Color blindness

Introduction: Color Vision defect can be observed in various diseases of optic nerve and retina and also a significant number of people suffer from the inherited condition of red and green color defect.  Methods: A cross-sectional descritptive study was designed with purposive sampling of students from various schools of Kathmandu Valley. All children were subjected to color vision evaluation using Ishihara Isochromatic color plates along with other examination to rule out any other causes of color deficiency.  Results: A total of 2001 students were examined, 1050 male students and 951 females with mean age of 10.35 (±2.75) and 10.54 (±2.72) respectively. Among the total students examined, 2.1% had some form of color vision defects. Of the male population , 3.9% had color vision defects while none of the female was found with the deficiency.  Conclusions: The prelevance of color vision defect in Nepal is significant and comparable with the prelevance quoted in the studies from diffe...

ABSTRACT Purpose: Evaluation of computer based color deficiency test. Materials and Methods: Two hundred and sixty seven volunteers have been checked using both traditional Ishihara plates and a computer diagnosis program using LCD monitors. Results: The prevalence of red green color vision deficiency (RG-CVD) was 8.75% of male participants, no female participants were diagnosed, both in the paper based test, and in the computer based test. Computer based test gave 100% sensitivity and 98.78% specificity. Conclusion: Presenting the computer based color deficiency test software on LCD screen can be used for screening of color vision deficiency with nearly similar sensitivity and specificity to the Ishihara test with the advantage reducing the cost through decreasing required resources over time,and decreasing the time to analyze the results.

The overlays used by the Irlen method and the Intuitive system are A4 plastic sheets, with one ‘shiny’ and one ‘matte’ side. Wilkins, on the basis of his group’s research, concurs with Irlen’s opinion that filters should be individually-prescribed, as there exists an optimal color for each individual which will reduce their visual stress symptoms and facilitate their reading to the greatest extent (Wilkins, 2003; Wilkins et al. 2005; though see Simmers et al., 2001). The basic set of colors provided by the Irlen method and the Intuitive system are broadly similar (the chromaticity of the Intuitive Overlays, along with other details, can be found in Wilkins, 1994). In both systems, a patient’s optimal overlay is chosen using a process of elimination, often combined with questions relating to any visual stress symptoms the patient may be suffering from. This study describes the history of color overlays, the use of them as a treatment and various theoretical mechanisms which potentially explain the effects of colored filters on reading such as magnocellular theory.

Le daltonisme confusion des couleurs rouge et vert touche 8.8-9% des caucasiens et 0.4% des caucasiennes (à ne pas confondre avec créoles =antillais, guyanais ou réunionnais) qui ont donc des déficiences de perception des couleurs dont 4.6% = deutéranomalie et les 3.4% autres se répartissent de façon presqu'égale entre protanomalie, deutéranopie et protanopie, donc à peu près 1% de chaque catégorie). Le daltonisme a été décrit il y a deux siècles par le chimiste John Dalton 1766-1884 père de la théorie atomique, lui-même atteint de l'anomalie, et a été le premier à attirer l'attention sur ce genre d'affection. Pour Denden A., certains daltoniens auraient une vision scotopique meilleure que des sujets normaux. Pour Karma les protanopes ont un seuil scotopique plus élevé alors que chez d'autres types de daltoniens ce seuil est comme chez les sujets normaux. Pour Chapanis et Hecht et Hsia les protans sont moins sensibles en vision scotopique aux stimuli de longueur d'onde plus grande que les sujets normaux.

L'achromatopsie, dystrophie des cônes stationnaire, est une maladie congénitale rare 1/30'000 à 1/50'000, transmise selon un mode autosomique récessif, et qui présente une hétérogénéité génétique : trois gènes et un locus candidat seraient impliqués dans cette affection (Ne pas confondre :
1. MONOCHROMATISME= qui n'a qu'un type de cône fonctionnel et distingue une seule couleur, et ACHROMATOPSIE / ACHROMATISME qui n'a aucune vision de cônes et ne voit qu'avec les bâtonnets ;

2. DICHROMATES= n'ont que deux types de cônes au lieu de trois ;

3. la VISION EN NOIR ET GRIS incolore de la vision scotopique pcq PANCHROMATIQUE mais avec un maximum de sensibilité pour la longueur d'onde de 507 nanomètres, avec la VISION MONOCHROMATIQUE qui désigne la vision d'une seule fréquence ou longueur d'onde lumineuse), et surtout pas de la lumière blanche. Lumière monochromatique désigne une lumière composée de rayonnement d'une seule fréquence ou lambda= longueur d'onde ; il n'existe pratiquement pas de rayonnement monochromatique pur).

La TRICHROMIE est le principe (utilisé notamment en photographie, en cinéma, et en télévision) permettant de reproduite toutes les couleurs seulement à partir de trois couleurs primaires ou fondamentales, procédé mis au point par Louis Ducos du Hauron. On a toutefois identifié une mutation donnant à un faible pourcentage de la population, principalement de sexe féminin, des cônes sensibles au jaune.

La propriété / différenciation subjective des couleurs n'existe que dans notre cerveau, et deux personnes ne perçoivent pas la même longueur d'onde et un flux énergétique avec la même nuance.
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Reviews of modern productions of Marlowe’s Tamburlaine often note a three-hundred-year hiatus between a recorded performance in 1641, just before the closing of the theatres, and Tyrone Guthrie’s revival at the Old Vic in 1951. While the statement is mostly true with respect to Marlowe’s play, Tamerlane or Timūr Lenk and the Ottoman emperor Bayazid I (Marlowe’s Bajazeth) had important theatrical incarnations in the 1700s before they declined into parody in the 1800s. When Marlowe’s play was revived in the modern era, the main characters reclaimed their dignity, but they also acquired markers of racial, ethnic, or religious otherness that had not been prominent earlier. Timūr’s (and Bayazid’s) varied theatrical representations illustrate the malleability of iconic cultural figures, the sometimes problematic emphasis on ethnic difference in modern theatrical practice, and the challenges and opportunities of cross-racial casting.

Over a decade of research and debate, many educational policies around the world have shaped and transformed radically the education framework, in an effort to combat the racial inequality in schools.
In that essay, I try to illustrate the framework of color-blind ideology, considering if this is the best way of achieving race equality in education. It is true, that this issue is a really controversial one, which unavoidably shed the light on many contradictions, relevant with racial inequalities, cultural and social hierarchies and so on.
The reason that I would like to engage with such a subject, is that the issue of race-equality, touches many social aspects beyond education. For instance: human rights, social and educational justice, power relations of domination and subordination, the concept of whiteness, and other inherited contradictions in educational structure like the curriculum, the quality of teachers and  so on.

In the first part of essay, I  examine separately the roots and the political background of colorblind ideology, bringing then to the surface the attractive elements and the dilemmas of adoption such an ideology.
It is right or wrong to wear colorblind lens?
Are colorblind attitudes always right?
If not in what context does colorblind ideology work?
In the second part, we will discuss the opposite aspect of colorblindness, supporting the view that it is an optical and mental delusion of racial reality, which promote a new type of racism in and out of school gate.
Finally, we conclude with our main argument, suggesting some alternative ways or educational/pedagogical paths, of achieving race equality in education.

We report a study of the incidence of ‘colour-blindness’ in southern and central Africa, and we compare the African data with data from various European groups. There was a surprisingly high incidence of tritan errors (yellow–blue defect). The likelihood of making tritan errors increased with age, and was greater in rural areas than in towns. In Europe, no tritan errors were made by samples from the U.K., Eire or Spain, but some tritan errors were made by a sample from southern Greece. In contrast, most of a British sample of people over sixty-five years old makes tritan errors. Although tritan errors were the most frequent, they were often accompanied by protan and deutan errors. This mixed pattern of errors is consistent with the condition being acquired rather than congenital. Many languages of southern Africa categorise blues and greens with the same term. If the tritanopia we report has been endemic, it may have reduced the ‘perceptual pressure’ to split the blue-with-green categories into separate blue and green terms; a speculation consistent with Rivers, W. H. R. (1901. Introduction to A. C. Haddon (Ed.), Reports on the Cambridge Anthropological Expedition to the Torres Straits. Cambridge: Cambridge University Press) © 1998 Elsevier Science Ltd. All rights reserved..

ABSTRACT Purpose: Evaluation of computer based color deficiency test. Materials and Methods: Two hundred and sixty seven volunteers have been checked using both traditional Ishihara plates and a computer diagnosis program using LCD monitors. Results: The prevalence of red green color vision deficiency (RG-CVD) was 8.75% of male participants, no female participants were diagnosed, both in the paper based test, and in the computer based test. Computer based test gave 100% sensitivity and 98.78% specificity. Conclusion: Presenting the computer based color deficiency test software on LCD screen can be used for screening of color vision deficiency with nearly similar sensitivity and specificity to the Ishihara test with the advantage reducing the cost through decreasing required resources over time,and decreasing the time to analyze the results.