Two-dimensional biocompatible plasmonic contact lenses for color blindness correction.

Color blindness, or color vision deficiency (CVD), is an ocular disease that suppresses the recognition of different colors. Recently, tinted glasses and lenses have been studied as hopeful devices for color blindness correction. In this study, 2D biocompatible and flexible plasmonic contact lenses were fabricated using polydimethylsiloxane (PDMS) and a low-cost, and simple design based on the soft nano-lithography method and investigated for correction of red-green (deuteranomaly) color blindness. In addition, the stability test of the fabricated plasmonic contact lenses was investigated into the phosphate buffered saline (PBS) solution and the proposed lens offers an excellent stability into the PBS solution. The plasmonic contact lens proposed herein is based on the plasmonic surface lattice resonance (SLR) phenomenon and offers a good color filter for color blindness correction. The biocompatibility, low cost, stability, and simple fabrication of these contact lenses can offer new insights for applications of color blindness correction.

Adaptive Changes in Color Vision from Long-Term Filter Usage in Anomalous but Not Normal Trichromacy.

For over 150 years, spectrally selective filters have been proposed to improve the vision of observers with color vision deficiencies [1]. About 6% of males and <1% of females have anomalies in their gene arrays coded on the X chromosome that result in significantly decreased spectral separation between their middle- (M-) and long- (L-) wave sensitive cone photoreceptors [2]. These shifts alter individuals' color-matching and chromatic discrimination such that they are classified as anomalous trichromats [3, 4]. Broad-band spectrally selective filters proposed to improve the vision of color-deficient observers principally modify the illuminant and are largely ineffective in enhancing discrimination or perception because they do not sufficiently change the relative activity of M- and L-photoreceptors [5, 6]. Properly tailored notch filters, by contrast, might increase the difference of anomalous M- and L-cone signals. Here, we evaluated the effects of long-term usage of a commercial filter designed for this purpose on luminance and chromatic contrast response, estimated with a signal detection-based scaling method. We found that sustained use over two weeks was accompanied by increased chromatic contrast response in anomalous trichromats. Importantly, these improvements were observed when tested without the filters, thereby demonstrating an adaptive visual response. Normal observers and a placebo control showed no such changes in contrast response. These findings demonstrate a boosted chromatic response from exposure to enhanced chromatic contrasts in observers with reduced spectral discrimination. They invite the suggestion that modifications of photoreceptor signals activate a plastic post-receptoral substrate that could potentially be exploited for visual rehabilitation.

Spectral Filter Selection for Increasing Chromatic Diversity in CVD Subjects.

This paper analyzes, through computational simulations, which spectral filters increase the number of discernible colors (NODC) of subjects with normal color vision, as well as red-green anomalous trichromats and dichromats. The filters are selected from a set of filters in which we have modeled spectral transmittances. With the selected filters we have carried out simulations performed using the spectral reflectances captured either by a hyperspectral camera or by a spectrometer. We have also studied the effects of these filters on color coordinates. Finally, we have simulated the results of two widely used color blindness tests: Ishihara and Farnsworth-Munsell 100 Hue (FM100). In these analyses the selected filters are compared with the commercial filters from EnChroma and VINO companies. The results show that the increase in NODC with the selected filters is not relevant. The simulation results show that none of these chosen filters help color vision deficiency (CVD) subjects to pass the set of color blindness tests studied. These results obtained using standard colorimetry support the hypothesis that the use of color filters does not cause CVDs to have a perception similar to that of a normal observer.

Metasurface-based contact lenses for color vision deficiency.

We embed large-scale, plasmonic metasurfaces into off-the-shelf rigid gas permeable contact lenses and study their ability to serve as visual aids for color vision deficiency. In this study, we specifically address deuteranomaly, which is the most common class of color vision deficiency. This condition is caused by a redshift of the medium-type cone photoreceptor and leads to ambiguity in the color perception of red and green and their combinations. The effect of the metasurface-based contact lenses on the color perception was simulated using Commission Internationale de l'Eclairage (CIE) color spaces and conventional models of the human color-sensitive photoreceptors. Comparison between normal color vision and uncorrected and corrected deuteranomaly by the proposed element demonstrates the ability offered by the nanostructured contact lens to shift back incorrectly perceived pigments closer to the original pigments. The maximal improvement in the color perception error before and after the proposed correction for deuteranomaly is up to a factor of $\sim{10}$∼10. In addition, an Ishihara-based color test was also simulated, showing the contrast restoration achieved by the element, for deuteranomaly conditions.

How to display data by color schemes compatible with red-green color perception deficiencies.

Visualization of data concerns most scientists. The use of color is required in order to display multidimensional information. In addition, color encoding a univariate image can improve the interpretation significantly. However up to 10% of the adult male population are affected by a red-green color perception deficiency which hampers the correct interpretation and appreciation of color encoded information. This work attempts to give guidelines on how to display a given dataset in a balanced manner. Three novel color maps are proposed providing readers with normal color perception a maximum of color contrast while being a good compromise for readers with color perception deficiencies.

Using Patterns to Encode Color Information for Dichromats.

Color is one of the most common ways to convey information in visualization applications. Color vision deficiency (CVD) affects approximately 200 million individuals worldwide and considerably degrades their performance in understanding such contents by creating red-green or blue-yellow ambiguities. While several content-specific methods have been proposed to resolve these ambiguities, they cannot achieve this effectively in many situations for contents with a large variety of colors. More importantly, they cannot facilitate color identification. We propose a technique for using patterns to encode color information for individuals with CVD, in particular for dichromats. We present the first content-independent method to overlay patterns on colored visualization contents that not only minimizes ambiguities but also allows color identification. Further, since overlaying patterns does not compromise the underlying original colors, it does not hamper the perception of normal trichromats. We validated our method with two user studies: one including 11 subjects with CVD and 19 normal trichromats, and focused on images that use colors to represent multiple categories; and another one including 16 subjects with CVD and 22 normal trichromats, which considered a broader set of images. Our results show that overlaying patterns significantly improves the performance of dichromats in several color-based visualization tasks, making their performance almost similar to normal trichromats'. More interestingly, the patterns augment color information in a positive manner, allowing normal trichromats to perform with greater accuracy.

Special tinted contact lens on colour-defects.

PURPOSE: The objective of this study was to determine the visual function of colour-deficient subjects when wearing special red tint contact lenses. MATERIALS AND METHODS: A total of 17 subjects with congenital colour vision deficiency (14 deutans and 3 protans), voluntarily participated in this study. The average age for the subjects was 23.00 ± 4.06 years old. Visual functions tested were visual acuity (LogMAR), contrast sensitivity (FACT Chart) and stereopsis (TNO and Howard Dolman tests). Two types of special red tint lenses were used in this study; Type I (light red) and Type II (dark red). RESULTS: The protans and deutans showed no significant changes in visual acuity and contrast sensitivity when wearing either type of contact lens. Stereopsis testing using the Horward-Dolman test gave no significant changes but significant differences were seen using the TNO test. Stereopsis using the TNO test was significantly poorer with the red tinted contact lenses compared to without for both protons and deutans. Testing binocularly with Ishihara plates showed that 88% (n=15) of patients passed the test with Type I and Type II contact lenses. When D15 test was done, 3 patients (17.6%) were 'normal' when using the Type I contact lenses and 2 patients (11.8%) were 'normal' when using the Type II contact lenses. However, with FM100Hue test, most patients showed deutan responses. Total error scores (TES) were found to be higher with Type I and Type II contact lenses compared to without. CONCLUSIONS: The Type I and II special tinted contact lens used in this study did not cause a reduction of visual acuity and contrast sensitivity for the colour defects. Stereopsis was also not reduced with the Type I and Type II contact lenses for the colour defects except when tested with the TNO test. Colour vision defects became difficult to detect using the Ishihara plates but FM100Hue test did not show any improvement with the Type I and Type II contact lenses.

Quantitative assessment of commercial filter 'aids' for red-green colour defectives.

The claims made for 43 commercial filter 'aids', that they improve the colour discrimination of red-green colour defectives, are assessed for protanomaly and deuteranomaly by changes in the colour spacing of traffic signals (European Standard EN 1836:2005) and of the Farnsworth D15 test. Spectral transmittances of the 'aids' are measured and tristimulus values with and without 'aids' are computed using cone fundamentals and the spectral power distributions of either the D15 chips illuminated by CIE Illuminant C or of traffic signals. Chromaticities (l,s) are presented in cone excitation diagrams for protanomaly and deuteranomaly in terms of the relative excitation of their long (L), medium (M) and short (S) wavelength-sensitive cones. After correcting for non-uniform colour spacing in these diagrams, standard deviations parallel to the l and s axes are computed and enhancement factors E(l) and E(s) are derived as the ratio of 'aided' to 'unaided' standard deviations. Values of E(l) for traffic signals with most 'aids' are <1 and many do not meet the European signal detection standard. A few 'aids' have expansive E(l) factors but with inadequate utility: the largest being 1.2 for traffic signals and 1.3 for the D15 colours. Analyses, replicated for 19 'aids' from one manufacturer using 658 Munsell colours inside the D15 locus, yield E(l) factors within 1% of those found for the 16 D15 colours.

Visual contents adaptation for colour vision deficiency using customised ICC profile.

PURPOSE: Approximately, 1 of 12 persons in the world has colour vision deficiency (CVD), named colour blindness. While the amount of graphic information in digital contents is continuing to increase dramatically, assistive tools for colour vision deficiencies remain scarce. METHODS: We developed a method to generate customised International Colour Consortium (ICC) colour profiles for patients suffering from CVD, which could adjust graphic contents according to individual needs. Compensation rules for the pale or dark range of red and green colours were established, and an ICC profile was generated using this set of rules. RESULTS: The passing rate for Ishihara test was 99.5% when the generated profile was applied to 10 Ishihara plates and tested on individuals suffering from red deficiency, and green deficiency (5, and 15 participants, respectively). The time used to generate the compensation profile was 12.9 min on average, including the time taken to explain the test to the participants. CONCLUSION: Reliable results were achieved with a relatively low effort in comparison with methods currently utilised in professional clinics, and does not need expensive instruments.

Abnormal colour vision is a handicap to playing cricket but not an insurmountable one.

BACKGROUND: Two studies have reported that abnormal colour vision is under-represented among cricketers, presumably because cricketers with abnormal colour vision have difficulty seeing the red ball against the green grass of the cricket field and the green foliage around it. We have previously reported on the difficulties of five cricketers with abnormal colour vision but we have also reported that one of Australia's finest cricketers was a protanope. This survey was undertaken to confirm the under-representation of abnormal colour vision among cricketers and to ascertain whether those playing tend to be (1) those with a mild colour vision deficiency, (2) bowlers rather than batsman and (3) prefer to field close to the batsman rather than in the outfield. METHODS: The colour vision of 293 members of seven Melbourne Premier cricket clubs was tested using the Ishihara test. Those who failed were examined further to confirm their abnormal colour vision, to assess its severity with the Farnsworth D15 test and to classify it as either protan or deutan using the Medmont C100 test. A questionnaire about cricketing ability and problems playing cricket was administered. RESULTS: Twenty-six (8.9 per cent) of the cricketers had abnormal colour vision, of whom six played in the First Grade (6.7 per cent of First Grade players). The proportion of cricketers with a severe deficiency was significantly less than expected for the First Grade players. There were only two protans. Bowlers were not over-represented among the colour vision defective cricketers but those preferring to field close to the batsman were significantly over-represented. CONCLUSION: Abnormal colour vision is a modest handicap to playing cricket, especially at the higher levels of the game. It may impede batting and the ability to field in the outfield.

Impact of congenital colour vision defects on occupation.

AIMS: To investigate whether there is an association between congenital colour vision defects (CVD) and occupational choice and employment history, in order to inform the debate about the value of universal childhood screening for these disorders. METHODS: Participants were 6422 males and 6112 females from the 1958 British birth cohort, followed from birth to 33 years, whose colour vision was assessed (Ishihara test) at 11 years. RESULTS: A total of 431 males (6.7%) had CVD. Men with CVD had pursued some careers for which normal colour vision is currently regarded as essential; for example, eight men (3.1%) with CVD were in the police, armed forces, or fire-fighting service at 33 years compared to 141 men (3.8%) with normal colour vision. They were, however, under-represented compared to those with normal colour vision, in other occupations; for example, no men with CVD were employed in electrical and electronic engineering at 33 years compared to 15 men (0.4%) with normal colour vision. CONCLUSIONS: The findings of this study suggest there is little to be gained by continuing with existing school screening programmes for CVD, whose primary purpose is to advise affected children against certain careers. Other ways of informing young people about potential occupational difficulties and pathways for referral for specialist assessment are likely to be more useful.

Calculated impact of higher-order monochromatic aberrations on retinal image quality in a population of human eyes.

We calculated the impact of higher-order aberrations on retinal image quality and the magnitude of the visual benefit expected from their correction in a large population of human eyes. Wave aberrations for both eyes of 109 normal subjects and 4 keratoconic patients were measured for 3-, 4-, and 5.7-mm pupils with a Shack-Hartmann sensor. Retinal image quality was estimated by means of the modulation transfer function (MTF) in white light. The visual benefit was calculated as the ratio of the MTF when the monochromatic higher-order aberrations are corrected to the MTF corresponding to the best correction of defocus and astigmatism. On average, the impact of the higher-order aberrations for a 5.7-mm pupil in normal eyes is similar to an equivalent defocus of approximately 0.3 D. The average visual benefit for normal eyes at 16 c/deg is approximately 2.5 for a 5.7-mm pupil and is negligible for small pupils (1.25 for a 3-mm pupil). The benefit varies greatly among eyes, with some normal eyes showing almost no benefit and others a benefit higher than 4 at 16 c/deg across a 5.7-mm pupil. The benefit for keratoconic eyes is much larger. The benefit at 16 c/deg is 12 and 3 for 5.7- and 3-mm pupils, respectively, averaged across four keratoconics. These theoretical benefits could be realized in normal viewing conditions but only under specific conditions.

Testability of a color vision screening test in a population with mental retardation.

PURPOSE: The purpose of this study was to determine the testability of the "Co or Vision Testing Made Easy" color vision test, marketed as a screening test for young children, in a population of individuals with mental retardation. The test uses simple geometric figures that are easily identified. Previously, the test has demonstrated validity as a measure of color deficiency. METHODS: The test was presented to Special Olympic athletes, who are individuals with mental retardation or significant developmental delay, at four sites: the 1997 World Winter Games in Toronto, Canada; the Texas Summer Games in Houston, Texas; the Massachusetts Summer Games in Boston, Massachusetts; and Regional European Swim Competition in Seville, Spain. The criteria for passing was 8 correct responses on the first trial or 9 of 9 on the second attempt. RESULTS: Testability in Toronto, Canada; Houston, Texas; and Seville, Spain was high--95.5%, 98.7%, and 95.7%, respectively. Testability, however, dropped to 78.8% during the Boston, Massachusetts screening. There was no apparent difference in the testing environment that would account for the difference. The overall rate of testability was 93.2% for the 1078 athletes screened. The frequency of males identified as color deficient was similar to that expected in the general population; only two females (in Spain) failed the color vision screening. CONCLUSIONS: The "Color Vision Testing Made Easy" color vision test was successfully completed by a very high percentage of Special Olympics athletes. These results suggest that this test is useful in screening this population for color deficiencies, and that the prevalence of color vision deficiencies is approximately the same in individuals with mental retardation as in the general population.

[Pigment method to train color vision in the rehabilitation of railway workers with congenital disorders of color perception]. / Pigmentnyi metod trenirovki tsvetnogo zreniia dlia reabilitatsii zheleznodorozhnikov s vrozhdennymi rasstroistvami tsvetooshchushcheniia.

The authors elaborated an effective method to master color vision through pigment tables. The method enables subnormal trichromats to normalize or improve colors perception and relieve existing disorders. The training course for deuteranomalopia "C" patients should comprise 8-10 procedures, that for deuteranomalopia "B" and protanopia "C" patients-11-13 procedures, that for protanopia B" patients--under 20 procedures. The effects remain at least 1 year after the course.