Color Vision Deficiency Research Articles

A large population study reveals a novel association between congenital color vision deficiency and environmental factors.

To assess the associations between the prevalence of congenital color vision deficiency (CVD) and genetics and environment, represented by place of origin (ethnic background) and place of birth, respectively. This is a retrospective study of the computerized database of the northern recruitment center of Israel of 53,895 consecutive male Jewish conscripts 16-19years old, who completed the medical profiling process between 1988 and 2011. CVD was diagnosed using the 24-pseudo-isochromatic plate Ishihara test. Associations of CVD prevalence with sociodemographic variables, anthropometric indices, refractive errors, and mainly place of origin and place of birth were tested by both univariate analysis and multivariate regression models. Elevated BMI (obesity) and blood pressure (hypertension), as well as myopia, were all positively associated with congenital CVD. The composition of the study population provides a unique opportunity to investigate the relationship between ethnicity and environment. The prevalence of CVD significantly differs among subpopulations of different ethnic background as well as among those who were born in different geographical locations. Additionally, differences in the prevalence of CVD (1.2-1.6%) were observed among conscripts from the same origin, who were born in Israel, compared to those who were born elsewhere. Both place of origin (p < 0.01) and place of birth (p < 0.05) were associated with the prevalence of CVD in a multivariable regression model. This study affirms previously established associations of CVD with certain variables and reveals a possible novel association of CVD with environmental factors.

The Effects of a Blue-Light Filtering Versus Clear Intraocular Implant on Color Appearance.

PurposeMore than a dozen studies have investigated whether blue-light filtering (BLF) intraocular lens (IOL) implants influence color vision, generally finding they do not. These studies have not tested color vision per se; rather, they have measured color vision deficiencies or chromatic discrimination. Here, we used additive trichromatic colorimetry to assess color appearance in participants with BLF and clear IOL.MethodsSeventy-six participants were recruited from two populations: older participants (n = 52) with BLF and clear IOL (n = 98 eyes; M = 67.33 ± 7.48 years; 58.8% female; 25.5% non-White), and young adult control participants (n = 24; M = 21.0 ± 5.13 years; 70.8% female; 41.5% non-White). Participants used a custom-built tricolorimeter to mix three primaries until a perceived perfect neutral white was achieved. Color appearance, expressed as chromaticity coordinates, was measured with a spectral radiometer (ILS950).ResultsBetween subjects, the BLF IOL chromaticity coordinates (x = 0.34, y = 0.35, u′ = 0.21, v′ = 0.48) were not significantly different from the clear IOL (x = 0.34, y = 0.33, u′ = 0.22, v′ = 0.48). BLF and clear IOL were also not different within-contralateral subjects (n = 21; BLF x = 0.34, y = 0.33, u′ = 0.22, v′ = 0.47; clear x = 0.34, y = 0.33, u′ = 0.21, v′ = 0.48). Both IOL groups differed from young adults (v′[0.45; P = 0.001], x[0.31; P = 0.008], and y[ 0.30, P < 0.000], but not u′[0.21]).ConclusionsOne advantage of geometric representation of color space is the ability to specify the appearance (rather than spectral composition) of any light mixture by specific coordinates. Using this system, only minor differences in color appearance were found between a BLF, clear IOL, and young natural lens.Translational RelevanceWhen color perception is directly measured, the BLF and clear IOL are not meaningfully different.

Gamut mapping based image enhancement algorithm for color deficiencies.

This study presents an approach for enhancing color images for color vision deficiencies. The proposed approach is separated into three stages. First, the type and severity of a color deficient observer (CDO) were evaluated. Following that, the perceived color gamut was assessed using a physiologically-based color deficiency simulation model. Finally, images prepared for color normal observers (CNOs) were re-colored using a gamut mapping method to map colors from the gamut of a CNO to that of a CDO. Two psychophysical experiments were carried out to validate this method, and the results suggest that it is a promising solution for the CDOs. The unique feature of the present method is to include a gamut mapping method to enhance the color discrimination by preserving the perceived hue.

A mathematical approach to assess the ability of light filters to improve color discriminability of color vision deficient persons

Color vision deficiency (CVD) is a frequent condition that alters color perception to such an extent that many people encounter serious difficulties on their everyday lives. In this work, we present a strategy to analyze the effectiveness of light filters aimed to improve color discriminability of persons with CVD. The calculations are based on a simple model of color discrimination which has been successfully applied to several animal species. We first tested the calculations on three well-known commercial lenses designed for persons with CVD. In agreement with results of clinical studies, the calculations show that the highly colored lenses (VINO® and X-Chrom®) enhance chromaticity contrasts between problematic colors, whereas the more neutral Enchroma® do not provide any benefit. Also, we predict that two light filters proposed in recent works for novel lenses would not improve the performance of the commercial ones. Since the mathematical approach presented in this work enables predictive filter assessment, it opens the door to future research on the design of more effective lenses to improve color discriminability of persons with CVD. The calculations allow for large-scale screening of numerous light filters and different colored stimuli, CVD conditions, light sources, etc.

ColourSpot, a novel gamified tablet-based test for accurate diagnosis of color vision deficiency in young children

There is a need for a straightforward, accessible and accurate pediatric test for color vision deficiency (CVD). We present and evaluate ColourSpot, a self-administered, gamified and color calibrated tablet-based app, which diagnoses CVD from age 4. Children tap colored targets with saturations that are altered adaptively along the three dichromatic confusion lines. Two cohorts (Total, N = 772; Discovery, N = 236; Validation, N = 536) of 4–7-year-old boys were screened using the Ishihara test for Unlettered Persons and the Neitz Test of Color Vision. ColourSpot was evaluated by testing any child who made an error on the Ishihara Unlettered test alongside a randomly selected control group who made no errors. Psychometric functions were fit to the data and “threshold ratios” were calculated as the ratio of tritan to protan or deutan thresholds. Based on the threshold ratios derived using an optimal fitting procedure that best categorized children in the discovery cohort, ColourSpot showed a sensitivity of 1.00 and a specificity of 0.97 for classifying CVD against the Ishihara Unlettered in the independent validation cohort. ColourSpot was also able to categorize individuals with ambiguous results on the Ishihara Unlettered. Compared to the Ishihara Unlettered, the Neitz Test generated an unacceptably high level of false positives. ColourSpot is an accurate test for CVD, which could be used by anyone to diagnose CVD in children from the start of their education. ColourSpot could also have a wider impact: its interface could be adapted for measuring other aspects of children’s visual performance.

Rainbow color map distorts and misleads research in hydrology – guidance for better visualizations and science communication

Abstract. Nowadays color in scientific visualizations is standard and extensively used to group, highlight or delineate different parts of data in visualizations. The rainbow color map (also known as jet color map) is famous for its appealing use of the full visual spectrum with impressive changes in chroma and luminance. Besides attracting attention, science has for decades criticized the rainbow color map for its non-linear and erratic change of hue and luminance along the data variation. The missed uniformity causes a misrepresentation of data values and flaws in science communication. The rainbow color map is scientifically incorrect and hardly decodable for a considerable number of people due to color vision deficiency (CVD) or other vision impairments. Here we aim to raise awareness of how widely used the rainbow color map still is in hydrology. To this end, we perform a paper survey scanning for color issues in around 1000 scientific publications in three different journals including papers published between 2005 and 2020. In this survey, depending on the journal, 16 %–24 % of the publications have a rainbow color map and around the same ratio of papers (18 %–29 %) uses red–green elements often in a way that color is the only possibility to decode the visualized groups of data. Given these shares, there is a 99.6 % chance to pick at least one visual problematic publication in 10 randomly chosen papers from our survey. To overcome the use of the rainbow color maps in science, we propose some tools and techniques focusing on improvement of typical visualization types in hydrological science. We give guidance on how to avoid, improve and trust color in a proper and scientific way. Finally, we outline an approach how the rainbow color map flaws should be communicated across different status groups in science.

Considerations for Categorizing and Visualizing Numerical Information: A Case Study of Fire Occurrence Prediction Models in the Province of Ontario, Canada

Wildland fire management decision-makers need to quickly understand large amounts of quantitative information under stressful conditions. Categorization and visualization “schemes” have long been used to help, but how they are done affects the speed and accuracy of interpretation. Using traditional fire management schemes can unduly restrict the design of new products. Our design process for Ontario’s fine-scale, spatially explicit, daily fire occurrence prediction (FOP) models led us to develop guidance for designing new schemes. We show selected historical fire management schemes and describe our method. It includes specifying goals and requirements, exploring design options and making trade-offs. The design options include gradient continuity, hue selection, range completeness and scale linearity. We apply our method to a case study on designing the scheme for Ontario’s FOP models. We arrived at a smooth, nonlinear scale that accommodates data spanning many orders of magnitude. The colouring draws attention according to levels of concern, reveals meaningful spatial patterns and accommodates some colour vision deficiencies. Our method seems simple now but reconciles complex considerations and is useful for mapping many other datasets. Our method improved the clarity and ease of interpretation of several information products used by fire management decision-makers.

English

BACKGROUND Colour vision is a function of three types of cone pigments present in the retina. Colour vision deficiency is an important disorder of vision that may pose a handicap to the performance of an affected individual. The prevalence of colour blindness varies in different geographical areas. The identification and estimation of the prevalence of colour vision deficiency in school-going children will help to educate and guide the caregivers to help the children in selecting their profession. This study was done to estimate the prevalence, sex distribution, and types of colour vision deficiency among school-going children of 5 to 15 years. METHODS A cross-sectional observational study was done among 500 students to evaluate the colour vision during the period from 1st January 2018 to 30th June 2019 at the Regional Institute of Ophthalmology, Kolkata. Ishihara’s pseudo isochromatic colour vision chart 38th edition was used to assess the school children for colour vision status. The children who were found to be colour blind were further classified into degree and types of colour vision deficiency. RESULTS A total of 500 students (250 male &amp; 250 female) of surrounding schools, in the age group of 5 years to 15 years, were screened. 480 students (96 %) had normal colour vision while 20 (4 %) students were found to have defective colour vision. Prevalence (4 %) for colour blindness was found to be higher in males (3.6 %) than females (0.4 %). It was observed that out of 20 (4 %) colour-blind subjects 3.6 % were protanopes and 0.4 % were deuteranopes. CONCLUSIONS The present study shows the prevalence of colour blindness found to be quite low (4 %) and more common in males (3.6 %) in comparison to females (0.4 %). Protanomaly (3.6 %) was more common than deuteranomaly (0.4 %). KEYWORDS Colour Blindness, Protanomaly, Deuteranomaly, School Children

Prevalence of Color Blindness Among Medical Students

Aim: To find out the prevalence of color blindness among medical students.&#x0D; Study Design: Descriptive cross-sectional.&#x0D; Place and Duration of Study: Study was conducted at Chaudry Mohammad Akram teaching and research hospital, Superior university during December 2020 to May 2021.&#x0D; Methodology: All the medical students having age range between 21-25 years were included in the study. An ophthalmologist did ocular examination, after that color vision was checked by putting Ishihara plates. The score less than 12 out of 14 red-green test plates were labelled as color blind. Data was analyzed by using the SPSS version 20. Chi-square was used to find out the association of color blindness with age groups and gender. p-value less than 0.05 was considered as significant.&#x0D; Results: The mean age with standard deviation of study participants was 23.27 ± 0.87 years. The prevalence of color blindness among medical students was 2% out of which 1.7% were having strong red-green deficiency while only 0.3% were with mild red-green deficiency. Majority of participants with color blindness were noted in the age group of 22 years while very few were in the other age groups of medical students but these results were non-significant. On the other hand, all the color blind was male but no association was found as the p-value was more than 0.05.&#x0D; Conclusion: Current study reported that about 2% of medical students are affected by color vision deficiency. So there is a need of proper visual screening program among medical undergraduates for early detection of color blindness and counselling session for them.

Image recoloring for color vision deficiency compensation: a survey

People with color vision deficiency (CVD) have a reduced capability to discriminate different colors. This impairment can cause inconveniences in the individuals’ daily lives and may even expose them to dangerous situations, such as failing to read traffic signals. CVD affects approximately 200 million people worldwide. In order to compensate for CVD, a significant number of image recoloring studies have been proposed. In this survey, we briefly review the representative existing recoloring methods and categorize them according to their methodological characteristics. Concurrently, we summarize the evaluation metrics, both subjective and quantitative, introduced in the existing studies and compare the state-of-the-art studies using the experimental evaluation results with the quantitative metrics.

Prevalence and types of color vision deficiency among primary school students in Alexandria

Purpose The aim of this study was to determine the prevalence and types of color vision deficiency (CVD) among primary school students in Alexandria, Egypt. Setting This study was carried out at three primary schools in Alexandria, Egypt. Patients and methods This cross-sectional study was carried out among three primary school students in Alexandria, Egypt. Ocular examination including visual acuity and color vision testing with Ishihara plates (38-plate edition) was performed for all the students included. Further assessment using the Farnsworth–Munsell 100-hue test was performed for students who failed the Ishihara plates test. Results A total of 1000 (495 males and 505 females) school students were screened for CVD. The mean age of the students was 9±2.16 years. The overall prevalence of CVD was 1.9%, with a prevalence of 2.8 and 0.9% in males and females, respectively, a statistically significant difference (P=0.04). Among the CVD students, 36.8% had deuteranopia, 31.5% had deuteranomaly, 26.3% had protanopia, and 5.3% had tritanopia. Conclusion The prevalence of CVD was 1.9%, with a male predominance, among primary school students in Alexandria. Deutan color vision defects were the most prevalent.

RFID AND VIRTUAL REALITY TEST SETUP FOR VISUALLY IMPAIRED ASSISTIVE TECHNOLOGY

Visual impairments often pose serious restrictions on a visually impaired person and there is a considerable number of persons, especially among aging population, which depend on assistive technology to sustain their quality of life. Development and testing of assistive technology for visually impaired requires gathering information and conducting studies on both healthy and visually impaired individuals in a controlled environment. We propose test setup for visually impaired persons by creating RFID based assistive environment – Visual Impairment Friendly RFID Room. The test setup can be used to evaluate RFID object localization and its use by visually impaired persons. To certain extent every impairment has individual characteristics as different individuals may better respond to different subsets of visual information. We use virtual reality prototype to both simulate visual impairment and map full visual information to the subset that visually impaired person can perceive. Time-domain color mapping real-time image processing is used to evaluate the virtual reality prototype targeting color vision deficiency.

Frequency of Color Blindness in Driving License Candidates Presenting in Allied Hospital, Faisalabad

Background: Color vision is an integral part of visual functions. Defective color vision may leadto difficulties in daily activities and even choosing and continuing in a certain profession. Colorvision deficiency or blindness may be congenital or acquired due to retinal or optic nerve disorders Aim: To investigate the frequency of color blindness or weakness in driving license candidates presenting for medical exam, for the year 2019. Methodology: The study design was descriptive cross sectional and the sampling technique wasnon probability convenient sampling. The place of study was eye outdoor of Allied Hospital,Faisalabad. The sample size was 13,637 based on inclusion criteria. The subjects ranged in agefrom 18 years onwards to a maximum presentation of 76 years with mean age as 30.728 ±10.131.Both genders were included in the study. Visual acuity was tested on Snellen’s Chart andrefraction, if needed, was performed to obtain best corrected acuity. Results: The results of the study showed that most of the subjects had 6/6 vision as 96.6% in righteye and 96.5% in left eye, 6/9 as 2.8% and 2.9% and 6/12 as 0.3% and 0.4% respectively for rightand left eye. The frequency of normal color vision was 94%, 4.9% for red green deficiency and 1.1% for color blindness. Conclusion: A frequency of 4.9% and 1.1% for color deficiency and color blindness respectively, in drivers, indicates that color vision must be tested to avoid any possible accidents related todeficient color perception. Keywords: Driving license, colorblindness

The Predictive Role of Thyroid Hormone Levels for Early Diabetic Retinal Changes in Experimental Rat and Human Diabetes.

PurposeIn diabetic subjects, early visual functional alterations such as color vision deficiencies (CVDs) are known to precede clinically apparent diabetic retinopathy. Prominent photoreceptor outer segment degeneration and an increase in the number of retinal dual cones (co-expressing S- and M-opsins simultaneously) have been described in diabetic rat models, suggesting a connection with the development of CVDs. As cone opsin expression is controlled by thyroid hormones, we investigated the diabetic retina in association with thyroid hormone alterations.MethodsIn rat models of type 1 and 2 diabetes, dual cones were labeled by immunohistochemistry, and their numbers were analyzed in relation to free triiodothyronine (fT3) and free thyroxine (fT4) levels. Quantification of dual cones was also performed in human postmortem retinas. Additionally, a cross-sectional case–control study was performed where thyroid hormone levels were measured and color vision was assessed with Lanthony desaturated D15 discs.ResultsA higher number of dual cones was detectable in diabetic rats, correlating with fT4 levels. Dual cones were also present in postmortem human retinas, with higher numbers in the three diabetic retinas. As expected, age was strongly associated with CVDs in human patients, and the presence of diabetes also increased the risk. However, the current study failed to detect any effect of thyroid hormones on the development of CVDs.ConclusionsOur results point toward the involvement of thyroid homeostasis in the opsin expression changes in diabetic rats and human samples. The evaluation of the possible clinical consequences warrants further research.

Methodology for heuristic evaluation of the accessibility of statistical charts for people with low vision and color vision deficiency

Methodology for heuristic evaluation of the accessibility of statistical charts for people with low vision and color vision deficiency

Appearance of special colors in deuteranomalous trichromacy

Deuteranomalous color matching behavior is different from normal because the middle-wavelength sensitive cones contain an abnormal Lʹ pigment instead of the M pigment of the normal observer. However, there is growing evidence that deuteranomalous color experience is not very different from that of normal trichromats. Here, normal and deuteranomalous observers chose monochromatic unique yellow lights. They also chose broadband lights, displayed on a computer monitor, that corresponded to eight special colors: the Hering unique hues (red, yellow, green, blue), and binary colors perceptually midway between them (orange, lime, cyan, purple). Deuteranomalous monochromatic unique yellow was shifted towards red, but all the broadband special color selections were physically similar for normal and deuteranomalous observers. Deuteranomalous special colors, including monochromatic unique yellow, were similar to those of normal observers when expressed in a color-opponent chromaticity diagram based on their own visual pigments, but only if (1) color-opponent responses were normalized to white, and (2) the deuteranomalous diagram was expanded along the r – g dimension to compensate for the reduced difference between deuteranomalous L- and Lʹ-cone photopigments. Particularly, deuteranomalous observers did not choose binary colors with extra r – g impact to overcome their insensitivity along the r – g dimension. This result can only be compatible with the known abnormality of the deuteranomalous Lʹ photopigment if deuteranomalous observers adjust their perceptual representation of colors to compensate for their color vision deficiency.

Fast contrast and naturalness preserving image recolouring for dichromats

People with colour vision deficiency (CVD) may have difficulty recognising or discriminating colours. To enhance their visual details, some methods have been developed to enhance colour contrast. Recently, researchers realized the importance of preserving naturalness in the processed images to avoid decreasing the quality of vision (QOV) and state-of-the-art image recolouring methods succeeded in realising both contrast enhancement and naturalness preservation by utilising optimisation model. However, the high computational cost of these methods prevents their wide application in daily lives. Moreover, these methods cannot automatically resolve the trade-off between contrast enhancement and naturalness preservation. This paper proposes Optimized Dichromacy Projection (ODP) as a novel high-speed image recolouring technique for dichromacy compensation. ODP achieves both contrast enhancement and naturalness preservation by computing an optimized projection from the colour gamut of normal vision to the colour gamut of dichromacy and can automatically adapt the weight of contrast enhancement and naturalness preservation to the property of individual images. Qualitative, quantitative, and subjective evaluation experiments show that the proposed method can generate images of qualities competitive to the state-of-the-art methods while drastically improving computation time.

Impact of new chelating agents on ocular abnormalities in β-thalassemia major patients

Objectives The objectives of this study were to assess ocular changes in β-thalassemia major patients who have received multiple transfusions and different chelating agents. Patients and methods A cross-sectional study of 90 β-thalassemia major patients from age group 14 to 24 years were selected as case group, and 90 age-matched and sex-matched healthy participants were considered as a control group. Full medical history and thorough physical examinations were done to all patient groups. Ocular examination, including visual acuity, refraction testing, slit-lamp examination, funduscopy, tonometry, perimetry, tear-breakup time test, and color-vision testing, was performed for all the participants. We computed the frequency and duration of blood transfusion, the mean serum ferritin level, pretransfusion hemoglobin concentration, the type, duration, and daily dose of chelation therapy for thalassemia patients based on their records. Results All thalassemic patients were asymptomatic, but abnormal ocular findings [dry eye (13.3%), cataract (10%), retinal changes (16.7%), color-vision deficiency (3.33%), ocular hypertension (6.67%), and visual acuity (8.88%)] were seen in 58.9% of thalassemic group. The prevalence of ocular abnormalities in the control group was 19.4%, which was significantly lower than that in thalassemia patients (P=0.000). No significant correlation was found between ocular abnormalities and mean serum ferritin level (P=0.627) and mean hemoglobin concentration (P=0.143). A positive correlation between the number of blood transfusions with the presence of ocular abnormalities was found to be statistically significant (P=0.005). Recommendations As life expectancy for β-thalassemia patients extends, regular ophthalmologic evaluation to detect early changes in their ocular system is recommended.

Colour vision deficiency: the 'unseen' disability.

Colour vision deficiency: the 'unseen' disability.

A novel image quality assessment method and coefficient of quality for digital solutions of colour blindness

Eyesight is one of the primary senses that human beings have. Reports show that colour blindness, a form of colour vision deficiency (CVD), affects about 8% of the male population and 0.5% of female population. The Assistive Technology Act of 2004 lays focus on technologies that help individuals with disabilities and deficiencies. With the rapid advancement in technologies, several assistive solutions are available for visually impaired or CVD patients. Such solutions involve simulation and compensation of conflicting colours to help the colour blind in the visual perception of colours. Given the increased usage of the web, post the pandemic, these solutions improve the quality of life for the colour blind. Defining the image quality assessment criteria for such digital solutions becomes imperative. The study proposes a novel method for image quality assessment of digital solutions aimed at assisting the colour blind users. The proposed coefficient of quality (CQ) would be useful to rank colour compensation and recolouring algorithms. Experiments were conducted with a novel questionnaire set designed for this quality measurement. The results affirm the efficiency of the assessment method proposed. This will also provide objective feedback to the researchers and experts in this area to improve their solutions for CVD patients.