Colour vision deficiencies in Alzheimer's disease

Objective: visual disorders are among the earliest symptoms of Alzheimer's disease. It is, however, still controversial as to whether Alzheimer's disease impairs colour vision. In this study, colour vision of Alzheimer's disease patients was tested using the Ishihara test and the PV‐16 choice test. The latter test, primarily designed for children, was chosen in order to avoid problems due to cognitive decline. Methods: 26 patients with mild to severe Alzheimer's disease (M:F=5:21; mean age: 80±9 years, range: 53-95 years) and 25 controls (M:F=5:20; mean age 80±10 years, range: 56-100 years) were rated after undergoing complete neuro‐ophthalmologic examination. Results: the Alzheimer's disease patients made significantly more unspecific errors in the Ishihara test (P=0.02) and in the PV‐16 choice test (P=0.0008) than the controls. No relation between test performance and severity of Alzheimer's disease was found. Conclusions: Alzheimer's disease patients have an unspecific colour vision deficiency independent of the severity of the diseas

What do Elementary School Librarians Know and Believe about Students with Color Vision Deficiencies?

Colour vision deficiencies affect approximately eight percent of the male population, yet the condition is often overlooked in the educational setting despite the pervasiveness of colour in the school. The purpose of this study was to explore how elementary school librarians provide instruction and prepare the library environment to meet the needs of students with colour vision deficiencies. Findings indicate that elementary school librarians in Virginia did not feel knowledgeable about colour vision deficiencies but were interested in knowing more and expressed a desire to make changes. The case study participants\u27ʹ knowledge increased from pre-­‐‑test to post-­‐‑test. There were noticeable changes in beliefs and desires to change behaviours. The changes in the case study participants lend support to the need for colour vision deficiency awareness training for elementary school educators

Cone opsins, colour blindness and cone dystrophy: Genotype-phenotype correlations

X-linked cone photoreceptor disorders caused by mutations in the OPN1LW (L) and OPN1MW (M) cone opsin genes on chromosome Xq28 include a range of conditions from mild stable red-green colour vision deficiencies to severe cone dystrophies causing progressive loss of vision and blindness. Advances in molecular genotyping and functional analyses of causative variants, combined with deep retinal phenotyping, are unravelling genetic mechanisms underlying the variability of cone opsin disorders.

Image optimization model for users with colour vision deficiencies

Predmet disertacije jeste optimizacija digitalne slike kada ograničenje nije vezano za način reprodukcije već za samog posmatrača, odnosno optimizacija opaženog kvaliteta digitalne slike od strane osoba sa poremećajima viđenja boja. Predloženi model optimizacije slike poboljšava distinkciju boja i opseg boja slike za korisnike sa različitim težinama poremećaja viđenja boja uz očuvanje prirodnosti slike. Metodološki okvir ispitivanja, koji uključuje kvantitativnu analizu računarskih simulacija, analizu eye-tracking podataka i subjektivno ocenjivanje poboljšanja opaženog kvaliteta test slika, daje sistematičnu i pouzdanu verifikaciju efektnosti predloženih metoda adaptacije boja slike.The subject of the thesis was the digital image optimization when an observer represents the main image reproduction limitation or, in other words, the optimization of the perceived image quality by individuals with colour vision deficiencies. The proposed image optimization model enhances colour distinction and gamut for users with different severities of colourblindness while preserving the image naturalness. The used methodological framework, including a quantitative analysis of computer simulations, an analysis of eye-tracking data and a subjective evaluation of the perceived image quality, provides systematic and reliable effectiveness verification of the proposed colour adaptation methods

The use of augmented reality apps to make laboratories more accessible to people with colour vision deficiencies

Colour is an important part of how we understand the world around us, from choosing fresh fruit and vegetables to reading traffic lights. Learning and research in science also has a large focus on colour, using colour and colour-based observations to inform experiments and interpret results. For people with a colour blindness, better described as colour vision deficiency (CVD), the colour focus of science can be an implicit barrier to learning or science-based careers. This study first explores the ways in which chemistry experiments can be inaccessible to people with CVD and next assesses tools that could be used to improve the accessibility of laboratories in STEM. Recognising components of experiments that may prove challenging to CVD participants is a proactive approach to improving CVD accessibility, but they can be difficult to identify. There are several augmented reality (AR) apps available for mobile devices which can simulate CVD vision but no scientific evidence has been shown on their accuracy. During this study, four of these AR CVD simulating apps were evaluated using the Farnsworth D15 hue-based colour vision test results from eleven participants. The best performing CVD simulating app, based on scientific evidence, was then used to evaluate current undergraduate chemistry experiments at The University of Sydney. Of the 24 experiments identified as being potentially challenging for students with CVD, we applied CVD simulation to five chemistry experiments experienced by First Year students. In the final part of this study, we evaluated the potential of AR apps assisting CVD participants in a laboratory environment. Farnsworth D15 colour test were used again to evaluate colour naming, colour filtering and colour shifting functions of AR CVD assistive apps. These CVD assistive apps were then applied during a live chemistry experiment to evaluate their real-life laboratory applicability. The results of this study will be presented along with recommendations of which apps and practices are best applied to improve the accessibility of STEM laboratories to CVD students

The misuse of colour in science communication

The accurate representation of data is essential in science communication. However, colour maps that visually distort data through uneven colour gradients or are unreadable to those with colour-vision deficiency remain prevalent in science. These include, but are not limited to, rainbow-like and red–green colour maps. Here, we present a simple guide for the scientific use of colour. We show how scientifically derived colour maps report true data variations, reduce complexity, and are accessible for people with colour-vision deficiencies. We highlight ways for the scientific community to identify and prevent the misuse of colour in science, and call for a proactive step away from colour misuse among the community, publishers, and the press

Colour constancy in dichromats and trichromats: dependence on task

An important topic in the field of colour vision is the impact of colour vision deficiencies on daily life tasks. Investigating the extent to which colour constancy (i.e. the ability to recognise surface colour under different illuminants) is preserved in colour vision- deficient observers can provide us with insight into the nature and function of trichromatic colour vision. The first chapter of this thesis provides a summary of the very basics of colour vision, colour vision deficiencies, as well as colour constancy. Studies conducted on the colour constancy abilities of colour-vision-deficient observers versus those with normal colour vision are reviewed. The second chapter presents and reports the aims and methods of the proposed experiment (which could not take place due to the COVID-19 pandemic). This experiment investigated the colour constancy abilities of trichromats versus dichromats using two different colour constancy tasks (2D achromatic adjustment vs. 3D blocks-copying/selection task) and aimed to show how colour constancy depends on observer type as well as task type. The third chapter comprises of a computerised simulation. This simulation aimed to model the colour constancy of “ideal” observers when presented with various surfaces and illuminants. These observers involve simulated normal trichromats, anomalous trichromats and dichromats. A variety of yellow, blue, green and red illuminant shifts (from neutral daylight) were used, and surface chromaticity and observer types were compared. Overall, whilst no three-way interaction between illuminant shift, surface chromaticity and observer type were found in the simulation, strong main effects were found. It is suggested that a combination of simulated and experimental research is needed to understand the colour constancy mechanisms underpinning dichromacy and trichromacy at multiple levels (cone-based, cognitive and computational)

Multidimensional scaling of D15 caps: Color-vision defects among tobacco smokers?

Tobacco smoke contains a range of toxins including carbon monoxide and cyanide. With specialized cells and high metabolic demands, the optic nerve and retina are vulnerable to toxic exposure. We examined the possible effects of smoking on color vision: specifically, whether smokers perceive a different pattern of suprathreshold color dissimilarities from nonsmokers. It is already known that smokers differ in threshold color discrimination, with elevated scores on the Roth 28-Hue Desaturated panel test. Groups of smokers and nonsmokers, matched for sex and age, followed a triadic procedure to compare dissimilarities among 32 pigmented stimuli (the caps of the saturated and desaturated versions of the D15 panel test). Multidimensional scaling was applied to quantify individual variations in the salience of the axes of color space. Despite the briefness, simplicity, and “low-tech” nature of the procedure, subtle but statistically significant differences did emerge: on average the smoking group were significantly less sensitive to red–green differences. This is consistent with some form of injury to the optic nerve

Multidimensional scaling reveals a color dimension unique to 'color-deficient' observers

Normal color vision depends on the relative rates at which photons are absorbed in three types of retinal cone:short-wave (S), middle-wave (M) and long-wave (L) cones, maximally sensitive near 430, 530 and 560nm, respectively. But 6% of men exhibit an X-linked variant form of color vision called deuteranomaly [1]. Their color vision is thought to depend on S cones and two forms of long-wave cone (L, L′) [2,3]. The two types of L cone contain photopigments that are maximally sensitive near 560nm, but their spectral sensitivities are different enough that the ratio of their activations gives a useful chromatic signal

Sex-related differences in chromatic sensitivity

Generally women are believed to be more discriminating than men in the use of colour names and this is often taken to imply superior colour vision. However, if both X-chromosome linked colour deficient males (~8%) and females (<1%) as well as heterozygote female carriers (~15%) are excluded from comparisons, then differences between men and women in red-green colour discrimination have been reported as not being significant (e.g., Pickford, 1944; Hood et al., 2006). We re-examined this question by assessing the performance of 150 males and 150 females on the Colour Assessment and Diagnosis (CAD) test (Rodriguez-Carmona, 2005). This is a sensitive test that yields small colour detection thresholds. The test employs direction-specific, moving, chromatic stimuli embedded in a background of random, dynamic, luminance contrast noise. A four-alternative, forced-choice procedure is employed to measure the subject’s thresholds for detection of colour signals in 16 directions in colour space, while ensuring that the subject cannot make use of any residual luminance contrast signals. In addition, we measured the Rayleigh anomaloscope matches in a subgroup of 111 males and 114 females. All the age-matched males (30.8 ± 9.7) and females (26.7 ± 8.8) had normal colour vision as diagnosed by a battery of conventional colour vision tests. Females with known colour deficient relatives were excluded from the study. Comparisons between the male and female groups revealed no significant differences in anomaloscope midpoints (p=0.709), but a significant difference in matching ranges (p=0.040); females on average tended to have a larger mean range (4.11) than males (3.75). Females also had significantly higher CAD thresholds than males along the red-green (p=0.0004), but not along the yellow-blue discrimination axis. The differences between males and females in red-green discrimination may be related to the heterozygosity in X-linked cone photopigment expression common among females