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Color vision deficiency

Authors:
  • The University of Sydney/Sydney Hospital & Sydney Eye Hospital

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Colour vision deficiency is one of the commonest disorders of vision and can be divided into congenital and acquired forms. Congenital colour vision deficiency affects as many as 8% of males and 0.5% of females--the difference in prevalence reflects the fact that the commonest forms of congenital colour vision deficiency are inherited in an X-linked recessive manner. Until relatively recently, our understanding of the pathophysiological basis of colour vision deficiency largely rested on behavioural data; however, modern molecular genetic techniques have helped to elucidate its mechanisms. The current management of congenital colour vision deficiency lies chiefly in appropriate counselling (including career counselling). Although visual aids may be of benefit to those with colour vision deficiency when performing certain tasks, the evidence suggests that they do not enable wearers to obtain normal colour discrimination. In the future, gene therapy remains a possibility, with animal models demonstrating amelioration following treatment.
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... CVD has been used interchangeably with the term "colour blindness" to describe poor visual functions of the cone opsin genes responsible for colour perception [3,4]. The physiological substrate of colour vision is the cone receptors of which there are three classes, each with different sensitivities to light wavelength including the blue cone-short wavelength, 420 nm; the green cone-medium wavelength, 530 nm; and the red cone-long wavelength, 560 nm [5,6]. There are three main forms of CVD, namely red-green, blueyellow and total colour blindness with red-green CVD being the most common of all [7]. ...
... Colour vision deficiency may be congenital (inherited) or acquired. While congenital colour vision deficiency (CCVD) arises from genetic disorder that affects the expression of the full complements of the cone genes, acquired colour deficiency results from environmental factors such as trauma, exposure to chemicals or reaction to certain medications [6,11,12]. The incidence of CCVD differs as per population, ethnicity and gender with a higher occurrence in males. ...
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Background Colour vision deficiency (CVD), also referred to as colour blindness, is the failure or decreased ability to distinguish between certain colours under normal lighting conditions. It is an X-linked genetic disorder with varying degrees of prevalence in different populations. There is presently no report on the prevalence of CVD among students of the selected tertiary institution. Hence, the present study was aimed at determining the occurrence and genetics of CVD among students from designated tertiary institutions in Lagos state. A cross-sectional survey was employed in recruiting 1191 study subjects from three tertiary institutions in Lagos, Nigeria. Results The overall occurrence of CVD among the study participants was 2.85%. There were 24 (4.29%) males and 10 (1.58%) females affected. Among the colour vision deficient individuals, 18 (1.51%) and 16 (1.34%) were deuteranomalous and protanomalous, respectively. Also, the prevalence of CVD varies across ethnic groups of the studied subjects with the highest occurrences (3.57%) observed in the Yoruba ethnic subpopulation and the least (1.45%) among the Hausas. Conclusions More males than females were found to be colour vision deficient, and there were more deutans than protans. Early screening for CVD should be encouraged among school children to guide the choice of future profession and help mitigate work hazards resulting from being colour deficient.
... The prevalence of color vision deficiencies (CVD) is around 8% in men and 0.5% in women [1,2]. People with CVD (called CVD observers), find difficulties in their daily lives such as: acknowledging the bad conservation state of some food, realizing when the other person is blushing, differentiating among players of different teams in sports, etc. [1]. ...
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There is a belief that observers with color vision deficiencies (CVD) perform better in detecting camouflaged objects than normal observers. Some studies have concluded contradictory findings when studying the performance of normal and CVD observers in the camouflage detection tasks in different conditions. This work presents a literature review on this topic, dividing it into three different and contradictory types of results: better performance for CVD, for normal observers, or same performance. Besides, two psychophysical experiments have been designed and carried out in a calibrated computer monitor on both normal and CVD human observers to measure the searching times of the different types of observers needed to find camouflaged stimuli in two different types of stimuli. Results show the trend that, in our experimental conditions, normal observers need shorter searching times than CVD observers in finding camouflaged stimuli both in images of natural scenes and in images with synthetic stimuli.
... The survey included individuals with visual acuity worse than 6/18 in either eye or the exclusion of patients with corneal opacity from intraocular measurement could have resulted in underestimating the prevalence of glaucoma [3] The estimated number of visually impaired people is globally 285 million, 39 million blind, and 246 million have low vision [1] . Blindness prevalence rates vary widely, but evidence suggests that approximately 21% of Africans are blind [4] . In Ethiopia, the prevalence of blindness and low vision are 3.7% and 1.6%, respectively [5] . ...
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Background Glaucoma is a neurodegenerative condition that affects the eye and is associated with increased intraocular pressure. Intraocular pressure is the fluid pressure inside the eye and its disturbance often is implicated in the development of pathologies such as glaucoma, uveitis and retinal detachment. The aim of the present study was to identify factors that affect the longitudinal intraocular pressure of glaucoma patients attending the ophthalmology clinic at Felege Hiwot Comprehensive Specialized Hospital, Bahir Dar, Ethiopia, using a Bayesian linear mixed model analysis. Methods In a longitudinal study with data obtained from glaucoma patients admitted to Felege Hiwot Hospital, the measurement of intraocular pressure change was applied. The study subjects were enrolled in the period between 1st January 2016 and 1st January 2020 and a total of 328 patients were selected for the study. Data were explored using descriptive statistics and individual and mean profile plots throughout study time. A Bayesian linear mixed model for the longitudinal data was used along with their model comparison, model estimation, model diagnosis and missing data analysis. Results The analysis included 328 individuals with 9 for maximum and 2 for minimum repeated measurements of intraocular pressure change, including the baseline. From the Bayesian linear mixed model variables, observation time, age, place of residence, gender, the cup-disk ratio of patients, type of medication (like Pilocarpin, Timolol with Pilocarpin, Timolol with Diamox with Pilocarpin), and blood pressure of the glaucoma patients significantly affected the intraocular pressure changes over time. However, the type of medication (Diamox and Timolol with Diamox) did not affect the intraocular pressure changes over time. Conclusion Based on the Bayesian linear mixed model analysis, we found that the predictor variables of age, blood pressure, family history, residence, gender, diabetic disease, treatment duration, stages of glaucoma, type of medication and cup-disk ratio significantly affected the average intraocular pressure and had a positive association with the responses of intraocular pressure of glaucoma patients. Furthermore, the type of medication was statistically significant and negatively associated with the responses to intraocular pressure. Recommendation We recommend the health professionals to give more attention to the type of medication especially Timolol with Pilocarpin, Timolol with Diamox and Timolol with Diamox with Pilocarpine. And taking the combination with the other type of medication minimizes the risk of blindness and intraocular pressure.
... People who suffer from CVD are usually described by their kind of deficiency. Based on the defect type, there are three CVD groups, including dichromacy (missing photoreceptor cone), anomalous trichromacy (faulty photoreceptor cone), and monochromacy (at least two missing photoreceptor cones) [91,92]. In recent years, extensive experiments have been conducted for CVD treatment. ...
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In recent years, wearable contact lenses for medical applications have attracted significant attention, as they enable continuous real-time recording of physiological information via active and noninvasive measurements. These devices play a vital role in continuous monitoring of intraocular pressure (IOP), noninvasive glucose monitoring in diabetes patients, drug delivery for the treatment of ocular illnesses, and colorblindness treatment. In specific, this class of medical devices is rapidly advancing in the area of drug loading and ocular drug release through incorporation of electrospun fibers. The electrospun fiber matrices offer a high surface area, controlled morphology, wettability, biocompatibility, and tunable porosity, which are highly desirable for controlled drug release. This article provides an overview of the advances of contact lens devices in medical applications with a focus on four main applications of these soft wearable devices: (i) IOP measurement and monitoring, (ii) glucose detection, (iii) ocular drug delivery, and (iv) colorblindness treatment. For each category and application, significant challenges and shortcomings of the current devices are thoroughly discussed, and new areas of opportunity are suggested. We also emphasize the role of electrospun fibers, their fabrication methods along with their characteristics, and the integration of diverse fiber types within the structure of the wearable contact lenses for efficient drug loading, in addition to controlled and sustained drug release. This review article also presents relevant statistics on the evolution of medical contact lenses over the last two decades, their strengths, and the future avenues for making the essential transition from clinical trials to real-world applications.
... The prevalence of CVD in our students, at 4.87% among the male population, was lower than that reported from the general population (6%-8%). [7,8] The reason could be that our sample was from a limited institutional population. ...
Article
Purpose: To evaluate the impact of color vision deficiency (CVD) in medical undergraduates by a more clinically applicable test. Methods: Cross-sectional study of 31 students with CVD (Ishihara diagnosed) asked to identify subject-specific signs/tests requiring color identification on a customized medical multispecialty designed color album test (CAT). They were further subjected to Farnsworth D-15 testing. Results: The error score of CVD students (4 ± 3.2) on 39 plates of color album test was highly significant as compared to the error score of color normal (0.3 ± 0.6). The CAT depicted linear correlation with Farnsworth D-15 and emerged as a valid tool of assessment. Ishihara interpretation did not correlate with the clinical impact of CVD. Nature of error suggests that CVD students can anticipate problems in dermatology, pathology, hematology, microbiology, and biochemistry. Conclusion: Color album test is a more clinically relevant test for CVD doctors to identify specialties where they can anticipate difficulties.
... Achromatopsia (ACHM) is a rare autosomal recessive inherited disease with an incidence of 1 in 30,000 [1][2][3]. ACHM is due to congenital dysfunction of the cone photoreceptors and biallelic mutations in six different genes (i.e., CNGA3, CNGB3, GNAT2, PDE6H, PDE6C, and ATF6) that are responsible for >90% of the cases [4]. Individuals affected by ACHM (achromats) are clinically characterized by poor visual acuity, absence of color perception, nystagmus, photophobia, and central scotoma [1,5,6]. ...
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Achromatopsia (ACHM) is an inherited autosomal recessive disease lacking cone photoreceptors functions. In this study, we characterize the time-frequency representation of the full-field electroretinogram (ffERG) component oscillatory potentials (OPs), to investigate the connections between photoreceptors and the inner retinal network using ACHM as a model. Time-frequency characterization of OPs was extracted from 52 controls and 41 achromat individuals. The stimulation via ffERG was delivered under dark-adaptation (DA, 3.0 and 10.0 cd·s·m−2) to assess mixed rod-cone responses. The ffERG signal was subsequently analyzed using a continuous complex Morlet transform. Time-frequency maps of both DA conditions show the characterization of OPs, disclosing in both groups two distinct time-frequency windows (~70–100 Hz and >100 Hz) within 50 ms. Our main result indicates a significant cluster (p < 0.05) in both conditions of reduced relative power (dB) in ACHM people compared to controls, mainly at the time-frequency window >100 Hz. These results suggest that the strongly reduced but not absent activity of OPs above 100 Hz is mostly driven by cones and only in small part by rods. Thus, the lack of cone modulation of OPs gives important insights into interactions between photoreceptors and the inner retinal network and can be used as a biomarker for monitoring cone connection to the inner retina.
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We set out to develop a simple objective test of functional colour vision based on eye movements made in response to moving patterns. We exploit the finding that while the motion of a colour-defined stimulus can be cancelled by adding a low-contrast luminance-defined stimulus moving in the opposite direction, the “equivalent luminance contrast” required for such cancellation is reduced when colour vision is abnormal. We used a consumer-grade infrared eye-tracker to measure eye movements made in response to coloured patterns drifting at different speeds. An automated analysis of these movements estimated individuals’ red-green equiluminant point and their equivalent luminance contrast. We tested 34 participants: 23 colour vision normal controls, 9 deuteranomalous and 2 protanomalous individuals. We obtained reliable estimates of strength of directed eye movements (i.e. combined optokinetic and voluntary tracking) for stimuli moving at 16 deg/s and could use these data to classify participants’ colour vision status with a sensitivity rate of 90.9% and a specificity rate of 91.3%. We conclude that an objective test of functional colour vision combining a motion-nulling technique with an automated analysis of eye movements can diagnose and assess the severity of protanopia and deuteranopia. The test places minimal demands on patients (who simply view a series of moving patterns for less than 90 s), requires modest operator expertise, and can be run on affordable hardware.
Article
Color vision deficiency (CVD) is a common ocular disorder that hampers patients’ color distinction capabilities, causing them difficulties in their daily life routine. Till date, a CVD cure has not been developed, and treatment courses, such as gene therapy, are yet to be applied on humans. Hence, patients opt for wearable visual aids such as tinted glasses/contact lenses, which achieve the latter by filtering out problematic wavelengths for blue‐yellow (440‐500 nm) and red‐green (540‐580 nm) CVD patients, thus, enabling them to distinguish between the colors. Here, we report the development of 3D printed glasses for color blindness management. A commercially available highly transparent resin (˃95%), was utilized, and two wavelength filtering dyes, with absorption ranges of 550‐580 nm and 440‐510 nm, respectively, were mixed with the resin. The tinted glasses were successfully 3D printed using Masked SLA 3D printer; dyes incorporated within the glasses exhibited high stability over one‐week period. The manufactured glasses successfully blocked more than 50% of the undesired wavelengths along with showing high transparency (˃85%) to the remaining portion of the visible light spectrum. When using the developed glasses, volunteers showed substantial improvements in Ishihara test scores, which signifies the potential of these glasses as CVD wearables. This article is protected by copyright. All rights reserved.
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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.
Chapter
It is 200 years since George Palmer suggested that colour vision depended on three classes of molecule or membrane. The present paper gives an introductory review of what is today known of the opsins, of the genes that encode them, and of the alterations to which they are subject. Several theories of anomalous trichromacy are briefly reviewed.
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A broadband red filter placed over one eye will have the effect of improving the ability of certain color vision defectives to name colors correctly. A red-tinted contact lens will have the same effect; such a device is marketed under the name, the X-Chrom lens. In this article, the author examines the basic properties of color vision defects, explains the optical effect of the red filter, and reviews several studies which evaluate the effect of the X-Chrom lens. He concludes that while the lens may allow the wearer to achieve a better score on certain color vision tests, it does not actually correct color vision in the natural environment. Deleterious effects of wearing a red filter are also discussed. It is advised that patients wearing the X-Chrom lens be fully apprised of its limitations and of dangers that may be created by the associated visual distortions.
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Citation DEANE B. JUDD, "Facts of Color-Blindness," J. Opt. Soc. Am. 33, 294-294 (1943) http://www.opticsinfobase.org/josa/abstract.cfm?URI=josa-33-6-294
Article
The color deficient often seek visual aids to mitigate their color confusions. The most popular aids are red high-pass filters worn monocularly. Any benefit offered by such aids is limited to specific tasks and/or hue regions and may be negated by deleterious side- effects, including reduced luminance and visual acuity, induced visual distortions, altered stereopsis, and impaired depth perception. Different types of filters, taking into account advances in the molecular genetics of color vision and in coating technology, may offer greater advantages. © 2000 John Wiley & Sons, Inc. Col Res Appl, 26, S269–S272, 2001