisms and dynamic color stimuli in binocular vision recovery in children with squint].

    PubMed

    Seleznev, A V; Vakurin, E A; Kashchenko, T P; Vakurina, A E; Abramova, T F

    2010-01-01

    A modified procedure for diploid treatment is proposed to disinhibit a functional scotoma and to develop binocular vision (BV) in children with squint. The procedure is to examine a special test object through rotary prisms and polaroid filters inserted into a modernized spectacle frame. During treatment there is an opportunity of simultaneously changing the color of the test object and the position of its image on the retina. The study enrolled children in whom previous traditional methods for BV recovery had failed. Treatment using the proposed procedure could recover bifoveal fusion in 88.3% of cases (as evidenced by synoptophore examination) and BY in 73.3% (as shown by scanning haploscopy). PMID:20608198

  2. 75 FR 10808 - CIBA Vision Corp.; Withdrawal of Color Additive Petitions

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-03-09

    .... SUPPLEMENTARY INFORMATION: In a notice published in the Federal Register of August 17, 2005 (70 FR 48426), FDA....) Pigment Violet 19, C.I. Pigment Yellow 154, and C.I. Pigment Red 122 as color additives in contact lenses.... Pigment Violet 19 (CAP 5C0278, Docket No. FDA-2005-C- 0245), C.I. Pigment Yellow 154 (CAP 5C0279,...

  3. True RGB line-scan camera for color machine vision applications

    NASA Astrophysics Data System (ADS)

    Lemstrom, Guy F.

    1994-10-01

    The design and technical capabilities of a true RGB 3 CCD chip color line scan camera are presented within this paper. The camera was developed for accurate color monitoring and analysis in industrial applications. A black & white line scan camera has been designed and built utilizing the same modular architecture of the color line scan camera. Color separation is made possible with a tri-chromatic RGB beam splitter. Three CCD linear arrays are precisely mounted to the output surfaces of the prism and the outputs of each CCD are exactly matched pixel by pixel. The beam splitter prism can be tailored to separate other spectral components than the standard RGB. A typical CCD can detect between 200 and 100 nm. Either two or three spectral regions can be separated using a beam splitter prism. The camera is totally digital and has a 16-bit parallel computer interface to communicate with a signal processing board. Because of the open architecture of the camera it's possible for the customer to design a board with some special functions handling the preprocessing of the data (for example RGB - HSI conversion). The camera can also be equipped with a high speed CPU-board with enough of local memory to do some image processing inside the camera before sending the data forward. The camera has been used in real industrial applications and has proven that its high resolution and high dynamic range can be used to measure minute color differences, enabling the separation or grading of objects such as minerals, food or other materials that could not otherwise be measured with a black and white camera.

  4. The Effect of Zeaxanthin on the Visual Acuity of Zebrafish

    PubMed Central

    Saidi, Eric A.; Davey, Pinakin Gunvant; Cameron, D. Joshua

    2015-01-01

    Oral supplementation of carotenoids such as zeaxanthin or lutein which naturally occur in human retina have been shown to improve vision and prevent progression of damage to advanced AMD in some studies. The zebrafish eye shares many physiological similarities with the human eye and is increasingly being used as model for vision research. We hypothesized that injection of zeaxanthin into the zebrafish eye would improve the visual acuity of the zebrafish over time. Visual acuity, calculated in cycles per degree, was measured in adult zebrafish to establish a consistent baseline using the optokinetic response. Zeaxanthin dissolved into phosphate buffered saline (PBS) or PBS only was injected into the anterior chamber of the right and left eyes of the Zebrafish. Visual acuities were measured at 1 week and 3, 8 and 12 weeks post-injection to compare to baseline values. Repeated measures ANOVA was used to compare visual acuities between fish injected with PBS and zeaxanthin. A significant improvement in visual acuity, 14% better than before the injection (baseline levels), was observed one week after injection with zeaxanthin (p = 0.04). This improvement peaked at more than 30% for some fish a few weeks after the injection and improvement in vision persisted at 3 weeks after injection (p = 0.006). The enhanced visual function was not significantly better than baseline at 8 weeks (p = 0.19) and returned to baseline levels 12 weeks after the initial injection (p = 0.50). Zeaxanthin can improve visual acuity in zebrafish eyes. Further studies are required to develop a better understanding of the role zeaxanthin and other carotenoids play during normal visual function. PMID:26267864

  5. The Heterozygote Superiority Hypothesis for Polymorphic Color Vision Is Not Supported by Long-Term Fitness Data from Wild Neotropical Monkeys

    PubMed Central

    Fedigan, Linda M.; Melin, Amanda D.; Addicott, John F.; Kawamura, Shoji

    2014-01-01

    The leading explanatory model for the widespread occurrence of color vision polymorphism in Neotropical primates is the heterozygote superiority hypothesis, which postulates that trichromatic individuals have a fitness advantage over other phenotypes because redgreen chromatic discrimination is useful for foraging, social signaling, or predator detection. Alternative explanatory models predict that dichromatic and trichromatic phenotypes are each suited to distinct tasks. To conclusively evaluate these models, one must determine whether proposed visual advantages translate into differential fitness of trichromatic and dichromatic individuals. We tested whether color vision phenotype is a significant predictor of female fitness in a population of wild capuchins, using longterm 26 years survival and fertility data. We found no advantage to trichromats over dichromats for three fitness measures fertility rates, offspring survival and maternal survival. This finding suggests that a selective mechanism other than heterozygote advantage is operating to maintain the color vision polymorphism. We propose that attention be directed to field testing the alternative mechanisms of balancing selection proposed to explain opsin polymorphism nichedivergence, frequencydependence and mutual benefit of association. This is the first indepth, longterm study examining the effects of color vision variation on survival and reproductive success in a naturallyoccurring population of primates. PMID:24404195

  6. Color vision in Lycaena butterflies: spectral tuning of receptor arrays in relation to behavioral ecology.

    PubMed

    Bernard, G D; Remington, C L

    1991-04-01

    Males of two closely related, co-occurring species of Lycaena butterflies have dorsally blue (Lycaena heteronea) or red-orange plus ultraviolet (Lycaena rubidus) wings. Males are selectively territorial against conspecific males. Virgin females accept only conspecific males, probably chosen by wing color. Females are nonterritorial and spend most of their adult activity ovipositing on the correct larval food plants. Eyes of both species contain four spectral types of visual pigments (P360, P437, P500, and P568) but the distribution of these pigments within the receptor mosaic is quite different between both species and sexes. The ventral eye region of L. heteronea is tetrachromatic but that of L. rubidus is trichromatic, lacking the blue-sensitive visual pigment P437. The dorsal eye region of males of both species is dichromatic (P360 and P437). Visual-pigment spectra and wing-reflectance spectra are well matched for effective discrimination of wings of conspecific males from those of other species. The dorsal region of female eyes is trichromatic, containing P360, P437, and P568. The third visual pigment, P568, is important for long-range detection by ovipositing females of red coloration on Eriogonum and Rumex food plants. P568 has the same absorbance spectrum as the human red-cone and is considerably red-shifted compared to the P530 possessed by most insects. That the sexes and closely related species can have such major differences in distribution of visual pigments indicates that the visual system is as readily altered as wing coloration in the course of adaptive evolution. PMID:2011588

  7. Losses of functional opsin genes, short-wavelength cone photopigments, and color vision--a significant trend in the evolution of mammalian vision.

    PubMed

    Jacobs, Gerald H

    2013-03-01

    All mammalian cone photopigments are derived from the operation of representatives from two opsin gene families (SWS1 and LWS in marsupial and eutherian mammals; SWS2 and LWS in monotremes), a process that produces cone pigments with respective peak sensitivities in the short and middle-to-long wavelengths. With the exception of a number of primate taxa, the modal pattern for mammals is to have two types of cone photopigment, one drawn from each of the gene families. In recent years, it has been discovered that the SWS1 opsin genes of a widely divergent collection of eutherian mammals have accumulated mutational changes that render them nonfunctional. This alteration reduces the retinal complements of these species to a single cone type, thus rendering ordinary color vision impossible. At present, several dozen species from five mammalian orders have been identified as falling into this category, but the total number of mammalian species that have lost short-wavelength cones in this way is certain to be much larger, perhaps reaching as high as 10% of all species. A number of circumstances that might be used to explain this widespread cone loss can be identified. Among these, the single consistent fact is that the species so affected are nocturnal or, if they are not technically nocturnal, they at least feature retinal organizations that are typically associated with that lifestyle. At the same time, however, there are many nocturnal mammals that retain functional short-wavelength cones. Nocturnality thus appears to set the stage for loss of functional SWS1 opsin genes in mammals, but it cannot be the sole circumstance. PMID:23286388

  8. Color measurements based on a color camera

    NASA Astrophysics Data System (ADS)

    Marszalec, Elzbieta A.; Pietikaeinen, Matti

    1997-08-01

    The domain of color camera applications is increasing all time due to recent progress in color machine vision research. Colorimetric measurement tasks are quite complex as the purpose of color measurement is to provide a quantitative evaluation of the phenomenon of colors as perceived by human vision. A proper colorimetric calibration of the color camera system is needed in order to make color a practical tool in machine vision. This paper discuses two approaches to color measurements based on a color camera and includes an overview of practical approaches to color camera calibration under unstable illumination conditions.

  9. G6PD haplotypes spanning Xq28 from F8C to red/green color vision

    SciTech Connect

    Filosa, S.; Lania, G.; Martini, G. ); Brancati, C.; Tagarelli, A. ); Calabro, V. Hammersmith Hospital, London ); Vulliamy, T.J.; Luzzatto, L. )

    1993-07-01

    The most telomeric region of the human X chromosome within band Xq28 consists of a gene-rich region of about 3 Mb which contains the genes for coagulation factor VIIIc, glucose-6-phosphate dehydrogenase (G6PD), and red/green color vision. The authors have studied five polymorphic sites from this region, in a sample of normal people from the Cosenza province of Southern Italy. These sites, which span a distance of some 350 kb, are in strong linkage disequilibrium. Of the 32 possible haplotypes only 10 were found, and 4 of these account for 80% of all X chromosomes analyzed. In addition, they found that all G6PD-deficient people with the G6PD Mediterranean mutation belong to only two haplotypes. One of these (Med 1) is found only within a small subregion of the area investigated, west of the Appennine mountain range. Most remarkably, all Med 1 G6PD-deficient individuals also had red/green color blindness. The more frequent haplotype (Med 2) is the same in Calabria and in Sardinia, where it accounts for about 90% of the G6PD Mediterranean mutations, despite the fact that gene flow between the populations of Sardinia and Southern Italy must have been limited. These data do not enable determination of whether the two types of G6PD Mediterranean have arisen through two separate identical mutational events or through a single mutational event followed by recombination. However, the data indicate relatively little recombination over an extended region of the X chromosome and they suggest that the G6PD Mediterranean mutation is recent by comparison to the other polymorphisms investigated. 44 refs., 4 figs., 5 tabs.

  10. Wavelet Based Multipurpose Color Image Watermarking by Using Dual Watermarks with Human Vision System Models

    NASA Astrophysics Data System (ADS)

    Tsai, Min-Jen; Lin, Chih-Wen

    In this study, we propose a complete architecture based on digital watermarking techniques to solve the issue of copyright protection and authentication for digital contents. We apply visible and semi-fragile watermarks as dual watermarks where visible watermarking is used to establish the copyright protection and semi-fragile watermarking authenticates and verifies the integrity of the watermarked image. In order to get the best tradeoff between the embedding energy of watermark and the perceptual translucence for visible watermark, the composite coefficients using global and local characteristics of the host and watermark images in the discrete wavelet transform (DWT) domain is considered with Human Vision System (HVS) models. To achieve the optimum noise reduction of the visibility thresholds for HVS in DWT domain, the contrast-sensitive function (CSF) and noise visible function (NVF) of perceptual model is applied which characterizes the global and local image properties and identifies texture and edge regions to determine the optimal watermark locations and strength at the watermark embedding stage. In addition, the perceptual weights according to the basis function amplitudes of DWT coefficients is fine tuned for the best quality of perceptual translucence in the design of the proposed watermarking algorithm. Furthermore, the semi-fragile watermark can detect and localize malicious attack effectively yet tolerate mild modifications such as JPEG compression and channel additive white Gaussian noise (AWGN). From the experimental results, our proposed technique not only improves the PSNR values and visual quality than other algorithms but also preserves the visibility of the watermark visible under various signal processing and advanced image recovery attacks.

  11. Dynamic Visual Acuity: a Functionally Relevant Research Tool

    NASA Technical Reports Server (NTRS)

    Peters, Brian T.; Brady, Rachel A.; Miller, Chris A.; Mulavara, Ajitkumar P.; Wood, Scott J.; Cohen, Helen S.; Bloomberg, Jacob J.

    2010-01-01

    Coordinated movements between the eyes and head are required to maintain a stable retinal image during head and body motion. The vestibulo-ocular reflex (VOR) plays a significant role in this gaze control system that functions well for most daily activities. However, certain environmental conditions or interruptions in normal VOR function can lead to inadequate ocular compensation, resulting in oscillopsia, or blurred vision. It is therefore possible to use acuity to determine when the environmental conditions, VOR function, or the combination of the two is not conductive for maintaining clear vision. Over several years we have designed and tested several tests of dynamic visual acuity (DVA). Early tests used the difference between standing and walking acuity to assess decrements in the gaze stabilization system after spaceflight. Supporting ground-based studies measured the responses from patients with bilateral vestibular dysfunction and explored the effects of visual target viewing distance and gait cycle events on walking acuity. Results from these studies show that DVA is affected by spaceflight, is degraded in patients with vestibular dysfunction, changes with target distance, and is not consistent across the gait cycle. We have recently expanded our research to include studies in which seated subjects are translated or rotated passively. Preliminary results from this work indicate that gaze stabilization ability may differ between similar active and passive conditions, may change with age, and can be affected by the location of the visual target with respect to the axis of motion. Use of DVA as a diagnostic tool is becoming more popular but the functional nature of the acuity outcome measure also makes it ideal for identifying conditions that could lead to degraded vision. By doing so, steps can be taken to alter the problematic environments to improve the man-machine interface and optimize performance.

  12. Vision screening in school children in Strzelin County

    NASA Astrophysics Data System (ADS)

    Zając, Marek

    2007-04-01

    Investigation of children vision is one of the most important tasks in pediatric medical care. According to World Health Organization screening done with rapid and simple tests should be considered as initial step of such care. Thanks to simple screening tests it is possible to identify children who probably are burden with eye problems and to distinguish them from the children with correct vision. Typical test for screening 6-years-old children (beginning their school education) includes, among others, evaluation of visual acuity for far and/or near and evaluation of binocular vision. This contribution describes the methods and results of screening program covering 21 elementary schools and 450 children in Strzelin County (Lower Silesia). Visual acuity was measured with help of SCOLATEST TM and binocular vision with RANDOM DOT E STEREOTEST. Additionally color recognition was tested with Ishihara Children Plates. The results suggest that almost 29% of investigated children have refraction error (9% being myopes and 20% being hyperopes), and 9% has problems with binocular vision.

  13. Self-organized criticality and color vision: A guide to water-protein landscape evolution

    NASA Astrophysics Data System (ADS)

    Phillips, J. C.

    2013-02-01

    We focus here on the scaling properties of small interspecies differences between red cone opsin transmembrane proteins, using a hydropathic elastic roughening tool previously applied to the rhodopsin rod transmembrane proteins. This tool is based on a non-Euclidean hydropathic metric realistically rooted in the atomic coordinates of 5526 protein segments, which thereby encapsulates universal non-Euclidean long-range differential geometrical features of water films enveloping globular proteins in the Protein Data Bank. Whereas the rhodopsin blue rod water films are smoothest in humans, the red cone opsins’ water films are optimized for smoothness in cats and elephants, consistent with protein species landscapes that evolve differently in different contexts. We also analyze red cone opsins in the chromatophore-containing family of chameleons, snakes, zebrafish and goldfish, where short- and long-range (BLAST and hydropathic) amino acid (aa) correlations are found with values as large as 97%-99%. We use hydropathic aa optimization to estimate the maximum number Nmax of color shades that the human eye can discriminate, and obtain 106

  14. Color matrix display simulation based upon luminance and chromatic contrast sensitivity of early vision

    NASA Technical Reports Server (NTRS)

    Martin, Russel A.; Ahumada, Albert J., Jr.; Larimer, James O.

    1992-01-01

    This paper describes the design and operation of a new simulation model for color matrix display development. It models the physical structure, the signal processing, and the visual perception of static displays, to allow optimization of display design parameters through image quality measures. The model is simple, implemented in the Mathematica computer language, and highly modular. Signal processing modules operate on the original image. The hardware modules describe backlights and filters, the pixel shape, and the tiling of the pixels over the display. Small regions of the displayed image can be visualized on a CRT. Visual perception modules assume static foveal images. The image is converted into cone catches and then into luminance, red-green, and blue-yellow images. A Haar transform pyramid separates the three images into spatial frequency and direction-specific channels. The channels are scaled by weights taken from human contrast sensitivity measurements of chromatic and luminance mechanisms at similar frequencies and orientations. Each channel provides a detectability measure. These measures allow the comparison of images displayed on prospective devices and, by that, the optimization of display designs.

  15. Color-detection thresholds in rhesus macaque monkeys and humans

    PubMed Central

    Gagin, Galina; Bohon, Kaitlin S.; Butensky, Adam; Gates, Monica A.; Hu, Jiun-Yiing; Lafer-Sousa, Rosa; Pulumo, Reitumetse L.; Qu, Jane; Stoughton, Cleo M.; Swanbeck, Sonja N.; Conway, Bevil R.

    2014-01-01

    Macaque monkeys are a model of human color vision. To facilitate linking physiology in monkeys with psychophysics in humans, we directly compared color-detection thresholds in humans and rhesus monkeys. Colors were defined by an equiluminant plane of cone-opponent color space. All subjects were tested on an identical apparatus with a four-alternative forced-choice task. Targets were 2° square, centered 2° from fixation, embedded in luminance noise. Across all subjects, the change in detection thresholds from initial testing to plateau performance (“learning”) was similar for +L − M (red) colors and +M − L (bluish-green) colors. But the extent of learning was higher for +S (lavender) than for −S (yellow-lime); moreover, at plateau performance, the cone contrast at the detection threshold was higher for +S than for −S. These asymmetries may reflect differences in retinal circuitry for S-ON and S-OFF. At plateau performance, the two species also had similar detection thresholds for all colors, although monkeys had shorter reaction times than humans and slightly lower thresholds for colors that modulated L/M cones. We discuss whether these observations, together with previous work showing that monkeys have lower spatial acuity than humans, could be accounted for by selective pressures driving higher chromatic sensitivity at the cost of spatial acuity amongst monkeys, specifically for the more recently evolved L − M mechanism. PMID:25027164

  16. Color-detection thresholds in rhesus macaque monkeys and humans.

    PubMed

    Gagin, Galina; Bohon, Kaitlin S; Butensky, Adam; Gates, Monica A; Hu, Jiun-Yiing; Lafer-Sousa, Rosa; Pulumo, Reitumetse L; Qu, Jane; Stoughton, Cleo M; Swanbeck, Sonja N; Conway, Bevil R

    2014-01-01

    Macaque monkeys are a model of human color vision. To facilitate linking physiology in monkeys with psychophysics in humans, we directly compared color-detection thresholds in humans and rhesus monkeys. Colors were defined by an equiluminant plane of cone-opponent color space. All subjects were tested on an identical apparatus with a four-alternative forced-choice task. Targets were 2° square, centered 2° from fixation, embedded in luminance noise. Across all subjects, the change in detection thresholds from initial testing to plateau performance (“learning”) was similar for +L − M (red) colors and +M − L (bluish-green) colors. But the extent of learning was higher for +S (lavender) than for −S (yellow-lime); moreover, at plateau performance, the cone contrast at the detection threshold was higher for +S than for −S. These asymmetries may reflect differences in retinal circuitry for S-ON and S-OFF. At plateau performance, the two species also had similar detection thresholds for all colors, although monkeys had shorter reaction times than humans and slightly lower thresholds for colors that modulated L/M cones. We discuss whether these observations, together with previous work showing that monkeys have lower spatial acuity than humans, could be accounted for by selective pressures driving higher chromatic sensitivity at the cost of spatial acuity amongst monkeys, specifically for the more recently evolved L − M mechanism. PMID:25027164

  17. Acuity-driven gigapixel visualization.

    PubMed

    Papadopoulos, Charilaos; Kaufman, Arie E

    2013-12-01

    We present a framework for acuity-driven visualization of super-high resolution image data on gigapixel displays. Tiled display walls offer a large workspace that can be navigated physically by the user. Based on head tracking information, the physical characteristics of the tiled display and the formulation of visual acuity, we guide an out-of-core gigapixel rendering scheme by delivering high levels of detail only in places where it is perceivable to the user. We apply this principle to gigapixel image rendering through adaptive level of detail selection. Additionally, we have developed an acuity-driven tessellation scheme for high-quality Focus-and-Context (F+C) lenses that significantly reduces visual artifacts while accurately capturing the underlying lens function. We demonstrate this framework on the Reality Deck, an immersive gigapixel display. We present the results of a user study designed to quantify the impact of our acuity-driven rendering optimizations in the visual exploration process. We discovered no evidence suggesting a difference in search task performance between our framework and naive rendering of gigapixel resolution data, while realizing significant benefits in terms of data transfer overhead. Additionally, we show that our acuity-driven tessellation scheme offers substantially increased frame rates when compared to naive pre-tessellation, while providing indistinguishable image quality. PMID:24051856

  18. Alouatta Trichromatic Color Vision: Cone Spectra and Physiological Responses Studied with Microspectrophotometry and Single Unit Retinal Electrophysiology

    PubMed Central

    Silveira, Luiz Carlos L.; Saito, Cézar A.; da Silva Filho, Manoel; Kremers, Jan; Bowmaker, James K.; Lee, Barry B.

    2014-01-01

    The howler monkeys (Alouatta sp.) are the only New World primates to exhibit routine trichromacy. Both males and females have three cone photopigments. However, in contrast to Old World monkeys, Alouatta has a locus control region upstream of each opsin gene on the X-chromosome and this might influence the retinal organization underlying its color vision. Post-mortem microspectrophotometry (MSP) was performed on the retinae of two male Alouatta to obtain rod and cone spectral sensitivities. The MSP data were consistent with only a single opsin being expressed in each cone and electrophysiological data were consistent with this primate expressing full trichromacy. To study the physiological organization of the retina underlying Alouatta trichromacy, we recorded from retinal ganglion cells of the same animals used for MSP measurements with a variety of achromatic and chromatic stimulus protocols. We found MC cells and PC cells in the Alouatta retina with similar properties to those previously found in the retina of other trichromatic primates. MC cells showed strong phasic responses to luminance changes and little response to chromatic pulses. PC cells showed strong tonic response to chromatic changes and small tonic response to luminance changes. Responses to other stimulus protocols (flicker photometry; changing the relative phase of red and green modulated lights; temporal modulation transfer functions) were also similar to those recorded in other trichromatic primates. MC cells also showed a pronounced frequency double response to chromatic modulation, and with luminance modulation response saturation accompanied by a phase advance between 10–20 Hz, characteristic of a contrast gain mechanism. This indicates a very similar retinal organization to Old-World monkeys. Cone-specific opsin expression in the presence of a locus control region for each opsin may call into question the hypothesis that this region exclusively controls opsin expression. PMID:25405863

  19. [Current views on vision of mammals].

    PubMed

    Khokhlova, T V

    2012-01-01

    In the review, research data are presented on mammals' vision including visual pigments, color and contrast vision, and visual behaviour in different species. It is shown that in course of evolution mammals were gradually losing the elements of daylight cone vision system that are typical of other vertebrates. In monotremes, visual pigments SWS2 (cone blue-sensitive 2) and MWS/LWS (green/red-sensitive) are still present, as well as rod RH1. Theria, except some primates, also have two cone visual pigments: SWS1 (ultraviolet/violet or blue-sensitive 1) and MWS/LWS along with rod RH1. Humans and some other higher primates evolved the new visual pigment, MWS, and acquired trichromatic vision. Marine mammals (cetaceans and pinnipeds) and some species of other orders have lost also the visual pigment SWS1, probably due to specificity of processing the information received by these cones. Current view on mammals' vision with two cone pigments and rods is presented. Data on maximum spectral sensitivity of visual pigments in different species and orders are given along with data on spatial contrast sensation. High visual acuity has been acquired by ungulates, artiodactyls, and primates, while the highest one--by humans with their specialized fovea. PMID:23330397

  20. From A Physical Color Stimulus To A Psychological Color Percept

    NASA Astrophysics Data System (ADS)

    Sporea, Dan G.; Tonnquist, Gunnar

    1989-08-01

    The paper discusses the complexity of color vision in humans, considering the main aspects involved: the physical aspect, the psychophysical aspect, the physiological aspect and the psychological aspect. The meanings of the term color associated to each such aspect (asfor example, color stimulus, color valence, neural color signal and color percept) are introduced. Some types of color defective vision, relevant for color display users, are indicated. The methods to generate color stimuli in modern display devices, employing different technologies, are compared.

  1. A double dissociation of the acuity and crowding limits to letter identification, and the promise of improved visual screening.

    PubMed

    Song, Shuang; Levi, Dennis M; Pelli, Denis G

    2014-01-01

    Here, we systematically explore the size and spacing requirements for identifying a letter among other letters. We measure acuity for flanked and unflanked letters, centrally and peripherally, in normals and amblyopes. We find that acuity, overlap masking, and crowding each demand a minimum size or spacing for readable text. Just measuring flanked and unflanked acuity is enough for our proposed model to predict the observer's threshold size and spacing for letters at any eccentricity. We also find that amblyopia in adults retains the character of the childhood condition that caused it. Amblyopia is a developmental neural deficit that can occur as a result of either strabismus or anisometropia in childhood. Peripheral viewing during childhood due to strabismus results in amblyopia that is crowding limited, like peripheral vision. Optical blur of one eye during childhood due to anisometropia without strabismus results in amblyopia that is acuity limited, like blurred vision. Furthermore, we find that the spacing:acuity ratio of flanked and unflanked acuity can distinguish strabismic amblyopia from purely anisometropic amblyopia in nearly perfect agreement with lack of stereopsis. A scatter diagram of threshold spacing versus acuity, one point per patient, for several diagnostic groups, reveals the diagnostic power of flanked acuity testing. These results and two demonstrations indicate that the sensitivity of visual screening tests can be improved by using flankers that are more tightly spaced and letter like. Finally, in concert with Strappini, Pelli, Di Pace, and Martelli (submitted), we jointly report a double dissociation between acuity and crowding. Two clinical conditions-anisometropic amblyopia and apperceptive agnosia-each selectively impair either acuity A or the spacing:acuity ratio S/A, not both. Furthermore, when we specifically estimate crowding, we find a double dissociation between acuity and crowding. Models of human object recognition will need to

  2. A double dissociation of the acuity and crowding limits to letter identification, and the promise of improved visual screening

    PubMed Central

    Song, Shuang; Levi, Dennis M.; Pelli, Denis G.

    2014-01-01

    Here, we systematically explore the size and spacing requirements for identifying a letter among other letters. We measure acuity for flanked and unflanked letters, centrally and peripherally, in normals and amblyopes. We find that acuity, overlap masking, and crowding each demand a minimum size or spacing for readable text. Just measuring flanked and unflanked acuity is enough for our proposed model to predict the observer's threshold size and spacing for letters at any eccentricity. We also find that amblyopia in adults retains the character of the childhood condition that caused it. Amblyopia is a developmental neural deficit that can occur as a result of either strabismus or anisometropia in childhood. Peripheral viewing during childhood due to strabismus results in amblyopia that is crowding limited, like peripheral vision. Optical blur of one eye during childhood due to anisometropia without strabismus results in amblyopia that is acuity limited, like blurred vision. Furthermore, we find that the spacing:acuity ratio of flanked and unflanked acuity can distinguish strabismic amblyopia from purely anisometropic amblyopia in nearly perfect agreement with lack of stereopsis. A scatter diagram of threshold spacing versus acuity, one point per patient, for several diagnostic groups, reveals the diagnostic power of flanked acuity testing. These results and two demonstrations indicate that the sensitivity of visual screening tests can be improved by using flankers that are more tightly spaced and letter like. Finally, in concert with Strappini, Pelli, Di Pace, and Martelli (submitted), we jointly report a double dissociation between acuity and crowding. Two clinical conditions—anisometropic amblyopia and apperceptive agnosia—each selectively impair either acuity A or the spacing:acuity ratio S/A, not both. Furthermore, when we specifically estimate crowding, we find a double dissociation between acuity and crowding. Models of human object recognition will need

  3. Color vision test

    MedlinePlus

    ... difficulty telling the difference between red/purple and green/purple Protanopia -- difficulty telling the difference between blue/green and red/green Tritanopia -- difficulty telling the difference ...

  4. Preschool visual acuity screening tests.

    PubMed Central

    Friendly, D S

    1978-01-01

    The purpose of the study was to evaluate the relative merits of two screening tests used for visual acuity assessment of preschool children. The tests that were compared were the Good-Lite Company versions of the E-Test and of the STYCAR (Screening Test for Young Children and Retardates). The former is the most popular method for evaluating central acuity in young children in this nation; the STYCAR is a relatively new letter-matching-test developed in England, where it is widely employed. The E-Test poses left-right orientation problems which are eliminated by the symmetrical letters H, T, O and V utilized in the Letter-Matching-Test. Both visual acuity tests were administered on two separate occasions by personnel from the Prevention of Blindness Society of Metropolitan Washington to 633 preschool children in Washington, D.C. By random selection, 150 of the children received the E-Test at both sessions, 162 children received the Letter-Matching-Test at both sessions, 160 chilt athe the second session, and 161 children received the Letter-Matching-Test at the first session and the E-Test at the second session. The author medically examined the eyes of 408 of the 633 children without knowledge of which test had been initially administered. Statistical analysis of the data obtained from the study indicated that the Letter-Matching-Test was significantly better in terms of testability rates, group and individual instruction time, and performance time. The E-Test was more reliable in terms of test-retest acuity scores and was also more valid in terms of agreement between pass-fail results obtained at the first screening session and two levels of pass-fail refraction criteria. Images FIGURE 4 FIGURE 5 FIGURE 7 A FIGURE 7 B FIGURE 9 A FIGURE 9 B PMID:754379

  5. Effects of Horizontal Acceleration on Human Visual Acuity and Stereopsis

    PubMed Central

    Horng, Chi-Ting; Hsieh, Yih-Shou; Tsai, Ming-Ling; Chang, Wei-Kang; Yang, Tzu-Hung; Yauan, Chien-Han; Wang, Chih-Hung; Kuo, Wu-Hsien; Wu, Yi-Chang

    2015-01-01

    The effect of horizontal acceleration on human visual acuity and stereopsis is demonstrated in this study. Twenty participants (mean age 22.6 years) were enrolled in the experiment. Acceleration from two different directions was performed at the Taiwan High-Speed Rail Laboratory. Gx and Gy (< and >0.1 g) were produced on an accelerating platform where the subjects stood. The visual acuity and stereopsis of the right eye were measured before and during the acceleration. Acceleration <0.1 g in the X- or Y-axis did not affect dynamic vision and stereopsis. Vision decreased (mean from 0.02 logMAR to 0.25 logMAR) and stereopsis declined significantly (mean from 40 s to 60.2 s of arc) when Gx > 0.1 g. Visual acuity worsened (mean from 0.02 logMAR to 0.19 logMAR) and poor stereopsis was noted (mean from 40 s to 50.2 s of arc) when Gy > 0.1 g. The effect of acceleration from the X-axis on the visual system was higher than that from the Y-axis. During acceleration, most subjects complained of ocular strain when reading. To our knowledge, this study is the first to report the exact levels of visual function loss during Gx and Gy. PMID:25607601

  6. Effects of horizontal acceleration on human visual acuity and stereopsis.

    PubMed

    Horng, Chi-Ting; Hsieh, Yih-Shou; Tsai, Ming-Ling; Chang, Wei-Kang; Yang, Tzu-Hung; Yauan, Chien-Han; Wang, Chih-Hung; Kuo, Wu-Hsien; Wu, Yi-Chang

    2015-01-01

    The effect of horizontal acceleration on human visual acuity and stereopsis is demonstrated in this study. Twenty participants (mean age 22.6 years) were enrolled in the experiment. Acceleration from two different directions was performed at the Taiwan High-Speed Rail Laboratory. Gx and Gy (< and >0.1 g) were produced on an accelerating platform where the subjects stood. The visual acuity and stereopsis of the right eye were measured before and during the acceleration. Acceleration <0.1 g in the X- or Y-axis did not affect dynamic vision and stereopsis. Vision decreased (mean from 0.02 logMAR to 0.25 logMAR) and stereopsis declined significantly (mean from 40 s to 60.2 s of arc) when Gx > 0.1 g. Visual acuity worsened (mean from 0.02 logMAR to 0.19 logMAR) and poor stereopsis was noted (mean from 40 s to 50.2 s of arc) when Gy > 0.1 g. The effect of acceleration from the X-axis on the visual system was higher than that from the Y-axis. During acceleration, most subjects complained of ocular strain when reading. To our knowledge, this study is the first to report the exact levels of visual function loss during Gx and Gy. PMID:25607601

  7. Color Blindness Simulations

    MedlinePlus

    ... many disables? The fastest growing segment? Myths of disability The Law The Rules Accessibility Resources Page Updates, additions Contact Us For assistance contact your NOAA Line Office Section 508 Coordinator Color blindness Simulations Normal Color Vision Deuteranopia Color blindness marked ...

  8. A Retrospective Study of Causes of Low Vision in Saud Arabia, A Case of Eye World Medical Complex in Riyadh.

    PubMed

    Z Alotaibi, Abdullah

    2016-01-01

    Vision is the ability of seeing with a definite understanding of features, color and contrast, and to distinguish between objects visually. In the year 1999, the World Health Organization (WHO) and the International Agency for the Prevention of Blindness formulated a worldwide project for the eradication of preventable loss of sight with the subject of "Vision 2020: the Right to Sight". This global program aims to eradicate preventable loss of sight by the year 2020. This study was conducted to determine the main causes of low vision in Saudi Arabia and also to assess their visual improvement after using low vision aids (LVD).The study is a retrospective study and was conducted in low vision clinic at Eye World Medical Complex in Riyadh, Saudi Arabia. The file medical record of 280 patients attending low vision clinics from February 2008 to June 2010 was included. A data sheet was filled which include: age, gender, cause of low vision, unassisted visual acuity for long distances and short distances, low vision devices needed for long distances and short distances that provides best visual acuity. The result shows that the main cause of low vision was Optic atrophy (28.9%). Retinitis pigmentosa was the second cause of low vision, accounting for 73 patients (26%) followed by Diabetic retinopathy and Macular degeneration with 44 patients (15.7%) and 16 patients (5.7%) respectively. Inter family marriage could be one of the main causes of low vision. Public awareness should be embarked on for enlightenment on ocular diseases result in consanguineous marriage. Also, it is an important issue to start establishing low vision clinics in order to improve the situation. PMID:26652071

  9. Color Vision Variation as Evidenced by Hybrid L/M Opsin Genes in Wild Populations of Trichromatic Alouatta New World Monkeys.

    PubMed

    Matsushita, Yuka; Oota, Hiroki; Welker, Barbara J; Pavelka, Mary S; Kawamura, Shoji

    2014-01-01

    Platyrrhine (New World) monkeys possess highly polymorphic color vision owing to allelic variation of the single-locus L/M opsin gene on the X chromosome. Most species consist of female trichromats and female and male dichromats. Howlers (genus Alouatta) are an exception; they are considered to be routinely trichromatic with L and M opsin genes juxtaposed on the X chromosome, as seen in catarrhine primates (Old World monkeys, apes, and humans). Yet it is not known whether trichromacy is invariable in howlers. We examined L/M opsin variation in wild howler populations in Costa Rica and Nicaragua (Alouatta palliata) and Belize (A. pigra), using fecal DNA. We surveyed exon 5 sequences (containing the diagnostic 277th and 285th residues for λmax) for 8 and 18 X chromosomes from Alouatta palliata and A. pigra, respectively. The wavelengths of maximal absorption (λmax) of the reconstituted L and M opsin photopigments were 564 nm and 532 nm, respectively, in both species. We found one M-L hybrid sequence with a recombinant 277/285 haplotype in Alouatta palliata and two L-M hybrid sequences in A. pigra. The λmax values of the reconstituted hybrid photopigments were in the range of 546~554 nm, which should result in trichromat phenotypes comparable to those found in other New World monkey species. Our finding of color vision variation due to high frequencies of L/M hybrid opsin genes in howlers challenges the current view that howlers are routine and uniform trichromats. These results deepen our understanding of the evolutionary significance of color vision polymorphisms and routine trichromacy and emphasize the need for further assessment of opsin gene variation as well as behavioral differences among subtypes of trichromacy. PMID:24523565

  10. Identification and Detection of Simple 3D Objects with Severely Blurred Vision

    PubMed Central

    Kallie, Christopher S.; Legge, Gordon E.; Yu, Deyue

    2012-01-01

    Purpose. Detecting and recognizing three-dimensional (3D) objects is an important component of the visual accessibility of public spaces for people with impaired vision. The present study investigated the impact of environmental factors and object properties on the recognition of objects by subjects who viewed physical objects with severely reduced acuity. Methods. The experiment was conducted in an indoor testing space. We examined detection and identification of simple convex objects by normally sighted subjects wearing diffusing goggles that reduced effective acuity to 20/900. We used psychophysical methods to examine the effect on performance of important environmental variables: viewing distance (from 10–24 feet, or 3.05–7.32 m) and illumination (overhead fluorescent and artificial window), and object variables: shape (boxes and cylinders), size (heights from 2–6 feet, or 0.61–1.83 m), and color (gray and white). Results. Object identification was significantly affected by distance, color, height, and shape, as well as interactions between illumination, color, and shape. A stepwise regression analysis showed that 64% of the variability in identification could be explained by object contrast values (58%) and object visual angle (6%). Conclusions. When acuity is severely limited, illumination, distance, color, height, and shape influence the identification and detection of simple 3D objects. These effects can be explained in large part by the impact of these variables on object contrast and visual angle. Basic design principles for improving object visibility are discussed. PMID:23111613

  11. The Psychological Implications of Being Color Blind

    ERIC Educational Resources Information Center

    Snyder, C. R.

    1973-01-01

    The author describes his experience with color-defective vision, and suggests that children be given a color-vision test at vision screening time in school to detect color-defective vision in children and thus minimize frustrating color-learning experiences. (MC)

  12. Visual Acuity During Treadmill Walking

    NASA Technical Reports Server (NTRS)

    Peters, B. T.; Brady, R.; vanEmmerik, R. E. A.; Bloomberg, Jacob J.

    2006-01-01

    An awareness of the physical world is essential for successful navigation through the environment. Vision is the means by which this awareness is made possible for most people. However, without adequate compensation, the movements of the body during walking could impair vision. Previous research has shown how the eyes, head and trunk movements are coordinated to provide the compensation necessary for clear vision, but the overall effectiveness of these coordinated movements is unknown. The goal of the research presented here was to provide a direct measure of visual performance during locomotion, while also investigating the degree to which coordinated head and body movements can be altered to facilitate the goal of seeing clearly.

  13. Visual acuity and magnification devices in dentistry.

    PubMed

    Perrin, Philippe; Eichenberger, Martina; Neuhaus, Klaus W; Lussi, Adrian

    2016-01-01

    This review discusses visual acuity in dentistry and the influence of optical aids. Studies based on objective visual tests at a dental working distance were included. These studies show dramatic individual variation independent of the dentists’ age. The limitations due to presbyopia begin at an age of 40 years. Dental professionals should have their near vision tested regularly. Visual deficiencies can be compensated with magnification aids. It is important to differentiate between Galilean and Keplerian loupes. The lightweight Galilean loupes allow an almost straight posture and offer improved ergonomics. Younger dentists profit more from the ergonomic aspects, while dentists over the age of 40 can compensate their age-related visual deficiencies when using this type of loupe. Keplerian loupes, with their superior optical construction, improve the visual performance for dentists of all age groups. The optical advantages come at the cost of ergonomic constraints due to the weight of these loupes. The microscope is highly superior visually and ergonomically, and it is indispensable for the visual control of endodontic treatments. PMID:27023468

  14. Color-Blindness vs. Race Matters: Pre-School Education and the Need for a Communal Vision

    ERIC Educational Resources Information Center

    Hein, Christina Judith

    2004-01-01

    The author discerns two trends ruling with many of the teachers, intellectuals, and citizens of the United States. One is the color-blind-myth that Williams (1997) cites in her essay, "The Emperor's New Clothes": "I don't think about color, therefore your problems don't exist," is the phrase that she attributes to this "school of idealism". The…

  15. Part task investigation of multispectral image fusion using gray scale and synthetic color night-vision sensor imagery for helicopter pilotage

    NASA Astrophysics Data System (ADS)

    Steele, Paul M.; Perconti, Philip

    1997-06-01

    Today, night vision sensor and display systems used in the pilotage or navigation of military helicopters are either long wave IR thermal sensors (8 - 12 microns) or image intensified, visible and near IR (0.6 - 0.9 microns), sensors. The sensor imagery is displayed using a monochrome phosphor on a Cathode Ray Tube or night vision goggle. Currently, there is no fielded capability to combine the best attributes of the emissive radiation sensed by the thermal sensor and the reflected radiation sensed by the image intensified sensor into a single fused image. However, recent advances in signal processing have permitted the real time image fusion and display of multispectral sensors in either monochrome or synthetic chromatic form. The merits of such signal processing is explored. A part task simulation using a desktop computer, video playback unit, and a biocular head mounted display was conducted. Response time and accuracy measures of test subject responses to visual perception tasks were taken. Subjective ratings were collected to determine levels of pilot acceptance. In general, fusion based formats resulted in better subject performance. The benefits of integrating synthetic color to fused imagery, however, is dependent on the color algorithm used, the visual task performed, and scene content.

  16. A single cohort prospective trial of the immediate effects of spinal manipulation on visual acuity

    PubMed Central

    Athaide, Michelle; Rego, Carol; Budgell, Brian

    2016-01-01

    Introduction: There is no high quality evidence on which to judge the generalizability of isolated reports of improvement in vision following manipulation. The current paucity of research results also precludes the thoughtful design of a controlled, prospective clinical study. Hence, the purpose of the current study was to test the feasibility of conducting a clinical trial of the acute effects of spinal manipulation on visual acuity. Methods: New adult patients presenting to a community based chiropractic clinic were recruited into a single cohort prospective trial to determine the immediate effects of cervical spinal manipulation on visual acuity. Results: The experimental protocol was well accepted by patients and caused minimal or no disruption of the clinic routine. By some measures, chiropractic treatment was accompanied by statistically significant improvements in visual acuity. Discussion: The results of this study indicate that it is quite feasible to conduct a prospective, community based clinical study of the acute effects of spinal manipulation on visual acuity. PMID:27069271

  17. Prenatal and Early Childhood Exposure to Tetrachloroethylene and Adult Vision

    PubMed Central

    Getz, Kelly D.; Janulewicz, Patricia A.; Rowe, Susannah; Weinberg, Janice M.; Winter, Michael R.; Martin, Brett R.; Vieira, Veronica M.; White, Roberta F.

    2012-01-01

    Background: Tetrachloroethylene (PCE; or perchloroethylene) has been implicated in visual impairments among adults with occupational and environmental exposures as well as children born to women with occupational exposure during pregnancy. Objectives: Using a population-based retrospective cohort study, we examined the association between prenatal and early childhood exposure to PCE-contaminated drinking water on Cape Cod, Massachusetts, and deficits in adult color vision and contrast sensitivity. Methods: We estimated the amount of PCE that was delivered to the family residence from participants’ gestation through 5 years of age. We administered to this now adult study population vision tests to assess acuity, contrast sensitivity, and color discrimination. Results: Participants exposed to higher PCE levels exhibited lower contrast sensitivity at intermediate and high spatial frequencies compared with unexposed participants, although the differences were generally not statistically significant. Exposed participants also exhibited poorer color discrimination than unexposed participants. The difference in mean color confusion indices (CCI) was statistically significant for the Farnsworth test but not Lanthony’s D-15d test [Farnsworth CCI mean difference = 0.05, 95% confidence interval (CI): 0.003, 0.10; Lanthony CCI mean difference = 0.07, 95% CI: –0.02, 0.15]. Conclusions: Prenatal and early childhood exposure to PCE-contaminated drinking water may be associated with long-term subclinical visual dysfunction in adulthood, particularly with respect to color discrimination. Further investigation of this association in similarly exposed populations is necessary. PMID:22784657

  18. Prediction of Visual Acuity from Wavefront Aberrations

    NASA Technical Reports Server (NTRS)

    Watson, Andrew B. (Inventor); Ahumada, Albert J. (Inventor)

    2013-01-01

    A method for generating a visual acuity metric, based on wavefront aberrations (WFAs), associated with a test subject and representing classes of imperfections, such as defocus, astigmatism, coma and spherical aberrations, of the subject's visual system. The metric allows choices of different image template, can predict acuity for different target probabilities, can incorporate different and possibly subject-specific neural transfer functions, can predict acuity for different subject templates, and incorporates a model of the optotype identification task.

  19. Fast 3D reconstruction of tool wear based on monocular vision and multi-color structured light illuminator

    NASA Astrophysics Data System (ADS)

    Wang, Zhongren; Li, Bo; Zhou, Yuebin

    2014-11-01

    Fast 3D reconstruction of tool wear from 2D images has great importance to 3D measuring and objective evaluating tool wear condition, determining accurate tool change and insuring machined part's quality. Extracting 3D information of tool wear zone based on monocular multi-color structured light can realize fast recovery of surface topography of tool wear, which overcomes the problems of traditional methods such as solution diversity and slow convergence when using SFS method and stereo match when using 3D reconstruction from multiple images. In this paper, a kind of new multi-color structured light illuminator was put forward. An information mapping model was established among illuminator's structure parameters, surface morphology and color images. The mathematical model to reconstruct 3D morphology based on monocular multi-color structured light was presented. Experimental results show that this method is effective and efficient to reconstruct the surface morphology of tool wear zone.

  20. How colorful! A feature it is, isn't it?

    NASA Astrophysics Data System (ADS)

    Lebowsky, Fritz

    2015-01-01

    A display's color subpixel geometry provides an intriguing opportunity for improving readability of text. True type fonts can be positioned at the precision of subpixel resolution. With such a constraint in mind, how does one need to design font characteristics? On the other hand, display manufactures try hard in addressing the color display's dilemma: smaller pixel pitch and larger display diagonals strongly increase the total number of pixels. Consequently, cost of column and row drivers as well as power consumption increase. Perceptual color subpixel rendering using color component subsampling may save about 1/3 of color subpixels (and reduce power dissipation). This talk will try to elaborate the following questions, based on simulation of several different layouts of subpixel matrices: Up to what level are display device constraints compatible with software specific ideas of rendering text? How much of color contrast will remain? How to best consider preferred viewing distance for readability of text? How much does visual acuity vary at 20/20 vision? Can simplified models of human visual color perception be easily applied to text rendering on displays? How linear is human visual contrast perception around band limit of a display's spatial resolution? How colorful does the rendered text appear on the screen? How much does viewing angle influence the performance of subpixel layouts and color subpixel rendering?

  1. Part I: Sound color in the music of Gyorgy Kurtag, Part II: "Leopard's Path," thirteen visions for chamber ensemble

    NASA Astrophysics Data System (ADS)

    Iachimciuc, Igor

    The dissertation is in two parts, a theoretical study and a musical composition. In Part I the music of Gyorgy Kurtag is analyzed from the point of view of sound color. A brief description of what is understood by the term sound color, and various ways of achieving specific coloristic effects, are presented in the Introduction. An examination of Kurtag's approaches to the domain of sound color occupies the chapters that follow. The musical examples that are analyzed are selected from Kurtag's different compositional periods, showing a certain consistency in sound color techniques, the most important of which are already present in the String Quartet, Op. 1. The compositions selected for analysis are written for different ensembles, but regardless of the instrumentation, certain principles of the formation and organization of sound color remain the same. Rather than relying on extended instrumental techniques, Kurtag creates a large variety of sound colors using traditional means such as pitch material, register, density, rhythm, timbral combinations, dynamics, texture, spatial displacement of the instruments, and the overall musical context. Each sound color unit in Kurtag's music is a separate entity, conceived as a complete microcosm. Sound color units can either be juxtaposed as contrasting elements, forming sound color variations, or superimposed, often resulting in a Klangfarbenmelodie effect. Some of the same gestural figures (objets trouves) appear in different compositions, but with significant coloristic modifications. Thus, the principle of sound color variations is not only a strong organizational tool, but also a characteristic stylistic feature of the music of Gyorgy Kurtag. Part II, Leopard's Path (2010), for flute, clarinet, violin, cello, cimbalom, and piano, is an original composition inspired by the painting of Jesse Allen, a San Francisco based artist. The composition is conceived as a cycle of thirteen short movements. Ten of these movements are

  2. Pediatric and adult vision restoration after optic nerve sheath decompression for idiopathic intracranial hypertension.

    PubMed

    Bersani, Thomas A; Meeker, Austin R; Sismanis, Dimitrios N; Carruth, Bryant P

    2016-06-01

    To compare presentations of idiopathic intracranial hypertension and efficacy of optic nerve sheath decompression between adult and pediatric patients, a retrospective cohort study was completed All idiopathic intracranial hypertension patients undergoing optic nerve sheath decompression by one surgeon between 1991 and 2012 were included. Pre-operative and post-operative visual fields, visual acuity, color vision, and optic nerve appearance were compared between adult and pediatric (<18 years) populations. Outcome measures included percentage of patients with complications or requiring subsequent interventions. Thirty-one adults (46 eyes) and eleven pediatric patients (18 eyes) underwent optic nerve sheath decompression for vision loss from idiopathic intracranial hypertension. Mean deviation on visual field, visual acuity, color vision, and optic nerve appearance significantly improved across all subjects. Pre-operative mean deviation was significantly worse in children compared to adults (p=0.043); there was no difference in mean deviation post-operatively (p=0.838). Significantly more pediatric eyes (6) presented with light perception only or no light perception than adult eyes (0) (p=0.001). Pre-operative color vision performance in children (19%) was significantly worse than in adults (46%) (p=0.026). Percentage of patients with complications or requiring subsequent interventions did not differ between groups. The consistent improvement after surgery and low rate of complications suggest optic nerve sheath decompression is safe and effective in managing vision loss due to adult and pediatric idiopathic intracranial hypertension. Given the advanced pre-operative visual deficits seen in children, one might consider a higher index of suspicion in diagnosing, and earlier surgical intervention in treating pediatric idiopathic intracranial hypertension. PMID:27163674

  3. Improved Vision from Severe Compressive Optic Neuropathy by Apical Cavernous Hemangioma.

    PubMed

    Kang, Hyera; Takahashi, Yasuhiro; Nishimura, Kunihiro; Yasuda, Muneyoshi; Akutsu, Hiroyoshi; Kakizaki, Hirohiko

    2016-01-01

    A 59-year-old woman had a 1-year history of right vision loss. Her visual acuity was then 0.01 OD, and the critical flicker frequency (CFF) was 8 Hz OD. Goldmann perimetry examination showed inferior suppression of the right visual field center. Funduscopic examination revealed normal coloring of the right optic disc. Imaging studies showed an apical oval tumor. The optic nerve was compressed by both the tumor and the superior rectus muscle/levator palpebrae superioris complex. The tumor was dissected from the surrounding tissues and completely extracted. Histopathologic examination confirmed a cavernous hemangioma. The patient underwent three cycles of postoperative steroid pulse therapy. One year after the surgery, her visual acuity and CFF improved to 1.0 and 32 Hz OD, respectively. Her right visual field was within the normal range. PMID:27099610

  4. Improved Vision from Severe Compressive Optic Neuropathy by Apical Cavernous Hemangioma

    PubMed Central

    Kang, Hyera; Takahashi, Yasuhiro; Nishimura, Kunihiro; Yasuda, Muneyoshi; Akutsu, Hiroyoshi; Kakizaki, Hirohiko

    2016-01-01

    A 59-year-old woman had a 1-year history of right vision loss. Her visual acuity was then 0.01 OD, and the critical flicker frequency (CFF) was 8 Hz OD. Goldmann perimetry examination showed inferior suppression of the right visual field center. Funduscopic examination revealed normal coloring of the right optic disc. Imaging studies showed an apical oval tumor. The optic nerve was compressed by both the tumor and the superior rectus muscle/levator palpebrae superioris complex. The tumor was dissected from the surrounding tissues and completely extracted. Histopathologic examination confirmed a cavernous hemangioma. The patient underwent three cycles of postoperative steroid pulse therapy. One year after the surgery, her visual acuity and CFF improved to 1.0 and 32 Hz OD, respectively. Her right visual field was within the normal range. PMID:27099610

  5. Vision-based drone flight control and crowd or riot analysis with efficient color histogram based tracking

    NASA Astrophysics Data System (ADS)

    Müller, Thomas; Müller, Markus

    2011-05-01

    Object tracking is a direct or indirect key issue in many different military applications like visual surveillance, automatic visual closed-loop control of UAVs (unmanned aerial vehicles) and PTZ-cameras, or in the field of crowd evaluations in order to detect or analyse a riot emergence. Of course, a high robustness is the most important feature of the underlying tracker, but this is hindered significantly the more the tracker needs to have low calculation times. In the UAV application introduced in this paper the tracker has to be extraordinarily quick. In order to optimize the calculation time and the robustness in combination as far as possible, a highly efficient tracking procedure is presented for the above mentioned application fields which relies on well-known color histograms but uses them in a novel manner. This procedure bases on the calculation of a color weighting vector representing the significances of object colors like a kind of an object's color finger print. Several examples from the above mentioned military applications are shown to demonstrate the practical relevance and the performance of the presented tracking approach.

  6. Contact Lenses for Vision Correction

    MedlinePlus

    ... Contact Lenses Colored Contact Lenses Contact Lenses for Vision Correction Written by: Kierstan Boyd Reviewed by: Brenda ... on the surface of the eye. They correct vision like eyeglasses do and are safe when used ...

  7. Crowding and visual acuity measured in adults using paediatric test letters, pictures and symbols.

    PubMed

    Lalor, Sarah J H; Formankiewicz, Monika A; Waugh, Sarah J

    2016-04-01

    Crowding refers to the degradation of visual acuity for target optotypes with, versus without, surrounding features. Crowding is important clinically, however the effect of target-flanker spacing on acuity for symbols and pictures, compared to letters, has not been investigated. Five adults with corrected-to-normal vision had visual acuity measured for modified single target versions of Kay Pictures, Lea Symbols, HOTV and Cambridge Crowding Cards, tests. Single optotypes were presented in isolation and with surrounding features placed 0-5 stroke-widths away. Visual acuity measured with Kay Picture optotypes is 0.13-0.19logMAR better than for other test optotypes and varies significantly across picture. The magnitude of crowding is strongest when the surrounding features abut, or are placed 1 stroke-width away from the target optotype. The slope of the psychometric function is steeper in the region just beyond maximum crowding. Crowding is strongest and the psychometric function steepest, with the Cambridge Crowding Cards arrangement, than when any single optotype is surrounded by a box. Estimates of crowding extent are less variable across test when expressed in units of stroke-width, than optotype-width. Crowding for single target presentations of letters, symbols and pictures used in paediatric visual acuity tests can be maximised and made more sensitive to change in visual acuity, by careful selection of optotype, by surrounding the target with similar flankers, and by using a closer target-flanker separation than half an optotype-width. PMID:26878696

  8. Creation of an Accurate Algorithm to Detect Snellen Best Documented Visual Acuity from Ophthalmology Electronic Health Record Notes

    PubMed Central

    French, Dustin D; Gill, Manjot; Mitchell, Christopher; Jackson, Kathryn; Kho, Abel; Bryar, Paul J

    2016-01-01

    Background Visual acuity is the primary measure used in ophthalmology to determine how well a patient can see. Visual acuity for a single eye may be recorded in multiple ways for a single patient visit (eg, Snellen vs. Jäger units vs. font print size), and be recorded for either distance or near vision. Capturing the best documented visual acuity (BDVA) of each eye in an individual patient visit is an important step for making electronic ophthalmology clinical notes useful in research. Objective Currently, there is limited methodology for capturing BDVA in an efficient and accurate manner from electronic health record (EHR) notes. We developed an algorithm to detect BDVA for right and left eyes from defined fields within electronic ophthalmology clinical notes. Methods We designed an algorithm to detect the BDVA from defined fields within 295,218 ophthalmology clinical notes with visual acuity data present. About 5668 unique responses were identified and an algorithm was developed to map all of the unique responses to a structured list of Snellen visual acuities. Results Visual acuity was captured from a total of 295,218 ophthalmology clinical notes during the study dates. The algorithm identified all visual acuities in the defined visual acuity section for each eye and returned a single BDVA for each eye. A clinician chart review of 100 random patient notes showed a 99% accuracy detecting BDVA from these records and 1% observed error. Conclusions Our algorithm successfully captures best documented Snellen distance visual acuity from ophthalmology clinical notes and transforms a variety of inputs into a structured Snellen equivalent list. Our work, to the best of our knowledge, represents the first attempt at capturing visual acuity accurately from large numbers of electronic ophthalmology notes. Use of this algorithm can benefit research groups interested in assessing visual acuity for patient centered outcome. All codes used for this study are currently

  9. Acuity assessment of non-verbal infants and children: clinical experience with the acuity card procedure.

    PubMed

    Mohn, G; van Hof-van Duin, J; Fetter, W P; de Groot, L; Hage, M

    1988-04-01

    The acuity card procedure was used to assess the visual acuity of 510 neurologically normal and abnormal infants and children. Acuity estimates were obtained for 93 per cent of 842 binocular and 279 monocular tests. The observed development of binocular acuity of normal fullterm and preterm infants agreed well with previous reports using the traditional forced-choice preferential looking technique. Monocular tests seemed to support earlier suggestions that grating acuity may be relatively insensitive to strabismic amblyopia. Infants at risk of later neurological deficits but developing normally had only a slight delay in development of acuity, but there was a high incidence of acuity deficits (54 per cent) among those with severe neurological defects. The great majority of a group of multiply handicapped children had low acuity for age. Repeat tests showed a high degree of test-retest consistency. The acuity card procedure was a successful and useful method for assessing the acuity of infants and children who cannot be tested with standard ophthalmological methods. PMID:3384203

  10. Test Re-Test Reliability and Validity of Different Visual Acuity and Stereoacuity Charts Used in Preschool Children

    PubMed Central

    Moganeswari, Diana; Srinivasan, Krithica; Jacob, George P

    2015-01-01

    Background Preschool vision screenings are cost effective ways to detect children with vision impairments. The use of any vision tests in children must be age appropriate, testable, repeatable and valid. Aim To compare the test re-test reliability, sensitivity and specificity of different visual acuity and stereo acuity charts used in preschool children. Materials and Methods Monocular visual acuity of 90 subjects (180 eyes) of age 36 to 71 months was assessed with HOTV, Lea and E-chart in a preschool located in a semi urban area, Manipal, Karnataka. After the vision assessment, stereo acuity was recorded using Frisby and Titmus stereo charts followed by comprehensive eye examination. Repeated measurements of visual acuity and stereo acuity were done one week after the initial assessment. Results Mean age of children was 53± 10 months with equal gender distribution. Intra class correlation (ICC) of Lea, HOTV, E-chart, Frisby and Titmus charts were 0.96, 0.99, 0.92, 1.0 and 1.0 respectively. The area under receiver operating curve (ROC) for Lea and E-chart was 0.892 and 0.776. HOTV was considered as the gold standard as it showed the least difference on repeated measurements. The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of E-chart was 99, 15, 45, 94 and 21.8 percent, and Lea was 93, 56, 59 and 92 percent. The sensitivity, specificity, PPV and NPV of Frisby was 75, 27, 9, 92 percent were as of Titmus was 75, 13, 8 and 85 percent respectively. Conclusion HOTV chart can be used as the gold standard for measuring visual acuity of pre-schoolers in a semi urban area. Lea chart can be used in the absence of HOTV chart. Frisby and Titmus charts are good screening tools, but with poor diagnostic criteria. PMID:26675120

  11. Strong tilt illusions always reduce orientation acuity.

    PubMed

    Solomon, Joshua A; Morgan, Michael J

    2009-03-01

    The apparent spatial orientation of an object can differ from its physical orientation when differently oriented objects surround it. This is the "tilt illusion". Previously [Solomon, J. A., & Morgan, M. J. (2006). Stochastic re-calibration: Contextual effects on perceived tilt. Proceedings of the Royal Society of London. Series B, Biological Sciences, 273, 2681-2686], we reported a loss of orientation acuity whenever a large physical tilt was required to compensate for the tilt illusion and make a target appear horizontal. Since all of those targets appeared to be at least approximately horizontal, we concluded that orientation acuity was not wholly determined by the target's apparent orientation. In the present study, we used oblique (i.e. neither horizontal nor vertical) reference orientations to more directly examine the effect of perceived orientation on orientation acuity. The results show that when surround and reference were parallel, there was no tilt illusion and acuity was high. Acuity suffered whenever the tilt illusion caused a large discrepancy between the target's physical and perceived tilts. Since this was true even for tilted references, context-induced acuity loss cannot be simply an "oblique effect" of the target's physical orientation. PMID:19268684

  12. The importance of measuring dynamic visual acuity.

    PubMed

    Muzdalo, Natasa Vujko

    2013-04-01

    In their everyday life, people interact with different objects, static as well as those in motion. However, dynamic acuity is rarely checked in medical examinations, even those preceding the issue of driving license. In order for driving to be safe, good eyesight or good correction with visual aids is imperative. Beside good eyesight, drivers also have to have good reflexes and short reaction span. The aim of this study was to compare dynamic and static visual acuity in order to observe how they vary among individuals. Twenty female and male participants, 65 years of age, took part in the study and the comparison was made with the results provided by 20 20-year old participants. Dynamic acuity was tested using the Landolt-ring optotype which was simulating movement velocity of 72 km/h. T-test demonstrated the presence of a statistically significant difference between dynamic and static acuity among the participants from 62 to 68 years of age (t = 15.852; df = 39; p < 0.01). Within the same group, dynamic acuity (mean = 0.887; std. deviation = 0.297) proved to be significantly worse than static acuity (mean = 1.40; std. deviation = 0.317). By comparing the results measured within the older group of participants with those measured in the younger group, it was shown that there exists a statistically significant difference (t = 0.275; df = 58; p < 0,05) between the older and younger group in their dynamic binocular acuity with correction. Younger participants had better dynamic binocular acuity with correction (mean = 1.063; std. deviation = 0.259) than the older participants (mean = 0.884; std. deviation = 0.298). The differences between dynamic and static acuity and its degradation in the older age groups have to be taken into account when issuing driving licenses. The future of research lies within the study of correlation between the age and acuity in order that the results can be applied in practice. PMID:23837257

  13. Peripheral Color Demo

    PubMed Central

    2015-01-01

    A set of structured demonstrations of the vividness of peripheral color vision is provided by arrays of multicolored disks scaled with eccentricity. These demonstrations are designed to correct the widespread misconception that peripheral color vision is weak or nonexistent. PMID:27551354

  14. Objective evaluation of the visual acuity in human eyes

    NASA Astrophysics Data System (ADS)

    Rosales, M. A.; López-Olazagasti, E.; Ramírez-Zavaleta, G.; Varillas, G.; Tepichín, E.

    2009-08-01

    Traditionally, the quality of the human vision is evaluated by a subjective test in which the examiner asks the patient to read a series of characters of different sizes, located at a certain distance of the patient. Typically, we need to ensure a subtended angle of vision of 5 minutes, which implies an object of 8.8 mm high located at 6 meters (normal or 20/20 visual acuity). These characters constitute what is known as the Snellen chart, universally used to evaluate the spatial resolution of the human eyes. The mentioned process of identification of characters is carried out by means of the eye - brain system, giving an evaluation of the subjective visual performance. In this work we consider the eye as an isolated image-forming system, and show that it is possible to isolate the function of the eye from that of the brain in this process. By knowing the impulse response of the eye´s system we can obtain, in advance, the image of the Snellen chart simultaneously. From this information, we obtain the objective performance of the eye as the optical system under test. This type of results might help to detect anomalous situations of the human vision, like the so called "cerebral myopia".

  15. Recovery of stereo acuity in adults with amblyopia

    PubMed Central

    Astle, Andrew T; McGraw, Paul V; Webb, Ben S

    2011-01-01

    Disruption of visual input to one eye during early development leads to marked functional impairments of vision, commonly referred to as amblyopia. A major consequence of amblyopia is the inability to encode binocular disparity information leading to impaired depth perception or stereo acuity. If amblyopia is treated early in life (before 4 years of age), then recovery of normal stereoscopic function is possible. Treatment is rarely undertaken later in life (adulthood) because declining levels of neural plasticity are thought to limit the effectiveness of standard treatments. Here, the authors show that a learning-based therapy, designed to exploit experience-dependent plastic mechanisms, can be used to recover stereoscopic visual function in adults with amblyopia. These cases challenge the long-held dogma that the critical period for visual development and the window for treating amblyopia are one and the same. PMID:22707543

  16. Photovoltaic restoration of sight with high visual acuity

    PubMed Central

    Lorach, Henri; Goetz, Georges; Smith, Richard; Lei, Xin; Mandel, Yossi; Kamins, Theodore; Mathieson, Keith; Huie, Philip; Harris, James; Sher, Alexander; Palanker, Daniel

    2015-01-01

    Patients with retinal degeneration lose sight due to gradual demise of photoreceptors. Electrical stimulation of the surviving retinal neurons provides an alternative route for delivery of visual information. We demonstrate that subretinal arrays with 70 μm photovoltaic pixels provide highly localized stimulation, with electrical and visual receptive fields of comparable sizes in rat retinal ganglion cells. Similarly to normal vision, retinal response to prosthetic stimulation exhibits flicker fusion at high frequencies, adaptation to static images and non-linear spatial summation. In rats with retinal degeneration, these photovoltaic arrays provide spatial resolution of 64 ± 11 μm, corresponding to half of the normal visual acuity in pigmented rats. Ease of implantation of these wireless and modular arrays, combined with their high resolution opens the door to functional restoration of sight. PMID:25915832

  17. Dynamic Visual Acuity and Landing Sickness in Crewmembers Returning from Long-Duration Spaceflight

    NASA Technical Reports Server (NTRS)

    Rosenberg, M. J. F.; Peters, B. T.; Reschke, M. F.

    2016-01-01

    Long-term exposure to microgravity causes sensorimotor adaptations that result in functional deficits upon returning to a gravitational environment. At landing the vestibular system and the central nervous system, responsible for coordinating head and eye movements, are adapted to microgravity and must re-adapt to the gravitational environment. This re-adaptation causes decrements in gaze control and dynamic visual acuity, with astronauts reporting oscillopsia and blurred vision. Dynamic visual acuity (DVA) is assessed using an oscillating chair (Figure 1) developed in the Neuroscience Laboratory at JSC. This chair is lightweight and easily portable for quick deployment in the field. The base of the chair is spring-loaded and allows for manual oscillation of the subject. Using a metronome, the chair is vertically oscillated +/- 2 cm at 2 Hz by an operator, to simulate walking. While the subject is being oscillated, they are asked to discern the direction of Landolt-C optotypes of varying sizes presented on a screen 1 m from the subject and record their direction using a gamepad. The visual acuity thresholds are determined using an algorithm that alters the size of the optotype based on the previous responses of the subject using a forced-choice best parameter estimation that is able to rapidly converge on the threshold value. Visual acuity thresholds are determined both for static (seated) and dynamic (oscillating) conditions. Dynamic visual acuity is defined as the difference between the dynamic and static conditions.

  18. Leaders of progressions in wild mixed-species troops of saddleback (Saguinus fuscicollis) and mustached tamarins (S. mystax), with emphasis on color vision and sex.

    PubMed

    Smith, Andrew C; Buchanan-Smith, Hannah M; Surridge, Alison K; Mundy, Nicholas I

    2003-12-01

    Leadership of travel progression is an important aspect of group living. It is widely believed that trichromacy evolved to facilitate the detection and selection of fruit in the dappled light of a forest. Further, it has been proposed that in New World primate species, which typically contain a range of color vision phenotypes, at least one female in a group will be trichromatic (i.e., having three types of visual pigment, in contrast to the two types of pigment found in dichromatic individuals) and will lead the group to fruiting trees. We examine progression leadership within two wild mixed-species troops of saddleback (Saguinus fuscicollis) and mustached (Saguinus mystax) tamarins over a complete year. As whole units, the mixed-species troops were most frequently led by a mustached tamarin. This is the first time that mixed-species group leadership and individual leadership have been quantified in these tamarin species. In terms of single-species intragroup leadership, neither the visual status (dichromatic or trichromatic) nor the sex of individuals had a consistent effect across species. Saddleback tamarin groups were led by males more frequently than females, while evidence suggests that mustached tamarins may be female-led. The notion that all groups contain at least one trichromatic female that leads the troop to feeding trees was not supported. PMID:14669267

  19. Potential acuity meter for predicting visual acuity after Nd:YAG posterior capsulotomy

    SciTech Connect

    Smiddy, W.E.; Radulovic, D.; Yeo, J.H.; Stark, W.J.; Maumenee, A.E.

    1986-03-01

    We studied 30 patients with opacifications of the posterior capsule to determine if the potential acuity meter (PAM) could accurately predict final visual outcome after Nd:YAG discussion. The final visual acuity was within one line of the PAM prediction in 22 of 30 patients (73%), better by two or more lines in seven patients (23%), and worse in one patient (4%) by two lines. Although in thicker capsules the final acuity was occasionally better than the PAM prediction, the rates of false negative and false positive predictions were very low. Mild cystoid macular edema (3 patients), age-related macular degeneration (3 patients), intraocular lens status, and level of initial acuity did not diminish PAM accuracy. The PAM effectively predicts final visual acuity after YAG posterior capsulotomy, when used in a patient, unhurried manner.

  20. Evaluation of a Public Child Eye Health Tertiary Facility for Pediatric Cataract in Southern Nigeria I: Visual Acuity Outcome

    PubMed Central

    Duke, Roseline E.; Adio, Adedayo; Oparah, Sidney K.; Odey, Friday; Eyo, Okon A.

    2016-01-01

    Purpose: A retrospective study of the outcome of congenital and developmental cataract surgery was conducted in a public child eye health tertiary facility in children <16 years of age in Southern Nigeria, as part of an evaluation. Materials and Method: Manual Small Incision Cataract Surgery with or without anterior vitrectomy was performed. The outcome measures were visual acuity (VA) and change (gain) in visual acuity. The age of the child at onset, duration of delay in presentation, ocular co-morbidity, non ocular co-morbidity, gender, and pre operative visual acuity were matched with postoperative visual acuity. A total of 66 children were studied for a period of six weeks following surgery. Results: Forty eight (72.7%) children had bilateral congenital cataracts and 18 (27.3%) children had bilateral developmental cataracts. There were 38(57.6%) males and 28 (42.4%) females in the study. Thirty Five (53%) children had good visual outcome (normal vision range 6/6/ -6/18) post-operatively. The number of children with blindness (vision <3/60) decreased from 61 (92.4%) pre-operatively to 4 (6.1%) post-operatively. Post operative complication occurred in 6.8% of cases six week after surgery. Delayed presentation had an inverse relationship with change (gain) in visual acuity (r = - 0.342; p-value = 0.005). Pre-operative visual acuity had a positive relationship with post operative change (gain) in visual acuity (r = 0.618; p-value = 0.000). Conclusion: Predictors of change in visual acuity in our study were; delayed presentation and pre-operative VA. Cataract surgery in children showed clinical benefit. PMID:27347247

  1. A Colour Vision Experiment.

    ERIC Educational Resources Information Center

    Lovett, David; Hore, Kevin

    1991-01-01

    The model for color vision put forward by Edwin Land is explained. The aspects of the theory that can be demonstrated within the classroom are described. A random arrangement of straight-edged colored areas mounted on a screen, called a Mondrian, projectors, and a computer are used to calculate reflectance. (KR)

  2. Basic design principles of colorimetric vision systems

    NASA Astrophysics Data System (ADS)

    Mumzhiu, Alex M.

    1998-10-01

    Color measurement is an important part of overall production quality control in textile, coating, plastics, food, paper and other industries. The color measurement instruments such as colorimeters and spectrophotometers, used for production quality control have many limitations. In many applications they cannot be used for a variety of reasons and have to be replaced with human operators. Machine vision has great potential for color measurement. The components for color machine vision systems, such as broadcast quality 3-CCD cameras, fast and inexpensive PCI frame grabbers, and sophisticated image processing software packages are available. However the machine vision industry has only started to approach the color domain. The few color machine vision systems on the market, produced by the largest machine vision manufacturers have very limited capabilities. A lack of understanding that a vision based color measurement system could fail if it ignores the basic principles of colorimetry is the main reason for the slow progress of color vision systems. the purpose of this paper is to clarify how color measurement principles have to be applied to vision systems and how the electro-optical design features of colorimeters have to be modified in order to implement them for vision systems. The subject of this presentation far exceeds the limitations of a journal paper so only the most important aspects will be discussed. An overview of the major areas of applications for colorimetric vision system will be discussed. Finally, the reasons why some customers are happy with their vision systems and some are not will be analyzed.

  3. [Predicting visual acuity in media opacities and uncorrectable refractive errors. Assessing so-called "retinal visual acuity"].

    PubMed

    Lachenmayr, B

    1990-01-01

    Three different components contribute to the modulation transfer function of the visual system: (1) formation of the optical image (refractive media, pupil); (2) scattering of light in the prereceptoral layers of the retina; (3) neuronal processing in the retina und superior visual centers. In the presence of media opacities or non-correctable refractive errors, the clinical question often arises as to which macular function can be expected under the assumption of normal optical image formation (e.g. prior to cataract extraction, corneal transplantation, or vitrectomy). Simple tests such as light projection, color discrimination, and two-point discrimination cannot provide adequate information about macular function. The same holds true for the global luminance ERG. The X-ray phosphene is obsolete. The Maddox rod (with limitations), transilluminated Amsler grid, and various entoptic phenomena (Purkinje vascular phenomenon, foveal chagrin, Haidinger's brushes, blue field phenomenon) are available as qualitative subjective tests. Maxwellian view systems with pinhole aperture (potential acuity meter PAM) and the interferometers (retinometer, visometer, SITE-IRAS interferometer) provide quantitative subjective methods. The flash VECP is primarily a qualitative objective test that allows semiquantitative acuity prediction under special conditions (unilateral opacities). Psychophysical criteria that are less affected by the quality of the retinal image show promising developments in future subjective tests, e.g. optotypes in positive contrast, optotypes or targets superimposed on a background of optical noise, or hyperacuity. Future objective test developments are pattern VECP or even pattern ERG elicited by interferometric stimulation, speckle VECP and focal ERG. PMID:2083891

  4. Visual Acuity of Children: United States.

    ERIC Educational Resources Information Center

    Health Services and Mental Health Administration (DHEW), Bethesda, MD.

    National estimates based on the findings from the Health Examination Survey in 1963 to 1965 of uncorrected monocular and binocular visual-acuity levels of children were studied. A nationwide sample of 7,417 children was selected to represent the approximately 24 million noninstitutionalized American children between ages 6 and 11 years. Testing…

  5. Visual acuity and associated factors. The Central India Eye and Medical Study.

    PubMed

    Nangia, Vinay; Jonas, Jost B; Sinha, Ajit; Gupta, Rajesh; Agarwal, Shubhra

    2011-01-01

    Visual acuity is a major parameter for quality of vision and quality of life. Information on visual acuity and its associated factors in rural societies almost untouched by any industrialization is mostly non-available. It was, therefore, the purpose of our study to determine the distribution of visual acuity and its associated factors in a rural population not marked influenced by modern lifestyle. The population-based Central India Eye and Medical Study included 4711 subjects (aged 30+ years), who underwent a detailed ophthalmologic examination including visual acuity measurement. Visual acuity measurements were available for 4706 subjects with a mean age of 49.5±13.4 years (range: 30-100 years). BCVA decreased significantly (P<0.001) from the moderately hyperopic group (0.08±0.15 logMAR) to the emmetropic group (0.16±0.52 logMAR), the moderately myopic group (0.28±0.33 logMAR), the highly hyperopic group (0.66±0.62 logMAR) and finally the highly myopic group (1.32±0.92 logMAR). In multivariate analysis, BCVA was significantly associated with the systemic parameters of lower age (P<0.001), higher level of education (P<0.001), higher body stature (P<0.001) and higher body mass index (P<0.001), and with the ophthalmic parameters of more hyperopic refractive error (spherical equivalent) (P<0.001), shorter axial length (P<0.001), lower degree of nuclear cataract (P<0.001), and lower intraocular pressure (P = 0.006). The results suggest that in the rural population of Central India, major determinants of visual acuity were socioeconomic background, body stature and body mass index, age, refractive error, cataract and intraocular pressure. PMID:21829503

  6. Color space conversion for linear color grading

    NASA Astrophysics Data System (ADS)

    Lee, Dah-Jye

    2000-10-01

    Color grading is an important process for various industries such as food processing, fruit and vegetable grading, etc. Quality and price are often determined by the color of product. For example, darker red color for apples means higher price. In color machine vision applications, image is acquired with a color CCD camera that outputs color information in three channels, red, gree, and blue. When grading color, these three primary colors must be processed to determine the color level for separation. A very popular color space conversion technique for color image processing is RGB-to-HSI, where HSI represents hue, saturation, and intensity, respectively. However, the conversion result is still 3D information that makes determining color grades very difficult. A new color space conversion technique that can be implemented for high-speed real-time processing for color grading is introduced in this paper. Depending on the application, different color space conversion equations must be used. The result of this technique is a simple one-dimensional array that represents different color levels. This linear array makes linear color grading adjustment possible.

  7. Impact of visual acuity on developing literacy at age 4–5 years: a cohort-nested cross-sectional study

    PubMed Central

    Bruce, Alison; Fairley, Lesley; Chambers, Bette; Wright, John; Sheldon, Trevor A

    2016-01-01

    Objectives To estimate the prevalence of poor vision in children aged 4–5 years and determine the impact of visual acuity on literacy. Design Cross-sectional study linking clinical, epidemiological and education data. Setting Schools located in the city of Bradford, UK. Participants Prevalence was determined for 11 186 children participating in the Bradford school vision screening programme. Data linkage was undertaken for 5836 Born in Bradford (BiB) birth cohort study children participating both in the Bradford vision screening programme and the BiB Starting Schools Programme. 2025 children had complete data and were included in the multivariable analyses. Main outcome measures Visual acuity was measured using a logMAR Crowded Test (higher scores=poorer visual acuity). Literacy measured by Woodcock Reading Mastery Tests-Revised (WRMT-R) subtest: letter identification (standardised). Results The mean (SD) presenting visual acuity was 0.14 (0.09) logMAR (range 0.0–1.0). 9% of children had a presenting visual acuity worse than 0.2logMAR (failed vision screening), 4% worse than 0.3logMAR (poor visual acuity) and 2% worse than 0.4logMAR (visually impaired). Unadjusted analysis showed that the literacy score was associated with presenting visual acuity, reducing by 2.4 points for every 1 line (0.10logMAR) reduction in vision (95% CI −3.0 to −1.9). The association of presenting visual acuity with the literacy score remained significant after adjustment for demographic and socioeconomic factors reducing by 1.7 points (95% CI −2.2 to −1.1) for every 1 line reduction in vision. Conclusions Prevalence of decreased visual acuity was high compared with other population-based studies. Decreased visual acuity at school entry is associated with reduced literacy. This may have important implications for the children's future educational, health and social outcomes. PMID:26883240

  8. Impact on stereo-acuity of two presbyopia correction approaches: monovision and small aperture inlay

    PubMed Central

    Fernández, Enrique J.; Schwarz, Christina; Prieto, Pedro M.; Manzanera, Silvestre; Artal, Pablo

    2013-01-01

    Some of the different currently applied approaches that correct presbyopia may reduce stereovision. In this work, stereo-acuity was measured for two methods: (1) monovision and (2) small aperture inlay in one eye. When performing the experiment, a prototype of a binocular adaptive optics vision analyzer was employed. The system allowed simultaneous measurement and manipulation of the optics in both eyes of a subject. The apparatus incorporated two programmable spatial light modulators: one phase-only device using liquid crystal on silicon technology for wavefront manipulation and one intensity modulator for controlling the exit pupils. The prototype was also equipped with a stimulus generator for creating retinal disparity based on two micro-displays. The three-needle test was programmed for characterizing stereo-acuity. Subjects underwent a two-alternative forced-choice test. The following cases were tested for the stimulus placed at distance: (a) natural vision; (b) 1.5 D monovision; (c) 0.75 D monovision; (d) natural vision and small pupil; (e) 0.75 D monovision and small pupil. In all cases the standard pupil diameter was 4 mm and the small pupil diameter was 1.6 mm. The use of a small aperture significantly reduced the negative impact of monovision on stereopsis. The results of the experiment suggest that combining micro-monovision with a small aperture, which is currently being implemented as a corneal inlay, can yield values of stereoacuity close to those attained under normal binocular vision. PMID:23761846

  9. Collinear facilitation in color vision.

    PubMed

    Huang, Pi-Chun; Mullen, Kathy T; Hess, Robert F

    2007-01-01

    The detection of a luminance-defined Gabor is improved by two high contrast, aligned, flanking Gabors, an effect termed collinear facilitation. We investigate whether this facilitation also occurs for isoluminant chromatic stimuli, and whether it can occur for chromatic targets with luminance flanks and vice versa. We measured collinear facilitation for Gabor stimuli (0.75 cpd, 1 octave bandwidth) of three different contrast types: achromatic, red-green that isolates the L/M-cone opponent mechanism, and blue-yellow that isolates the S-cone opponent mechanism. Three conditions were investigated: (1) target and flanks all of the same contrast type and spatial phase; (2) target and flanks of the same contrast type but opposite phases (0 degrees and 180 degrees ); and (3) target and flanks of different contrast types (chromatic with achromatic contrast) and two opposite phase combinations. We find that a similar degree of collinear facilitation occurs for the isoluminant chromatic stimuli as for the achromatic stimuli, and all exhibit phase dependency. Facilitation did not occur, however, between chromatic and achromatic target and flanking stimuli. This suggests that at the level of collinear facilitation, the chromatic and the achromatic postreceptoral mechanisms have their own spatial interactions that are segregated from one another. PMID:17997661

  10. Colorful Collage: Visions of Flowers

    ERIC Educational Resources Information Center

    Skophammer, Karen

    2011-01-01

    The technique of what people today call "collage" is not new. In Victorian times, elaborate art was created from bristly horsehair as a type of collage. The modern collage dates to the early 1900s when Picasso pasted newspaper on a drawing. In 1919 Karl Schwitters, a German artist, developed collage into an art form that was as important as…

  11. Variable acuity remote viewing system flight demonstration

    NASA Technical Reports Server (NTRS)

    Fisher, R. W.

    1983-01-01

    The Variable Acuity Remote Viewing System (VARVS), originally developed under contract to the Navy (ONR) as a laboratory brassboard, was modified for flight demonstration. The VARVS system was originally conceived as a technique which could circumvent the acuity/field of view/bandwidth tradeoffs that exists in remote viewing to provide a nearly eye limited display in both field of view (160 deg) and resolution (2 min arc) while utilizing conventional TV sensing, transmission, and display equipment. The modifications for flight demonstration consisted of modifying the sensor so it could be installed and flow in a Piper PA20 aircraft, equipped for remote control and modifying the display equipment so it could be integrated with the NASA Research RPB (RPRV) remote control cockpit.

  12. Acuity of mental representations of pitch.

    PubMed

    Janata, Petr

    2012-04-01

    Singing in one's mind or forming expectations about upcoming notes both require that mental images of one or more pitches will be generated. As with other musical abilities, the acuity with which such images are formed might be expected to vary across individuals and may depend on musical training. Results from several behavioral tasks involving intonation judgments indicate that multiple memory systems contribute to the formation of accurate mental images for pitch, and that the functionality of each is affected by musical training. Electrophysiological measures indicate that the ability to form accurate mental images is associated with greater engagement of auditory areas and associated error-detection circuitry when listeners imagine ascending scales and make intonation judgments about target notes. A view of auditory mental images is espoused in which unified mental image representations are distributed across multiple brain areas. Each brain area helps shape the acuity of the unified representation based on current behavioral demands and past experience. PMID:22524362

  13. 21 CFR 886.1150 - Visual acuity chart.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Visual acuity chart. 886.1150 Section 886.1150...) MEDICAL DEVICES OPHTHALMIC DEVICES Diagnostic Devices § 886.1150 Visual acuity chart. (a) Identification. A visual acuity chart is a device that is a chart, such as a Snellen chart with block letters...

  14. 21 CFR 886.1150 - Visual acuity chart.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Visual acuity chart. 886.1150 Section 886.1150...) MEDICAL DEVICES OPHTHALMIC DEVICES Diagnostic Devices § 886.1150 Visual acuity chart. (a) Identification. A visual acuity chart is a device that is a chart, such as a Snellen chart with block letters...

  15. 21 CFR 886.1150 - Visual acuity chart.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Visual acuity chart. 886.1150 Section 886.1150...) MEDICAL DEVICES OPHTHALMIC DEVICES Diagnostic Devices § 886.1150 Visual acuity chart. (a) Identification. A visual acuity chart is a device that is a chart, such as a Snellen chart with block letters...

  16. 21 CFR 886.1150 - Visual acuity chart.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Visual acuity chart. 886.1150 Section 886.1150...) MEDICAL DEVICES OPHTHALMIC DEVICES Diagnostic Devices § 886.1150 Visual acuity chart. (a) Identification. A visual acuity chart is a device that is a chart, such as a Snellen chart with block letters...

  17. 21 CFR 886.1150 - Visual acuity chart.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Visual acuity chart. 886.1150 Section 886.1150...) MEDICAL DEVICES OPHTHALMIC DEVICES Diagnostic Devices § 886.1150 Visual acuity chart. (a) Identification. A visual acuity chart is a device that is a chart, such as a Snellen chart with block letters...

  18. Is acuity enough? Other considerations in clinical investigations of visual prostheses.

    PubMed

    Lepri, Bernard P

    2009-06-01

    Visual impairing eye diseases are the major frontier facing ophthalmic research today in light of our rapidly aging population. The visual skills necessary for improving the quality of daily function and life are inextricably linked to these impairing diseases. Both research and reimbursement programs are emphasizing outcome-based results. Is improvement in visual acuity alone enough to improve the function and quality of life of visually impaired persons? This perspective summarizes the types of effectiveness endpoints for clinical investigations of visual prostheses that go beyond visual acuity. The clinical investigation of visual prostheses should include visual function, functional vision and quality of life measures. Specifically, they encompass contrast sensitivity, orientation and mobility, activities of daily living and quality of life assessments. The perspective focuses on the design of clinical trials for visual prostheses and the methods of determining effectiveness above and beyond visual acuity that will yield outcomes that are measured by improved function in the visual world and quality of life. The visually impaired population is the primary consideration in this presentation with particular emphases on retinitis pigmentosa and age-related macular degeneration. Clinical trials for visual prostheses cannot be isolated from the need for medical rehabilitation in order to obtain measurements of effectiveness that produce outcomes/evidence-based success. This approach will facilitate improvement in daily function and quality of life of patients with diseases that cause chronic vision impairment. PMID:19458402

  19. One of the most well-established age-related changes in neural activity disappears after controlling for visual acuity.

    PubMed

    Porto, Fábio H G; Tusch, Erich S; Fox, Anne M; Alperin, Brittany R; Holcomb, Phillip J; Daffner, Kirk R

    2016-04-15

    Numerous studies using a variety of imaging techniques have reported age-related differences in neural activity while subjects carry out cognitive tasks. Surprisingly little attention has been paid to the potential impact of age-associated changes in sensory acuity on these findings. Studies in the visual modality frequently report that their subjects had "normal or corrected- to-normal vision." However, in most cases, there is no indication that visual acuity was actually measured, and it is likely that the investigators relied largely on self-reported visual status of subjects, which is often inaccurate. We investigated whether differences in visual acuity influence one of the most commonly observed findings in the event-related potentials literature on cognitive aging, a reduction in posterior P3b amplitude, which is an index of cognitive decision-making/updating. Well-matched young (n=26) and old adults (n=29) participated in a visual oddball task. Measured visual acuity with corrective lenses was worse in old than young adults. Results demonstrated that the robust age-related decline in P3b amplitude to visual targets disappeared after controlling for visual acuity, but was unaffected by accounting for auditory acuity. Path analysis confirmed that the relationship between age and diminished P3b to visual targets was mediated by visual acuity, suggesting that conveyance of suboptimal sensory data due to peripheral, rather than central, deficits may undermine subsequent neural processing. We conclude that until the relationship between age-associated differences in visual acuity and neural activity during experimental tasks is clearly established, investigators should exercise caution attributing results to differences in cognitive processing. PMID:26825439

  20. New Methods for Testing Infant Vision.

    ERIC Educational Resources Information Center

    Gwiazda, Jane; And Others

    1979-01-01

    Based on studies and clinical findings, two techniques for testing infant vision are described: near-retinoscopy (used to assess the refractive state of infants and young children) and a fast preferential looking procedure (used to assess the acuity of infants up to one year of age). (DLS)

  1. Comparison of acuity tests and pattern evoked potential criteria: two mechanisms underly acuity maturation in man.

    PubMed

    Spekreijse, H

    1983-10-01

    A comparative study of acuity tests and pattern evoked potential (EP) criteria was performed on a total of 307 subjects, 214 of them at an age between 2 months post-term and 12 years. All were examined ophthalmologically prior to testing. It was shown that both psychophysical and EP estimated acuity improve in the same way until puberty. From birth to about 6 months a rapid improvement is found. This fast phase can probably be attributed to retinal morphological maturation. During this period a fair estimate of acuity can be obtained by determining the checksize that yields the largest EP; a conclusion of practical importance for screening. The subsequent slow improvement phase, which ends around puberty, is reflected in the development of the waveform of the pattern onset EP. Since it correlates with the growth of a spatial contrast specific component of extrastriate origin in the EP, the slow improvement phase most likely reflects maturation of central processes. PMID:6639719

  2. Visual Acuity of Simulated Thalamic Visual Prostheses in Normally Sighted Humans

    PubMed Central

    Jeffries, Ailsa; Pezaris, John S.

    2013-01-01

    Simulation in normally sighted individuals is a crucial tool to evaluate the performance of potential visual prosthesis designs prior to human implantation of a device. Here, we investigated the effects of electrode count on visual acuity, learning rate and response time in 16 normally sighted subjects using a simulated thalamic visual prosthesis, providing the first performance reports for thalamic designs. A new letter recognition paradigm using a multiple-optotype two-alternative forced choice task was adapted from the Snellen eye chart, and specifically devised to be readily communicated to both human and non-human primate subjects. Validation of the method against a standard Snellen acuity test in 21 human subjects showed no significant differences between the two tests. The novel task was then used to address three questions about simulations of the center-weighted phosphene patterns typical of thalamic designs: What are the expected Snellen acuities for devices with varying numbers of contacts, do subjects display rapid adaptation to the new visual modality, and can response time in the task provide clues to the mechanisms of perception in low-resolution artificial vision? Population performance (hit rate) was significantly above chance when viewing Snellen 20/200 optotypes (Log MAR 1.0) with 370 phosphenes in the central 10 degrees of vision, ranging to Snellen 20/800 (Log MAR 1.6) with 25 central phosphenes. Furthermore, subjects demonstrated learning within the 1–2 hours of task experience indicating the potential for an effective rehabilitation and possibly better visual performance after a longer period of training. Response time differences suggest that direct letter perception occurred when hit rate was above 75%, whereas a slower strategy like feature-based pattern matching was used in conditions of lower relative resolution. As pattern matching can substantially boost effective acuity, these results suggest post-implant therapy should specifically

  3. Photometric Compliance of Tablet Screens and Retro-Illuminated Acuity Charts As Visual Acuity Measurement Devices

    PubMed Central

    Livingstone, I. A. T.; Tarbert, C. M.; Giardini, M. E.; Bastawrous, A.; Middleton, D.; Hamilton, R.

    2016-01-01

    Mobile technology is increasingly used to measure visual acuity. Standards for chart-based acuity tests specify photometric requirements for luminance, optotype contrast and luminance uniformity. Manufacturers provide some photometric data but little is known about tablet performance for visual acuity testing. This study photometrically characterised seven tablet computers (iPad, Apple inc.) and three ETDRS (Early Treatment Diabetic Retinopathy Study) visual acuity charts with room lights on and off, and compared findings with visual acuity measurement standards. Tablet screen luminance and contrast were measured using nine points across a black and white checkerboard test screen at five arbitrary brightness levels. ETDRS optotypes and adjacent white background luminance and contrast were measured. All seven tablets (room lights off) exceeded the most stringent requirement for mean luminance (≥ 120 cd/m2) providing the nominal brightness setting was above 50%. All exceeded contrast requirement (Weber ≥ 90%) regardless of brightness setting, and five were marginally below the required luminance uniformity threshold (Lmin/Lmax ≥ 80%). Re-assessing three tablets with room lights on made little difference to mean luminance or contrast, and improved luminance uniformity to exceed the threshold. The three EDTRS charts (room lights off) had adequate mean luminance (≥ 120 cd/m2) and Weber contrast (≥ 90%), but all three charts failed to meet the luminance uniformity standard (Lmin/Lmax ≥ 80%). Two charts were operating beyond manufacturer’s recommended lamp replacement schedule. With room lights on, chart mean luminance and Weber contrast increased, but two charts still had inadequate luminance uniformity. Tablet computers showed less inter-device variability, higher contrast, and better luminance uniformity than charts in both lights-on and lights-off environments, providing brightness setting was >50%. Overall, iPad tablets matched or marginally out

  4. Photometric Compliance of Tablet Screens and Retro-Illuminated Acuity Charts As Visual Acuity Measurement Devices.

    PubMed

    Livingstone, I A T; Tarbert, C M; Giardini, M E; Bastawrous, A; Middleton, D; Hamilton, R

    2016-01-01

    Mobile technology is increasingly used to measure visual acuity. Standards for chart-based acuity tests specify photometric requirements for luminance, optotype contrast and luminance uniformity. Manufacturers provide some photometric data but little is known about tablet performance for visual acuity testing. This study photometrically characterised seven tablet computers (iPad, Apple inc.) and three ETDRS (Early Treatment Diabetic Retinopathy Study) visual acuity charts with room lights on and off, and compared findings with visual acuity measurement standards. Tablet screen luminance and contrast were measured using nine points across a black and white checkerboard test screen at five arbitrary brightness levels. ETDRS optotypes and adjacent white background luminance and contrast were measured. All seven tablets (room lights off) exceeded the most stringent requirement for mean luminance (≥ 120 cd/m2) providing the nominal brightness setting was above 50%. All exceeded contrast requirement (Weber ≥ 90%) regardless of brightness setting, and five were marginally below the required luminance uniformity threshold (Lmin/Lmax ≥ 80%). Re-assessing three tablets with room lights on made little difference to mean luminance or contrast, and improved luminance uniformity to exceed the threshold. The three EDTRS charts (room lights off) had adequate mean luminance (≥ 120 cd/m2) and Weber contrast (≥ 90%), but all three charts failed to meet the luminance uniformity standard (Lmin/Lmax ≥ 80%). Two charts were operating beyond manufacturer's recommended lamp replacement schedule. With room lights on, chart mean luminance and Weber contrast increased, but two charts still had inadequate luminance uniformity. Tablet computers showed less inter-device variability, higher contrast, and better luminance uniformity than charts in both lights-on and lights-off environments, providing brightness setting was >50%. Overall, iPad tablets matched or marginally out

  5. Response Classification Images in Vernier Acuity

    NASA Technical Reports Server (NTRS)

    Ahumada, Albert J., Jr.; Beard, B. L.; Ellis, Stephen R. (Technical Monitor)

    1997-01-01

    Orientation selective and local sign mechanisms have been proposed as the basis for vernier acuity judgments. Linear image features contributing to discrimination can be determined for a two choice task by adding external noise to the images and then averaging the noises separately for the four types of stimulus/response trials. This method is applied to a vernier acuity task with different spatial separations to compare the predictions of the two theories. Three well-practiced observers were presented around 5000 trials of a vernier stimulus consisting of two dark horizontal lines (5 min by 0.3 min) within additive low-contrast white noise. Two spatial separations were tested, abutting and a 10 min horizontal separation. The task was to determine whether the target lines were aligned or vertically offset. The noises were averaged separately for the four stimulus/response trial types (e.g., stimulus = offset, response = aligned). The sum of the two 'not aligned' images was then subtracted from the sum of the 'aligned' images to obtain an overall image. Spatially smoothed images were quantized according to expected variability in the smoothed images to allow estimation of the statistical significance of image features. The response images from the 10 min separation condition are consistent with the local sign theory, having the appearance of two linear operators measuring vertical position with opposite sign. The images from the abutting stimulus have the same appearance with the two operators closer together. The image predicted by an oriented filter model is similar, but has its greatest weight in the abutting region, while the response images fall to nonsignificance there. The response correlation image method, previously demonstrated for letter discrimination, clarifies the features used in vernier acuity.

  6. Modeling acuity for optotypes varying in complexity.

    PubMed

    Watson, Andrew B; Ahumada, Albert J

    2012-01-01

    Watson and Ahumada (2008) described a template model of visual acuity based on an ideal-observer limited by optical filtering, neural filtering, and noise. They computed predictions for selected optotypes and optical aberrations. Here we compare this model's predictions to acuity data for six human observers, each viewing seven different optotype sets, consisting of one set of Sloan letters and six sets of Chinese characters, differing in complexity (Zhang, Zhang, Xue, Liu, & Yu, 2007). Since optical aberrations for the six observers were unknown, we constructed 200 model observers using aberrations collected from 200 normal human eyes (Thibos, Hong, Bradley, & Cheng, 2002). For each condition (observer, optotype set, model observer) we estimated the model noise required to match the data. Expressed as efficiency, performance for Chinese characters was 1.4 to 2.7 times lower than for Sloan letters. Efficiency was weakly and inversely related to perimetric complexity of optotype set. We also compared confusion matrices for human and model observers. Correlations for off-diagonal elements ranged from 0.5 to 0.8 for different sets, and the average correlation for the template model was superior to a geometrical moment model with a comparable number of parameters (Liu, Klein, Xue, Zhang, & Yu, 2009). The template model performed well overall. Estimated psychometric function slopes matched the data, and noise estimates agreed roughly with those obtained independently from contrast sensitivity to Gabor targets. For optotypes of low complexity, the model accurately predicted relative performance. This suggests the model may be used to compare acuities measured with different sets of simple optotypes. PMID:23024356

  7. Comparison of binocular through-focus visual acuity with monovision and a small aperture inlay.

    PubMed

    Schwarz, Christina; Manzanera, Silvestre; Prieto, Pedro M; Fernández, Enrique J; Artal, Pablo

    2014-10-01

    Corneal small aperture inlays provide extended depth of focus as a solution to presbyopia. As this procedure is becoming more popular, it is interesting to compare its performance with traditional approaches, such as monovision. Here, binocular visual acuity was measured as a function of object vergence in three subjects by using a binocular adaptive optics vision analyzer. Visual acuity was measured at two luminance levels (photopic and mesopic) under several optical conditions: 1) natural vision (4 mm pupils, best corrected distance vision), 2) pure-defocus monovision ( + 1.25 D add in the nondominant eye), 3) small aperture monovision (1.6 mm pupil in the nondominant eye), and 4) combined small aperture and defocus monovision (1.6 mm pupil and a + 0.75 D add in the nondominant eye). Visual simulations of a small aperture corneal inlay suggest that the device extends DOF as effectively as traditional monovision in photopic light, in both cases at the cost of binocular summation. However, individual factors, such as aperture centration or sensitivity to mesopic conditions should be considered to assure adequate visual outcomes. PMID:25360355

  8. Comparison of binocular through-focus visual acuity with monovision and a small aperture inlay

    PubMed Central

    Schwarz, Christina; Manzanera, Silvestre; Prieto, Pedro M.; Fernández, Enrique J.; Artal, Pablo

    2014-01-01

    Corneal small aperture inlays provide extended depth of focus as a solution to presbyopia. As this procedure is becoming more popular, it is interesting to compare its performance with traditional approaches, such as monovision. Here, binocular visual acuity was measured as a function of object vergence in three subjects by using a binocular adaptive optics vision analyzer. Visual acuity was measured at two luminance levels (photopic and mesopic) under several optical conditions: 1) natural vision (4 mm pupils, best corrected distance vision), 2) pure-defocus monovision ( + 1.25 D add in the nondominant eye), 3) small aperture monovision (1.6 mm pupil in the nondominant eye), and 4) combined small aperture and defocus monovision (1.6 mm pupil and a + 0.75 D add in the nondominant eye). Visual simulations of a small aperture corneal inlay suggest that the device extends DOF as effectively as traditional monovision in photopic light, in both cases at the cost of binocular summation. However, individual factors, such as aperture centration or sensitivity to mesopic conditions should be considered to assure adequate visual outcomes. PMID:25360355

  9. How well do you see what you hear? The acuity of visual-to-auditory sensory substitution

    PubMed Central

    Haigh, Alastair; Brown, David J.; Meijer, Peter; Proulx, Michael J.

    2013-01-01

    Sensory substitution devices (SSDs) aim to compensate for the loss of a sensory modality, typically vision, by converting information from the lost modality into stimuli in a remaining modality. “The vOICe” is a visual-to-auditory SSD which encodes images taken by a camera worn by the user into “soundscapes” such that experienced users can extract information about their surroundings. Here we investigated how much detail was resolvable during the early induction stages by testing the acuity of blindfolded sighted, naïve vOICe users. Initial performance was well above chance. Participants who took the test twice as a form of minimal training showed a marked improvement on the second test. Acuity was slightly but not significantly impaired when participants wore a camera and judged letter orientations “live”. A positive correlation was found between participants' musical training and their acuity. The relationship between auditory expertise via musical training and the lack of a relationship with visual imagery, suggests that early use of a SSD draws primarily on the mechanisms of the sensory modality being used rather than the one being substituted. If vision is lost, audition represents the sensory channel of highest bandwidth of those remaining. The level of acuity found here, and the fact it was achieved with very little experience in sensory substitution by naïve users is promising. PMID:23785345

  10. Vision problems

    MedlinePlus

    ... which nothing can be seen) Vision loss and blindness are the most severe vision problems. Causes Vision ... that look faded. The most common cause of blindness in people over age 60. Eye infection, inflammation, ...

  11. Defining lactation acuity to improve patient safety and outcomes.

    PubMed

    Mannel, Rebecca

    2011-05-01

    While substantial evidence exists identifying risks factors associated with premature weaning from breastfeeding, there are no previously published definitions of patient acuity in the lactation field. This article defines evidence-based levels of lactation acuity based on maternal and infant characteristics. Patient acuity, matching severity of illness to intensity of care required, is an important determinant of patient safety and outcomes. It is often used as part of a patient classification system to determine staffing needs and acceptable workloads in health care settings. As acuity increases, more resources, including more skilled clinicians, are needed to provide optimal care. Developing an evidence-based definition of lactation acuity can help to standardize terminology, more effectively distribute health care staff resources, encourage research to verify the validity and reliability of lactation acuity, and potentially improve breastfeeding initiation and duration rates. PMID:21527797

  12. Presbyopia: a pilot investigation of the barriers and benefits of near visual acuity correction among a rural Filipino population

    PubMed Central

    2014-01-01

    Background Presbyopia is the age-related decline in accommodation that diminishes the ability of the eye to focus on near objects. Presbyopia is common and easy to correct; however, many communities lack access to basic eye care. The purpose of this project was to assess the burden of uncorrected presbyopia in a rural Filipino population and to pilot an intervention aimed at increasing access to reading glasses in the community. Methods Individuals above the age of 40 who presented to a health outreach in the Philippines were invited to undergo a near vision exam to detect the presence of functional presbyopia and be fitted with ready-made, single-vision glasses. The change in stereoacuity was used as a surrogate measure of functional improvement after near vision correction. A questionnaire was administered to assess this population’s perceived barriers and benefits to correcting near vision. Results The average age of the participants was 57 ± 11 years, with 87.6% of participants having an uncorrected near visual acuity of <20/50. Reading glasses improved near vision to 20/40 or better in 77.7% of participants having near-vision impairment (uncorrected near visual acuity of <20/40). Over 75% of participants also showed improvement in stereoacuity. Cost, rather than availability, was perceived to be the greater barrier to the procurement of glasses, and 84% of participants reported that the glasses dispensed would greatly improve their ability to earn a living. Conclusions Dispensing ready-made, single-vision glasses is a simple and cost-effective intervention to improve near vision and enhance depth perception. A greater understanding of the barriers and benefits to correcting near vision will inform the design and execution of a sustainable program to correct presbyopia in developing countries. PMID:24467667

  13. Visual training improves underwater vision in children.

    PubMed

    Gislén, Anna; Warrant, Eric J; Dacke, Marie; Kröger, Ronald H H

    2006-10-01

    Children in a tribe of sea-gypsies from South-East Asia have been found to have superior underwater vision compared to European children. In this study, we show that the improved underwater vision of these Moken children is not due to better contrast sensitivity in general. We also show that European children can achieve the same underwater acuity as the Moken children. After 1 month of underwater training (11 sessions) followed by 4 months with no underwater activities, European children showed improved underwater vision and distinct bursts of pupil constriction. When tested 8 months after the last training session in an outdoor pool in bright sunlight-comparable to light environments in South-East Asia-the children had attained the same underwater acuity as the sea-gypsy children. The achieved performance can be explained by the combined effect of pupil constriction and strong accommodation. PMID:16806388

  14. Normal Visual Acuity and Electrophysiological Contrast Gain in Adults with High-Functioning Autism Spectrum Disorder.

    PubMed

    Tebartz van Elst, Ludger; Bach, Michael; Blessing, Julia; Riedel, Andreas; Bubl, Emanuel

    2015-01-01

    A common neurodevelopmental disorder, autism spectrum disorder (ASD), is defined by specific patterns in social perception, social competence, communication, highly circumscribed interests, and a strong subjective need for behavioral routines. Furthermore, distinctive features of visual perception, such as markedly reduced eye contact and a tendency to focus more on small, visual items than on holistic perception, have long been recognized as typical ASD characteristics. Recent debate in the scientific community discusses whether the physiology of low-level visual perception might explain such higher visual abnormalities. While reports of this enhanced, "eagle-like" visual acuity contained methodological errors and could not be substantiated, several authors have reported alterations in even earlier stages of visual processing, such as contrast perception and motion perception at the occipital cortex level. Therefore, in this project, we have investigated the electrophysiology of very early visual processing by analyzing the pattern electroretinogram-based contrast gain, the background noise amplitude, and the psychophysical visual acuities of participants with high-functioning ASD and controls with equal education. Based on earlier findings, we hypothesized that alterations in early vision would be present in ASD participants. This study included 33 individuals with ASD (11 female) and 33 control individuals (12 female). The groups were matched in terms of age, gender, and education level. We found no evidence of altered electrophysiological retinal contrast processing or psychophysical measured visual acuities. There appears to be no evidence for abnormalities in retinal visual processing in ASD patients, at least with respect to contrast detection. PMID:26379525

  15. Normal Visual Acuity and Electrophysiological Contrast Gain in Adults with High-Functioning Autism Spectrum Disorder

    PubMed Central

    Tebartz van Elst, Ludger; Bach, Michael; Blessing, Julia; Riedel, Andreas; Bubl, Emanuel

    2015-01-01

    A common neurodevelopmental disorder, autism spectrum disorder (ASD), is defined by specific patterns in social perception, social competence, communication, highly circumscribed interests, and a strong subjective need for behavioral routines. Furthermore, distinctive features of visual perception, such as markedly reduced eye contact and a tendency to focus more on small, visual items than on holistic perception, have long been recognized as typical ASD characteristics. Recent debate in the scientific community discusses whether the physiology of low-level visual perception might explain such higher visual abnormalities. While reports of this enhanced, “eagle-like” visual acuity contained methodological errors and could not be substantiated, several authors have reported alterations in even earlier stages of visual processing, such as contrast perception and motion perception at the occipital cortex level. Therefore, in this project, we have investigated the electrophysiology of very early visual processing by analyzing the pattern electroretinogram-based contrast gain, the background noise amplitude, and the psychophysical visual acuities of participants with high-functioning ASD and controls with equal education. Based on earlier findings, we hypothesized that alterations in early vision would be present in ASD participants. This study included 33 individuals with ASD (11 female) and 33 control individuals (12 female). The groups were matched in terms of age, gender, and education level. We found no evidence of altered electrophysiological retinal contrast processing or psychophysical measured visual acuities. There appears to be no evidence for abnormalities in retinal visual processing in ASD patients, at least with respect to contrast detection. PMID:26379525

  16. Functional Visual Acuity of Early Presbyopia

    PubMed Central

    Watanabe, Kazuhiro; Shigeno, Yuta; Saiki, Megumi; Torii, Hidemasa; Kaido, Minako; Tsubota, Kazuo

    2016-01-01

    Purpose To evaluate visual function in patients with early presbyopia using the functional visual acuity (FVA) test. Methods This study included 27 eyes of 27 healthy older volunteers (mean age, 44.1 ± 2.6 years) and 14 eyes of 14 healthy young volunteers (mean age, 28.4±4.8 years). The distance-corrected visual acuity (DCVA), distance-corrected near VA (DCNVA), subjective amplitude of accommodation (AA), and distance and near pupillary diameters were measured. The distance FVA and distance-corrected near FVA (DCNFVA) were measured using the FVA Measurement System. The standard Schirmer test and standard tear break-up time measurement also were performed. Results The logarithm of the minimum angle of resolution (logMAR) DCVA was better than 0 in all subjects. The percentages of subjects with logMAR DCNVA below 0 was significantly lower in the presbyopia group than in the young group. The DCNFVA in the presbyopia group was significantly (P < 0.001) poorer than the DCNVA in that group. Significant linear negative correlations were seen between the DCNVA and AA (r = -0.507, P < 0.001) and the DCNFVA and AA (r = -0.681, P < 0.001) in the older subjects. Stepwise regression analysis showed that only the AA was a significant factor predictive of the DCNFVA in the presbyopia group. Tear function parameters were not adopted in the regression model. Conclusions Measurement of the DCNFVA can detect decreased AA in early presbyopia better than measurement of the conventional near VA. The DCNFVA is a good index for early presbyopia. PMID:26959362

  17. The Physics of Colour Vision.

    ERIC Educational Resources Information Center

    Goldman, Martin

    1985-01-01

    An elementary physical model of cone receptor cells is explained and applied to complexities of human color vision. One-, two-, and three-receptor systems are considered, with the later shown to be the best model for the human eye. Color blindness is also discussed. (DH)

  18. Tinkertoy Color-Addition Device.

    ERIC Educational Resources Information Center

    Ferguson, Joe L.

    1995-01-01

    Describes construction and use of a simple home-built device, using an overhead projector, for use in demonstrations of the addition of various combinations of red, green, and blue light. Useful in connection with discussions of color, color vision, or color television. (JRH)

  19. Dynamic Visual Acuity and Landing Sickness in Crewmembers Returning from Long-Duration Spaceflight

    NASA Technical Reports Server (NTRS)

    Rosenberg, M.J.F; Peters, B.T.; Reschke, M. F.

    2016-01-01

    Long-term exposure to microgravity causes sensorimotor adaptations that result in functional deficits upon returning to a gravitational environment. At landing the vestibular system and the central nervous system, responsible for coordinating head and eye movements, are adapted to microgravity and must re-adapt to the gravitational environment. This re-adaptation causes decrements in gaze control and dynamic visual acuity, with astronauts reporting oscillopsia and blurred vision. Dynamic visual acuity (DVA) is assessed using an oscillating chair developed in the Neuroscience Laboratory at JSC. This chair is lightweight and easily portable for quick deployment in the field. The base of the chair is spring-loaded and allows for manual oscillation of the subject. Using a metronome, the chair is vertically oscillated plus or minus 2 cm at 2 Hz by an operator, to simulate walking. While the subject is being oscillated, they are asked to discern the direction of Landolt-C optotypes of varying sizes and record their direction using a gamepad. The visual acuity thresholds are determined using an algorithm that alters the size of the optotype based on the previous response of the subject using a forced-choice best parameter estimation that is able to rapidly converge on the threshold value. Visual acuity thresholds were determined both for static (seated) and dynamic (oscillating) conditions. Dynamic visual acuity is defined as the difference between the dynamic and static conditions. Dynamic visual acuity measures will be taken prior to flight (typically L-180, L-90, and L-60) and up to eight times after landing, including up to 3 times on R plus 0. Follow up measurements will be taken at R plus 1 (approximately 36 hours after landing). Long-duration International Space Station crewmembers will be tested once at the refueling stop in Europe and once again upon return to Johnson Space Center. In addition to DVA, subjective ratings of motion sickness will be recorded

  20. Electrical Stimulation of Visual Cortex Can Immediately Improve Spatial Vision.

    PubMed

    Reinhart, Robert M G; Xiao, Wenxi; McClenahan, Laura J; Woodman, Geoffrey F

    2016-07-25

    We can improve human vision by correcting the optics of our lenses [1-3]. However, after the eye transduces the light, visual cortex has its own limitations that are challenging to correct [4]. Overcoming these limitations has typically involved innovative training regimes that improve vision across many days [5, 6]. In the present study, we wanted to determine whether it is possible to immediately improve the precision of spatial vision with noninvasive direct-current stimulation. Previous work suggested that visual processing could be modulated with such stimulation [7-9]. However, the short duration and variability of such effects made it seem unlikely that spatial vision could be improved for more than several minutes [7, 10]. Here we show that visual acuity in the parafoveal belt can be immediately improved by delivering noninvasive direct current to visual cortex. Twenty minutes of anodal stimulation improved subjects' vernier acuity by approximately 15% and increased the amplitude of the earliest visually evoked potentials in lockstep with the behavioral effects. When we reversed the orientation of the electric field, we impaired resolution and reduced the amplitude of visually evoked potentials. Next, we found that anodal stimulation improved acuity enough to be measurable with the relatively coarse Snellen test and that subjects with the poorest acuity benefited the most from stimulation. Finally, we found that stimulation-induced acuity improvements were accompanied by changes in contrast sensitivity at high spatial frequencies. PMID:27374337

  1. Photovoltaic restoration of sight with high visual acuity in rats with retinal degeneration

    NASA Astrophysics Data System (ADS)

    Palanker, D.; Goetz, G.; Lorach, H.; Mandel, Y.; Smith, R.; Boinagrov, D.; Lei, X.; Kamins, T.; Harris, J.; Mathieson, K.; Sher, A.

    2015-03-01

    Patients with retinal degeneration lose sight due to gradual demise of photoreceptors. Electrical stimulation of the surviving retinal neurons provides an alternative route for delivery of visual information. Subretinal photovoltaic arrays with 70μm pixels were used to convert pulsed near-IR light (880-915nm) into pulsed current to stimulate the nearby inner retinal neurons. Network-mediated responses of the retinal ganglion cells (RGCs) could be modulated by pulse width (1-20ms) and peak irradiance (0.5-10 mW/mm2). Similarly to normal vision, retinal response to prosthetic stimulation exhibited flicker fusion at high frequencies, adaptation to static images, and non-linear spatial summation. Spatial resolution was assessed in-vitro and in-vivo using alternating gratings with variable stripe width, projected with rapidly pulsed illumination (20-40Hz). In-vitro, average size of the electrical receptive fields in normal retina was 248+/-59μm - similar to their visible light RF size: 249+/-44μm. RGCs responded to grating stripes down to 67μm using photovoltaic stimulation in degenerate rat retina, and 28μm with visible light in normal retina. In-vivo, visual acuity in normally-sighted controls was 29+/-5μm/stripe, vs. 63+/-4μm/stripe in rats with subretinal photovoltaic arrays, corresponding to 20/250 acuity in human eye. With the enhanced acuity provided by eye movements and perceptual learning in human patients, visual acuity might exceed the 20/200 threshold of legal blindness. Ease of implantation and tiling of these wireless arrays to cover a large visual field, combined with their high resolution opens the door to highly functional restoration of sight.

  2. Color image segmentation considering human sensitivity for color pattern variations

    NASA Astrophysics Data System (ADS)

    Yoon, Kuk-Jin; Kweon, In-So

    2001-10-01

    Color image segmentation plays an important role in the computer vision and image processing area. In this paper, we propose a novel color image segmentation algorithm in consideration of human visual sensitivity for color pattern variations by generalizing K-means clustering. Human visual system has different color perception sensitivity according to the spatial color pattern variation. To reflect this effect, we define the CCM (Color Complexity Measure) by calculating the absolute deviation with Gaussian weighting within the local mask and assign weight value to each color vector using the CCM values.

  3. Brief Report: Visual Acuity in Children with Autism Spectrum Disorders

    ERIC Educational Resources Information Center

    Albrecht, Matthew A.; Stuart, Geoffrey W.; Falkmer, Marita; Ordqvist, Anna; Leung, Denise; Foster, Jonathan K.; Falkmer, Torbjorn

    2014-01-01

    Recently, there has been heightened interest in suggestions of enhanced visual acuity in autism spectrum disorders (ASD) which was sparked by evidence that was later accepted to be methodologically flawed. However, a recent study that claimed children with ASD have enhanced visual acuity (Brosnan et al. in "J Autism Dev Disord"…

  4. Are Individual Differences in Reading Speed Related to Extrafoveal Visual Acuity and Crowding?

    PubMed Central

    Frömer, Romy; Dimigen, Olaf; Niefind, Florian; Krause, Niels; Kliegl, Reinhold; Sommer, Werner

    2015-01-01

    Readers differ considerably in their speed of self-paced reading. One factor known to influence fixation durations in reading is the preprocessing of words in parafoveal vision. Here we investigated whether individual differences in reading speed or the amount of information extracted from upcoming words (the preview benefit) can be explained by basic differences in extrafoveal vision—i.e., the ability to recognize peripheral letters with or without the presence of flanking letters. Forty participants were given an adaptive test to determine their eccentricity thresholds for the identification of letters presented either in isolation (extrafoveal acuity) or flanked by other letters (crowded letter recognition). In a separate eye-tracking experiment, the same participants read lists of words from left to right, while the preview of the upcoming words was manipulated with the gaze-contingent moving window technique. Relationships between dependent measures were analyzed on the observational level and with linear mixed models. We obtained highly reliable estimates both for extrafoveal letter identification (acuity and crowding) and measures of reading speed (overall reading speed, size of preview benefit). Reading speed was higher in participants with larger uncrowded windows. However, the strength of this relationship was moderate and it was only observed if other sources of variance in reading speed (e.g., the occurrence of regressive saccades) were eliminated. Moreover, the size of the preview benefit—an important factor in normal reading—was larger in participants with better extrafoveal acuity. Together, these results indicate a significant albeit moderate contribution of extrafoveal vision to individual differences in reading speed. PMID:25789812

  5. PERSPECTIVE: Is acuity enough? Other considerations in clinical investigations of visual prostheses

    NASA Astrophysics Data System (ADS)

    Lepri, Bernard P.

    2009-06-01

    Visual impairing eye diseases are the major frontier facing ophthalmic research today in light of our rapidly aging population. The visual skills necessary for improving the quality of daily function and life are inextricably linked to these impairing diseases. Both research and reimbursement programs are emphasizing outcome-based results. Is improvement in visual acuity alone enough to improve the function and quality of life of visually impaired persons? This perspective summarizes the types of effectiveness endpoints for clinical investigations of visual prostheses that go beyond visual acuity. The clinical investigation of visual prostheses should include visual function, functional vision and quality of life measures. Specifically, they encompass contrast sensitivity, orientation and mobility, activities of daily living and quality of life assessments. The perspective focuses on the design of clinical trials for visual prostheses and the methods of determining effectiveness above and beyond visual acuity that will yield outcomes that are measured by improved function in the visual world and quality of life. The visually impaired population is the primary consideration in this presentation with particular emphases on retinitis pigmentosa and age-related macular degeneration. Clinical trials for visual prostheses cannot be isolated from the need for medical rehabilitation in order to obtain measurements of effectiveness that produce outcomes/evidence-based success. This approach will facilitate improvement in daily function and quality of life of patients with diseases that cause chronic vision impairment. The views and opinions are those of the author and do not necessarily reflect those of the US Food and Drug Administration, the US Department of Health and Human Services or the Public Health Service.

  6. Coincidence anticipation and dynamic visual acuity in young adolescents.

    PubMed

    Millslagle, Duane

    2004-12-01

    Research involving college-age students and women fast pitch softball players indicated that coincidence anticipation and dynamic visual acuity are different visual abilities. This study used an alternative procedure to measure dynamic visual acuity to re-examine their relationship. Coincidence anticipation and dynamic visual acuity were measured in 24 young adolescents (12 boys, 12 girls) 11 to 14 years of age. During the dynamic visual acuity procedure, the subject tracked an object of a constant size while the researcher manipulated the object's velocity. Analysis indicated that they are different visual abilities. Findings indicated that the dynamic visual acuity of boys was significantly better than that of girls, and coincidence anticipation between boys and girls did not differ. PMID:15739838

  7. On the optical theory of underwater vision in humans

    NASA Astrophysics Data System (ADS)

    Gislén, Anna; Gislén, Lars

    2004-11-01

    Defocus changes the visual contrast sensitivity function, thereby creating a complex curve with local dips and peaks. Since underwater vision in humans is severely defocused, we used optical theory and the phenomenon of spurious resolution to predict how well humans can see in this environment. The values obtained correspond well with experimental measurements of underwater human acuity from earlier studies and even point to an opportunity for humans with exceptional contrast sensitivity to see better underwater than the children in those studies. The same theory could be useful when discussing the visual acuity of amphibious animals, as they may use pupil constriction as a means of improving underwater vision.

  8. On the optical theory of underwater vision in humans.

    PubMed

    Gislén, Anna; Gislén, Lars

    2004-11-01

    Defocus changes the visual contrast sensitivity function, thereby creating a complex curve with local dips and peaks. Since underwater vision in humans is severely defocused, we used optical theory and the phenomenon of spurious resolution to predict how well humans can see in this environment. The values obtained correspond well with experimental measurements of underwater human acuity from earlier studies and even point to an opportunity for humans with exceptional contrast sensitivity to see better underwater than the children in those studies. The same theory could be useful when discussing the visual acuity of amphibious animals, as they may use pupil constriction as a means of improving underwater vision. PMID:15535363

  9. Low light comparison of target visibility with night vision goggles

    NASA Astrophysics Data System (ADS)

    Craig, Gregory; Brulotte, Michel; Carignan, Stephan; Macuda, Todd; Jennings, Sion

    2008-04-01

    Different night vision goggle image intensification technologies were tested to compare goggle performance in low light conditions. A total of four different night vision goggles were tested in a laboratory dark room. The laboratory tests consisted of viewing Landolt acuity stimuli of different contrast levels with each set of goggles and without the goggles in full light conditions (baseline performance). The results from the laboratory testing indicated that there were significant differences in acuity between the NVGs, particularly for low contrast targets. These data suggest that NVG standards developed using high contrast targets, even in low light conditions may not provide the full story of how the NVG will perform in flight.

  10. Wavefront technology for vision and ophthalmology

    NASA Astrophysics Data System (ADS)

    Liang, Junzhong

    2003-07-01

    Wavefront technology promises to change the way vision care will be conducted. Wavefront-sensing optometers provide instant, accurate measurement of the total wave aberration of the eye, and that one measurement contains all the information needed for refractive vision diagnosis and refractive vision correction. Wavefront optometers are now being used to create individualized laser vision correction based, not on the coventional sphero-cylindrical correction, but rather on the total wavefront errors in patients' eyes. Comprehensive vision diagnosis based on the wave aberration and the image quality derived from it is far different from the conventional test of visual acuity. Wavefront technology has made it possible to image microscopic features as small as the photoreceptors and to improve resolution of retinal imaging techniques for early diagnosis of retinal diseases. This article is a review covering the hsitory and progress being made in the development of the wavefront technologies.

  11. Comparative visual acuity of coleoid cephalopods.

    PubMed

    Sweeney, Alison M; Haddock, Steven H D; Johnsen, Sönke

    2007-12-01

    The pelagic realm of the ocean is characterized by extremely clear water and a lack of surfaces. Adaptations to the visual ecology of this environment include transparency, fluorescence, bioluminescence, and deep red or black pigmentation. While the signals that pelagic organisms send are increasingly well-understood, the optical capabilities of their viewers, especially for predators with camera-like vision such as fish and squid, are almost unknown. Aquatic camera-like vision is characterized by a spherical lens focusing an image on the retina. Here, we measured the resolving power of the lenses of eight species of pelagic cephalopods to obtain an approximation of their visual capabilities. We did this by focusing a standard resolution target through dissected lenses and calculating their modulation transfer functions. The modulation transfer function (MTF) is the single most complete expression of the resolving capabilities of a lens. Since the optical and retinal capabilities of an eye are generally well-matched, we considered our measurements of cephalopod lens MTF to be a good proxy for their visual capabilities in vivo. In general, squid have optical capabilities comparable to other organisms generally assumed to have good vision, such as fish and birds. Surprisingly, the optical capability of the eye of Vampyroteuthis infernalis rivals that of humans. PMID:21669760

  12. Multiparameter vision testing apparatus

    NASA Technical Reports Server (NTRS)

    Hunt, S. R., Jr.; Homkes, R. J.; Poteate, W. B.; Sturgis, A. C. (Inventor)

    1975-01-01

    Compact vision testing apparatus is described for testing a large number of physiological characteristics of the eyes and visual system of a human subject. The head of the subject is inserted into a viewing port at one end of a light-tight housing containing various optical assemblies. Visual acuity and other refractive characteristics and ocular muscle balance characteristics of the eyes of the subject are tested by means of a retractable phoroptor assembly carried near the viewing port and a film cassette unit carried in the rearward portion of the housing (the latter selectively providing a variety of different visual targets which are viewed through the optical system of the phoroptor assembly). The visual dark adaptation characteristics and absolute brightness threshold of the subject are tested by means of a projector assembly which selectively projects one or both of a variable intensity fixation target and a variable intensity adaptation test field onto a viewing screen located near the top of the housing.

  13. Visual acuity testability of children in Bama and Banki towns of Borno State, Nigeria: The need to adopt HOTV protocol in school health programmes

    PubMed Central

    Delia, Tumba; Adamu, Adiel A.; Ngilari, Usiju M.

    2012-01-01

    Despite the importance of visual acuity testing in children, no standard testing protocol was found for primary school pupils. Visual acuity screening was conducted on 400 primary school pupils in Nigeria using the HOTV protocol, nearly all the pupils 390/400 (97.5 %) had good binocular vision, only 10/400 (2.5 %) had poor vision which were monocular. Of those with poor monocular vision, 6/10 (60 %) involved the right eye while 4/10 (40 %) the left eye; these pupils were referred to the ophthalmologist for further evaluation. Because of its easy usage, the HOTV protocol can be adopted by school health programmes especially for the primary school pupils.

  14. Visual color image processing

    NASA Astrophysics Data System (ADS)

    Qiu, Guoping; Schaefer, Gerald

    1999-12-01

    In this paper, we propose a color image processing method by combining modern signal processing technique with knowledge about the properties of the human color vision system. Color signals are processed differently according to their visual importance. The emphasis of the technique is on the preservation of total visual quality of the image and simultaneously taking into account computational efficiency. A specific color image enhancement technique, termed Hybrid Vector Median Filtering is presented. Computer simulations have been performed to demonstrate that the new approach is technically sound and results are comparable to or better than traditional methods.

  15. The Frequency of Decreased Visual Acuity in Orbital Fractures.

    PubMed

    Kim, Yeon Soo; Kim, Joo Ho; Hwang, Kun

    2015-07-01

    The aim of this systematic review is to summarize and evaluate the effect of orbital fractures (blowout fractures and nonblowout fractures) on visual acuity. In PubMed search and Scopus search, the terms "orbital fracture OR maxillofacial injury OR facial trauma OR craniofacial fracture," and "visual acuity OR functional outcome OR visual outcome OR improving document of visual acuity OR blindness OR optic nerve neuropathy" were used, which resulted in 1634 and 1152 papers, respectively. Of the 2226 titles excluding 560 duplicated titles, 227 abstracts were reviewed. Of the 227 abstracts reviewed, the authors found 56 potentially relevant full-text articles, of which 5 studies met our inclusion criteria. The odds ratio and 95% confidence intervals from each study were abstracted. The statistical analysis was performed with review manager (The Nordic Cochrane Centre). A summary of 5 studies affirmed that 43 patients among 532 orbital fractures (8.1%) had decreased visual acuity. Twelve patients among 159 blowout fractures (7.5%) had decreased visual acuity. Thirty-one patients among 373 orbital fractures other than pure blowout fractures (8.3%) had decreased visual acuity. In orbital fractures other than pure blowout fractures, the frequency of decreased visual acuity was higher than pure blowout fractures (n = 532, odds ratio, 2.23, 95% confidence interval = 1.06-4.70). Surgeons should acknowledge this with patients before surgery. PMID:26114513

  16. Visual acuity in the short-tailed opossum (Monodelphis domestica)

    PubMed Central

    Dooley, James C.; Nguyen, Hoang; Seelke, Adele M. H.; Krubitzer, Leah

    2013-01-01

    Monodelphis domestica (short-tailed opossum) is an emerging animal model for studies of neural development due to the extremely immature state of the nervous system at birth and its subsequent rapid growth to adulthood. Yet little is known about its normal sensory discrimination abilities. In the present investigation, visual acuity was determined in this species using the optokinetic test (OPT), which relies on involuntary head tracking of a moving stimulus and can be easily elicited using a rotating visual stimulus of varying spatial frequencies. Using this methodology, we determined that the acuity of Monodelphis is 0.58 cycles per degree (cpd), which is similar to the acuity of rats using the same methodology, and higher than in mice. However, acuity in the short-tailed opossum is lower than in other marsupials. This is in part due to the methodology used to determine acuity, but may also be due to differences in diel patterns, lifestyle and phylogeny. We demonstrate that for the short-tailed opossum, the OPT is a rapid and reliable method of determining a baseline acuity and can be used to study enhanced acuities due to cortical plasticity. PMID:22871523

  17. Vision Impairment Among Older Adults Residing in Subsidized Housing Communities

    PubMed Central

    McGwin, Gerald; Kline, Lanning B.; Owsley, Cynthia

    2015-01-01

    Purpose of the Study: To examine the rate of vision impairment and the relationship between vision impairment, cognitive impairment, and chronic comorbid conditions in residents of federally subsidized senior housing facilities. Design: Cross-sectional, observational study. Methods: Vision screening events were held at 14 subsidized senior housing facilities in Jefferson County, Alabama for residents aged 60 years and older. Visual function (distance vision, near vision, and contrast sensitivity) measured with habitual correction if worn, cognitive status, and chronic comorbid conditions (hypertension, heart problems, circulation problems, and diabetes) were assessed. Results: A total of 238 residents participated in the vision screenings. Most residents (75%) were African American. Vision impairment was common, with 40% of participants failing the distance acuity screening and 58% failing the near acuity screening; failure was defined as vision worse than 20/40 in either eye. Additionally, 65% failed the contrast sensitivity screening. A total of 30.6% of seniors had cognitive impairment. Regarding comorbid chronic conditions, 31% had circulation problems, 39% had diabetes, 41% had heart problems, and 76% had hypertension (59% had 2 or more of these). Visual acuity differed significantly between cognitive status groups and with the presence of heart and circulation problems. Implications: This study is among the first to provide information about vision impairment in this socioeconomically disadvantaged group of older adults. Vision impairment was common. Cognitive impairment and comorbid chronic conditions accounted for a small to moderate percentage of the variance in distance vision, near vision, and contrast sensitivity. Future studies should focus on strategies to facilitate access to eye care in this vulnerable population. PMID:26055771

  18. Low Vision

    MedlinePlus

    ... Cases of Low Vision (in thousands) by Age, Gender, and Race/Ethnicity Table for 2010 U.S. Prevalent ... Cases of Low Vision (in thousands) by Age, Gender, and Race/Ethnicity Table for 2000 U.S. Prevalent ...

  19. Plaque Brachytherapy for Uveal Melanoma: A Vision Prognostication Model

    SciTech Connect

    Khan, Niloufer; Khan, Mohammad K.; Bena, James; Macklis, Roger; Singh, Arun D.

    2012-11-01

    Purpose: To generate a vision prognostication model after plaque brachytherapy for uveal melanoma. Methods and Materials: All patients with primary single ciliary body or choroidal melanoma treated with iodine-125 or ruthenium-106 plaque brachytherapy between January 1, 2005, and June 30, 2010, were included. The primary endpoint was loss of visual acuity. Only patients with initial visual acuity better than or equal to 20/50 were used to evaluate visual acuity worse than 20/50 at the end of the study, and only patients with initial visual acuity better than or equal to 20/200 were used to evaluate visual acuity worse than 20/200 at the end of the study. Factors analyzed were sex, age, cataracts, diabetes, tumor size (basal dimension and apical height), tumor location, and radiation dose to the tumor apex, fovea, and optic disc. Univariate and multivariable Cox proportional hazards were used to determine the influence of baseline patient factors on vision loss. Kaplan-Meier curves (log rank analysis) were used to estimate freedom from vision loss. Results: Of 189 patients, 92% (174) were alive as of February 1, 2011. At presentation, visual acuity was better than or equal to 20/50 and better than or equal to 20/200 in 108 and 173 patients, respectively. Of these patients, 44.4% (48) had post-treatment visual acuity of worse than 20/50 and 25.4% (44) had post-treatment visual acuity worse than 20/200. By multivariable analysis, increased age (hazard ratio [HR] of 1.01 [1.00-1.03], P=.05), increase in tumor height (HR of 1.35 [1.22-1.48], P<.001), and a greater total dose to the fovea (HR of 1.01 [1.00-1.01], P<.001) were predictive of vision loss. This information was used to develop a nomogram predictive of vision loss. Conclusions: By providing a means to predict vision loss at 3 years after treatment, our vision prognostication model can be an important tool for patient selection and treatment counseling.

  20. A phytochemical-rich diet may explain the absence of age-related decline in visual acuity of Amazonian hunter-gatherers in Ecuador.

    PubMed

    London, Douglas S; Beezhold, Bonnie

    2015-02-01

    Myopia is absent in undisturbed hunter-gatherers but ubiquitous in modern populations. The link between dietary phytochemicals and eye health is well established, although transition away from a wild diet has reduced phytochemical variety. We hypothesized that when larger quantities and greater variety of wild, seasonal phytochemicals are consumed in a food system, there will be a reduced prevalence of degenerative-based eye disease as measured by visual acuity. We compared food systems and visual acuity across isolated Amazonian Kawymeno Waorani hunter-gatherers and neighboring Kichwa subsistence agrarians, using dietary surveys, dietary pattern observation, and Snellen Illiterate E visual acuity examinations. Hunter-gatherers consumed more food species (130 vs. 63) and more wild plants (80 vs. 4) including 76 wild fruits, thereby obtaining larger variety and quantity of phytochemicals than agrarians. Visual acuity was inversely related to age only in agrarians (r = -.846, P < .001). As hypothesized, when stratified by age (<40 and ≥ 40 years), Mann-Whitney U tests revealed that hunter-gatherers maintained high visual acuity throughout life, whereas agrarian visual acuity declined (P values < .001); visual acuity of younger participants was high across the board, however, did not differ between groups (P > .05). This unusual absence of juvenile-onset vision problems may be related to local, organic, whole food diets of subsistence food systems isolated from modern food production. Our results suggest that intake of a wider variety of plant foods supplying necessary phytochemicals for eye health may help maintain visual acuity and prevent degenerative eye conditions as humans age. PMID:25636674

  1. Eleven Colors That Are Almost Never Confused

    NASA Astrophysics Data System (ADS)

    Boynton, Robert M.

    1989-08-01

    1.1. Three functions of color vision. Setting aside the complex psychological effects of color, related to esthetics, fashion, and mood, three relatively basic functions of color vision, which can be examined scientifically, are discernable. (1) With the eye in a given state of adaptation, color vision allows the perception of signals that otherwise would be below threshold, and therefore lost to perception. Evidence for this comes from a variety of two-color threshold experiments. (2) Visible contours can be maintained by color differences alone, regardless of the relative radiances of the two parts of the field whose junction defines the border. For achromatic vision, contour disappears at the isoluminant point. (3) Color specifies what seems to be an absolute property of a surface, one that enhances its recognizability and allows a clearer separation and classification of non-contiguous elements in the visual field.

  2. Computer vision based room interior design

    NASA Astrophysics Data System (ADS)

    Ahmad, Nasir; Hussain, Saddam; Ahmad, Kashif; Conci, Nicola

    2015-12-01

    This paper introduces a new application of computer vision. To the best of the author's knowledge, it is the first attempt to incorporate computer vision techniques into room interior designing. The computer vision based interior designing is achieved in two steps: object identification and color assignment. The image segmentation approach is used for the identification of the objects in the room and different color schemes are used for color assignment to these objects. The proposed approach is applied to simple as well as complex images from online sources. The proposed approach not only accelerated the process of interior designing but also made it very efficient by giving multiple alternatives.

  3. Tobias Mayer--experiments on visual acuity (1755).

    PubMed

    Scheerer, E

    1987-01-01

    The pioneering experimental work of Tobias Mayer (1723-1762) on visual acuity, published in 1755 in Latin, is presented in English translation. Mayer distinguished between two kinds of visual acuity, the one (30 arc sec) for single objects seen against a uniform background, the other (1 arc min) for more complex objects such as gratings, grids, or checkerboards. Strong illumination did not improve visual acuity. For targets seen in the light of a candle, the visual angle needed for resolution was inversely proportional to the cube root of the distance of the candle and therefore to the sixth root of 'brightness'. The historical significance of Mayer's work on visual acuity is briefly outlined. PMID:3154942

  4. The development of an obstetric triage acuity tool.

    PubMed

    Paisley, Kathleen S; Wallace, Ruth; DuRant, Patricia G

    2011-01-01

    The purpose of this article is to describe the journey a multicampus hospital system took to improve the obstetric triage process. A review of literature revealed no current comprehensive obstetric acuity tool, and thus our team developed a tool with a patient flow process, revised and updated triage nurse competencies, and then educated the nurses about the new tool and process. Data were collected to assess the functionality of the new process in assigning acuity upon patient arrival, conveying appropriate acuities based on patient complaints, and initiating the medical screening examination, all within prescribed time intervals. Initially data indicated that processes were still not optimal, and re-education was provided for all triage nurses. This improved all data points. The result of this QI project is that our patients are now seen based on their acuity within designated time frames. PMID:21857199

  5. Adaptive optics for peripheral vision

    NASA Astrophysics Data System (ADS)

    Rosén, R.; Lundström, L.; Unsbo, P.

    2012-07-01

    Understanding peripheral optical errors and their impact on vision is important for various applications, e.g. research on myopia development and optical correction of patients with central visual field loss. In this study, we investigated whether correction of higher order aberrations with adaptive optics (AO) improve resolution beyond what is achieved with best peripheral refractive correction. A laboratory AO system was constructed for correcting peripheral aberrations. The peripheral low contrast grating resolution acuity in the 20° nasal visual field of the right eye was evaluated for 12 subjects using three types of correction: refractive correction of sphere and cylinder, static closed loop AO correction and continuous closed loop AO correction. Running AO in continuous closed loop improved acuity compared to refractive correction for most subjects (maximum benefit 0.15 logMAR). The visual improvement from aberration correction was highly correlated with the subject's initial amount of higher order aberrations (p = 0.001, R 2 = 0.72). There was, however, no acuity improvement from static AO correction. In conclusion, correction of peripheral higher order aberrations can improve low contrast resolution, provided refractive errors are corrected and the system runs in continuous closed loop.

  6. Sporadic Visual Acuity Loss in the Comparison of Age-Related Macular Degeneration Treatments Trials (CATT)

    PubMed Central

    Kim, Benjamin J.; Ying, Gui-Shuang; Huang, Jiayan; Levy, Nicole E.; Maguire, Maureen G.

    2014-01-01

    Purpose To evaluate transient, large visual acuity (VA) decreases, termed sporadic vision loss, during anti-vascular endothelial growth factor treatment for neovascular age-related macular degeneration (AMD). Design Cohort within a randomized clinical trial. Methods Setting Comparison of AMD Treatments Trials (CATT). Study Population 1185 CATT patients. Main Outcome Measures incidence of sporadic vision loss and odds ratio (OR) for association with patient and ocular factors. Sporadic vision loss was a decline of ≥ 15 letters from the previous visit, followed by a return at the next visit to no more than 5 letters worse than the visit before the VA loss. Results There were 143 sporadic vision loss events in 122/1185 (10.3%) patients. Mean VA at two years for those with and without sporadic vision loss was 58.5 (~20/63) and 68.4 (~20/40) letters, respectively (P < 0.001). Among patients treated pro re nata, no injection was given for 27.6% (27/98) of sporadic vision loss events. Multivariate analysis demonstrated that baseline predictors for sporadic vision loss included worse baseline VA (OR 2.92, 95%CI:1.65–5.17 for ≤ 20/200 compared with ≥ 20/40), scar (OR 2.21, 95%CI:1.22–4.01), intraretinal foveal fluid on optical coherence tomography (OR 1.80, 95%CI:1.11–2.91), and medical history of anxiety (OR 1.90, 95%CI:1.12–3.24) and syncope (OR 2.75, 95%CI:1.45–5.22). Refraction decreased the likelihood of sporadic vision loss (OR 0.62, 95%CI:0.42–0.91). Conclusions Approximately 10% of CATT patients had sporadic vision loss. Baseline predictors included AMD-related factors and factors independent of AMD. These data are relevant for clinicians in practice and those involved in clinical trials. PMID:24727261

  7. Recognition of Ramps and Steps by People with Low Vision

    PubMed Central

    Bochsler, Tiana M.; Legge, Gordon E.; Gage, Rachel; Kallie, Christopher S.

    2013-01-01

    Purpose. Detection and recognition of ramps and steps are important for the safe mobility of people with low vision. Our primary goal was to assess the impact of viewing conditions and environmental factors on the recognition of these targets by people with low vision. A secondary goal was to determine if results from our previous studies of normally sighted subjects, wearing acuity-reducing goggles, would generalize to low vision. Methods. Sixteen subjects with heterogeneous forms of low vision participated—acuities from approximately 20/200 to 20/2000. They viewed a sidewalk interrupted by one of five targets: a single step up or down, a ramp up or down, or a flat continuation of the sidewalk. Subjects reported which of the five targets was shown, and percent correct was computed. The effects of viewing distance, target–background contrast, lighting arrangement, and subject locomotion were investigated. Performance was compared with a group of normally sighted subjects who viewed the targets through acuity-reducing goggles. Results. Recognition performance was significantly better at shorter distances and after locomotion (compared with purely stationary viewing). The effects of lighting arrangement and target–background contrast were weaker than hypothesized. Visibility of the targets varied, with the step up being more visible than the step down. Conclusions. The empirical results provide insight into factors affecting the visibility of ramps and steps for people with low vision. The effects of distance, target type, and locomotion were qualitatively similar for low vision and normal vision with artificial acuity reduction. However, the effects of lighting arrangement and background contrast were only significant for subjects with normal vision. PMID:23221068

  8. Olfactory acuity in theropods: palaeobiological and evolutionary implications

    PubMed Central

    Zelenitsky, Darla K.; Therrien, François; Kobayashi, Yoshitsugu

    2008-01-01

    This research presents the first quantitative evaluation of the olfactory acuity in extinct theropod dinosaurs. Olfactory ratios (i.e. the ratio of the greatest diameter of the olfactory bulb to the greatest diameter of the cerebral hemisphere) are analysed in order to infer the olfactory acuity and behavioural traits in theropods, as well as to identify phylogenetic trends in olfaction within Theropoda. A phylogenetically corrected regression of olfactory ratio to body mass reveals that, relative to predicted values, the olfactory bulbs of (i) tyrannosaurids and dromaeosaurids are significantly larger, (ii) ornithomimosaurs and oviraptorids are significantly smaller, and (iii) ceratosaurians, allosauroids, basal tyrannosauroids, troodontids and basal birds are within the 95% CI. Relative to other theropods, olfactory acuity was high in tyrannosaurids and dromaeosaurids and therefore olfaction would have played an important role in their ecology, possibly for activities in low-light conditions, locating food, or for navigation within large home ranges. Olfactory acuity was the lowest in ornithomimosaurs and oviraptorids, suggesting a reduced reliance on olfaction and perhaps an omnivorous diet in these theropods. Phylogenetic trends in olfaction among theropods reveal that olfactory acuity did not decrease in the ancestry of birds, as troodontids, dromaeosaurids and primitive birds possessed typical or high olfactory acuity. Thus, the sense of smell must have remained important in primitive birds and its presumed decrease associated with the increased importance of sight did not occur until later among more derived birds. PMID:18957367

  9. Visual acuity in mammals: effects of eye size and ecology.

    PubMed

    Veilleux, Carrie C; Kirk, E Christopher

    2014-01-01

    Previous comparative research has attributed interspecific variation in eye size among mammals to selection related to visual acuity. Mammalian species have also been hypothesized to differ in visual acuity partly as a result of differences in ecology. While a number of prior studies have explored ecological and phylogenetic effects on eye shape, a broad comparative analysis of the relationships between visual acuity, eye size and ecology in mammals is currently lacking. Here we use phylogenetic comparative methods to explore these relationships in a taxonomically and ecologically diverse sample of 91 mammal species. These data confirm that axial eye length and visual acuity are significantly positively correlated in mammals. This relationship conforms to expectations based on theoretical optics and prior analyses of smaller comparative samples. Our data also demonstrate that higher visual acuity in mammals is associated with: (1) diurnality and (2) predatory habits once the effects of eye size and phylogeny have been statistically controlled. These results suggest that interspecific variation in mammalian visual acuity is the result of a complex interplay between phylogenetic history, visual anatomy and ecology. PMID:24603494

  10. Preferential looking and recognition acuities in clinical amblyopia.

    PubMed

    Mandava, N; Simon, J W; Jenkins, P L

    1991-01-01

    Although others have noted a correlation between grating and recognition acuities (RA) when both tests are performed on the same day, the value of preferential looking (PL) in predicting eventual visual outcome has not been studied. PL acuities of 64 preverbal patients considered at risk of amblyopia were measured. When these children became verbal, their visual acuities were determined using standard recognition acuity tests. Based on intervening amblyopia treatment between PL and RA measures, 40 patients were designated the minimal treatment group (MTG) and 24 the intensive treatment group (ITG). Chi-square analysis for the MTG showed agreement (P less than .005) between PL and RA in identifying better, equal, and worse eyes. Interocular ratios of PL and RA were significantly correlated for the MTG (P less than .001), but not for the ITG. Monocularly, a consistent correlation between PL and RA was not found. Our data suggest that PL is predictive of recognition acuity in patients whose visual acuity was expected to remain stable. PMID:1757857

  11. The color lexicon of the Somali language.

    PubMed

    Brown, Angela M; Isse, Abdirizak; Lindsey, Delwin T

    2016-03-01

    This empirical study had three goals: (a) to describe Somali color naming and its motifs, (b) to relate color naming by Somali informants to their color vision, and (c) to search for historical and demographic clues about the diversity of Somali color naming. Somali-speaking informants from Columbus, Ohio provided monolexemic color terms for 83 or 145 World Color Survey (WCS) color samples. Proximity analysis reduced the 103 color terms to the eight chromatic color meanings from the WCS plus black, white, and gray. Informants' data sets were grouped by spectral clustering analysis into four WCS color naming motifs named after the terms for the cool colors: (a) Green-Blue, (b) Grue (a single term meaning "green or blue"), (c) Gray, and (d) Dark. The results show that, first, the Somali language has about four motifs among its speakers. Second, individuals' color vision test results and their motifs were not correlated, suggesting that multiple motifs do not arise from individual variation in color vision. Last, the Somali color lexicon has changed over the past century. New color terms often came from the names of familiar colored objects, and informants' motifs were closely related to their ages and genders, suggesting that the diversity of color naming across speakers of Somali probably results from ongoing language change. PMID:26982527

  12. The Need for Vision in Teaching Orientation and Mobility.

    ERIC Educational Resources Information Center

    Wiener, W. R.; And Others

    1992-01-01

    Three experiments examined the ability of blind individuals and individuals simulating the visual acuity of 20/400 to monitor the behaviors of a cane traveler in various environments and at distances between 10 feet and 25 feet. Results suggested that at least some vision is needed for instructors monitoring visually impaired individuals learning…

  13. Vision Screening: A Study of 297 Head Start Children.

    ERIC Educational Resources Information Center

    Morse, A. R.; And Others

    1987-01-01

    Vision assessments were provided to 297 preschoolers in nine Head Start programs in New York State. The protocol used provided a thorough evaluation and required only seven minutes per child. Sixty-three children (21.2%) were referred for further evaluation. Visual deficits detected included decreased acuity, strabismus, astigmatism, and…

  14. How Does My Child's Vision Affect His Reading?

    ERIC Educational Resources Information Center

    Eberly, Donald W.

    Various eye problems and the effects they can have on children's reading abilities are explored in this pamphlet, which is one of a series designed to answer parents' questions about their children's reading development. Topics discussed are the demands on vision made by reading, problems that affect visual acuity (nearsightedness, farsightedness,…

  15. 75 FR 47883 - Qualification of Drivers; Exemption Applications; Vision

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-08-09

    ... System published in the Federal Register on January 17, 2008 (73 FR 3316), or you may visit http... childhood. The best corrected visual acuity in his right eye is 20/15 and in his left eye, 20/50. Following.... Etheridge Mr. Etheridge, 45, has had complete loss of vision in his right eye since 1971 due to trauma....

  16. Seeing Steps and Ramps with Simulated Low Acuity: Impact of Texture and Locomotion

    PubMed Central

    Bochsler, Tiana M.; Legge, Gordon E.; Kallie, Christopher S.; Gage, Rachel

    2012-01-01

    Purpose Detecting and recognizing steps and ramps is an important component of the visual accessibility of public spaces for people with impaired vision. The present study, which is part of a larger program of research on visual accessibility, investigated the impact of two factors that may facilitate the recognition of steps and ramps during low-acuity viewing. Visual texture on the ground plane is an environmental factor that improves judgments of surface distance and slant. Locomotion (walking) is common during observations of a layout, and may generate visual motion cues that enhance the recognition of steps and ramps. Methods In two experiments, normally sighted subjects viewed the targets monocularly through blur goggles that reduced acuity to either approx. 20/150 Snellen (mild blur) or 20/880 (severe blur). The subjects judged whether a step, ramp or neither was present ahead on a sidewalk. In the texture experiment, subjects viewed steps and ramps on a surface with a coarse black-and-white checkerboard pattern. In the locomotion experiment, subjects walked along the sidewalk toward the target before making judgments. Results Surprisingly, performance was lower with the textured surface than with a uniform surface, perhaps because the texture masked visual cues necessary for target recognition. Subjects performed better in walking trials than in stationary trials, possibly because they were able to take advantage of visual cues that were only present during motion. Conclusions We conclude that under conditions of simulated low acuity, large, high-contrast texture elements can hinder the recognition of steps and ramps while locomotion enhances recognition. PMID:22863792

  17. All Vision Impairment

    MedlinePlus

    ... Jobs Home > Statistics and Data > All Vision Impairment All Vision Impairment Vision Impairment Defined Vision impairment is ... being blind by the U.S. definition.) The category “All Vision Impairment” includes both low vision and blindness. ...

  18. Low Vision FAQs

    MedlinePlus

    ... Jobs Home > Low Vision > Low Vision FAQs Healthy Vision Diabetes Diabetes Home How Much Do You Know? ... los Ojos Cómo hablarle a su oculista Low Vision FAQs What is low vision? Low vision is ...

  19. Living with vision loss

    MedlinePlus

    Diabetes - vision loss; Retinopathy - vision loss; Low vision; Blindness - vision loss ... Low vision is a visual disability. Wearing regular glasses or contacts does not help. People with low vision have ...

  20. The Best Colors for Audio-Visual Materials for More Effective Instruction.

    ERIC Educational Resources Information Center

    Start, Jay

    A number of variables may affect the ability of students to perceive, and learn from, instructional materials. The objectives of the study presented here were to determine the projected color that provided the best visual acuity for the viewer, and the necessary minimum exposure time for achieving maximum visual acuity. Fifty…

  1. The Concept of Visual Acuity Ratio to the Maximum Level of Individual Visual Acuity—The Evaluation Method of Background Luminance and Visual Distance on Visibility Taking into Account of Individual Visual Acuity—

    NASA Astrophysics Data System (ADS)

    Akizuki, Yuki; Inoue, Youko

    We use the maximum level of individual visual acuity (MVA) as an index for the individual visual ability. Also, we define the concept of the ratio of visual acuity under various environmental conditions for the MVA as Visual Acuity Ratio (VAR), in order to describe differences between individual visibilities. An experiment was carried out using various levels of background luminance and visual distance. The visual acuity of subjects in two age groups (Young and Aged) was measured by using Landolt’s eye chart (luminance contrast: 0.93). The Aged subjects’ vision was corrected by two kinds of spectacles: ones for myopia / presbyopia. Under conditions providing sufficient visual acuity, the subjects’ order of individual visual acuity was unchanged. Therefore, MVA can be used as an index for the visual ability of the individual. Regardless of corrected conditions, the individual visual acuity reaches the maximum level under 800cd/m2 and the corrected position. The results of the eyesight test can be used as a substitution for MVA. Visual acuity is changing under environmental conditions, and a degree of the changes varies with age, corrected conditions, and differences in visual acuity. Under the corrected position, the relationship between background luminance and VAR is constant regardless of age group, corrected conditions and differences of visual acuity. The relationship between visual distance and VAR differs by age and corrected conditions. However, in the neighborhood of the corrected position, the relationship between visual distance and VAR is constant regardless of differences between individual visibilities. The concept of VAR is applicable to past studies.

  2. Vision Loss in Older Adults.

    PubMed

    Pelletier, Allen L; Rojas-Roldan, Ledy; Coffin, Janis

    2016-08-01

    Vision loss affects 37 million Americans older than 50 years and one in four who are older than 80 years. The U.S. Preventive Services Task Force concludes that current evidence is insufficient to assess the balance of benefits and harms of screening for impaired visual acuity in adults older than 65 years. However, family physicians play a critical role in identifying persons who are at risk of vision loss, counseling patients, and referring patients for disease-specific treatment. The conditions that cause most cases of vision loss in older patients are age-related macular degeneration, glaucoma, ocular complications of diabetes mellitus, and age-related cataracts. Vitamin supplements can delay the progression of age-related macular degeneration. Intravitreal injection of a vascular endothelial growth factor inhibitor can preserve vision in the neovascular form of macular degeneration. Medicated eye drops reduce intraocular pressure and can delay the progression of vision loss in patients with glaucoma, but adherence to treatment is poor. Laser trabeculoplasty also lowers intraocular pressure and preserves vision in patients with primary open-angle glaucoma, but long-term studies are needed to identify who is most likely to benefit from surgery. Tight glycemic control in adults with diabetes slows the progression of diabetic retinopathy, but must be balanced against the risks of hypoglycemia and death in older adults. Fenofibrate also slows progression of diabetic retinopathy. Panretinal photocoagulation is the mainstay of treatment for diabetic retinopathy, whereas vascular endothelial growth factor inhibitors slow vision loss resulting from diabetic macular edema. Preoperative testing before cataract surgery does not improve outcomes and is not recommended. PMID:27479624

  3. Visual acuity and sensitivity increase allometrically with body size in butterflies.

    PubMed

    Rutowski, R L; Gislén, Lars; Warrant, Eric J

    2009-03-01

    In insects, the surface area of the compound eye increases with body size both within and between species with only a slight negative allometry. This increase in surface area permits changes in eye structure that affect the eye's acuity and sensitivity, two features of eye performance that cannot be simultaneously maximized. Hence, as eye size varies within a lineage, so will the compromises between features that maximize acuity and those that maximize sensitivity. We examined these compromises in four species of nymphalid butterflies that varied in body mass over almost two orders of magnitude. The largest of these species was crepuscular and so additionally may indicate the potential effect of life style on eye structure. Across these species, as body size increased, facet diameters increased while interommatidial angles decreased. Finally, the eye parameter was fairly constant across species except in the crepuscular species in which some notably large values were observed in the frontal visual field. Based on our measurements, large butterflies have more acute and more sensitive vision than smaller butterflies. However, full understanding of the behavioral implications of this relationship awaits information on the temporal resolution of their eyes because typical flight velocities also increase with body size. PMID:18809509

  4. Quantum mechanical/molecular mechanical structure, enantioselectivity, and spectroscopy of hydroxyretinals and insights into the evolution of color vision in small white butterflies.

    PubMed

    Sekharan, Sivakumar; Yokoyama, Shozo; Morokuma, Keiji

    2011-12-29

    Since Vogt's discovery of A(3)-retinal or 3-hydroxyretinal in insects in 1983 and Matsui's discovery of A(4)-retinal or 4-hydroxyretinal in firefly squid in 1988, hydroxyretinal-protein interactions mediating vision have remained largely unexplored. In the present study, A(3)- and A(4)-retinals are theoretically incorporated into squid and bovine visual pigments by use of the hybrid quantum mechanics/molecular mechanics [SORCI+Q//B3LYP/6-31G(d):Amber96] method, and insights into structure, enantioselectivity, and spectroscopy are gathered and presented for the first time. Contrary to general perception, our findings rule out the formation of a hydrogen bond between the hydroxyl-bearing β-ionone ring portion of retinal and opsin. Compared to A(1)-pigments, A(3)- and A(4)-pigments exhibit slightly blue-shifted absorption maxima due to increase in bond-length alternation of the hydroxyretinal. We suggest that (i) the binding site of firefly squid (Watasenia scintillans) opsin is very similar to that of the Japanese common squid (Todarodes pacificus) opsin; (ii) the molecular mechanism of spectral tuning in small white butterflies involve sites S116 and T185 and breaking of a hydrogen bond between sites E180 and T185; and finally (iii) A(3)-retinal may have occurred during the conversion of A(1)- to A(2)-retinal and insects may have acquired them, in order to absorb light in the blue-green wavelength region and to speed up the G-protein signaling cascade. PMID:22087641

  5. QM/MM Structure, Enantioselectivity and Spectroscopy of HydroxyRetinals and Insights into the Evolution of Color Vision in Small White Butterflies

    PubMed Central

    Sekharan, Sivakumar; Yokoyama, Shozo

    2011-01-01

    Since Vogt’s discovery of A3-retinal or 3-hydroxyretinal in insects in 1983 and Matsui’s discovery of A4-retinal or 4-hydroxyretinal in firefly squid in 1988, hydroxyretinal-protein interactions mediating vision remains largely unexplored. In the present study, A3- and A4-retinals are theoretically incorporated into squid and bovine visual pigments using the hybrid quantum mechanics/molecular mechanics (SORCI+Q//B3LYP/6-31G(d):Amber96) method and insights into the structure, enantioselectivity and spectroscopy are gathered and presented for the first time. Contrary to general perception, our findings rule out the formation of hydrogen bond between the hydroxyl-bearing β-ionone ring part of retinal and opsin. Compared to A1-pigments, A3- and A4-pigments exhibit slightly blue-shifted absorption maxima due to increase in bond-length alternation of the hydroxyretinal. We suggest that, (i) The binding site of firefly squid (Watasenia scintillians) opsin is very similar to that of the Japanese common squid (Todarodes pacificus) opsin, (ii) Molecular mechanism of spectral tuning in the small white butterflies involve sites S116, T185 and breaking of hydrogen bond between sites E180 and T185; and finally, (iii) A3-retinal may have occurred during the conversion of A1- to A2-retinal and insects may have acquired them, in order to absorb light in the blue-green wavelength region and to speed up the G-protein signaling cascade. PMID:22087641

  6. Preclinical metrics to predict through-focus visual acuity for pseudophakic patients

    PubMed Central

    Alarcon, Aixa; Canovas, Carmen; Rosen, Robert; Weeber, Henk; Tsai, Linda; Hileman, Kendra; Piers, Patricia

    2016-01-01

    This study compares the clinical through-focus visual acuity (VA) in patients implanted with different intraocular lens (IOL) to optical bench testing of the same IOLs to evaluate the suitability of optical metrics of predicting clinical VA. Modulation transfer function and phase transfer function for different spatial frequencies and US Air Force pictures were measured using an optical bench for two monofocal IOLs, three multifocal IOLs and an extended range of vision IOL. Four preclinical metrics were calculated and compared to the clinical through-focus VA collected in three different clinical studies (243 patients in total). All metrics were well correlated (R2≥0.89) with clinical data and may be suitable for predicting through-focus VA in pseudophakic eyes. PMID:27231628

  7. Causes and Prognosis of Visual Acuity Loss at the Time of Initial Presentation in Idiopathic Intracranial Hypertension

    PubMed Central

    Chen, John J.; Thurtell, Matthew J.; Longmuir, Reid A.; Garvin, Mona K.; Wang, Jui-Kai; Wall, Michael; Kardon, Randy H.

    2015-01-01

    Purpose. To determine the etiology and prognosis of visual acuity loss in idiopathic intracranial hypertension (IIH) at presentation and to provide objective measures to predict visual outcome. Methods. A retrospective review of 660 patients with IIH (2009–2013) identified 31 patients (4.7%) with 48 eyes having best-corrected visual acuity (BCVA) of 20/25 or worse on initial presentation. Fundus photography, optical coherence tomography (OCT) of the optic disc and macula, and perimetry were used to determine the causes and prognosis of vision loss. Segmentation of the macula OCT was performed using the Iowa Reference Algorithm to determine the retinal ganglion cell-inner plexiform layer complex (GCL-IPL) thickness. Results. Outer retinal changes alone caused decreased BCVA at initial presentation in 22 eyes (46%): subretinal fluid in 16, chorioretinal folds in 5, and peripapillary choroidal neovascularization in 1. The vision loss was reversible except for some eyes with chorioretinal folds. Optic neuropathy alone caused decreased BCVA in 10 eyes (21%) and coexisting outer retinal changes and optic neuropathy caused decreased BCVA in 16 eyes (33%). A GCL-IPL thickness less than or equal to 70 μm at initial presentation or progressive thinning of greater than or equal to 10 μm within 2 to 3 weeks compared with baseline correlated with poor visual outcome. Conclusions. Visual acuity loss in IIH can be caused by both outer retinal changes and optic neuropathy. Vision loss from outer retinal changes is mostly reversible. The outcome of patients with coexisting outer retinal changes and optic neuropathy or optic neuropathy alone depends on the degree of optic neuropathy, which can be predicted by the GCL-IPL thickness. PMID:26070058

  8. Visual acuity and patient satisfaction at varied distances and lighting conditions after implantation of an aspheric diffractive multifocal one-piece intraocular lens

    PubMed Central

    Chang, Daniel H

    2016-01-01

    Purpose The aim of the study is to evaluate the visual acuity and patient satisfaction at varied distances under photopic and mesopic lighting conditions in patients bilaterally implanted with aspheric diffractive multifocal one-piece intraocular lenses. Methods In this retrospective–prospective study, 16 patients with a mean age of 66.2±9.2 years (range: 50–81 years) who had undergone bilateral phacoemulsification surgery with implantation of a Tecnis multifocal one-piece intraocular lens (ZMB00) were evaluated. Monocular and binocular uncorrected and distance-corrected visual acuities were measured at distance (20 ft), intermediate (70–80 cm), and near (35–40 cm) under photopic (85 cd/m2) and mesopic (3 cd/m2) lighting conditions and were compared using the paired t-test. All patients also completed a subjective questionnaire. Results At a mean follow-up of 9.5±3.9 months, distance, near, and intermediate visual acuity improved significantly from preoperative acuity. Under photopic and mesopic conditions, 93.8% and 62.5% of patients, respectively, had binocular uncorrected intermediate visual acuity of 20/40 or better, and 62.5% and 31.3% of patients had binocular uncorrected near visual acuity of 20/20 or better. All patients were satisfied with their overall vision without using glasses and/or contact lenses when compared with before surgery. A total of 87.5% of patients reported no glare and 68.8% of patients reported no halos around lights at night. Conclusion Tecnis multifocal one-piece intraocular lenses provide good distance, intermediate, and near visual acuity under photopic as well as mesopic lighting conditions. High levels of spectacle independence with low levels of photic phenomenon were achieved, resulting in excellent patient satisfaction. PMID:27536061

  9. Handling qualities comparison of panoramic night vision goggles and 46-deg. night vision goggles

    NASA Astrophysics Data System (ADS)

    Craig, Gregory; Jennings, Sion; Thorndycraft, David

    2003-09-01

    Night Vision Goggles allow the user to see in extremely low illumination levels but the visual information provided by Night Vision Goggles has a limited field-of-view that diminishes handling-qualities in the night flying environment. Panoramic Night Vision Goggles were designed to correct this problem by providing a 100° horizontal field-of-view which is larger than currently used Night Vision Goggles. However, in the first generation Panoramic Night Vision Goggle, the improved field of view came at the cost of diminished resolution, contrast and central overlap area when compared to conventional Night Vision Goggles. This paper describes an evaluation that was conducted in the variable stability NRC Bell-205 helicopter to examine the influence on system handling qualities of the Panoramic Night Vision Goggles and a 46° field-of-view UK Night Vision Goggle. Five pilots flew the ADS-33D hover, sidestep and pirouette manoeuvres in simulated night conditions with the UK Night Vision Goggle and the Panoramic Night Vision Goggle. Both subjective and objective measures of task performance were obtained. Handling-qualities ratings showed the pirouette was performed better with the Panoramic Night Vision Goggles. This was the only manoeuvre where there was a clear-cut handling qualities improvement when using the Panoramic Night Vision Goggles. Other manoeuvres such as the sidestep and hover did not show definitive handling qualities rating differences between the two Night Vision Goggle types. The flight test results were interpreted in terms of the design trade-offs of the two night vision systems, with regard to the different acuity, binocular overlaps and fields-of-view.

  10. Leading Vision

    ERIC Educational Resources Information Center

    Fawcett, Gay

    2004-01-01

    The current educational landscape makes it imperative that a vision statement become more than a fine-sounding statement that is laminated, hung on the wall, and quickly forgotten. If educators do not have a clear image of the future they wish to create, then someone will be ready to create it for them. But with a clear vision of the future, a…

  11. Learning Visions.

    ERIC Educational Resources Information Center

    Phelps, Margaret S.; And Others

    This paper describes LEARNing Visions, a K-12 intervention program for at-risk youth in Jackson County, Tennessee, involving a partnership between the schools, local businesses, Tennessee Technological University, and Visions Five (a private company). Jackson County is characterized by an undereducated population, a high employment rate, and a low…

  12. The discrepancy between central foveal thickness and best corrected visual acuity in cystoid macular edema secondary to central retinal vein occlusion after intravitreal lucentis® injection.

    PubMed

    Hua, Rui; Li, Chenyan; Hu, Yuedong; Chen, Lei

    2015-06-01

    Cystoid macular edema is a common retinal disorder with the potential for significant vision-related morbidity, and intravitreal lucentis(®) injection is confirmed to be an effective therapy approach. In the present study, we investigated the discrepancy between central foveal thickness and best corrected visual acuity in such lesions and infered that intravitreal lucentis(®) injection may help the visual function, related to the renewal of cells. PMID:25818575

  13. Long Duration Head-Down Tilt Bed Rest Studies: Safety Considerations Regarding Vision Health

    NASA Technical Reports Server (NTRS)

    Cromwell, Ronita L.; Zanello, S. B.; Yarbough, P. O.; Ploutz-Snyder, Robert; Taibbi, G.; Vizzeri, G.

    2012-01-01

    Visual symptoms reported in astronauts returning from long duration missions in low Earth orbit, including hyperopic shift, choroidal folds, globe flattening and papilledema, are thought to be related to fluid shifts within the body due to microgravity exposure. Because of this possible relation to fluid shifts, safety considerations have been raised regarding the ocular health of head-down tilt (HDT) bed rest subjects. HDT is a widely used ground ]based analog that simulates physiological changes of spaceflight, including fluid shifts. Thus, vision monitoring has been performed in bed rest subjects in order to evaluate the safety of HDT with respect to vision health. Here we report ocular outcomes in 9 healthy subjects (age range: 27-48 years; Male/Female ratio: 8/1) completing bed rest Campaign 11, an integrated, multidisciplinary 70-day 6 degrees HDT bed rest study. Vision examinations were performed on a weekly basis, and consisted of office-based (2 pre- and 2 post-bed rest) and in-bed testing. The experimental design was a repeated measures design, with measurements for both eyes taken for each subject at each planned time point. Findings for the following tests were all reported as normal in each testing session for every subject: modified Amsler grid, red dot test, confrontational visual fields, color vision and fundus photography. Overall, no statistically significant differences were observed for any of the measures, except for both near and far visual acuity, which increased during the course of the study. This difference is not considered clinically relevant as may result from the effect of learning. Intraocular pressure results suggest a small increase at the beginning of the bed rest phase (p=0.059) and lesser increase at post-bed rest with respect to baseline (p=0.046). These preliminary results provide the basis for further analyses that will include correlations between intraocular pressure change pre- and post-bed rest, and optical coherence

  14. Ultra-Rapid Vision in Birds

    PubMed Central

    Boström, Jannika E.; Dimitrova, Marina; Canton, Cindy; Håstad, Olle; Qvarnström, Anna; Ödeen, Anders

    2016-01-01

    Flying animals need to accurately detect, identify and track fast-moving objects and these behavioral requirements are likely to strongly select for abilities to resolve visual detail in time. However, evidence of highly elevated temporal acuity relative to non-flying animals has so far been confined to insects while it has been missing in birds. With behavioral experiments on three wild passerine species, blue tits, collared and pied flycatchers, we demonstrate temporal acuities of vision far exceeding predictions based on the sizes and metabolic rates of these birds. This implies a history of strong natural selection on temporal resolution. These birds can resolve alternating light-dark cycles at up to 145 Hz (average: 129, 127 and 137, respectively), which is ca. 50 Hz over the highest frequency shown in any other vertebrate. We argue that rapid vision should confer a selective advantage in many bird species that are ecologically similar to the three species examined in our study. Thus, rapid vision may be a more typical avian trait than the famously sharp vision found in birds of prey. PMID:26990087

  15. Human Time-Frequency Acuity Beats the Fourier Uncertainty Principle

    NASA Astrophysics Data System (ADS)

    Oppenheim, Jacob N.; Magnasco, Marcelo O.

    2013-01-01

    The time-frequency uncertainty principle states that the product of the temporal and frequency extents of a signal cannot be smaller than 1/(4π). We study human ability to simultaneously judge the frequency and the timing of a sound. Our subjects often exceeded the uncertainty limit, sometimes by more than tenfold, mostly through remarkable timing acuity. Our results establish a lower bound for the nonlinearity and complexity of the algorithms employed by our brains in parsing transient sounds, rule out simple “linear filter” models of early auditory processing, and highlight timing acuity as a central feature in auditory object processing.

  16. "A moment's monument": the central vision of Italian sculptor Medardo Rosso (1858-1928).

    PubMed

    Melcher, David; Bacci, Francesca

    2003-01-01

    One of the basic limitations on visual perception is that it is impossible, in any given moment, to see the world sharply and full of colors beyond the central area of the visual field. This fact was popularized and brought to the attention of artists in the nineteenth century. To accurately represent the 'impression', or vision of a single glance, an artistic work should contain only a central area in focus surrounded by a progressively greater blur. The work of the Italian sculptor Medardo Rosso (1858-1928) may be the first artistic representation of differences in central and peripheral acuity. Despite using the medium of sculpture, typically three-dimensional, Rosso conceived of his art as two-dimensional because in a given moment it is possible to view a scene from only one viewpoint. The analysis of Rosso's photographs of his own sculptures emphasizes the areas of detail and relative blur, allowing a reconstruction of his point de vue unique--where the observer should stand when viewing that specific sculpture. We argue that the role of central and peripheral vision in subjective perception is critical to understanding the work of Rosso, aptly defined by critics as monument d'un instant. PMID:14651319

  17. Computational vision

    NASA Technical Reports Server (NTRS)

    Barrow, H. G.; Tenenbaum, J. M.

    1981-01-01

    The range of fundamental computational principles underlying human vision that equally apply to artificial and natural systems is surveyed. There emerges from research a view of the structuring of vision systems as a sequence of levels of representation, with the initial levels being primarily iconic (edges, regions, gradients) and the highest symbolic (surfaces, objects, scenes). Intermediate levels are constrained by information made available by preceding levels and information required by subsequent levels. In particular, it appears that physical and three-dimensional surface characteristics provide a critical transition from iconic to symbolic representations. A plausible vision system design incorporating these principles is outlined, and its key computational processes are elaborated.

  18. Computer vision

    NASA Technical Reports Server (NTRS)

    Gennery, D.; Cunningham, R.; Saund, E.; High, J.; Ruoff, C.

    1981-01-01

    The field of computer vision is surveyed and assessed, key research issues are identified, and possibilities for a future vision system are discussed. The problems of descriptions of two and three dimensional worlds are discussed. The representation of such features as texture, edges, curves, and corners are detailed. Recognition methods are described in which cross correlation coefficients are maximized or numerical values for a set of features are measured. Object tracking is discussed in terms of the robust matching algorithms that must be devised. Stereo vision, camera control and calibration, and the hardware and systems architecture are discussed.

  19. Simulation of color deficiency in virtual reality.

    PubMed

    Jin, Bei; Ai, Zhuming; Rasmussen, Mary

    2005-01-01

    Color deficiency protanopia is simulated in a virtual home environment. A color database is created to set the corresponding relation between each color for normal vision and for protanopia. Based on this database, a second texture system is set up for the home model. The proper texture system is used according to the user's choice on the interactive menu. PMID:15718732

  20. Computer Vision Systems

    NASA Astrophysics Data System (ADS)

    Gunasekaran, Sundaram

    Food quality is of paramount consideration for all consumers, and its importance is perhaps only second to food safety. By some definition, food safety is also incorporated into the broad categorization of food quality. Hence, the need for careful and accurate evaluation of food quality is at the forefront of research and development both in the academia and industry. Among the many available methods for food quality evaluation, computer vision has proven to be the most powerful, especially for nondestructively extracting and quantifying many features that have direct relevance to food quality assessment and control. Furthermore, computer vision systems serve to rapidly evaluate the most readily observable foods quality attributes - the external characteristics such as color, shape, size, surface texture etc. In addition, it is now possible, using advanced computer vision technologies, to “see” inside a food product and/or package to examine important quality attributes ordinarily unavailable to human evaluators. With rapid advances in electronic hardware and other associated imaging technologies, the cost-effectiveness and speed of computer vision systems have greatly improved and many practical systems are already in place in the food industry.

  1. Theoretical research on color indirect effects

    NASA Astrophysics Data System (ADS)

    Liu, T. C.; Liao, Changjun; Liu, Songhao

    1995-05-01

    Color indirect effects (CIE) means the physiological and psychological effects of color resulting from color vision. In this paper, we study CIE from the viewpoints of the integrated western and Chinese traditional medicine and the time quantum theory established by C. Y. Liu et al., respectively, and then put forward the color-automatic-nervous-subsystem model that could color excites parasympathetic subsystem and hot color excites sympathetic subsystem. Our theory is in agreement with modern color vision theory, and moreover, it leads to the resolution of the conflict between the color code theory and the time code theory oncolor vision. For the latitude phenomena on athlete stars number and the average lifespan, we also discuss the possibility of UV vision. The applications of our theory lead to our succeeding in explaining a number of physiological and psychological effects of color, in explaining the effects of age on color vision, and in explaining the Chinese chromophototherapy. We also discuss its application to neuroimmunology. This research provides the foundation of the clinical applications of chromophototherapy.

  2. 78 FR 12815 - Qualification of Drivers; Exemption Applications; Vision

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-02-25

    ... vision, good color vision, and a good field of vision when using both eyes. His condition is stable and... and the docket numbers for this notice. Note that all comments received will be posted without change... FR 82132), or you may visit http://www.gpo.gov/fdsys/pkg/FR-2010-12-29/pdf/2010-32876.pdf ....

  3. Color constancy for an unseen surface.

    PubMed

    Norman, Liam J; Akins, Kathleen; Heywood, Charles A; Kentridge, Robert W

    2014-12-01

    The illumination of a scene strongly affects our perception of objects in that scene, e.g., the pages of a book illuminated by candlelight will appear quite yellow relative to other types of artificial illuminants. Yet at the same time, the reader still judges the pages as white, their surface color unaffected by the interplay of paper and illuminant. It has been shown empirically that we can indeed report two quite different interpretations of "color": one is dependent on the constant surface spectral reflectance of an object (surface color) and the other on the power of light of different wavelengths reflected from that object (reflected color). How then are these two representations related? The common view, dating from Aristotle, is that our experience of surface color is derived from reflected color or, in more familiar terms, that color perception follows from color sensation. By definition, color constancy requires that vision "discounts the illuminant"; thus, it seems reasonable that vision begins with the color of objects as they naively appear and that we infer from their appearances their surface color. Here, we question this classic view. We use metacontrast-masked priming and, by presenting the unseen prime and the visible mask under different illuminants, dissociate two ways in which the prime matched the mask: in surface color or in reflected color. We find that priming of the mask occurs when it matches the prime in surface color, not reflected color. It follows that color perception can arise without prior color sensation. PMID:25456450

  4. Improving Vision

    NASA Technical Reports Server (NTRS)

    2003-01-01

    Many people are familiar with the popular science fiction series Star Trek: The Next Generation, a show featuring a blind character named Geordi La Forge, whose visor-like glasses enable him to see. What many people do not know is that a product very similar to Geordi's glasses is available to assist people with vision conditions, and a NASA engineer's expertise contributed to its development. The JORDY(trademark) (Joint Optical Reflective Display) device, designed and manufactured by a privately-held medical device company known as Enhanced Vision, enables people with low vision to read, write, and watch television. Low vision, which includes macular degeneration, diabetic retinopathy, and glaucoma, describes eyesight that is 20/70 or worse, and cannot be fully corrected with conventional glasses.

  5. Vision problems

    MedlinePlus

    ... in dealing with eye emergencies if: You experience partial or complete blindness in one or both eyes, ... a family history of diabetes Eye itching or discharge Vision changes that seem related to medication (DO ...

  6. Vision Underwater.

    ERIC Educational Resources Information Center

    Levine, Joseph S.

    1980-01-01

    Provides information regarding underwater vision. Includes a discussion of optically important interfaces, increased eye size of organisms at greater depths, visual peculiarities regarding the habitat of the coastal environment, and various pigment visual systems. (CS)

  7. Color Blindness

    MedlinePlus

    ... three color cone cells to determine our color perception. Color blindness can occur when one or more ... Anyone who experiences a significant change in color perception should see an ophthalmologist (Eye M.D.). Next ...

  8. Astronaut Charles Conrad during visual acuity experiments over Laredo

    NASA Technical Reports Server (NTRS)

    1965-01-01

    Astronaut Charles Conrad Jr., pilot for the prime crew on the Gemini 5 space flight, takes pictures of predetermined land areas during visual acuity experiments over Laredo, Texas. The experiments will aid in learning to identify known terrestrial features under controlled conditions.

  9. Astronauts Cooper and Conrad prepare cameras during visual acuity tests

    NASA Technical Reports Server (NTRS)

    1965-01-01

    Astronauts L. Gordon Cooper Jr. (left), command pilot, and Charles Conrad Jr., pilot, the prime crew of the Gemini 5 space flight, prepare their cameras while aboard a C-130 aircraft flying near Laredo. The two astronauts are taking part in a series of visual acuity experiments to aid them in learning to identify known terrestrial features under controlled conditions.

  10. Acuity systems dialogue and patient classification system essentials.

    PubMed

    Harper, Kelle; McCully, Crystal

    2007-01-01

    Obtaining resources for quality patient care is a major responsibility of nurse leaders and requires accurate information in the political world of budgeting. Patient classification systems (PCS) assist nurse managers in controlling cost and improving patient care while appropriately using financial resources. This paper communicates acuity systems development, background, flaws, and components while discussing a few tools currently available. It also disseminates the development of a new acuity tool, the Patient Classification System. The PCS tool, developed in a small rural hospital, uses 5 broad concepts: (1) medications, (2) complicated procedures, (3) education, (4) psychosocial issues, and (5) complicated intravenous medications. These concepts embrace a 4-tiered scale that differentiates significant patient characteristics and assists in staffing measures for equality in patient staffing and improving quality of care and performance. Data obtained through use of the PCS can be used by nurse leaders to effectively and objectively lobby for appropriate patient care resources. Two questionnaires distributed to registered nurses on a medical-surgical unit evaluated the nurses' opinion of the 5 concepts and the importance for establishing patient acuity for in-patient care. Interrater reliability among nurses was 87% with the author's acuity tool. PMID:17909428

  11. The Approximate Number System Acuity Redefined: A Diffusion Model Approach

    PubMed Central

    Park, Joonkoo; Starns, Jeffrey J.

    2015-01-01

    While all humans are capable of non-verbally representing numerical quantity using so-called the approximate number system (ANS), there exist considerable individual differences in its acuity. For example, in a non-symbolic number comparison task, some people find it easy to discriminate brief presentations of 14 dots from 16 dots while others do not. Quantifying individual ANS acuity from such a task has become an essential practice in the field, as individual differences in such a primitive number sense is thought to provide insights into individual differences in learned symbolic math abilities. However, the dominant method of characterizing ANS acuity—computing the Weber fraction (w)—only utilizes the accuracy data while ignoring response times (RT). Here, we offer a novel approach of quantifying ANS acuity by using the diffusion model, which accounts both accuracy and RT distributions. Specifically, the drift rate in the diffusion model, which indexes the quality of the stimulus information, is used to capture the precision of the internal quantity representation. Analysis of behavioral data shows that w is contaminated by speed-accuracy tradeoff, making it problematic as a measure of ANS acuity, while drift rate provides a measure more independent from speed-accuracy criterion settings. Furthermore, drift rate is a better predictor of symbolic math ability than w, suggesting a practical utility of the measure. These findings demonstrate critical limitations of the use of w and suggest clear advantages of using drift rate as a measure of primitive numerical competence. PMID:26733929

  12. Comparability of ophthalmic diagnoses by clinical and Reading Center examiners in the Visual Acuity Impairment Survey Pilot Study.

    PubMed

    Sperduto, R D; Hiller, R; Podgor, M J; Palmberg, P; Ferris, F L; Wentworth, D

    1986-12-01

    Technologic advances in ophthalmic equipment offer the possibility of replacing direct clinical examinations with Reading Center evaluations of data recorded in epidemiologic studies. Clinical and Reading Center examiners made independent ophthalmic diagnoses of 133 right and 132 left eyes of 138 adults in the Visual Acuity Impairment Survey Pilot Study, carried out in three US cities, Boston, Detroit, and Minneapolis, in August 1981-December 1982. The Reading Center diagnosed eye conditions using only photographic and visual field data collected at the time of the clinical examination. In the comparisons of clinical and Reading Center evaluations reported here, only eyes judged by the examiners to have pathology severe enough to reduce visual acuity to 6/9 or worse were classified as having pathology. (No visual acuity criterion was required for the diagnosis of glaucoma or diabetic retinopathy.) There was agreement in diagnostic assessments between clinical and Reading Center examiners in about 80% of eyes. The kappa statistic, which adjusts for chance agreement, was in the fair to good range: 0.60 for 133 right eyes and 0.62 for 132 left eyes. When the Reading Center examiners were provided with additional information on medical history, refractive error and best corrected visual acuity, the agreement between clinical and Reading Center assessments among the subset of eyes with 6/9 or worse vision again was in the fair to good range, with kappas of 0.61 for 45 right eyes and 0.68 for 48 left eyes. Inter-observer agreement between Reading Center examiners in diagnosing pathology was in the good to excellent range. Use of Reading Centers in future epidemiologic studies should be considered, but elimination of the clinical examinations is not recommended until modifications in the protocol described here have been made and shown to improve levels of agreement between clinical and Reading Center examiners. PMID:3776982

  13. Running head: What color is it

    NASA Technical Reports Server (NTRS)

    Young, Andrew T.

    1988-01-01

    Color vision provides low-resolution spectrophotometric information about candidate materials for planetary surfaces that is comparable in precision to wideband photoelectric photometry, and considerably superior to Voyager TV data. Briefly explained are the basic concepts, teminology, and notation of color science. Also shown is how to convert a reflectance spectrum into a color specification. An Appendix lists a simple computer subroutine to convert spectral reflectance into CIE coordinates, and the text explains how to convert these to a surface color in a standard color atlas. Target and printed Solar System colors are compared to show how accurate are the printed colors.

  14. Color constancy in Japanese animation

    NASA Astrophysics Data System (ADS)

    Ichihara, Yasuyo G.

    2006-01-01

    In this study, we measure the colors used in a Japanese Animations. The result can be seen on CIE-xy color spaces. It clearly shows that the color system is not a natural appearance system but an imagined and artistic appearance system. Color constancy of human vision can tell the difference in skin and hair colors between under moonlight and day light. Human brain generates a match to the memorized color of an object from daylight viewing conditions to the color of the object in different viewing conditions. For example, Japanese people always perceive the color of the Rising Sun in the Japanese flag as red even in a different viewing condition such as under moonlight. Color images captured by a camera cannot present those human perceptions. However, Japanese colorists in Animation succeeded in painting the effects of color constancy not only under moonlight but also added the memory matching colors. They aim to create a greater impact on viewer's perceptions by using the effect of the memory matching colors. In this paper, we propose the Imagined Japanese Animation Color System. This system in art is currently a subject of research in Japan. Its importance is that it could also provide an explanation on how human brain perceives the same color under different viewing conditions.

  15. Applying Color.

    ERIC Educational Resources Information Center

    Burton, David

    1984-01-01

    Most schools teach the triadic color system, utilizing red, blue, and yellow as primary colors. Other systems, such as additive and subtractive color systems, Munsell's Color Notation System, and the Hering Opponent Color Theory, can broaden children's concepts and free them to better choose color in their own work. (IS)

  16. Adherence to Occlusion Therapy in the First Six Months of Follow-Up and Visual Acuity among Participants in the Infant Aphakia Treatment Study (IATS)

    PubMed Central

    Drews-Botsch, Carolyn D.; Celano, Marianne; Kruger, Stacey; Hartmann, E. Eugenie

    2012-01-01

    Purpose. Achieving good vision in infants born with a unilateral cataract is believed to require early surgery and consistent occlusion of the fellow eye. This article examines the relationship between adherence to patching and grating acuity. Methods. Data came from the Infant Aphakia Treatment Study, a randomized clinical trial of treatment for unilateral congenital cataract. Infants were either left aphakic (n = 53) or had an intraocular lens implanted (n = 55). Patching was prescribed 1 hour per day per month of age until 8 months of age and 50% of waking hours thereafter. Adherence was measured as the mean percentage of prescribed patching reported in a 7-day diary completed 2 months after surgery, and 48-hour recall interviews conducted 3 and 6 months after surgery. Grating visual acuity was measured within 1 month of the infant's first birthday (n = 108) using Teller Acuity Cards by a tester masked to treatment. Nonparametric correlations were used to examine the relationship with grating acuity. Results. On average, caregivers reported patching 84.3% (SD = 31.2%) of prescribed time and adherence did not differ by treatment (t = −1.40, df = 106, p = 0.16). Adherence was associated with grating acuity (rSpearman = −0.27, p < 0.01), but more so among pseudophakic (rSpearman = −0.41, p < 0.01) than aphakic infants (rSpearman = −0.10, p = 0.49). Conclusions. This study empirically has shown that adherence to patching during the first 6 months after surgery is associated with better grating visual acuity at 12 months of age after treatment for unilateral cataract and that implanting an intraocular lens is not associated with adherence. (ClinicalTrials.gov number, NCT00212134.) PMID:22491410

  17. Acuity of a Cryptochrome and Vision-Based Magnetoreception System in Birds

    PubMed Central

    Solov'yov, Ilia A.; Mouritsen, Henrik; Schulten, Klaus

    2010-01-01

    Abstract The magnetic compass of birds is embedded in the visual system and it has been hypothesized that the primary sensory mechanism is based on a radical pair reaction. Previous models of magnetoreception have assumed that the radical pair-forming molecules are rigidly fixed in space, and this assumption has been a major objection to the suggested hypothesis. In this article, we investigate theoretically how much disorder is permitted for the radical pair-forming, protein-based magnetic compass in the eye to remain functional. Our study shows that only one rotational degree of freedom of the radical pair-forming protein needs to be partially constrained, while the other two rotational degrees of freedom do not impact the magnetoreceptive properties of the protein. The result implies that any membrane-associated protein is sufficiently restricted in its motion to function as a radical pair-based magnetoreceptor. We relate our theoretical findings to the cryptochromes, currently considered the likeliest candidate to furnish radical pair-based magnetoreception. PMID:20655831

  18. Intelligent robots and computer vision; Proceedings of the Seventh Meeting, Cambridge, MA, Nov. 7-11, 1988

    SciTech Connect

    Casasent, D.P.

    1989-01-01

    Various papers on intelligent robots and computer vision are presented. The general topics addressed include: pattern recognition, boundary description in pattern recognition, image processing, segmentation and feature extraction, color vision and multisensor processing, neural nets, image understanding, fuzzy logic in image processing and computer vision, robot vision software, parallel computer vision architectures, three-dimensional object recognition, and intelligent control of robot systems.

  19. Composition of a Vision Screen for Servicemembers With Traumatic Brain Injury: Consensus Using a Modified Nominal Group Technique

    PubMed Central

    Finkelstein, Marsha; Llanos, Imelda; Scheiman, Mitchell; Wagener, Sharon Gowdy

    2014-01-01

    Vision impairment is common in the first year after traumatic brain injury (TBI), including among service members whose brain injuries occurred during deployment in Iraq and Afghanistan. Occupational therapy practitioners provide routine vision screening to inform treatment planning and referral to vision specialists, but existing methods are lacking because many tests were developed for children and do not screen for vision dysfunction typical of TBI. An expert panel was charged with specifying the composition of a vision screening protocol for servicemembers with TBI. A modified nominal group technique fostered discussion and objective determinations of consensus. After considering 29 vision tests, the panel recommended a nine-test vision screening that examines functional performance, self-reported problems, far–near acuity, reading, accommodation, convergence, eye alignment and binocular vision, saccades, pursuits, and visual fields. Research is needed to develop reliable, valid, and clinically feasible vision screening protocols to identify TBI-related vision disorders in adults. PMID:25005505

  20. Reasoning about color in Prolog

    NASA Astrophysics Data System (ADS)

    Batchelor, Bruce G.; Whelan, Paul F.

    1994-10-01

    The use of color as a basis for segmenting images is attractive for a wide variety of industrial inspection applications, especially in the manufacturing of domestic goods, food, pharmaceuticals, toiletries and electronics. Human beings define colors, not formulae, or computer programs. Moreover, no two people have an identical view of what a color set, such as 'canary yellow' is. The article argues that teaching by showing is more relevant than the accepted methods of Color Science, in the design of factory-floor vision systems. Fast hardware for color recognition has been available for several years but has not yet received universal acceptance. This article explains how this equipment can be used in conjunction with symbolic processing software, based on the Artificial Intelligence language Prolog. Using this hardware-software system, a programmer is able to express ideas about colors in a natural way. The concepts of color set union, intersection, generalization and interpolation are all discussed.

  1. [Prediction of postoperative visual acuity in retinal detachment with macular involvement].

    PubMed

    Yasukawa, T; Fukuda, T; Kishimoto, M; Ogura, Y

    1995-03-01

    We used laser interferometry (LI) and a potential acuity meter (PAM) to predict visual acuity after surgery for patients with rhegmatogenous retinal detachment with macular involvement. Thirty one eyes of 31 patients with retinal detachment were treated with scleral buckling procedures. Postoperative visual acuity was correlated with preoperative measurements of the LI and PAM, preoperative visual acuity by Landort's ring, and the estimated duration of macular detachment. The correlation between the duration of macular detachment and the postoperative visual acuity was not good (r = 0.55, p < 0.01). Although the preoperative visual acuity showed a relatively good correlation with postoperative visual acuity (r = 0.62, p < 0.01), the results of the LI and PAM provided a better correlation (LI; r = 0.73, PAM; r = 0.71). Our results suggest that the LI and PAM are useful to predict the visual acuity after retinal reattachment in patients with preoperative macular detachment. PMID:7732924

  2. Improving Vision among Older Adults: Behavioral Training to Improve Sight

    PubMed Central

    DeLoss, Denton J.; Watanabe, Takeo; Andersen, George J.

    2015-01-01

    A major problem for the rapidly growing population of older adults (age 65 and older) is age-related declines in vision, which have been associated with increased risk of falls and vehicle crashes. Research suggests that the increased risk is associated with declines in contrast sensitivity and acuity. We examined whether perceptual learning could be used to improve age-related declines in contrast sensitivity. Older and younger adults were trained over seven days using a forced-choice orientation discrimination task with stimuli that varied in contrast with multiple levels of additive noise. The results indicate that older individuals, following training, performed as well as pre-trained college-aged participants. Improvements transferred to an untrained orientation, and were not associated with changes in retinal illuminance. Improvements in far acuity in younger individuals and near acuity in older individuals were also found. These findings indicate that behavioral interventions can greatly improve visual performance for older adults. PMID:25749697

  3. Ultraviolet vision may be widespread in bats

    USGS Publications Warehouse

    Gorresen, P. Marcos; Cryan, Paul; Dalton, David C.; Wolf, Sandy; Bonaccorso, Frank

    2015-01-01

    Insectivorous bats are well known for their abilities to find and pursue flying insect prey at close range using echolocation, but they also rely heavily on vision. For example, at night bats use vision to orient across landscapes, avoid large obstacles, and locate roosts. Although lacking sharp visual acuity, the eyes of bats evolved to function at very low levels of illumination. Recent evidence based on genetics, immunohistochemistry, and laboratory behavioral trials indicated that many bats can see ultraviolet light (UV), at least at illumination levels similar to or brighter than those before twilight. Despite this growing evidence for potentially widespread UV vision in bats, the prevalence of UV vision among bats remains unknown and has not been studied outside of the laboratory. We used a Y-maze to test whether wild-caught bats could see reflected UV light and whether such UV vision functions at the dim lighting conditions typically experienced by night-flying bats. Seven insectivorous species of bats, representing five genera and three families, showed a statistically significant ‘escape-toward-the-light’ behavior when placed in the Y-maze. Our results provide compelling evidence of widespread dim-light UV vision in bats.

  4. Color indirect effects on melatonin regulation

    NASA Astrophysics Data System (ADS)

    Mian, Tian; Liu, Timon C.; Li, Yan

    2002-04-01

    Color indirect effect (CIE) is referred to as the physiological and psychological effects of color resulting from color vision. In previous papers, we have studied CIE from the viewpoints of the integrated western and Chinese traditional medicine, put forward the color-autonomic- nervous-subsystem model (CAM), and provided its time-theory foundation. In this paper, we applied it to study light effects on melatonin regulation in humans, and suggested that it is CIE that mediates light effects on melatonin suppression.

  5. Color Perception Requirements of 4,000 Jobs

    ERIC Educational Resources Information Center

    Barker, Donald G.

    1971-01-01

    Tabulation of the color discrimination requisites of a representative sample of jobs revealed that the majority of jobs require little or no color perception aptitude. Jobs requiring color discrimination were listed by Dictionary of Occupational Titles for the use of counselors in the guidance of clients with defective color vision. (Author)

  6. Panic attacks and interoceptive acuity for cardiac sensations.

    PubMed

    Asmundson, G J; Sandler, L S; Wilson, K G; Norton, G R

    1993-02-01

    It has been suggested that perception of visceral changes, and cognitive reactions to such changes, may be important for triggering panic attacks. It remains to be determined, however, whether people with panic attacks are actually characterized by enhanced perceptual acuity for interoceptive stimuli. The purpose of this study was to explore the relationship between panic attacks and awareness for cardiac sensations using an objective heartbeat discrimination procedure. Twenty panickers and 20 nonpanickers were given 60 trials of the Whitehead heartbeat discrimination procedure. Thirty trials were given during rest and 30 following hyperventilation. Results indicated that panic attacks were not related to enhanced interoceptive acuity for cardiac sensations, either at rest or following hyperventilation. These results are discussed in terms of their relevance to cognitive models of panic. PMID:8442744

  7. Assessment of Visual Acuity in Relation to Central Nervous System Activation in Children with Mental Retardation.

    ERIC Educational Resources Information Center

    Jacobsen, Karl; Grottland, Havar; Flaten, Magne Arve

    2001-01-01

    Assessment of visual acuity, using Teller Acuity Cards, was combined with observations of behavioral state to indicate central nervous system activation in 24 individuals with mental retardation. Results indicate that forced-choice preferential-looking technique can be used to test visual acuity in this population unless the participant is drowsy.…

  8. Accommodation, Acuity, and their Relationship to Emmetropization in Infants

    PubMed Central

    Mutti, Donald O.; Mitchell, G. Lynn; Jones, Lisa A.; Friedman, Nina E.; Frane, Sara L.; Lin, Wendy K.; Moeschberger, Melvin L.; Zadnik, Karla

    2009-01-01

    Purpose To evaluate the relationship between accommodation, visual acuity, and emmetropization in human infancy. Methods Defocus at distance and near (57cm) was assessed using Mohindra and dynamic retinoscopy, respectively, in 262 normal birthweight infants at 3, 9, and 18 months of age. Preferential looking provided acuity data at the same ages. The spherical equivalent refractive error was measured by cycloplegic retinoscopy (cyclopentolate 1%). Results Univariate linear regression analyses showed no associations between the change in refractive error and defocus at distance or near. Change in refractive error was linearly related to the accommodative response at distance (R2 = 0.17, p<0.0001) and near (R2 = 0.13, p<0.0001). The ten subjects with the poorest emmetropization relative to the change predicted by the linear effects of their refractive error had higher average levels of hyperopic defocus at distance and near (p-values <0.043). Logistic regression showed a decrease in the odds of reaching +2.00D or less hyperopia by 18 months with increasing levels of hyperopia at 3 months, or if Mohindra retinoscopy was myopic combined with acuity better than the median level of 1.25 logMAR (area under the receiver operating characteristic curve = 0.78 (95% CI = 0.68, 0.88)). Conclusions The level of cycloplegic refractive error was the best single factor for predicting emmetropization by 18 months of age, with smaller contributions from visual acuity and Mohindra retinoscopy. The lack of correlation between defocus and change in refractive error does not support a simple model of emmetropization in response to the level of hyperopic defocus. Infants were capable of maintaining accurate average levels of accommodation across a range of moderate hyperopic refractive errors at 3 months of age. The association between the change in refractive error and accommodative response suggests that the amount of accommodation is a plausible visual signal for emmetropization. PMID

  9. Relationship among fMRI, contrast sensitivity and visual acuity.

    PubMed

    Leguire, L E; Algaze, A; Kashou, N H; Lewis, J; Rogers, G L; Roberts, C

    2011-01-01

    The purpose of this study was to ascertain whether visual acuity or contrast sensitivity function (CSF) is proportional to visual cortical function based on fMRI volume and level of activation or Z-score. Forced choice procedures were utilized to measure the monocular log minimal angle of resolution (logMAR) visual acuity and CSF. The CSF data were collapsed into a single index by the use of weighted mean contrast sensitivity (WMCS), being defined as the mean of the products of each spatial frequency multiplied by its corresponding contrast sensitivity. fMRI data had been obtained with a 1.5 T GE Signa scanner with visual stimuli including 1.0 and 2.0 c/deg vertical sinusoidal gratings. Subjects consisted of eight normal adults and five amblyopic patients, with the amblyopic subjects added to gauge whether the outcome was due to a restricted range of scores or the small number of study participants. In normal subjects, the fMRI volume and level of activation exhibited no statistically significant correlation with visual acuity at P<0.05. Statistically significant correlations were obtained between WMCS and fMRI volume (R=0.765, P=0.027) and fMRI level of activation (R=0.645, P=0.007), with right eye stimulation using the 1.0 c/deg grating. On the whole, statistically significant correlations between WMCS and fMRI parameters were maintained when subject age was held constant and when data from the five amblyopic subjects were included to expand the range of values and increase the number of data sets for analysis. fMRI volume and Z-score were more closely associated with the CSF, as defined by WMCS, than visual acuity. The results suggest that the CSF reflects the underlying visual cortical cells responsible for fMRI volume and the level of activation. PMID:21035430

  10. Presidential Visions.

    ERIC Educational Resources Information Center

    Gallin, Alice, Ed.

    1992-01-01

    This journal issue is devoted to the theme of university presidents and their visions of the future. It presents the inaugural addresses and speeches of 16 Catholic college and university presidents focusing on their goals, ambitions, and reasons for choosing to become higher education leaders at this particular time in the history of education in…

  11. Visions 2001.

    ERIC Educational Resources Information Center

    Rivero, Victor; Norman, Michele

    2001-01-01

    Reports on the views of 18 educational leaders regarding their vision on the future of education in an information age. Topics include people's diverse needs; relationships between morality, ethics, values, and technology; leadership; parental involvement; online courses from multiple higher education institutions; teachers' role; technology…

  12. Training Visions

    ERIC Educational Resources Information Center

    Training, 2011

    2011-01-01

    In this article, "Training" asks the 2011 winners to give their predictions for what training--either in general or specifically at their companies--will look like in the next five to 10 years. Perhaps their "training visions" will spark some ideas in one's organization--or at least help prepare for what might be coming in the next decade or so.

  13. Agrarian Visions.

    ERIC Educational Resources Information Center

    Theobald, Paul

    A new feature in "Country Teacher,""Agrarian Visions" reminds rural teachers that they can do something about rural decline. Like to populism of the 1890s, the "new populism" advocates rural living. Current attempts to address rural decline are contrary to agrarianism because: (1) telecommunications experts seek to solve problems of rural…

  14. Vision Loss, Sudden

    MedlinePlus

    ... of age-related macular degeneration. Spotlight on Aging: Vision Loss in Older People Most commonly, vision loss ... Some Causes and Features of Sudden Loss of Vision Cause Common Features* Tests Sudden loss of vision ...

  15. Blindness and vision loss

    MedlinePlus

    ... eye ( chemical burns or sports injuries) Diabetes Glaucoma Macular degeneration The type of partial vision loss may differ, ... tunnel vision and missing areas of vision With macular degeneration, the side vision is normal but the central ...

  16. Color blindness

    MedlinePlus

    ... have trouble telling the difference between red and green. This is the most common type of color ... color blindness often have problems seeing reds and greens, too. The most severe form of color blindness ...

  17. Vision and sports: a review of the literature.

    PubMed

    Stine, C D; Arterburn, M R; Stern, N S

    1982-08-01

    The basis for training visual abilities to enhance sports performance is explored. Optometric intervention in sports assumes the following statements to be true: 1. Athletes have better visual abilities than non-athletes and better athletes have better visual abilities than the poorer athletes, 2. Visual abilities are trainable, and 3. Visual training is transferable to the performance of the athlete. The literature demonstrates that athletes have better visual abilities than non-athletes. Studies have shown this to be true in the following areas of vision: Larger extent of visual fields, larger fields of recognition (peripheral acuity), larger motion perception fields, lower amounts of heterophoria at near and far, more consistent simultaneous vision, more accurate depth perception, better dynamic visual acuity, and better ocular motilities. The literature also shows that all of the above skills are trainable. Two studies are cited that support the belief that visual training is transferable to athletic performance but they suffer from inadequate experimental design. PMID:7130603

  18. Applied machine vision

    SciTech Connect

    Not Available

    1984-01-01

    This book presents the papers given at a conference on robot vision. Topics considered at the conference included the link between fixed and flexible automation, general applications of machine vision, the development of a specification for a machine vision system, machine vision technology, machine vision non-contact gaging, and vision in electronics manufacturing.

  19. Present Vision--Future Vision.

    ERIC Educational Resources Information Center

    Fitterman, L. Jeffrey

    This paper addresses issues of current and future technology use for and by individuals with visual impairments and blindness in Florida. Present technology applications used in vision programs in Florida are individually described, including video enlarging, speech output, large inkprint, braille print, paperless braille, and tactual output…

  20. Robotic vision. [process control applications

    NASA Technical Reports Server (NTRS)

    Williams, D. S.; Wilf, J. M.; Cunningham, R. T.; Eskenazi, R.

    1979-01-01

    Robotic vision, involving the use of a vision system to control a process, is discussed. Design and selection of active sensors employing radiation of radio waves, sound waves, and laser light, respectively, to light up unobservable features in the scene are considered, as are design and selection of passive sensors, which rely on external sources of illumination. The segmentation technique by which an image is separated into different collections of contiguous picture elements having such common characteristics as color, brightness, or texture is examined, with emphasis on the edge detection technique. The IMFEX (image feature extractor) system performing edge detection and thresholding at 30 frames/sec television frame rates is described. The template matching and discrimination approach to recognize objects are noted. Applications of robotic vision in industry for tasks too monotonous or too dangerous for the workers are mentioned.

  1. Visual Impairment Secondary to Congenital Glaucoma in Children: Visual Responses, Optical Correction and Use of Low Vision Aids

    PubMed Central

    Haddad, Maria Aparecida Onuki; Sampaio, Marcos Wilson; Oltrogge, Ernst Werner; Kara-José, Newton; Betinjane, Alberto Jorge

    2009-01-01

    INTRODUCTION Congenital glaucoma is frequently associated with visual impairment due to optic nerve damage, corneal opacities, cataracts and amblyopia. Poor vision in childhood is related to global developmental problems, and referral to vision habilitation/rehabilitation services should be without delay to promote efficient management of the impaired vision. OBJECTIVE To analyze data concerning visual response, the use of optical correction and prescribed low vision aids in a population of children with congenital glaucoma. METHOD The authors analyzed data from 100 children with congenital glaucoma to assess best corrected visual acuity, prescribed optical correction and low vision aids. RESULTS Fifty-five percent of the sample were male, 43% female. The mean age was 6.3 years. Two percent presented normal visual acuity levels, 29% mild visual impairment, 28% moderate visual impairment, 15% severe visual impairment, 11% profound visual impairment, and 15% near blindness. Sixty-eight percent received optical correction for refractive errors. Optical low vision aids were adopted for distance vision in 34% of the patients and for near vision in 6%. A manual monocular telescopic system with 2.8 × magnification was the most frequently prescribed low vision aid for distance, and for near vision a +38 diopter illuminated stand magnifier was most frequently prescribed. DISCUSSION AND CONCLUSION Careful low vision assessment and the appropriate prescription of optical corrections and low vision aids are mandatory in children with congenital glaucoma, since this will assist their global development, improving efficiency in daily life activities and promoting social and educational inclusion. PMID:19690654

  2. Computer vision

    SciTech Connect

    Not Available

    1982-01-01

    This paper discusses material from areas such as artificial intelligence, psychology, computer graphics, and image processing. The intent is to assemble a selection of this material in a form that will serve both as a senior/graduate-level academic text and as a useful reference to those building vision systems. This book has a strong artificial intelligence flavour, emphasising the belief that both the intrinsic image information and the internal model of the world are important in successful vision systems. The book is organised into four parts, based on descriptions of objects at four different levels of abstraction. These are: generalised images-images and image-like entities; segmented images-images organised into subimages that are likely to correspond to interesting objects; geometric structures-quantitative models of image and world structures; relational structures-complex symbolic descriptions of image and world structures. The book contains author and subject indexes.

  3. Pleiades Visions

    NASA Astrophysics Data System (ADS)

    Whitehouse, M.

    2016-01-01

    Pleiades Visions (2012) is my new musical composition for organ that takes inspiration from traditional lore and music associated with the Pleiades (Seven Sisters) star cluster from Australian Aboriginal, Native American, and Native Hawaiian cultures. It is based on my doctoral dissertation research incorporating techniques from the fields of ethnomusicology and cultural astronomy; this research likely represents a new area of inquiry for both fields. This large-scale work employs the organ's vast sonic resources to evoke the majesty of the night sky and the expansive landscapes of the homelands of the above-mentioned peoples. Other important themes in Pleiades Visions are those of place, origins, cosmology, and the creation of the world.

  4. Lambda Vision

    NASA Astrophysics Data System (ADS)

    Czajkowski, Michael

    2014-06-01

    There is an explosion in the quantity and quality of IMINT data being captured in Intelligence Surveillance and Reconnaissance (ISR) today. While automated exploitation techniques involving computer vision are arriving, only a few architectures can manage both the storage and bandwidth of large volumes of IMINT data and also present results to analysts quickly. Lockheed Martin Advanced Technology Laboratories (ATL) has been actively researching in the area of applying Big Data cloud computing techniques to computer vision applications. This paper presents the results of this work in adopting a Lambda Architecture to process and disseminate IMINT data using computer vision algorithms. The approach embodies an end-to-end solution by processing IMINT data from sensors to serving information products quickly to analysts, independent of the size of the data. The solution lies in dividing up the architecture into a speed layer for low-latent processing and a batch layer for higher quality answers at the expense of time, but in a robust and fault-tolerant way. This approach was evaluated using a large corpus of IMINT data collected by a C-130 Shadow Harvest sensor over Afghanistan from 2010 through 2012. The evaluation data corpus included full motion video from both narrow and wide area field-of-views. The evaluation was done on a scaled-out cloud infrastructure that is similar in composition to those found in the Intelligence Community. The paper shows experimental results to prove the scalability of the architecture and precision of its results using a computer vision algorithm designed to identify man-made objects in sparse data terrain.

  5. Marking parts to aid robot vision

    NASA Technical Reports Server (NTRS)

    Bales, J. W.; Barker, L. K.

    1981-01-01

    The premarking of parts for subsequent identification by a robot vision system appears to be beneficial as an aid in the automation of certain tasks such as construction in space. A simple, color coded marking system is presented which allows a computer vision system to locate an object, calculate its orientation, and determine its identity. Such a system has the potential to operate accurately, and because the computer shape analysis problem has been simplified, it has the ability to operate in real time.

  6. Computational models of human vision with applications

    NASA Technical Reports Server (NTRS)

    Wandell, B. A.

    1985-01-01

    Perceptual problems in aeronautics were studied. The mechanism by which color constancy is achieved in human vision was examined. A computable algorithm was developed to model the arrangement of retinal cones in spatial vision. The spatial frequency spectra are similar to the spectra of actual cone mosaics. The Hartley transform as a tool of image processing was evaluated and it is suggested that it could be used in signal processing applications, GR image processing.

  7. Micro-optical imaging concepts for an intraocular vision aid

    NASA Astrophysics Data System (ADS)

    Eix, Ilos; Stork, Wilhelm; Muller-Glaser, Klaus D.

    2004-03-01

    About 10 million people around the world are suffering from blindness, where the path of light is disturbed due to an opaque, irreversible damaged, and inoperable cornea. Although vision is not given to this group of population, the retina is still intact. To date, there is no artificial implant which is able to replace the natural cornea. The work presented here describes an approach to build and implant a micro-optical and microelectronic system to be used as an intraocular vision aid. By overcoming the disturbed light path, it yields to an improved visual acuity of the patient. The main aspect of this bio-mimetic system is to transfer information representing the patient's field of view to the retina. An image of the field of view is captured in real-time outside the eye. After employing data processing, it is wireless transferred to the implanted part of the vision aid. From there, the information emerging from a micro display is imaged to the retina via a micro-optical system. The limited display resolution available inside the eye and the limited dimensions of the eyeball build the constrains of the optical system. A combination of a spatial light modulator together with an imaging lens system realizes intelligent spatial information distribution schemes onto the retina. This ensures a high outcome of visual acuity in the central region of the retina. Various retinal acuities can be realized. The employment of in-vivo adjustment mechanisms of the focal plane is discussed.

  8. Detection and resolution of vanishing optotype letters in central and peripheral vision.

    PubMed

    Demirel, Shaban; Anderson, Roger S; Dakin, Steven C; Thibos, Larry N

    2012-04-15

    Previous studies of peripheral vision have shown that detection acuity is superior to resolution acuity for gratings over a range of contrasts, which is attributed to different limiting mechanisms (contrast insufficiency and neural undersampling) for the two tasks. To extend the analysis to letters in a way that avoided luminance cues, we used "vanishing optotype" characters, conveying second-order information, and constructed from tripole strokes having the same mean luminance as the surround. We measured the minimum letter size for detection and identification tasks for two different pairs of vanishing optotype characters (O vs. + and orthogonally oriented Landolt-C's) as a function of contrast in central and peripheral vision. Foveally there was no significant difference between detection acuity and resolution acuity for either pair of letters over a range of stimulus contrasts from 20% to 100%, indicating performance is contrast-limited for both tasks. The same result was obtained at 30° eccentricity in the peripheral field for the O vs. + letters, again indicating performance is contrast-limited for both tasks. However, resolution acuity for the Landolt-C letters was significantly worse than detection acuity in the periphery over the same range of contrasts, which suggests performance is limited by neural undersampling for these letters. All of our experimental results are explained by a model of neural sampling in which detection acuity is determined by the size of neural receptive fields relative to the dimensions of the tripole responsible for spatial contrast, whereas resolution acuity is determined by the spacing of receptive fields relative to the spacing between strokes responsible for letter form. PMID:22406660

  9. Colorful Chemistry.

    ERIC Educational Resources Information Center

    Williams, Suzanne

    1991-01-01

    Described is an color-making activity where students use food coloring, eyedroppers, and water to make various colored solutions. Included are the needed materials and procedures. Students are asked to write up the formulas for making their favorite color. (KR)

  10. Visual acuity testability and comparability in Australian preschool children: The Sydney Paediatric Eye Disease Study

    PubMed Central

    Leone, J F; Gole, G A; Mitchell, P; Kifley, A; Pai, A S-I; Rose, K A

    2012-01-01

    Purpose To establish standardised protocols for vision screening, testability and comparability of three different vision tests were examined in a population-based, cross-sectional sample of preschool children (Sydney Paediatric Eye Disease Study). Methods Measurement of presenting monocular distance visual acuity (VA) using the Amblyopia Treatment Study (ATS) HOTV protocol, was attempted by all (1774) children aged≥24 months. In addition, in children aged≥60 months (576), VA was also tested using the logMAR retro-illuminated HOTV or Early Treatment Diabetic Retinopathy Study (ETDRS) linear charts (CSV 1000). Children able to have both eyes tested monocularly were considered. Results Testability significantly increased with age for all VA tests. The ATS HOTV with an overall testability of 80% (females: 82%, males: 78%) was the most testable of the VA tests (P<0.0001). In children aged <3 years testability was low (≤47%) rising to≥80% in children aged≥3. In children≥60 months, testability was higher for the HOTV (94%) than the ETDRS (59%) chart. In those that did two VA tests, mean difference of the ATS HOTV compared with the HOTV(CSV) was −0.1, and compared with ETDRS was −0.12 (P<0.0001). Conclusions Children aged <3 years had poor VA testability, whereas those 3 years and above were highly testable using the ATS HOTV. The HOTV (CSV) retro-illuminated test was appropriate for children aged >5 years, and may be possible in younger children with early educational exposure. When comparing VA measures using these tests, the higher VA attained using the ATS HOTV, needs to be taken into account. PMID:22498798

  11. Dynamic visual acuity testing for screening patients with vestibular impairments

    PubMed Central

    Peters, Brian T.; Mulavara, Ajitkumar P.; Cohen, Helen S.; Sangi-Haghpeykar, Haleh; Bloomberg, Jacob J.

    2013-01-01

    Dynamic visual acuity (DVA) may be a useful indicator of the function of the vestibulo-ocular reflex (VOR) but most DVA tests involve active head motion in the yaw plane. During gait the passive, vertical VOR may be more relevant and passive testing would be less likely to elicit compensatory strategies. The goal of this study was to determine if testing dynamic visual acuity during passive vertical motion of the subject would differentiate normal subjects from patients with known vestibular disorders. Subjects, normals and patients who had been diagnosed with either unilateral vestibular weaknesses or were post-acoustic neuroma resections, sat in a chair that could oscillate vertically with the head either free or constrained with a cervical orthosis. They viewed a computer screen 2 m away that showed Landholt C optotypes in one of 8 spatial configurations and which ranged in size from 0.4 to 1.0 logMAR. They were tested while the chair was stationary and while it was moving. Scores were worse for both groups during the dynamic condition compared to the static condition. In the dynamic condition patients’ scores were significantly worse than normals’ scores. Younger and older age groups differed slightly but significantly; the sample size was too small to examine age differences by decade. The data suggest that many well-compensated patients have dynamic visual acuity that is as good as age-matched normals. Results of ROC analyses were only moderate, indicating that the differences between patients and normals were not strong enough, under the conditions tested, for this test to be useful for screening people to determine if they have vestibular disorders. Modifications of the test paradigm may make it more useful for screening potential patients. PMID:23000614

  12. Dynamic visual acuity testing for screening patients with vestibular impairments.

    PubMed

    Peters, Brian T; Mulavara, Ajitkumar P; Cohen, Helen S; Sangi-Haghpeykar, Haleh; Bloomberg, Jacob J

    2012-01-01

    Dynamic visual acuity (DVA) may be a useful indicator of the function of the vestibulo-ocular reflex (VOR) but most DVA tests involve active head motion in the yaw plane. During gait the passive, vertical VOR may be more relevant and passive testing would be less likely to elicit compensatory strategies. The goal of this study was to determine if testing dynamic visual acuity during passive vertical motion of the subject would differentiate normal subjects from patients with known vestibular disorders. Subjects, normals and patients who had been diagnosed with either unilateral vestibular weaknesses or were post-acoustic neuroma resections, sat in a chair that could oscillate vertically with the head either free or constrained with a cervical orthosis. They viewed a computer screen 2 m away that showed Landholt C optotypes in one of 8 spatial configurations and which ranged in size from 0.4 to 1.0 logMAR. They were tested while the chair was stationary and while it was moving. Scores were worse for both groups during the dynamic condition compared to the static condition. In the dynamic condition patients' scores were significantly worse than normals' scores. Younger and older age groups differed slightly but significantly; the sample size was too small to examine age differences by decade. The data suggest that many well-compensated patients have dynamic visual acuity that is as good as age-matched normals. Results of ROC analyses were only moderate, indicating that the differences between patients and normals were not strong enough, under the conditions tested, for this test to be useful for screening people to determine if they have vestibular disorders. Modifications of the test paradigm may make it more useful for screening potential patients. PMID:23000614

  13. Vision as a user interface

    NASA Astrophysics Data System (ADS)

    Koenderink, Jan

    2011-03-01

    The egg-rolling behavior of the graylag goose is an often quoted example of a fixed-action pattern. The bird will even attempt to roll a brick back to its nest! Despite excellent visual acuity it apparently takes a brick for an egg." Evolution optimizes utility, not veridicality. Yet textbooks take it for a fact that human vision evolved so as to approach veridical perception. How do humans manage to dodge the laws of evolution? I will show that they don't, but that human vision is an idiosyncratic user interface. By way of an example I consider the case of pictorial perception. Gleaning information from still images is an important human ability and is likely to remain so for the foreseeable future. I will discuss a number of instances of extreme non-veridicality and huge inter-observer variability. Despite their importance in applications (information dissemination, personnel selection,...) such huge effects have remained undocumented in the literature, although they can be traced to artistic conventions. The reason appears to be that conventional psychophysics-by design-fails to address the qualitative, that is the meaningful, aspects of visual awareness whereas this is the very target of the visual arts.

  14. The Recovery of Optical Quality after Laser Vision Correction

    PubMed Central

    Jung, Hyeong-Gi

    2013-01-01

    Purpose To evaluate the optical quality after laser in situ keratomileusis (LASIK) or serial photorefractive keratectomy (PRK) using a double-pass system and to follow the recovery of optical quality after laser vision correction. Methods This study measured the visual acuity, manifest refraction and optical quality before and one day, one week, one month, and three months after laser vision correction. Optical quality parameters including the modulation transfer function, Strehl ratio and intraocular scattering were evaluated with a double-pass system. Results This study included 51 eyes that underwent LASIK and 57 that underwent PRK. The optical quality three months post-surgery did not differ significantly between these laser vision correction techniques. Furthermore, the preoperative and postoperative optical quality did not differ significantly in either group. Optical quality recovered within one week after LASIK but took between one and three months to recover after PRK. The optical quality of patients in the PRK group seemed to recover slightly more slowly than their uncorrected distance visual acuity. Conclusions Optical quality recovers to the preoperative level after laser vision correction, so laser vision correction is efficacious for correcting myopia. The double-pass system is a useful tool for clinical assessment of optical quality. PMID:23908570

  15. Temporal perceptual coding using a visual acuity model

    NASA Astrophysics Data System (ADS)

    Adzic, Velibor; Cohen, Robert A.; Vetro, Anthony

    2014-02-01

    This paper describes research and results in which a visual acuity (VA) model of the human visual system (HVS) is used to reduce the bitrate of coded video sequences, by eliminating the need to signal transform coefficients when their corresponding frequencies will not be detected by the HVS. The VA model is integrated into the state of the art HEVC HM codec. Compared to the unmodified codec, up to 45% bitrate savings are achieved while maintaining the same subjective quality of the video sequences. Encoding times are reduced as well.

  16. Characteristics of Students Evaluated at a Residential School's Low Vision Clinics, 1981-1991.

    ERIC Educational Resources Information Center

    Wilkinson, M. E.; Stewart, I.

    1993-01-01

    Records of 360 students evaluated via outreach programs at the low vision clinics of the Iowa Braille and Sight Saving School over a 10-year period were analyzed concerning age, sex, ocular condition, best-corrected visual acuity at far and near, and recommended optical devices. (JDD)

  17. Ultrananocrystalline diamond-CMOS device integration route for high acuity retinal prostheses.

    PubMed

    Ahnood, A; Escudie, M C; Cicione, R; Abeyrathne, C D; Ganesan, K; Fox, K E; Garrett, D J; Stacey, A; Apollo, N V; Lichter, S G; Thomas, C D L; Tran, N; Meffin, H; Prawer, S

    2015-01-01

    High density electrodes are a new frontier for biomedical implants. Increasing the density and the number of electrodes used for the stimulation of retinal ganglion cells is one possible strategy for enhancing the quality of vision experienced by patients using retinal prostheses. The present work presents an integration strategy for a diamond based, high density, stimulating electrode array with a purpose built application specific integrated circuit (ASIC). The strategy is centered on flip-chip bonding of indium bumps to create high count and density vertical interconnects between the stimulator ASIC and an array of diamond neural stimulating electrodes. The use of polydimethylsiloxane (PDMS) housing prevents cross-contamination of the biocompatible diamond electrode with non-biocompatible materials, such as indium, used in the microfabrication process. Micro-imprint lithography allowed edge-to-edge micro-scale pattering of the indium bumps on non-coplanar substrates that have a form factor that can conform to body organs and thus are ideally suited for biomedical applications. Furthermore, micro-imprint lithography ensures the compatibility of lithography with the silicon ASIC and aluminum contact pads. Although this work focuses on 256 stimulating diamond electrode arrays with a pitch of 150 μm, the use of indium bump bonding technology and vertical interconnects facilitates implants with tens of thousands electrodes with a pitch as low as 10 μm, thus ensuring validity of the strategy for future high acuity retinal prostheses, and bionic implants in general. PMID:25877379

  18. Changes in Near Visual Acuity of Over Time in the Astronaut Corps

    NASA Technical Reports Server (NTRS)

    Taiym, Wafa; Wear, Mary L.; Locke, James; Mason, Sara; VanBaalen, Mary

    2014-01-01

    We hypothesized that visual impairment due to intracranial pressure (VIIP) would increase the rate of which presbyopia would occur in the astronaut population, with long durations flyers at an especially high risk. Presbyopia is characterized as the gradual loss of near visual acuity overtime due to a loss in ability to accommodate. It generally develops in the mid-40s and progresses until about age 65. This analysis considered annual vision exams conducted on active NASA astronauts with spaceflight experience currently between the ages of 40 to 60 years of age. Onset of presbyopia was characterized as a shift of at least 20 units on the standard Snellen test from one annual exam to the next. There were 236 short duration and 48 long duration flyers, the majority of whom did experience onset of presbyopia between age 40 and 60. This shift however, did not necessarily come after spaceflight. In comparing the short and long duration flyers the mean age of onset was 47 years old (SD+/-3.7). The mean of onset within the general population is 45 to 47 years old [1, 2]. The mean age of the onset of presbyopia as compared to the general population indicates that space flight does not induce early development of presbyopia.

  19. [On a binocular vision testing in concomitant strabismus].

    PubMed

    Seleznev, A V; Vakurin, E A; Kashchenko, T P

    2011-01-01

    Character of vision in 105 children with strabismus (with regular eye position) was tested using four dot test on different distance (5.0, 2.5, 1.0 m) and "Phorbis" device comprising phoropter and a set of light filters, that let us perform examination in the conditions of colour, polaroid and bitmapped division of visual fields. Stereoscopic vision was examined using original method based on anaglyph haploscopy. Binocular vision in strabismus was found to become more frequent as the distance and dissociating effect of light-filters decrease, and turned to be maximal in near testing in conditions of bitmapped haploscopy. Visual stereoscopic acuity in children with concomitant strabismus even on reaching regular eye position and binocular vision is significantly lower compared with healthy children of the same age. PMID:21800722

  20. The singular vision of William Charles Wells (1757-1817).

    PubMed

    Wade, Nicholas J; Ono, Hiroshi; Mapp, Alistair P; Lillakas, Linda

    2011-01-01

    William Charles Wells retained an interest in vision throughout his life. His first book was on single vision with two eyes; he integrated vision and eye movements to determine principles of visual direction. On the basis of experiments and observations he formulated three principles of visual direction, which can readily be demonstrated. In the course of these studies, he also examined visual acuity, accommodation and convergence, visual persistence, and visual vertigo. Insights into visual processing were mainly derived from observations of afterimages that were used to provide an index of how the eyes moved. His experiments enabled him to distinguish between the consequences of active and passive eye movements (later called outflow and inflow) as well as describing nystagmus following body rotation. After providing a brief account of Wells's life, his neglected research on vision is described and assessed. PMID:21253934

  1. The Effect of 3D Visual Simulator on Children’s Visual Acuity - A Pilot Study Comparing Two Different Modalities

    PubMed Central

    Ide, Takeshi; Ishikawa, Mariko; Tsubota, Kazuo; Miyao, Masaru

    2013-01-01

    Purpose : To evaluate the efficacy of two non-surgical interventions of vision improvement in children. Methods : A prospective, randomized, pilot study to compare fogging method and the use of head mounted 3D display. Subjects were children, between 5 to 15 years old, with normal best corrected visual acuity (BCVA) and up to -3D myopia. Subjects played a video game as near point work, and received one of the two methods of treatments. Measurements of uncorrected far visual acuity (UCVA), refraction with autorefractometer, and subjective accommodative amplitude were taken 3 times, at the baseline, after the near work, and after the treatment. Results : Both methods applied after near work, improved UCVA. Head mounted 3D display group showed significant improvement in UCVA and resulted in better UCVA than baseline. Fogging group showed improvement in subjective accommodative amplitude. While 3D display group did not show change in the refraction, fogging group’s myopic refraction showed significant increase indicating the eyes showed myopic change of eyes after near work and treatment. Discussion : Despite our lack of clear knowledge in the mechanisms, both methods improved UCVA after the treatments. The improvement in UCVA was not correlated to measured refraction values. Conclusion : UCVA after near work can be improved by repeating near and distant accommodation by fogging and 3D image viewing, although at the different degrees. Further investigation on mechanisms of improvements and their clinical significance are warranted. PMID:24222810

  2. Color as a language in architecture

    NASA Astrophysics Data System (ADS)

    Smedal, Grete

    2002-06-01

    This paper takes into consideration the role of color as a non-verbal language between human beings and the environment. The communication is based on the function of the color vision to separate and identify. A language about color can be based on the same. The concept behind the Natural Color System is color differentiation and color identification, which I find very useful both in color education of design students and in environmental color design work. A commission to plan the exterior use of color for a whole mining town on 78 degree(s) North in Longyearbyen, Spitsbergen, will illustrate my ideas. This will serve as an example of how these different 'languages' can work together. After a twenty years ongoing process this work is now almost fulfilled and the result will be shown in the presentation.

  3. One-stage model for color conversion.

    NASA Technical Reports Server (NTRS)

    Richards, W.

    1972-01-01

    Description of a one-stage approximation to the color-conversion model of Richards and Parks (1971). The modified model proposes three channels for color vision, each with different center-surround sensitivities. In its strongest form, the model predicts that the gain-setting control that alters the sensitivities of each channel is solely a function of achromatic contrast.

  4. Restoration of pretrabeculectomy visual acuity and a functioning filtering bleb in an eye with delayed suprachoroidal haemorrhage following trabeculectomy.

    PubMed

    Senthil, Sirisha; Gupta, Supriya; Balijepalli, Pasyanthi

    2015-01-01

    A 35-year-old myopic man with juvenile open angle glaucoma was referred to us with fluctuating intraocular pressure (IOP) and progression in his only seeing left eye. He had systemic features suggestive of Marfan's syndrome. He underwent trabeculectomy with low dose mitomycin-C with operative precautions to prevent postoperative hypotony in view of high myopia and scleral thinning. On the second postoperative day, he had severe pain in his left eye, with vomiting, and presented with decreased vision, high IOP and a flat anterior chamber. Ultrasound B scan revealed 360° haemorrhagic choroidal detachment. He was conservatively managed and monitored over the next 1 month with appropriate medical treatment. He not only recovered his pretrabeculectomy visual acuity but also had a well functioning bleb at the end of 2 months. PMID:26661281

  5. Functional Visual Acuity in Age-Related Macular Degeneration

    PubMed Central

    Tomita, Yohei; Nagai, Norihiro; Suzuki, Misa; Shinoda, Hajime; Uchida, Atsuro; Mochimaru, Hiroshi; Izumi-Nagai, Kanako; Sasaki, Mariko; Tsubota, Kazuo; Ozawa, Yoko

    2016-01-01

    ABSTRACT Purpose We evaluated whether a functional visual acuity (FVA) system can detect subtle changes in central visual acuity that reflect pathological findings associated with age-related macular degeneration (AMD). Methods Twenty-eight patients with unilateral AMD and logMAR monocular best corrected VA better than 0 in both eyes, as measured by conventional chart examination, were analyzed between November 2012 and April 2013. After measuring conventional VA, FVA, and contrast VA with best correction, routine eye examinations including spectral domain–optical coherence tomography were performed. Standard Schirmer test was performed, and corneal and lens densities were measured. Results The FVA score (p < 0.001) and visual maintenance ratio (p < 0.001) measured by the FVA system, contrast VA (p < 0. 01), and conventional VA (p < 0.01) were significantly worse in the AMD-affected eyes than in the fellow eyes. No significant differences were observed in the anterior segment conditions. Forward stepwise regression analysis demonstrated that the length of interdigitation zone disruption, as visualized by optical coherence tomography imaging, correlated with the FVA score (p < 0.01) but not with any other parameters investigated. Conclusions The FVA system detects subtle changes in best corrected VA in AMD-affected eyes and reflects interdigitation zone disruption, an anatomical change in the retina recorded by optical coherence tomography. Further studies are required to understand the value of the FVA system in detecting subtle changes in AMD. PMID:26583795

  6. Influences of multiple memory systems on auditory mental image acuity.

    PubMed

    Navarro Cebrian, Ana; Janata, Petr

    2010-05-01

    The influence of different memory systems and associated attentional processes on the acuity of auditory images, formed for the purpose of making intonation judgments, was examined across three experiments using three different task types (cued-attention, imagery, and two-tone discrimination). In experiment 1 the influence of implicit long-term memory for musical scale structure was manipulated by varying the scale degree (leading tone versus tonic) of the probe note about which a judgment had to be made. In experiments 2 and 3 the ability of short-term absolute pitch knowledge to develop was manipulated by presenting blocks of trials in the same key or in seven different keys. The acuity of auditory images depended on all of these manipulations. Within individual listeners, thresholds in the two-tone discrimination and cued-attention conditions were closely related. In many listeners, cued-attention thresholds were similar to thresholds in the imagery condition, and depended on the amount of training individual listeners had in playing a musical instrument. The results indicate that mental images formed at a sensory/cognitive interface for the purpose of making perceptual decisions are highly malleable. PMID:21117767

  7. Evaluation of vernier acuity near healed retinal laser lesions

    NASA Astrophysics Data System (ADS)

    Schmeisser, Elmar T.

    1997-05-01

    Seven Cynomolgus fasciculata who had graded laser lesions placed in own eye 6 years previously were evaluated for their vernier acuity by electrophysiologic recording techniques. In these experiments, 95 percent contrast vernier acuity targets were presented at high luminance levels to anesthetized primates. Visual evoked potentials were recorded by conventional means form scalp electrodes through hospital grade amplifiers. All animal testing was performed under IACUC approved protocols. The single q-switched pulses form a neodymium-YAG laser had produced lesions of 4 types: no visible change, minimal visible lesions, 'white dot' lesions and 'red dot' lesions in the eye at the time of placement. Single exposures had been made in four locations: 5 degrees superior, inferior and temporal to the fovea, and one foveally. Vernier recording proved somewhat successful in smaller animals with less than contained retinal hemorrhage lesions in the fovea. Initial analyses demonstrated a significant decrease of the pattern response signal/noise in the experimental eye overall, and an apparent relative loss of vernier signal in some lesioned eyes. Animals with the more severe lesions have somewhat degraded small patten responses and no recordable vernier response. Apparent lesser losses produced less effect.

  8. Changes in brain morphology in albinism reflect reduced visual acuity.

    PubMed

    Bridge, Holly; von dem Hagen, Elisabeth A H; Davies, George; Chambers, Claire; Gouws, Andre; Hoffmann, Michael; Morland, Antony B

    2014-07-01

    Albinism, in humans and many animal species, has a major impact on the visual system, leading to reduced acuity, lack of binocular function and nystagmus. In addition to the lack of a foveal pit, there is a disruption to the routing of the nerve fibers crossing at the optic chiasm, resulting in excessive crossing of fibers to the contralateral hemisphere. However, very little is known about the effect of this misrouting on the structure of the post-chiasmatic visual pathway, and the occipital lobes in particular. Whole-brain analyses of cortical thickness in a large cohort of subjects with albinism showed an increase in cortical thickness, relative to control subjects, particularly in posterior V1, corresponding to the foveal representation. Furthermore, mean cortical thickness across entire V1 was significantly greater in these subjects compared to controls and negatively correlated with visual acuity in albinism. Additionally, the group with albinism showed decreased gyrification in the left ventral occipital lobe. While the increase in cortical thickness in V1, also found in congenitally blind subjects, has been interpreted to reflect a lack of pruning, the decreased gyrification in the ventral extrastriate cortex may reflect the reduced input to the foveal regions of the ventral visual stream. PMID:23039995

  9. Knowledge-based interpretation of outdoor natural color scenes

    SciTech Connect

    Ohta, Y.

    1985-01-01

    One of the major targets in vision research is to develop a total vision system starting from images to a symbolic description, utilizing various knowledge sources. This book demonstrates a knowledge-based image interpretation system that analyzes natural color scenes. Topics covered include color information for region segmentation, preliminary segmentation of color images, and a bottom-up and top-down region analyzer.

  10. Principles of modern low vision rehabilitation.

    PubMed

    Markowitz, Samuel N

    2006-06-01

    Low vision rehabilitation is a new emerging subspecialty drawing from the traditional fields of ophthalmology, optometry, occupational therapy, and sociology, with an ever-increasing impact on our customary concepts of research, education, and services for the visually impaired patient. A multidisciplinary approach and coordinated effort are necessary to take advantage of new scientific advances and achieve optimal results for the patient. Accordingly, the intent of this paper is to outline the principles and details of a modern low vision rehabilitation service. All rehabilitation attempts must start with a first hand interview (the intake) for assessing functionality and priority tasks for rehabilitation, as well as assessing the patient's all-important cognitive skills. The assessment of residual visual functions follows the intake and offers a unique opportunity to measure, evaluate, and document accurately the extent of functional loss sustained by the patient from disease. An accurate assessment of residual visual functions includes assessment of visual acuity, contrast sensitivity, binocularity, refractive errors, perimetry, oculomotor functions, cortical visual integration, and light characteristics affecting visual functions. Functional vision assessment in low vision rehabilitation measures how well one uses residual visual functions to perform routine tasks, using different items under various conditions, throughout the day. Of the many functional vision skills known, reading skills is an obligatory item for all low vision rehabilitation assessments. Results of assessment guide rehabilitation professionals in developing rehabilitation plans for the individual and recommending appropriate low vision devices. The outcome from assessing residual visual functions is detection of visual functions that can be improved with the use of optical devices. Methods for prescribing devices such as image relocation with prisms to a preferred retinal locus, field

  11. Smartphone-Based Visual Acuity Measurement for Screening and Clinical Assessment

    PubMed Central

    Brady, Christopher J.; Eghrari, Allen O.; Labrique, Alain B.

    2016-01-01

    IMPORTANCE Visual acuity is the most frequently performed measure of visual function in clinical practice and most people worldwide living with visual impairment are living in low- and middle-income countries. OBJECTIVE To design and validate a smartphone-based visual acuity test that is not dependent on familiarity with symbols or letters commonly used in the English language. DESIGN, SETTING, AND PARTICIPANTS Validation study conducted from December 11, 2013, to March 4, 2014, comparing results from smartphone-based Peek Acuity to Snellen acuity (clinical normal) charts and the Early Treatment Diabetic Retinopathy Study (ETDRS) logMAR chart (reference standard). This study was nested within the 6-year follow-up of the Nakuru Eye Disease Cohort in central Kenya and included 300 adults aged 55 years and older recruited consecutively. MAIN OUTCOMES AND MEASURES Outcome measures were monocular logMAR visual acuity scores for each test: ETDRS chart logMAR, Snellen acuity, and Peek Acuity. Peek Acuity was compared, in terms of test-retest variability and measurement time, with the Snellen acuity and ETDRS logMAR charts in participants’ homes and temporary clinic settings in rural Kenya in 2013 and 2014. RESULTS The 95%CI limits for test-retest variability of smartphone acuity data were ±0.029 logMAR. The mean differences between the smartphone-based test and the ETDRS chart and the smartphone-based test and Snellen acuity data were 0.07 (95%CI, 0.05–0.09) and 0.08 (95%CI, 0.06–0.10) logMAR, respectively, indicating that smartphone-based test acuities agreed well with those of the ETDRS and Snellen charts. The agreement of Peek Acuity and the ETDRS chart was greater than the Snellen chart with the ETDRS chart (95%CI, 0.05–0.10; P = .08). The local Kenyan community health care workers readily accepted the Peek Acuity smartphone test; it required minimal training and took no longer than the Snellen test (77 seconds vs 82 seconds; 95%CI, 71–84 seconds vs 73–91

  12. Pediatric Low Vision

    MedlinePlus

    ... Asked Questions Español Condiciones Chinese Conditions Pediatric Low Vision What is Low Vision? Partial vision loss that cannot be corrected causes ... and play. What are the signs of Low Vision? Some signs of low vision include difficulty recognizing ...

  13. Vision Therapy News Backgrounder.

    ERIC Educational Resources Information Center

    American Optometric Association, St. Louis, MO.

    The booklet provides an overview on vision therapy to aid writers, editors, and broadcasters help parents, teachers, older adults, and all consumers learn more about vision therapy. Following a description of vision therapy or vision training, information is provided on how and why vision therapy works. Additional sections address providers of…

  14. Visual acuity in an opportunistic raptor, the chimango caracara (Milvago chimango).

    PubMed

    Potier, Simon; Bonadonna, Francesco; Kelber, Almut; Duriez, Olivier

    2016-04-01

    Raptors are always considered to have an extraordinary resolving power of their eyes (high visual acuity). Nevertheless, raptors differ in their diet and foraging tactics, which could lead to large differences in visual acuity. The visual acuity of an opportunist bird of prey, the Chimango caracara (Mivalgo chimango) was estimated by operant conditioning. Three birds were trained to discriminate two stimuli, a positive grey uniform pattern and a negative grating pattern stimulus. The visual acuity range from 15.08 to 39.83cycles/degrees. When compared to other birds, they have a higher visual acuity than non-raptorial birds, but they have the lowest visual acuity found in bird of prey so far. We discuss this result in the context of the ecology of the bird, with special focus on it is foraging tactic. PMID:26821187

  15. Uncalibrated color

    NASA Astrophysics Data System (ADS)

    Moroney, Nathan

    2006-01-01

    Color calibration or the use of color measurement processes to characterize the color properties of a device or workflow is often expected or assumed for many color reproduction applications. However it is interesting to consider applications or situations in which color calibration is not as critical. In the first case it is possible to imagine an implicit color calibration resulting from a standardization or convergence of the colorant and substrate spectrum. In the second case it is possible to imagine cases where the device color variability is significantly less than the user color thresholds or expectations for color consistency. There are still general requirements for this form of pragmatic color but they are generally lower than for the higher end of digital color reproduction. Finally it is possible to imagine an implicit calibration that leverages in some way the highly accurate memory color for the hue of common objects. This scenario culminates with a challenge to create a natural capture calibration standard that does not require individual calibration, is spectrally diverse, is inexpensive and is environmentally friendly.

  16. Flashing anomalous color contrast.

    PubMed

    Pinna, Baingio; Spillmann, Lothar; Werner, John S

    2004-01-01

    A new visual phenomenon that we call flashing anomalous color contrast is described. This phenomenon arises from the interaction between a gray central disk and a chromatic annulus surrounded by black radial lines. In an array of such figures, the central gray disk no longer appears gray, but assumes a color complementary to that of the surrounding annulus. The induced color appears: (1) vivid and saturated; (2) self-luminous, not a surface property; (3) flashing with eye or stimulus movement; (4) floating out of its confines; and (5) stronger in extrafoveal than in foveal vision. The strength of the effect depends on the number, length, width, and luminance contrast of the radial lines. The results suggest that the chromatic ring bounding the inner tips of the black radial lines induces simultaneous color contrast, whereas the radial lines elicit, in conjunction with the gray disk and the ring, the flashing, vividness, and high saturation of the effect. The stimulus properties inducing the illusion suggest that flashing anomalous color contrast may be based on asynchronous interactions among multiple visual pathways. PMID:15518215

  17. Color realism and color science.

    PubMed

    Byrne, Alex; Hilbert, David R

    2003-02-01

    The target article is an attempt to make some progress on the problem of color realism. Are objects colored? And what is the nature of the color properties? We defend the view that physical objects (for instance, tomatoes, radishes, and rubies) are colored, and that colors are physical properties, specifically, types of reflectance. This is probably a minority opinion, at least among color scientists. Textbooks frequently claim that physical objects are not colored, and that the colors are "subjective" or "in the mind." The article has two other purposes: First, to introduce an interdisciplinary audience to some distinctively philosophical tools that are useful in tackling the problem of color realism and, second, to clarify the various positions and central arguments in the debate. The first part explains the problem of color realism and makes some useful distinctions. These distinctions are then used to expose various confusions that often prevent people from seeing that the issues are genuine and difficult, and that the problem of color realism ought to be of interest to anyone working in the field of color science. The second part explains the various leading answers to the problem of color realism, and (briefly) argues that all views other than our own have serious difficulties or are unmotivated. The third part explains and motivates our own view, that colors are types of reflectances and defends it against objections made in the recent literature that are often taken as fatal. PMID:14598439

  18. Associations of Anisometropia with Unilateral Amblyopia, Interocular Acuity Difference and Stereoacuity in Preschoolers

    PubMed Central

    Ying, Gui-shuang; Huang, Jiayan; Maguire, Maureen; Quinn, Graham; Kulp, Marjean Taylor; Ciner, Elise; Cyert, Lynn; Orel-Bixler, Deborah

    2012-01-01

    Purpose To evaluate the relation of anisometropia with unilateral amblyopia, interocular acuity difference (IAD) and stereoacuity, among Head Start preschoolers, using both clinical notation and vector notation analyses. Design Multicenter, cross-sectional study. Participants 3- to 5-year-old participants in the Vision In Preschoolers (VIP) Study (N=4040). Methods Secondary analysis of VIP data from participants who had comprehensive eye examinations including monocular visual acuity (VA) testing, stereoacuity testing, and cycloplegic refraction. VA was retested with full cycloplegic correction when retest criteria were met. Unilateral amblyopia was defined as IAD ≥2 lines in logarithm of the Minimum Angle of Resolution (logMAR). Anisometropia was defined as ≥0.25 D (diopter) difference in spherical equivalent (SE) or in cylinder power, and also two approaches using power vector notation. The percentage with unilateral amblyopia, mean IAD, and mean stereoacuity were compared between anisometropic and isometropic children. Main Outcomes Measures The percentage with unilateral amblyopia, mean IAD, and mean stereoacuity. Results Compared with isometropic children, anisometropic children had a higher percentage of unilateral amblyopia (8% vs. 2%), larger mean IAD (0.07 vs. 0.05 logMAR) and worse mean stereoacuity (145 vs.117 arc sec) (all p<0.0001). Larger amounts of anisometropia were associated with higher percentages of unilateral amblyopia, larger IAD, and worse stereoacuity (trend p<0.001). Percentage of unilateral amblyopia was significantly increased with spherical equivalent (SE) anisometropia >0.5 D, cylindrical anisometropia >0.25 D, the vertical/horizontal meridian (J0) or oblique meridian (J45) >0.125 D, or vector dioptric distance (VDD) >0.35 D (all p<0.001). VDD had higher ability in detecting unilateral amblyopia than cylinder, SE, J0 and J45 (p<0.001). Conclusions The presence of and amount of anisometropia were associated with the presence of

  19. The Relationship between OCT-measured Central Retinal Thickness and Visual Acuity in Diabetic Macular Edema

    PubMed Central

    2008-01-01

    Objective To compare optical coherence tomography (OCT)-measured retinal thickness and visual acuity in eyes with diabetic macular edema (DME) both before and after macular laser photocoagulation. Design Cross-sectional and longitudinal study. Participants 210 subjects (251 eyes) with DME enrolled in a randomized clinical trial of laser techniques. Methods Retinal thickness was measured with OCT and visual acuity was measured with the electronic-ETDRS procedure. Main Outcome Measures OCT-measured center point thickness and visual acuity Results The correlation coefficients for visual acuity versus OCT center point thickness were 0.52 at baseline and 0.49, 0.36, and 0.38 at 3.5, 8, and 12 months post-laser photocoagulation. The slope of the best fit line to the baseline data was approximately 4.4 letters (95% C.I.: 3.5, 5.3) better visual acuity for every 100 microns decrease in center point thickness at baseline with no important difference at follow-up visits. Approximately one-third of the variation in visual acuity could be predicted by a linear regression model that incorporated OCT center point thickness, age, hemoglobin A1C, and severity of fluorescein leakage in the center and inner subfields. The correlation between change in visual acuity and change in OCT center point thickening 3.5 months after laser treatment was 0.44 with no important difference at the other follow-up times. A subset of eyes showed paradoxical improvements in visual acuity with increased center point thickening (7–17% at the three time points) or paradoxical worsening of visual acuity with a decrease in center point thickening (18%–26% at the three time points). Conclusions There is modest correlation between OCT-measured center point thickness and visual acuity, and modest correlation of changes in retinal thickening and visual acuity following focal laser treatment for DME. However, a wide range of visual acuity may be observed for a given degree of retinal edema and paradoxical

  20. Impairments to Vision

    MedlinePlus

    ... an external Non-Government web site. Impairments to Vision Normal Vision Diabetic Retinopathy Age-related Macular Degeneration In this ... pictures, fixate on the nose to simulate the vision loss. In diabetic retinopathy, the blood vessels in ...

  1. Retinal Detachment Vision Simulator

    MedlinePlus

    ... Retina Treatment Retinal Detachment Vision Simulator Retinal Detachment Vision Simulator Mar. 01, 2016 How does a detached or torn retina affect your vision? If a retinal tear is occurring, you may ...

  2. Binocular Vision

    PubMed Central

    Blake, Randolph; Wilson, Hugh

    2010-01-01

    This essay reviews major developments –empirical and theoretical –in the field of binocular vision during the last 25 years. We limit our survey primarily to work on human stereopsis, binocular rivalry and binocular contrast summation, with discussion where relevant of single-unit neurophysiology and human brain imaging. We identify several key controversies that have stimulated important work on these problems. In the case of stereopsis those controversies include position versus phase encoding of disparity, dependence of disparity limits on spatial scale, role of occlusion in binocular depth and surface perception, and motion in 3D. In the case of binocular rivalry, controversies include eye versus stimulus rivalry, role of “top-down” influences on rivalry dynamics, and the interaction of binocular rivalry and stereopsis. Concerning binocular contrast summation, the essay focuses on two representative models that highlight the evolving complexity in this field of study. PMID:20951722

  3. Vision Screening

    NASA Technical Reports Server (NTRS)

    1993-01-01

    The Visi Screen OSS-C, marketed by Vision Research Corporation, incorporates image processing technology originally developed by Marshall Space Flight Center. Its advantage in eye screening is speed. Because it requires no response from a subject, it can be used to detect eye problems in very young children. An electronic flash from a 35 millimeter camera sends light into a child's eyes, which is reflected back to the camera lens. The photorefractor then analyzes the retinal reflexes generated and produces an image of the child's eyes, which enables a trained observer to identify any defects. The device is used by pediatricians, day care centers and civic organizations that concentrate on children with special needs.

  4. Robot Vision

    NASA Technical Reports Server (NTRS)

    Sutro, L. L.; Lerman, J. B.

    1973-01-01

    The operation of a system is described that is built both to model the vision of primate animals, including man, and serve as a pre-prototype of possible object recognition system. It was employed in a series of experiments to determine the practicability of matching left and right images of a scene to determine the range and form of objects. The experiments started with computer generated random-dot stereograms as inputs and progressed through random square stereograms to a real scene. The major problems were the elimination of spurious matches, between the left and right views, and the interpretation of ambiguous regions, on the left side of an object that can be viewed only by the left camera, and on the right side of an object that can be viewed only by the right camera.

  5. Bandwidth of the contrast sensitivity function as an index of spatial vision with application to refraction.

    PubMed

    Jiang, B C; Scialfa, C T; Tyrrell, R A; Garvey, P M; Leibowitz, H W

    1990-04-01

    The contrast sensitivity function (CSF), although containing more information than traditional measures of acuity, has found difficulty gaining clinical acceptance. The hesitancy of clinicians to adopt the CSF stems, in part, from the fact that it is not as readily interpreted as is acuity. In order to facilitate such interpretation, five indices of spatial vision which are derivable from the CSF were examined in a sample of 287 persons aged 5 to 85 years. All indices were found to be both age-sensitive and strongly related to each other, but bandwidth of the CSF was chosen as a practical index for clinical settings. In a second study, acuity and CSF bandwidth were measured under 0 to +/- 1 D optical blur. It was found that the correction providing best acuity also maximized CSF bandwidth, and that bandwidth was more sensitive to optical blur than was acuity. Results support the assertion that CSF bandwidth is a readily interpreted index of spatial vision that can be measured efficiently within the context of clinical refraction. PMID:2342788

  6. Low Vision Aids and Low Vision Rehabilitation

    MedlinePlus

    ... The future will offer even more solutions. Newer technology for low vision aids While low vision devices ... magnifiers have long been the standard in assistive technology, advances in consumer electronics are also improving quality ...

  7. Vision function testing for a suprachoroidal retinal prosthesis: effects of image filtering

    NASA Astrophysics Data System (ADS)

    Barnes, Nick; Scott, Adele F.; Lieby, Paulette; Petoe, Matthew A.; McCarthy, Chris; Stacey, Ashley; Ayton, Lauren N.; Sinclair, Nicholas C.; Shivdasani, Mohit N.; Lovell, Nigel H.; McDermott, Hugh J.; Walker, Janine G.; BVA Consortium, for the

    2016-06-01

    Objective. One strategy to improve the effectiveness of prosthetic vision devices is to process incoming images to ensure that key information can be perceived by the user. This paper presents the first comprehensive results of vision function testing for a suprachoroidal retinal prosthetic device utilizing of 20 stimulating electrodes. Further, we investigate whether using image filtering can improve results on a light localization task for implanted participants compared to minimal vision processing. No controlled implanted participant studies have yet investigated whether vision processing methods that are not task-specific can lead to improved results. Approach. Three participants with profound vision loss from retinitis pigmentosa were implanted with a suprachoroidal retinal prosthesis. All three completed multiple trials of a light localization test, and one participant completed multiple trials of acuity tests. The visual representations used were: Lanczos2 (a high quality Nyquist bandlimited downsampling filter); minimal vision processing (MVP); wide view regional averaging filtering (WV); scrambled; and, system off. Main results. Using Lanczos2, all three participants successfully completed a light localization task and obtained a significantly higher percentage of correct responses than using MVP (p≤slant 0.025) or with system off (p\\lt 0.0001). Further, in a preliminary result using Lanczos2, one participant successfully completed grating acuity and Landolt C tasks, and showed significantly better performance (p=0.004) compared to WV, scrambled and system off on the grating acuity task. Significance. Participants successfully completed vision tasks using a 20 electrode suprachoroidal retinal prosthesis. Vision processing with a Nyquist bandlimited image filter has shown an advantage for a light localization task. This result suggests that this and targeted, more advanced vision processing schemes may become important components of retinal prostheses

  8. Seeing Color

    ERIC Educational Resources Information Center

    Texley, Juliana

    2005-01-01

    Colors are powerful tools for engaging children, from the youngest years onward. We hang brightly patterned mobiles above their cribs and help them learn the names of colors as they begin to record their own ideas in pictures and words. Colors can also open the door to an invisible world of electromagnetism, even when children can barely imagine…

  9. Predicting visual acuity from the structure of visual cortex

    PubMed Central

    Srinivasan, Shyam; Carlo, C. Nikoosh; Stevens, Charles F.

    2015-01-01

    Three decades ago, Rockel et al. proposed that neuronal surface densities (number of neurons under a square millimeter of surface) of primary visual cortices (V1s) in primates is 2.5 times higher than the neuronal density of V1s in nonprimates or many other cortical regions in primates and nonprimates. This claim has remained controversial and much debated. We replicated the study of Rockel et al. with attention to modern stereological precepts and show that indeed primate V1 is 2.5 times denser (number of neurons per square millimeter) than many other cortical regions and nonprimate V1s; we also show that V2 is 1.7 times as dense. As primate V1s are denser, they have more neurons and thus more pinwheels than similar-sized nonprimate V1s, which explains why primates have better visual acuity. PMID:26056277

  10. Collective enhancement of numerical acuity by meritocratic leadership in fish.

    PubMed

    Bisazza, Angelo; Butterworth, Brian; Piffer, Laura; Bahrami, Bahador; Miletto Petrazzini, Maria Elena; Agrillo, Christian

    2014-01-01

    It has been known for more than a century that interacting people can generally achieve more accurate decisions than single individuals. Here we show that interacting guppy fish (Poecilia reticulata) achieve a superior level of numerosity discrimination well beyond the average ability of the isolated individual fish. This enhancement of numerical acuity was observed in dyadic interactions when (Experiment 1) the dyad chose which larger shoal of guppies to join and when (Experiment 2) the dyad chose the higher or the lower numerosity among two decision options after having learned the task individually. Dyadic accuracy and that of the more competent member of each dyad matched closely, supporting the hypothesis that meritocratic leadership arises spontaneously between dyadically interacting fish, rather than the 'many wrongs' principle that has been used to explain group superiority in many species. PMID:24691116

  11. Sensitivity of The Dynamic Visual Acuity Test To Sensorimotor Change

    NASA Technical Reports Server (NTRS)

    Cohen, Helen; Bloomberg, Jacob; Elizalde, Elizabeth; Fregia, Melody

    1999-01-01

    Post-flight astronauts, acutely post-vestibular nerve section patients, and patients with severe chronic bilateral vestibular deficits have oscillopsia caused by reduced vestibulocular reflex gains and decreased postural stability. Therefore, as previous work has shown, a test of dynamic visual acuity (DVA), in which the subject must read numbers from a computer screen while standing still or walking in place provides a composite measure of sensorimotor integration. This measure may be useful for determining the level of recovery, post-flight, post-operatively, or after vestibular rehabilitation. To determine the sensitivity of DVA to change in impaired populations we have tested patients with acoustic neuromas before and during the first post-operative week after resection of the tumors, and with bilaterally labyrinthine deficient subjects before and after six weeks of balance rehabilitation therapy.

  12. NVG adjustment methods, eyepiece focus settings, and vision

    NASA Astrophysics Data System (ADS)

    Van Arsdel, Richard; Baldwin, J. Bruce; Hausmann, Martha A.; Harrington, Lawrence K.; Craig, Jeffrey L.; Koepke, Corbin G.

    2006-05-01

    Several studies and many anecdotal reports indicate that aircrew members focus night vision goggle (NVG) eyepiece lenses to more negative powers than would be expected based on refractive error, presumably due to instrument myopia, "dark focus" myopia, and other factors. Excessive negative power stimulates accommodation, introducing risks from discomfort, fatigue, and blurred vision. Aircrew members are trained to employ specific adjustment techniques to minimize "over-minusing" of eyepiece lens powers, but those techniques are prone to error. The currently fielded AN/AVS-9 NVG (F4949) has a focus range of (+2.0) to (-6.0) diopters, and meets the needs of most aircrew. However, the new AN/AVS-10 NVG panoramic night vision goggle (PNVG) has a fixed focus of (-1.0) diopters due to engineering design constraints. Accessory snap-on lenses are available, but data are needed to optimize the distribution of lens powers to be acquired and maintained. This study involved the characterization of vision (visual acuity, perceived quality, and comfort) as a function of: 1) eyepiece focus setting using trial lenses; 2) F4949 eyepiece focus adjustments using a point source vs. a Hoffman 20/20 box; and 3) PNVG eyepiece lens selections using a lens bar vs. snap-on lens selections. Eight subjects with normal (20/20 corrected) vision ranging in age from 23 years to 49 participated in this study. The experiments were conducted in the Aerospace Vision Experimental Laboratory and the Dynamic Vision Assessment Facility at Wright Patterson AFB, Ohio using F4949 and PNVG devices with a custom-designed NVG-compatible computer-based visual acuity acquisition system.

  13. Acute unilateral vision loss with optic disc oedema in retinitis pigmentosa.

    PubMed

    Patil-Chhablani, Preeti; Tyagi, Mudit; Kekunnaya, Ramesh; Narayanan, Raja

    2015-01-01

    A 36-year-old woman presented with acute vision loss and was found to have disc oedema and retinitis pigmentosa (RP). She presented with a history of acute, painless vision loss in her left eye over a period of 10 days. Her best-corrected visual acuity was 20/50, N6 in the right eye (OD) and 20/160, N6 in the left eye (OS). She was found to have a swollen optic disc and the examination of her fundus showed changes suggestive of RP. The diagnosis of RP was confirmed by electroretinogram, and after ruling out demyelinating changes in the central nervous system and other possible infectious causes of papillitis, she was treated with intravenous steroids followed by a course of oral steroid therapy. Following treatment, her visual acuity improved to 20/60. Acute vision loss may occur in patients with RP and prompt steroid therapy may result in partial visual recovery. PMID:26240107

  14. A versatile optoelectronic aid for low vision patients.

    PubMed

    Peláez-Coca, María Dolores; Vargas-Martín, Fernando; Mota, Sonia; Díaz, Javier; Ros-Vidal, Eduardo

    2009-09-01

    The purpose of this work is to describe a versatile optoelectronic aid for low vision rehabilitation based on reconfigurable hardware. This aid is easily adaptable to diverse pathologies (with different associated processing tasks) and to the progression of the visual impairment. This platform has a mobile configuration that uses a see-through head-mounted display (Nomad). We have implemented different types of vision enhancement on this versatile platform, and briefly summarize here their computational costs (in terms of hardware resource requirements). We have evaluated two representative capabilities of this aid (Augmented View and digital zoom) with measurements of visual acuity, contrast sensitivity and visual field. We have tested the Nomad head-mounted display and the Augmented View modality, in eight subjects with retinitis pigmentosa: the digital zoom was tested in six low vision subjects and nine normally-sighted subjects. We show that the Nomad display with Augmented View configuration does not impair the residual vision; and that there is an increase in visual acuity (VA) with the digital zoom configuration. The major advantage of this platform is that it can easily embed different image processing tasks and since it is based on a FPGA device, it can be specifically configured to tasks requiring real-time processing. PMID:19689551

  15. Quantifying nonhomogeneous colors in agricultural materials part I: method development.

    PubMed

    Balaban, M O

    2008-11-01

    Measuring the color of food and agricultural materials using machine vision (MV) has advantages not available by other measurement methods such as subjective tests or use of color meters. The perception of consumers may be affected by the nonuniformity of colors. For relatively uniform colors, average color values similar to those given by color meters can be obtained by MV. For nonuniform colors, various image analysis methods (color blocks, contours, and "color change index"[CCI]) can be applied to images obtained by MV. The degree of nonuniformity can be quantified, depending on the level of detail desired. In this article, the development of the CCI concept is presented. For images with a wide range of hue values, the color blocks method quantifies well the nonhomogeneity of colors. For images with a narrow hue range, the CCI method is a better indicator of color nonhomogeneity. PMID:19021817

  16. Evidence Based Medicine in Space Flight: Evaluation of Inflight Vision Data for Operational Decision-Making

    NASA Technical Reports Server (NTRS)

    Van Baalen, Mary; Mason, Sara; Foy, Millennia; Wear, Mary; Taiym, Wafa; Moynihan, Shannan; Alexander, David; Hart, Steve; Tarver, William

    2015-01-01

    Due to recently identified vision changes associated with space flight, JSC Space and Clinical Operations (SCO) implemented broad mission-related vision testing starting in 2009. Optical Coherence Tomography (OCT), 3 Tesla Brain and Orbit MRIs, Optical Biometry were implemented terrestrially for clinical monitoring. While no inflight vision testing was in place, already available onorbit technology was leveraged to facilitate in-flight clinical monitoring, including visual acuity, Amsler grid, tonometry, and ultrasonography. In 2013, on-orbit testing capabilities were expanded to include contrast sensitivity testing and OCT. As these additional testing capabilities have been added, resource prioritization, particularly crew time, is under evaluation.

  17. Color Categories and Color Appearance

    ERIC Educational Resources Information Center

    Webster, Michael A.; Kay, Paul

    2012-01-01

    We examined categorical effects in color appearance in two tasks, which in part differed in the extent to which color naming was explicitly required for the response. In one, we measured the effects of color differences on perceptual grouping for hues that spanned the blue-green boundary, to test whether chromatic differences across the boundary…

  18. Color Terms and Color Concepts

    ERIC Educational Resources Information Center

    Davidoff, Jules

    2006-01-01

    In their lead articles, both Kowalski and Zimiles (2006) and O'Hanlon and Roberson (2006) declare a general relation between color term knowledge and the ability to conceptually represent color. Kowalski and Zimiles, in particular, argue for a priority for the conceptual representation in color term acquisition. The complexities of the interaction…

  19. Vitrectomy combined with silicone oil tamponade in the treatment of severely traumatized eyes with the visual acuity of no light perception

    PubMed Central

    Yang, Shan-Shan; Jiang, Tao

    2013-01-01

    AIM To evaluate the efficacy of surgical treatment of vitrectomy combined with silicone oil tamponade in the treatment of severely traumatized eyes with the visual acuity of no light perception (NLP). METHODS This was a retrospective uncontrolled interventional case-series of 19 patients of severely traumatized eyes with NLP who underwent vitrectomy surgery at the Affiliated Hospital of Medical College, Qingdao University (Qingdao, China) during a 3-year period. We recorded perioperative factors with the potential to influence functional outcome including duration from the injury to intervention; causes for ocular trauma; open globe or closed globe injury; grade of vitreous hemorrhage; grade of endophthalmitis; grade of retinal detachment; size and location of intraocular foreign body (IOFB); extent and position of retinal defect; grade of proliferative vitreoretinopathy (PVR); type of surgery; perioperative complications and tamponade agent. The follow-up time was from 3 to 18 months, and the mean time was 12 months. RESULTS After a mean follow-up period of 12 months (3-18 months) 10.53% (2/19) of eyes had visual acuity of between 20/60 and 20/400, 52.63% (10/19) had visual acuity less than 20/400 but more than NLP, and 36.84% (7/19) remained NLP. Visual acuity was improved from NLP to light perception (LP) or better in 63.16% (12/19) of eyes and the rate of complete retinal reattachment was 73.68% (14/19). Good visual acuity all resulted from those patients of blunt trauma with intact eyewall (closed globe injury). The perioperative factors of poor visual acuity prognosis included delayed intervention; open globe injury; endophthalmitis; severe retinal detachment; large IOFB; macular defect; a wide range of retinal defects and severe PVR. CONCLUSION The main reasons of NLP after ocular trauma are severe vitreous hemorrhage opacity; refractive media opacity; retinal detachment; retinal and uveal damages and defects, especially defects of the macula; PVR and

  20. Real-time vision systems

    SciTech Connect

    Johnson, R.; Hernandez, J.E.; Lu, Shin-yee

    1994-11-15

    Many industrial and defence applications require an ability to make instantaneous decisions based on sensor input of a time varying process. Such systems are referred to as `real-time systems` because they process and act on data as it occurs in time. When a vision sensor is used in a real-time system, the processing demands can be quite substantial, with typical data rates of 10-20 million samples per second. A real-time Machine Vision Laboratory (MVL) was established in FY94 to extend our years of experience in developing computer vision algorithms to include the development and implementation of real-time vision systems. The laboratory is equipped with a variety of hardware components, including Datacube image acquisition and processing boards, a Sun workstation, and several different types of CCD cameras, including monochrome and color area cameras and analog and digital line-scan cameras. The equipment is reconfigurable for prototyping different applications. This facility has been used to support several programs at LLNL, including O Division`s Peacemaker and Deadeye Projects as well as the CRADA with the U.S. Textile Industry, CAFE (Computer Aided Fabric Inspection). To date, we have successfully demonstrated several real-time applications: bullet tracking, stereo tracking and ranging, and web inspection. This work has been documented in the ongoing development of a real-time software library.

  1. Tunnel vision: sharper gradient of spatial attention in autism.

    PubMed

    Robertson, Caroline E; Kravitz, Dwight J; Freyberg, Jan; Baron-Cohen, Simon; Baker, Chris I

    2013-04-17

    Enhanced perception of detail has long been regarded a hallmark of autism spectrum conditions (ASC), but its origins are unknown. Normal sensitivity on all fundamental perceptual measures-visual acuity, contrast discrimination, and flicker detection-is strongly established in the literature. If individuals with ASC do not have superior low-level vision, how is perception of detail enhanced? We argue that this apparent paradox can be resolved by considering visual attention, which is known to enhance basic visual sensitivity, resulting in greater acuity and lower contrast thresholds. Here, we demonstrate that the focus of attention and concomitant enhancement of perception are sharper in human individuals with ASC than in matched controls. Using a simple visual acuity task embedded in a standard cueing paradigm, we mapped the spatial and temporal gradients of attentional enhancement by varying the distance and onset time of visual targets relative to an exogenous cue, which obligatorily captures attention. Individuals with ASC demonstrated a greater fall-off in performance with distance from the cue than controls, indicating a sharper spatial gradient of attention. Further, this sharpness was highly correlated with the severity of autistic symptoms in ASC, as well as autistic traits across both ASC and control groups. These findings establish the presence of a form of "tunnel vision" in ASC, with far-reaching implications for our understanding of the social and neurobiological aspects of autism. PMID:23595736

  2. Scanner-based macroscopic color variation estimation

    NASA Astrophysics Data System (ADS)

    Kuo, Chunghui; Lai, Di; Zeise, Eric

    2006-01-01

    Flatbed scanners have been adopted successfully in the measurement of microscopic image artifacts, such as granularity and mottle, in print samples because of their capability of providing full color, high resolution images. Accurate macroscopic color measurement relies on the use of colorimeters or spectrophotometers to provide a surrogate for human vision. The very different color response characteristics of flatbed scanners from any standard colorimetric response limits the utility of a flatbed scanner as a macroscopic color measuring device. This metamerism constraint can be significantly relaxed if our objective is mainly to quantify the color variations within a printed page or between pages where a small bias in measured colors can be tolerated as long as the color distributions relative to the individual mean values is similar. Two scenarios when converting color from the device RGB color space to a standardized color space such as CIELab are studied in this paper, blind and semi-blind color transformation, depending on the availability of the black channel information. We will show that both approaches offer satisfactory results in quantifying macroscopic color variation across pages while the semi-blind color transformation further provides fairly accurate color prediction capability.

  3. Human Factors And Safety Considerations Of Night Vision Systems Flight

    NASA Astrophysics Data System (ADS)

    Verona, Robert W.; Rash, Clarence E.

    1989-03-01

    Military aviation night vision systems greatly enhance the capability to operate during periods of low illumination. After flying with night vision devices, most aviators are apprehensive about returning to unaided night flight. Current night vision imaging devices allow aviators to fly during ambient light conditions which would be extremely dangerous, if not impossible, with unaided vision. However, the visual input afforded with these devices does not approach that experienced using the unencumbered, unaided eye during periods of daylight illumination. Many visual parameters, e,g., acuity, field-of-view, depth perception, etc., are compromised when night vision devices are used. The inherent characteristics of image intensification based sensors introduce new problems associated with the interpretation of visual information based on different spatial and spectral content from that of unaided vision. In addition, the mounting of these devices onto the helmet is accompanied by concerns of fatigue resulting from increased head supported weight and shift in center-of-gravity. All of these concerns have produced numerous human factors and safety issues relating to thb use of night vision systems. These issues are identified and discussed in terms of their possible effects on user performance and safety.

  4. Tactile Spatial Acuity in Childhood: Effects of Age and Fingertip Size

    PubMed Central

    Peters, Ryan M.; Goldreich, Daniel

    2013-01-01

    Tactile acuity is known to decline with age in adults, possibly as the result of receptor loss, but less is understood about how tactile acuity changes during childhood. Previous research from our laboratory has shown that fingertip size influences tactile spatial acuity in young adults: those with larger fingers tend to have poorer acuity, possibly because mechanoreceptors are more sparsely distributed in larger fingers. We hypothesized that a similar relationship would hold among children. If so, children’s tactile spatial acuity might be expected to worsen as their fingertips grow. However, concomitant CNS maturation might result in more efficient perceptual processing, counteracting the effect of fingertip growth on tactile acuity. To investigate, we conducted a cross-sectional study, testing 116 participants ranging in age from 6 to 16 years on a precision-controlled tactile grating orientation task. We measured each participant's grating orientation threshold on the dominant index finger, along with physical properties of the fingertip: surface area, volume, sweat pore spacing, and temperature. We found that, as in adults, children with larger fingertips (at a given age) had significantly poorer acuity, yet paradoxically acuity did not worsen significantly with age. We propose that finger growth during development results in a gradual decline in innervation density as receptive fields reposition to cover an expanding skin surface. At the same time, central maturation presumably enhances perceptual processing. PMID:24454612

  5. Vernier Acuity and the Magnocellular System Revisited: Response to Skottun and Skoyles

    ERIC Educational Resources Information Center

    Keri, Szabolcs; Benedek, Gyorgy

    2010-01-01

    Skottun and Skoyles (2009) recently presented a comment on Vernier acuity and magnocellular dysfunctions in fragile X premutation carriers (Keri & Benedek, 2009). The authors concluded that our finding that the magnocellular deficit, as revealed by luminance-contrast sensitivity measurements, is associated with impaired Vernier acuity for…

  6. An investigation of the relation between sibilant production and somatosensory and auditory acuity

    PubMed Central

    Ghosh, Satrajit S.; Matthies, Melanie L.; Maas, Edwin; Hanson, Alexandra; Tiede, Mark; Ménard, Lucie; Guenther, Frank H.; Lane, Harlan; Perkell, Joseph S.

    2010-01-01

    The relation between auditory acuity, somatosensory acuity and the magnitude of produced sibilant contrast was investigated with data from 18 participants. To measure auditory acuity, stimuli from a synthetic sibilant continuum ([s]-[ʃ]) were used in a four-interval, two-alternative forced choice adaptive-staircase discrimination task. To measure somatosensory acuity, small plastic domes with grooves of different spacing were pressed against each participant’s tongue tip and the participant was asked to identify one of four possible orientations of the grooves. Sibilant contrast magnitudes were estimated from productions of the words ‘said,’ ‘shed,’ ‘sid,’ and ‘shid’. Multiple linear regression revealed a significant relation indicating that a combination of somatosensory and auditory acuity measures predicts produced acoustic contrast. When the participants were divided into high- and low-acuity groups based on their median somatosensory and auditory acuity measures, separate ANOVA analyses with sibilant contrast as the dependent variable yielded a significant main effect for each acuity group. These results provide evidence that sibilant productions have auditory as well as somatosensory goals and are consistent with prior results and the theoretical framework underlying the DIVA model of speech production. PMID:21110603

  7. Comparison of Dynamic Visual Acuity between Water Polo Players and Sedentary Students

    ERIC Educational Resources Information Center

    Quevedo-Junyent, Lluisa; Aznar-Casanova, Jose Antonio; Merindano-Encina, Dolores; Cardona, Genis; Sole-Forto, Joan

    2011-01-01

    In this study, we examined differences in dynamic visual acuity between elite and subelite water polo players and sedentary students. To measure dynamic visual acuity binocularly, we asked participants to indicate the orientation of a broken ring, similar to the Landolt C, which increased in size as it moved across a computer screen. Two different…

  8. Acuity of the Approximate Number System and Preschoolers' Quantitative Development

    ERIC Educational Resources Information Center

    van Marle, Kristy; Chu, Felicia W.; Li, Yaoran; Geary, David C.

    2014-01-01

    The study assessed the relations among acuity of the inherent approximate number system (ANS), performance on measures of symbolic quantitative knowledge, and mathematics achievement for a sample of 138 (64 boys) preschoolers. The Weber fraction (a measure of ANS acuity) and associated task accuracy were significantly correlated with mathematics…

  9. Improving color correction across camera and illumination changes by contextual sample selection

    NASA Astrophysics Data System (ADS)

    Wannous, Hazem; Lucas, Yves; Treuillet, Sylvie; Mansouri, Alamin; Voisin, Yvon

    2012-04-01

    In many tasks of machine vision applications, it is important that recorded colors remain constant, in the real world scene, even under changes of the illuminants and the cameras. Contrary to the human vision system, a machine vision system exhibits inadequate adaptability to the variation of lighting conditions. Automatic white balance control available in commercial cameras is not sufficient to provide reproducible color classification. We address this problem of color constancy on a large image database acquired with varying digital cameras and lighting conditions. A device-independent color representation may be obtained by applying a chromatic adaptation transform, from a calibrated color checker pattern included in the field of view. Instead of using the standard Macbeth color checker, we suggest selecting judicious colors to design a customized pattern from contextual information. A comparative study demonstrates that this approach ensures a stronger constancy of the colors-of-interest before vision control thus enabling a wide variety of applications.

  10. Ability of the D-15 panel tests and HRR pseudoisochromatic plates to predict performance in naming VDT colors.

    PubMed

    Ramaswamy, Shankaran; Hovis, Jeffery K

    2004-01-01

    Color codes in VDT displays often contain sets of colors that are confusing to individuals with color-vision deficiencies. The purpose of this study is to determine whether individuals with color-vision deficiencies (color defectives) can perform as well as individuals without color-vision deficiencies (color normals) on a colored VDT display used in the railway industry and to determine whether clinical color-vision tests can predict their performance. Of the 52 color defectives, 58% failed the VDT test. The kappa coefficients of agreement for the Farnsworth D-15, Adams desaturated D-15, and Richmond 3rd Edition HRR PIC diagnostic plates were significantly greater than chance. In particular, the D-15 tests have a high probability of predicting who fails the practical test. However, all three tests had an unacceptably high false-negative rate (9.5-35%); so that a practical test is still needed. PMID:15518229

  11. Color Analysis

    NASA Astrophysics Data System (ADS)

    Wrolstad, Ronald E.; Smith, Daniel E.

    Color, flavor, and texture are the three principal quality attributes that determine food acceptance, and color has a far greater influence on our judgment than most of us appreciate. We use color to determine if a banana is at our preferred ripeness level, and a discolored meat product can warn us that the product may be spoiled. The marketing departments of our food corporations know that, for their customers, the color must be "right." The University of California Davis scorecard for wine quality designates four points out of 20, or 20% of the total score, for color and appearance (1). Food scientists who establish quality control specifications for their product are very aware of the importance of color and appearance. While subjective visual assessment and use of visual color standards are still used in the food industry, instrumental color measurements are extensively employed. Objective measurement of color is desirable for both research and industrial applications, and the ruggedness, stability, and ease of use of today's color measurement instruments have resulted in their widespread adoption.

  12. International computer vision directory

    SciTech Connect

    Flora, P.C.

    1986-01-01

    This book contains information on: computerized automation technologies. State-of-the-art computer vision systems for many areas of industrial use are covered. Other topics discussed include the following automated inspection systems; robot/vision systems; vision process control; cameras (vidicon and solid state); vision peripherals and components; and pattern processor.

  13. Image Transform Based on the Distribution of Representative Colors for Color Deficient

    NASA Astrophysics Data System (ADS)

    Ohata, Fukashi; Kudo, Hiroaki; Matsumoto, Tetsuya; Takeuchi, Yoshinori; Ohnishi, Noboru

    This paper proposes the method to convert digital image containing distinguishing difficulty sets of colors into the image with high visibility. We set up four criteria, automatically processing by a computer, retaining continuity in color space, not making images into lower visible for people with normal color vision, and not making images not originally having distinguishing difficulty sets of colors into lower visible. We conducted the psychological experiment. We obtained the result that the visibility of a converted image had been improved at 60% for 40 images, and we confirmed the main criterion of the continuity in color space was kept.

  14. Processing of Color Words Activates Color Representations

    ERIC Educational Resources Information Center

    Richter, Tobias; Zwaan, Rolf A.

    2009-01-01

    Two experiments were conducted to investigate whether color representations are routinely activated when color words are processed. Congruency effects of colors and color words were observed in both directions. Lexical decisions on color words were faster when preceding colors matched the color named by the word. Color-discrimination responses…

  15. Smartphone serious games for vision and hearing assessment.

    PubMed

    Dias, Pedro; Aguiar, Bruno; Sousa, Filipe; Sousa, Augusto

    2015-01-01

    Falls are the second leading cause of accidental injury deaths worldwide. In this paper, it is intended to define methodologies that permit the evaluation of two potential factors which might have an impact on fall risk, these are: visual and hearing loss. The aim of the work developed is not to replace clinic visits, but to offer the user the means to continue the tracking of his vision and hearing at home, during the long time intervals between clinical tests. Tests conducted in a sample of our target users indicate a good ability to measure vision and hearing using an android smartphone and the proposed methodologies. While some tests require further validation, promising results were achieved in the most common tests for vision and hearing, presenting a good correlation between the system's results when compared to the traditional tests (for distance visual acuity) and the data gathered from the users (for hearing tests). PMID:25980863

  16. Vision, eye disease, and art: 2015 Keeler Lecture.

    PubMed

    Marmor, M F

    2016-02-01

    The purpose of this study was to examine normal vision and eye disease in relation to art. Ophthalmology cannot explain art, but vision is a tool for artists and its normal and abnormal characteristics may influence what an artist can do. The retina codes for contrast, and the impact of this is evident throughout art history from Asian brush painting, to Renaissance chiaroscuro, to Op Art. Art exists, and can portray day or night, only because of the way retina adjusts to light. Color processing is complex, but artists have exploited it to create shimmer (Seurat, Op Art), or to disconnect color from form (fauvists, expressionists, Andy Warhol). It is hazardous to diagnose eye disease from an artist's work, because artists have license to create as they wish. El Greco was not astigmatic; Monet was not myopic; Turner did not have cataracts. But when eye disease is documented, the effects can be analyzed. Color-blind artists limit their palette to ambers and blues, and avoid greens. Dense brown cataracts destroy color distinctions, and Monet's late canvases (before surgery) showed strange and intense uses of color. Degas had failing vision for 40 years, and his pastels grew coarser and coarser. He may have continued working because his blurred vision smoothed over the rough work. This paper can barely touch upon the complexity of either vision or art. However, it demonstrates some ways in which understanding vision and eye disease give insight into art, and thereby an appreciation of both art and ophthalmology. PMID:26563659

  17. [Hair colorants].

    PubMed

    Urbanek-Karłowska, B; Luks, E; Jedra, M; Kiss, E; Malanowska, M

    1997-01-01

    The properties, mode of action and its duration of the preparations used for hair dyeing are described, together with their chemical components, and also preparations of herbal origin. The chemical reactions are described in detail which lead the development of a color polymer occurring during hair dyeing. The studies are presented which are used for toxicological assessment of the raw materials which are the components of the colorants, and the list is included of hair colorants permitted for use in Poland. PMID:9562811

  18. (Computer vision and robotics)

    SciTech Connect

    Jones, J.P.

    1989-02-13

    The traveler attended the Fourth Aalborg International Symposium on Computer Vision at Aalborg University, Aalborg, Denmark. The traveler presented three invited lectures entitled, Concurrent Computer Vision on a Hypercube Multicomputer'', The Butterfly Accumulator and its Application in Concurrent Computer Vision on Hypercube Multicomputers'', and Concurrency in Mobile Robotics at ORNL'', and a ten-minute editorial entitled, It Concurrency an Issue in Computer Vision.'' The traveler obtained information on current R D efforts elsewhere in concurrent computer vision.

  19. Vision Sensors and Cameras

    NASA Astrophysics Data System (ADS)

    Hoefflinger, Bernd

    Silicon charge-coupled-device (CCD) imagers have been and are a specialty market ruled by a few companies for decades. Based on CMOS technologies, active-pixel sensors (APS) began to appear in 1990 at the 1 μm technology node. These pixels allow random access, global shutters, and they are compatible with focal-plane imaging systems combining sensing and first-level image processing. The progress towards smaller features and towards ultra-low leakage currents has provided reduced dark currents and μm-size pixels. All chips offer Mega-pixel resolution, and many have very high sensitivities equivalent to ASA 12.800. As a result, HDTV video cameras will become a commodity. Because charge-integration sensors suffer from a limited dynamic range, significant processing effort is spent on multiple exposure and piece-wise analog-digital conversion to reach ranges >10,000:1. The fundamental alternative is log-converting pixels with an eye-like response. This offers a range of almost a million to 1, constant contrast sensitivity and constant colors, important features in professional, technical and medical applications. 3D retino-morphic stacking of sensing and processing on top of each other is being revisited with sub-100 nm CMOS circuits and with TSV technology. With sensor outputs directly on top of neurons, neural focal-plane processing will regain momentum, and new levels of intelligent vision will be achieved. The industry push towards thinned wafers and TSV enables backside-illuminated and other pixels with a 100% fill-factor. 3D vision, which relies on stereo or on time-of-flight, high-speed circuitry, will also benefit from scaled-down CMOS technologies both because of their size as well as their higher speed.

  20. Evaluation of threshold color differences using printed samples.

    PubMed

    Huang, Min; Liu, Haoxue; Cui, Guihua; Luo, M Ronnier; Melgosa, Manuel

    2012-06-01

    The performances of uniform color spaces and color-difference formulae for predicting threshold color differences were investigated based on visual assessments of 893 pairs of printed color patches under a D65 source. The average ΔE(ab,10)* of the pairs was 1.1 units. A threshold psychophysical experiment was repeated three times by a panel of 16 observers with normal color vision. The experimental data were used to evaluate nine color-difference formulae and uniform color spaces using the standardized residual sum of squares (STRESS) measure. The results indicated that all formulae and spaces performed very similarly to each other, and outperformed CIELAB for threshold color differences. The chromaticity-discrimination ellipses were used to compare with previous results from small color differences [Color Res. Appl. (2011), doi:10.1002/col.20689], and they agreed with each other, except for the purple color center. PMID:22673417

  1. Vision Screening for Children 36 to <72 Months: Recommended Practices

    PubMed Central

    Cotter, Susan A.; Cyert, Lynn A.; Miller, Joseph M.; Quinn, Graham E.

    2015-01-01

    ABSTRACT Purpose This article provides recommendations for screening children aged 36 to younger than 72 months for eye and visual system disorders. The recommendations were developed by the National Expert Panel to the National Center for Children’s Vision and Eye Health, sponsored by Prevent Blindness, and funded by the Maternal and Child Health Bureau of the Health Resources and Services Administration, United States Department of Health and Human Services. The recommendations describe both best and acceptable practice standards. Targeted vision disorders for screening are primarily amblyopia, strabismus, significant refractive error, and associated risk factors. The recommended screening tests are intended for use by lay screeners, nurses, and other personnel who screen children in educational, community, public health, or primary health care settings. Characteristics of children who should be examined by an optometrist or ophthalmologist rather than undergo vision screening are also described. Results There are two current best practice vision screening methods for children aged 36 to younger than 72 months: (1) monocular visual acuity testing using single HOTV letters or LEA Symbols surrounded by crowding bars at a 5-ft (1.5 m) test distance, with the child responding by either matching or naming, or (2) instrument-based testing using the Retinomax autorefractor or the SureSight Vision Screener with the Vision in Preschoolers Study data software installed (version 2.24 or 2.25 set to minus cylinder form). Using the Plusoptix Photoscreener is acceptable practice, as is adding stereoacuity testing using the PASS (Preschool Assessment of Stereopsis with a Smile) stereotest as a supplemental procedure to visual acuity testing or autorefraction. Conclusions The National Expert Panel recommends that children aged 36 to younger than 72 months be screened annually (best practice) or at least once (accepted minimum standard) using one of the best practice approaches

  2. Polar Color

    NASA Technical Reports Server (NTRS)

    2004-01-01

    [figure removed for brevity, see original site]

    Released 3 May 2004 This nighttime visible color image was collected on January 1, 2003 during the Northern Summer season near the North Polar Troughs.

    This daytime visible color image was collected on September 4, 2002 during the Northern Spring season in Vastitas Borealis. The THEMIS VIS camera is capable of capturing color images of the martian surface using its five different color filters. In this mode of operation, the spatial resolution and coverage of the image must be reduced to accommodate the additional data volume produced from the use of multiple filters. To make a color image, three of the five filter images (each in grayscale) are selected. Each is contrast enhanced and then converted to a red, green, or blue intensity image. These three images are then combined to produce a full color, single image. Because the THEMIS color filters don't span the full range of colors seen by the human eye, a color THEMIS image does not represent true color. Also, because each single-filter image is contrast enhanced before inclusion in the three-color image, the apparent color variation of the scene is exaggerated. Nevertheless, the color variation that does appear is representative of some change in color, however subtle, in the actual scene. Note that the long edges of THEMIS color images typically contain color artifacts that do not represent surface variation.

    Image information: VIS instrument. Latitude 79, Longitude 346 East (14 West). 19 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with

  3. Quantum Color

    ScienceCinema

    Lincoln, Don

    2016-07-16

    The idea of electric charges and electricity in general is a familiar one to the science savvy viewer. However, electromagnetism is but one of the four fundamental forces and not the strongest one. The strongest of the fundamental forces is called the strong nuclear force and it has its own associated charge. Physicists call this charge ?color? in analogy with the primary colors, although there is no real connection with actual color. In this video, Fermilab?s Dr. Don Lincoln explains why it is that we live in a colorful world.

  4. Feasibility of a Clinical Trial of Vision Therapy for Treatment of Amblyopia

    PubMed Central

    Lyon, Don W.; Hopkins, Kristine; Chu, Raymond H.; Tamkins, Susanna M.; Cotter, Susan A.; Melia, B. Michele; Holmes, Jonathan M.; Repka, Michael X.; Wheeler, David T.; Sala, Nicholas A.; Dumas, Janette; Silbert, David I.

    2013-01-01

    Purpose We conducted a pilot randomized clinical trial of office-based active vision therapy for the treatment of childhood amblyopia to determine the feasibility of conducting a full-scale randomized clinical trial. Methods A training and certification program and manual of procedures were developed to certify therapists to administer a standardized vision therapy program in ophthalmology and optometry offices consisting of weekly visits for 16 weeks. Nineteen children, 7 to less than 13 years of age, with amblyopia (20/40–20/100) were randomly assigned to receive either 2 hours of daily patching with active vision therapy or 2 hours of daily patching with placebo vision therapy. Results Therapists in diverse practice settings were successfully trained and certified to perform standardized vision therapy in strict adherence with protocol. Subjects completed 85% of required weekly in-office vision therapy visits. Eligibility criteria based on age, visual acuity, and stereoacuity, designed to identify children able to complete a standardized vision therapy program and judged likely to benefit from this treatment, led to a high proportion of screened subjects being judged ineligible, resulting in insufficient recruitment. There were difficulties in retrieving adherence data for the computerized home therapy procedures. Conclusions This study demonstrated that a 16-week treatment trial of vision therapy was feasible with respect to maintaining protocol adherence; however, recruitment under the proposed eligibility criteria, necessitated by the standardized approach to vision therapy, was not successful. A randomized clinical trial of in-office vision therapy for the treatment of amblyopia would require broadening of the eligibility criteria and improved methods to gather objective data regarding the home therapy. A more flexible approach that customizes vision therapy based on subject age, visual acuity, and stereopsis, might be required to allow enrollment of a

  5. Motion detection using color templates

    NASA Astrophysics Data System (ADS)

    Chin, Kevin; Abbott, Derek

    1999-10-01

    The Horridge template model is an empirical motion detection model inspired by insect vision. This model has been successfully implemented on several micro-sensor VLSI chips using greyscale pixels. The template model is based on movement of detected edges rather than whole objects, which facilitate simple tracking techniques. Simple tracking algorithms developed by Nguyen have been successful in tracking coherent movement of objects in a simple environment. Due to the inherent edge detection nature of the template model, two closely spaced objects moving at the same speed relative to the template model sensor will appear to have a common edge and hence be interpreted as one object. Hence when the two objects separate, the tracking algorithm will be upset by the detection of two separate edges, resulting in a loss of tracking. This paper introduces a low-cost vision prototype, based on a color CMOS camera. Although this approach sacrifices auto gain control at each pixel, results are valid for controlled lighting conditions. We demonstrate working result, for indoor conditions, by extension of the template mole using the color CMOS sensor to form color templates. This enables the detection of color boundaries or edges of closely moving objects by exploiting the difference in color contrast between the objects. This paper also discusses the effectiveness of this technique in facilitating the independent tracking of multiple objects.

  6. Insects groom their antennae to enhance olfactory acuity

    PubMed Central

    Böröczky, Katalin; Wada-Katsumata, Ayako; Batchelor, Dale; Zhukovskaya, Marianna; Schal, Coby

    2013-01-01

    Grooming, a common behavior in animals, serves the important function of removing foreign materials from body surfaces. When antennal grooming was prevented in the American cockroach, Periplaneta americana, field emission gun scanning electron microscopy images revealed that an unstructured substance accumulated on nongroomed antennae, covering sensillar pores, but not on groomed antennae of the same individuals. Gas chromatography analysis of antennal extracts showed that over a 24-h period nongroomed antennae accumulated three to four times more cuticular hydrocarbons than groomed antennae. Moreover, nongroomed antennae accumulated significantly more environmental contaminants from surfaces (stearic acid) and from air (geranyl acetate) than groomed antennae. We hypothesized that the accumulation of excess native cuticular hydrocarbons on the antennae would impair olfactory reception. Electroantennogram experiments and single-sensillum recordings supported this hypothesis: antennae that were prevented from being groomed were significantly less responsive than groomed antennae to the sex pheromone component periplanone-B, as well as to the general odorants geranyl acetate and hexanol. We therefore conclude that antennal grooming removes excess native cuticular lipids and foreign chemicals that physically and/or chemically interfere with olfaction, and thus maintains the olfactory acuity of the antennae. Similar experimental manipulations of the German cockroach (Blattella germanica), carpenter ant (Camponotus pennsylvanicus), and the housefly (Musca domestica), which use different modes of antennal grooming, support the hypothesis that antennal grooming serves a similar function in a wide range of insect taxa. PMID:23382193

  7. From innervation density to tactile acuity: 1. Spatial representation.

    PubMed

    Brown, Paul B; Koerber, H Richard; Millecchia, Ronald

    2004-06-11

    We tested the hypothesis that the population receptive field representation (a superposition of the excitatory receptive field areas of cells responding to a tactile stimulus) provides spatial information sufficient to mediate one measure of static tactile acuity. In psychophysical tests, two-point discrimination thresholds on the hindlimbs of adult cats varied as a function of stimulus location and orientation, as they do in humans. A statistical model of the excitatory low threshold mechanoreceptive fields of spinocervical, postsynaptic dorsal column and spinothalamic tract neurons was used to simulate the population receptive field representations in this neural population of the one- and two-point stimuli used in the psychophysical experiments. The simulated and observed thresholds were highly correlated. Simulated and observed thresholds' relations to physiological and anatomical variables such as stimulus location and orientation, receptive field size and shape, map scale, and innervation density were strikingly similar. Simulated and observed threshold variations with receptive field size and map scale obeyed simple relationships predicted by the signal detection model, and were statistically indistinguishable from each other. The population receptive field representation therefore contains information sufficient for this discrimination. PMID:15140641

  8. Insects groom their antennae to enhance olfactory acuity.

    PubMed

    Böröczky, Katalin; Wada-Katsumata, Ayako; Batchelor, Dale; Zhukovskaya, Marianna; Schal, Coby

    2013-02-26

    Grooming, a common behavior in animals, serves the important function of removing foreign materials from body surfaces. When antennal grooming was prevented in the American cockroach, Periplaneta americana, field emission gun scanning electron microscopy images revealed that an unstructured substance accumulated on nongroomed antennae, covering sensillar pores, but not on groomed antennae of the same individuals. Gas chromatography analysis of antennal extracts showed that over a 24-h period nongroomed antennae accumulated three to four times more cuticular hydrocarbons than groomed antennae. Moreover, nongroomed antennae accumulated significantly more environmental contaminants from surfaces (stearic acid) and from air (geranyl acetate) than groomed antennae. We hypothesized that the accumulation of excess native cuticular hydrocarbons on the antennae would impair olfactory reception. Electroantennogram experiments and single-sensillum recordings supported this hypothesis: antennae that were prevented from being groomed were significantly less responsive than groomed antennae to the sex pheromone component periplanone-B, as well as to the general odorants geranyl acetate and hexanol. We therefore conclude that antennal grooming removes excess native cuticular lipids and foreign chemicals that physically and/or chemically interfere with olfaction, and thus maintains the olfactory acuity of the antennae. Similar experimental manipulations of the German cockroach (Blattella germanica), carpenter ant (Camponotus pennsylvanicus), and the housefly (Musca domestica), which use different modes of antennal grooming, support the hypothesis that antennal grooming serves a similar function in a wide range of insect taxa. PMID:23382193

  9. Acoustic basis of directional acuity in laboratory mice.

    PubMed

    Lauer, Amanda M; Slee, Sean J; May, Bradford J

    2011-10-01

    The acoustic basis of auditory spatial acuity was investigated in CBA/129 mice by relating patterns of behavioral errors to directional features of the head-related transfer function (HRTF). Behavioral performance was assessed by training the mice to lick a water spout during sound presentations from a "safe" location and to suppress the response during presentations from "warning" locations. Minimum audible angles (MAAs) were determined by delivering the safe and warning sounds from different locations in the inter-aural horizontal and median vertical planes. HRTFs were measured at the same locations by implanting a miniature microphone and recording the gain of sound energy near the ear drum relative to free field. Mice produced an average MAA of 31° when sound sources were located in the horizontal plane. Acoustic measures indicated that binaural inter-aural level differences (ILDs) and monaural spectral features of the HRTF change systematically with horizontal location and therefore may have contributed to the accuracy of behavioral performance. Subsequent manipulations of the auditory stimuli and the directional properties of the ear produced errors that suggest the mice primarily relied on ILD cues when discriminating changes in azimuth. The MAA increased beyond 80° when the importance of ILD cues was minimized by testing in the median vertical plane. Although acoustic measures demonstrated a less robust effect of vertical location on spectral features of the HRTF, this poor performance provides further evidence for the insensitivity to spectral cues that was noted during behavioral testing in the horizontal plane. PMID:21717290

  10. Cognitive aging and hearing acuity: modeling spoken language comprehension

    PubMed Central

    Wingfield, Arthur; Amichetti, Nicole M.; Lash, Amanda

    2015-01-01

    The comprehension of spoken language has been characterized by a number of “local” theories that have focused on specific aspects of the task: models of word recognition, models of selective attention, accounts of thematic role assignment at the sentence level, and so forth. The ease of language understanding (ELU) model (Rönnberg et al., 2013) stands as one of the few attempts to offer a fully encompassing framework for language understanding. In this paper we discuss interactions between perceptual, linguistic, and cognitive factors in spoken language understanding. Central to our presentation is an examination of aspects of the ELU model that apply especially to spoken language comprehension in adult aging, where speed of processing, working memory capacity, and hearing acuity are often compromised. We discuss, in relation to the ELU model, conceptions of working memory and its capacity limitations, the use of linguistic context to aid in speech recognition and the importance of inhibitory control, and language comprehension at the sentence level. Throughout this paper we offer a constructive look at the ELU model; where it is strong and where there are gaps to be filled. PMID:26124724

  11. Colored Chaos

    NASA Technical Reports Server (NTRS)

    2004-01-01

    [figure removed for brevity, see original site]

    Released 7 May 2004 This daytime visible color image was collected on May 30, 2002 during the Southern Fall season in Atlantis Chaos.

    The THEMIS VIS camera is capable of capturing color images of the martian surface using its five different color filters. In this mode of operation, the spatial resolution and coverage of the image must be reduced to accommodate the additional data volume produced from the use of multiple filters. To make a color image, three of the five filter images (each in grayscale) are selected. Each is contrast enhanced and then converted to a red, green, or blue intensity image. These three images are then combined to produce a full color, single image. Because the THEMIS color filters don't span the full range of colors seen by the human eye, a color THEMIS image does not represent true color. Also, because each single-filter image is contrast enhanced before inclusion in the three-color image, the apparent color variation of the scene is exaggerated. Nevertheless, the color variation that does appear is representative of some change in color, however subtle, in the actual scene. Note that the long edges of THEMIS color images typically contain color artifacts that do not represent surface variation.

    Image information: VIS instrument. Latitude -34.5, Longitude 183.6 East (176.4 West). 38 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of

  12. Vision Deficits in Adults with Down Syndrome

    PubMed Central

    Krinsky-McHale, Sharon J.; Silverman, Wayne; Gordon, James; Devenny, Darlynne A.; Oley, Nancy; Abramov, Israel

    2013-01-01

    Background In individuals with Down syndrome virtually all structures of the eye have some abnormality which likely diminishes vision. We examined basic vision functions in adults with Down syndrome. Materials and Methods Participants completed a battery of psychophysical tests which probed a comprehensive array of visual functions. The performance of adults with Down syndrome was compared to younger and older adults without intellectual disability. Results Adults with Down syndrome had significant vision deficits; reduced sensitivity across spatial frequencies and temporal modulation rates, reduced stereopsis, impaired vernier acuity, and anomalies in colour discrimination. The pattern of deficits observed was similar to those seen by researchers examining adults with Alzheimer’s disease. Conclusions Our findings suggest that a common mechanism may be responsible for the pattern of deficits observed, possibly the presence of Alzheimer’s disease neuropathology in the visual association cortex. We also showed that individuals with mild to moderate intellectual disability are capable of participating in studies employing state-of-the-art psychophysical procedures. This has wider implications in terms of their ability to participate in research that use similar techniques. PMID:23784802

  13. Color Metric.

    ERIC Educational Resources Information Center

    Illinois State Office of Education, Springfield.

    This booklet was designed to convey metric information in pictoral form. The use of pictures in the coloring book enables the more mature person to grasp the metric message instantly, whereas the younger person, while coloring the picture, will be exposed to the metric information long enough to make the proper associations. Sheets of the booklet…

  14. Color Poetry.

    ERIC Educational Resources Information Center

    Ferry, John E.

    1980-01-01

    Elementary students were asked to find 12 colors and 5 sounds in their immediate natural environment and to describe in writing where they saw each color in relationship to themselves. The writings formed a type of poetry which expressed involvement with and observation of the environment. (CM)

  15. Preschool children's vision screening in New Zealand: a retrospective evaluation of referral accuracy

    PubMed Central

    Langeslag-Smith, Miriam A; Vandal, Alain C; Briane, Vincent; Thompson, Benjamin; Anstice, Nicola S

    2015-01-01

    Objectives To assess the accuracy of preschool vision screening in a large, ethnically diverse, urban population in South Auckland, New Zealand. Design Retrospective longitudinal study. Methods B4 School Check vision screening records (n=5572) were compared with hospital eye department data for children referred from screening due to impaired acuity in one or both eyes who attended a referral appointment (n=556). False positive screens were identified by comparing screening data from the eyes that failed screening with hospital data. Estimation of false negative screening rates relied on data from eyes that passed screening. Data were analysed using logistic regression modelling accounting for the high correlation between results for the two eyes of each child. Primary outcome measure Positive predictive value of the preschool vision screening programme. Results Screening produced high numbers of false positive referrals, resulting in poor positive predictive value (PPV=31%, 95% CI 26% to 38%). High estimated negative predictive value (NPV=92%, 95% CI 88% to 95%) suggested most children with a vision disorder were identified at screening. Relaxing the referral criteria for acuity from worse than 6/9 to worse than 6/12 improved PPV without adversely affecting NPV. Conclusions The B4 School Check generated numerous false positive referrals and consequently had a low PPV. There is scope for reducing costs by altering the visual acuity criterion for referral. PMID:26614622

  16. Preserved Visual Acuity in Anterior Ischemic Optic Neuropathy Secondary to Giant Cell (temporal) Arteritis

    PubMed Central

    Antonio-Santos, Aileen A.; Murad-Kejbou, Sally J.; Foroozan, Rod; Yedavally, Sunita; Kaufman, David I.; Eggenberger, Eric R.

    2016-01-01

    OBJECTIVE To evaluate the prevalence and clinical profile of patients with biopsy-proven arteritic anterior ischemic optic neuropathy presenting with preserved visual acuity of 20/40 or better and those with an initial poor visual acuity of 20/50 or worse through a retrospective chart review RESULTS Nine of 37 patients with arteritic anterior ischemic optic neuropathy presented with a preserved visual acuity of 20/40 or better in the affected eye. All patients with preserved visual acuity had initial visual field defects that spared the central field. All 37 patients immediately received high-dose corticosteroid therapy. Visual acuity worsened by > 2 lines in one of nine patients (11%) with preserved visual acuity, with a corresponding progression of visual field constriction. CONCLUSION Although preserved visual acuity of 20/40 or better has traditionally been associated with the nonarteritic form of anterior ischemic optic neuropathy, giant cell arteritis should still be strongly considered, especially if they have giant cell arteritis systemic symptoms. PMID:26958148

  17. Long-term preservation of cone photoreceptors and visual acuity in rd10 mutant mice exposed to continuous environmental enrichment

    PubMed Central

    Strettoi, Enrica

    2014-01-01

    Purpose In human patients and animal models of retinitis pigmentosa (RP), a gradual loss of rod photoreceptors and decline in scotopic vision are the primary manifestations of the disease. Secondary death of cones and gradual, regressive remodeling of the inner retina follow and progress at different speeds according to the underlying genetic defect. In any case, the final outcome is near-blindness without a conclusive cure yet. We recently reported that environmental enrichment (EE), an experimental manipulation based on exposure to enhanced motor, sensory, and social stimulation, when started at birth, exerts clear beneficial effects on a mouse model of RP, by slowing vision loss. The purpose of this study was to investigate in the same mouse the long-term effects of chronic exposure to an EE and assess the outcome of this manipulation on cone survival, inner retinal preservation, and visual behavior. Methods Two groups of rd10 mutant mice were maintained in an EE or standard (ST) laboratory conditions up to 1 year of age. Then, retinal preservation was assessed with immunocytochemistry, confocal microscopy examination, cone counts, and electron microscopy of the photoreceptor layer, while visual acuity was tested behaviorally with a Prusky water maze. Results rd10 mice are a model of autosomal recessive RP with a typical rod-cone, center to the periphery pattern of photoreceptor degeneration. They carry a mutation of the rod-specific phosphodiesterase gene and undergo rod death that peaks at around P24, while cone electroretinogram (ERG) is extinct by P60. We previously showed that early exposure to an EE efficiently delays photoreceptor degeneration in these mutants, extending the time window of cone viability and cone-mediated vision well beyond the phase of maximum rod death. Here we find that a maintained EE can delay the degeneration of cones even in the long term. Confocal and electron microscopy examination of the retinas of the rd10 EE and ST mice at 1

  18. [Using spectra and visual modeling to study animal coloration].

    PubMed

    Yang, Can-Chao; Liang, Wei

    2013-12-01

    Animal coloration has many adaptive functions and plays an important role in signal communication both among intra- and interspecies. For example, it has been widely used in mate choice, intrasexual competition, and as aposematic or cryptic coloration in predator avoidance. Many colors and pigments also function in microbial resistance, structural support, photoprotection, and thermoregulation. Differing from human vision, based on RGB system, many other animals have tetrachromatic vision system, which includes the ultraviolet (UV) range that is undetectable by human eyes. Previous studies showed that ultraviolet is important in some species' social signaling and communication. Moreover, cone inner segments of most classes of vertebrate contain an oil droplet, which acts as a cut-off filter absorbing wavelengths below a critical value, and transmitting longer wavelengths. Animal and human vision is significantly different in that the classification of color by human standards may be a misleading for measuring animal coloration. Here, we illuminate how to use fiber spectrophotometer to quantify animal coloration, and analyze it by spectra analysis and visual modeling. As an example, we obtained plumage reflectance spectra from male and female scarlet minivets (Pericrocotus flammeus). This bird species is sexually dimorphic that the males have plumage color in black and red, while the females have grey and yellow accordingly. These plumage colors are typically generated from melanin and carotenoid pigments, which have an effect on antioxidant activity. Analysis of spectra segments provides hue, chroma, brightness and relative brightness of each wave range. Visual modeling maps color patches on tetrahedral color space and Robinson projection, meanwhile, calculates color span and color space volume which describe the color contrast and color diversity, respectively. In visual modeling, ambient light irradiance and spectral sensitivity of animal retinas are included

  19. Amblyopia and Binocular Vision

    PubMed Central

    Birch, Eileen E.

    2012-01-01

    Amblyopia is the most common cause of monocular visual loss in children, affecting 1.3% to 3.6% of children. Current treatments are effective in reducing the visual acuity deficit but many amblyopic individuals are left with residual visual acuity deficits, ocular motor abnormalities, deficient fine motor skills, and risk for recurrent amblyopia. Using a combination of psychophysical, electrophysiological, imaging, risk factor analysis, and fine motor skill assessment, the primary role of binocular dysfunction in the genesis of amblyopia and the constellation of visual and motor deficits that accompany the visual acuity deficit has been identified. These findings motivated us to evaluate a new, binocular approach to amblyopia treatment with the goals of reducing or eliminating residual and recurrent amblyopia and of improving the deficient ocular motor function and fine motor skills that accompany amblyopia. PMID:23201436

  20. The impact of target luminance and radiance on night vision device visual performance testing

    NASA Astrophysics Data System (ADS)

    Marasco, Peter L.; Task, H. Lee

    2003-09-01

    Visual performance through night-vision devices (NVDs) is a function of many parameters such as target contrast, objective and eyepiece lens focus, signal/noise of the image intensifier tube, quality of the image intensifier, night-vision goggle (NVG) gain, and NVG output luminance to the eye. The NVG output luminance depends on the NVG sensitive radiance emitted (or reflected) from the visual acuity target (usually a vision testing chart). The primary topic of this paper is the standardization (or lack thereof) of the radiance levels used for NVG visual acuity testing. The visual acuity chart light level might be determined in either photometric (luminance) units or radiometric (radiance) units. The light levels are often described as "starlight," "quarter moon," or "optimum" light levels and may not actually provide any quantitative photometric or radiometric information. While these terms may be useful to pilots and the users of night-vision devices, they are inadequate for accurate visual performance testing. This is because there is no widely accepted agreement in the night vision community as to the radiance or luminance level of the target that corresponds to the various named light levels. This paper examines the range of values for "starlight," "quarter moon," and "optimum" light commonly used by the night vision community and referenced in the literature. The impact on performance testing of variations in target luminance/radiance levels is also examined. Arguments for standardizing on NVG-weighted radiometric units for testing night-vision devices instead of photometric units are presented. In addition, the differences between theoretical weighted radiance and actual weighted radiance are also discussed.