Identification of OPN1LW Exon 3 Variants Impairing Red-Cone Function in Color Vision Deficiency

Dear Sir, As members of the state's medical board, the authors wish to share some of the difficulties encountered while testing candidates for color vision deficiency (CVD). Though many methods for color vision testing are available, there is no consensus on the ideal method, with different countries using different tests. In India, the Ishihara charts are the most widely used, with additional use of Edridge-Green lantern in civil services and Martin lantern in armed forces.[1,2] The Ishihara test is quick and easy and is an excellent screening tool to detect those with red-green CVD. However, it has a limited ability to classify CVD and determine its severity. Organizations that require the correct recognition of colored signals (principally transport groups such as the Civil Aviation Authority, Railways, Maritime, and Naval and Air force) depend on a standard lantern test which imitates actual signal systems simulating the workplace. Lanterns do not specifically screen for color defects. It is surprising that even now, the general design of lanterns has not changed very much since their creation in 1891. With the exception of the Farnsworth lantern used in the USA, there are scarce studies on the validation and reliability of lanterns. The panel tests, including the Farnsworth Panel D-15 and Farnsworth–Munsell 100-hue tests, are much more accurate in classifying color deficiency. Farnsworth Panel D-15 Test is considerably quicker and more convenient test for routine clinical use. Though not very sensitive, its speed and accuracy make it useful. The relative insensitivity can also be an asset in judging the practical significance of mild degrees of color deficiency. For example, individuals who fail the Ishihara plates but pass the D-15 panel will probably not have color discrimination problems under most circumstances and in most jobs.[3] Nagels anomaloscopes is considered the gold standard for color vision testing in clinical research, however, it is an expensive instrument requiring an experienced examiner's skills. Color vision is graded into higher and lower grade depending on the size of the aperture in the Edridge-Green lantern (1.3 mm vs. 13 mm),[1] with the technical services category of Indian civil services, which includes police services requiring higher grade of color vision. The United States police service no longer implements a color vision standard though monochromats are barred.[4] Those who fail initial color vision screening by pseudoisochromatic plates should be further evaluated by anamaloscope or D-15 test to include anomalous trichromats who are the most numerous among the CVD persons. In an ongoing study, 500 candidates who appeared in the divisional medical board were studied. Ishihara chart was used for initial screening of all candidates with further use of Edridge-Green lantern for candidates found to have CVD and selected for jobs requiring high grade of color vision. Sixty candidates (13%) were found to have CVD; 39 of those were selected for jobs requiring accurate color perception. None of the candidates found to have CVD on testing by Ishihara chart could pass the lantern test. Only 21 candidates found to have CVD were previously aware of their deficiency. Since color judgment is an integral part of work in various occupations, a screening test to establish color vision should be undertaken while giving career's advice. An early diagnosis of CVD might allow for early modifications in educational and other activities. Furthermore, there is a need to supplement the existing color vision tests for various services in India, with more objective, diagnostic tests such as the D-15, maintaining standard illumination. Use of color enhancing appliances (X-chrome and chromagen contact lenses) should be ruled out. Computer-based programs are needed so that easily reproducible and acceptable methods of testing are developed. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.

To investigate the influence of color vision on myopia development by testing refraction error and axial length of the eye for high school students with and without color vision deficiency (CVD). A school-based cross-sectional, cluster sample study was conducted to test the color vision and refractive error of 16,539 high school students. Students were screened for CVD using a pseudoisochromatic plate. CVD was confirmed in students failing the test using a Farnsworth-Munsell 100-Hue Test which also served to classify the subtype (protan or deutan). Three classmates of each CVD subject, matched in five myopia risk factors, were chosen to form the normal color vision (CN) control group. Ophthalmic examinations were performed to determine refractive status and axial length. Of the students, 309 were found to have red-green CVD and 927 were selected as the CN control group. The prevalence of myopia in the CVD group (45.6%) was significantly lower than that of the CN group (65.8%; P<0.001). The CVD group was also less myopic in refraction (P<0.001) than CN, and protan subjects had shorter axial lengths than those in the control group (P=0.007). Color vision deficiencies appear to influence the development of myopia. The observed lower incidence of myopia in people with CVD may be linked to the reduced functionality of the L/M chromatic mechanism.

Purpose: To assess the Medmont C100 test as a colour vision screening tool. Methods: One hundred and seventeen young male adults were screened with the Medmont C100, Ishihara plates, and the screening mode of the Oculus Anomaloscope tests. All subjects were tested under constant room illumination, namely that of a day light fluorescent lamp at 200 lux. Inclusion criteria were visual acuities (VA) of 20/20 or better with or without correction and absence of known ocular pathologies. Aided and unaided visual acuities were measured with the Snellen VA chart. Results: Five out of the 117 subjects, were found to have red-green colour vision deficiency (CVD) with Ishihara and anomaloscope tests indicating a 4.7% CVD prevalence, while the Medmont C100 test yielded 33 cases ofred-green deficiency indicating CVD prevalence of 28%. With the Ishihara test, all five subjects were identified as deutans, while the anomaloscope revealed three as deutans and two as pro-tans, and the Medmont C100 test identified all 33 cases as protans. Conclusion: The Medmont C100 test yielded significantly higher prevalence of protan CVD compared with the Ishihara platesand Anomaloscope tests. These findings suggest that caution should be taken when using Medmont C100 test for colour vision screening as it tends to give more false positive results with bias for pro-tans. (S Afr Optom 2011 70(1) 14-20)

Purpose: To assess the Medmont C100 test as a colour vision screening tool. Methods: One hundred and seventeen young male adults were screened with the Medmont C100, Ishihara plates, and the screening mode of the Oculus Anomaloscope tests. All subjects were tested under constant room illumination, namely that of a day light fluorescent lamp at 200 lux. Inclusion criteria were visual acuities (VA) of 20/20 or better with or without correction and absence of known ocular pathologies.Aided and unaided visual acuities were measured with the Snellen VA chart. Results: Five out of the117 subjects, were found to have red-green colour vision deficiency (CVD) with Ishihara and anomaloscope tests indicating a 4.7% CVD prevalence, while the Medmont C100 test yielded 33 cases of red-green deficiency indicating CVD prevalence of 28%. With the Ishihara test, all five subjects were identified as deutans, while the anomaloscope revealed three as deutans and two as protans, and the Medmont C100 test identified all 33 cases as protans. Conclusion: The Medmont C100 test yielded significantly higher prevalence of protan CVD compared with the Ishihara platesand Anomaloscope tests. These findings suggest that caution should be taken when using Medmont C100 test for colour vision screening as it tends togive more false positive results with bias for protans. (S Afr Optom 2011 70(1) 14-20)

Background: Pseudoisochromatic color vision tests are commonly used to screen for color vision deficiency (CVD). Although most color vision normal (CVN) individuals read all plates correctly, a remarkable proportion have errors. Objective: This study aimed to determine the typical and atypical error responses to the Ishihara and Waggoner PIP24 (W-PIP24) tests of CVN and CVD individuals. Methods: This study recruited 59 CVN and 63 congenital red-green CVD individuals. Participants were tested with the Ishihara and W-PIP24 tests. The participants’ responses were recorded, and typical and atypical errors were determined. Results: The rate of atypical errors in the CVN group was 21% in the Ishihara test and 9% in the W-PIP24 test, while those in the CVD group were 100% and 60%, respectively. The CVN and CVD groups tended to have more atypical errors on the Ishihara test than on the W-PIP24 test. Moreover, CVD individuals tended to have more atypical errors in the transformation plates in both tests. Conclusion: CVN individuals may misread the plates in the Ishihara and W-PIP24 tests for reasons other than the normality of color vision; therefore, counting only typical errors may eliminate the chance of CVN individuals misreading the number on the plates. The most significant finding of this study was that clinicians should perhaps only consider typical errors as “errors” on both tests.

Objective : To compare the Effectiveness Between Ishihara plates on iPad Air2 and traditional printed standard Ishihara test for screening red-green color vision deficiency in male population Design : Case-control Diagnostic Study Methods : Male volunteers (patients and relatives) from Thammasat hospital and students from grades 3-6 at Buengkhaoyorn school, Pathumtani province were recruited. All volunteers were initially examined for red-green color deficiency by standard Ishihara test, and Pseudochromatic color test application in iPad Air2 at 100% brightness. 49 participants who had positive standard Ishihara test and 264 participants who had negative standard Ishihara test were asked to take the Pseudochromatic color test application on iPad Air2, comparing the two results to determine the latter test’s effectiveness in screening red-green color deficiency. Results : A total of 313 selected volunteers were examined, age ranged from 6 to 80 years old. 49 participants who tested positive for red-green color vision deficiency using the Standard Ishihara test were also positive for red-green color vision deficiency using the Pseudochromatic color test application in iPad Air2. Another 264 volunteers who tested negative red-green color vision deficiency using the Standard Ishihara test also had negative red-green color vision deficiency using the Pseudochromatic color test application in iPad Air2. The sensitivity, specificity and positive predictive value for the Pseudochromatic color test was 100%, 100% and 100%. Discussion : The Pseudochromatic color test is a suitable substitute to the standard Ishihara test when used on an iPad Air2 at optimal lighting conditions. The use of free standard Ishihara test substitute applications on tablets may be suitable for screening color deficiency in resource limited settings.

Background: Colour vision deficiency (CVD) has a high prevalence and is often a handicap in everyday life. Those who have CVD will be better able to adapt and make more informed career choices, if they know about their deficiency. The fact that from 20 to 30 per cent of adults with abnormal colour vision do not know they have CVD suggests that colour vision is not tested as often as it should be. This may be because of practitioner uncertainty about which tests to use, how to interpret them and the advice that should be given to patients on the basis of the results. The purpose of this paper is to recommend tests for primary care assessment of colour vision and provide guidance on the advice that can be given to patients with CVD.Methods: The literature on colour vision tests and the relationship between the results of the tests and performance at practical colour tasks was reviewed.Results: The colour vision tests that are most suitable for primary care clinical practice are the Ishihara test, the Richmond HRR 4th edition 2002 test, the Medmont C‐100 test and the Farnsworth D15 test. These tests are quick to administer, give clear results and are easy to interpret. Tables are provided summarising how these tests should be interpreted, the advice that can be given to CVD patients on basis of the test results, and the occupations in which CVD is a handicap.Conclusion: Optometrists should test the colour vision of all new patients with the Ishihara and Richmond HRR (2002) tests. Those shown to have CVD should be assessed with the Medmont C‐100 test and the Farnsworth D15 test and given appropriate advice based on the test results.

Red-green colour vision deficiency (CVD) affects ~ 4% of Caucasians. Notch filters exist to simulate CVD when worn by colour vision normal (CVN) observers (simulation tools), or to improve colour discrimination when worn by CVD observers (compensation tools). The current study assesses effects of simulation (Variantor) and compensation (EnChroma) filters on performance in a variety of tasks. Experiments were conducted on 20 CVN and 16 CVD participants under no-filter and filter conditions (5 CVN used Variantor; 15 CVN and 16 CVD used EnChroma). Participants were tested on Ishihara and Farnsworth-Munsell 100 hue tests, CVA-UMinho colour discrimination and colour naming tasks and a board-game colour-sorting task. Repeated-measures ANOVAs found Variantor filters to significantly worsen CVN performance, mimicking protanopia. Mixed-model and repeated-measures ANOVAs demonstrate that EnChroma filters do not significantly enhance performance in CVD observers. Key EnChroma results were replicated in 8 CVD children (Ishihara test) and a sub-sample of 6 CVD adults (CVA-UMinho colour discrimination and colour naming tasks) for a smaller stimulus size. Pattern similarity exists across hue for discrimination thresholds and naming errors. Variantor filters are effective at mimicking congenital colour vision defects in CVN observers for all tasks, however EnChroma filters do not significantly compensate for CVD in any.

Color vision tests use estimative of threshold color discrimination or number of correct responses to evaluate performance in chromatic discrimination tasks. Both approaches have advantages and disadvantages. In the present investigation, we compared the number of errors during color discrimination task in normal trichromats and participants with color vision deficiency (CVD) using pseudoisochromatic stimuli at fixed saturation levels. We recruited 28 normal trichromats and eight participants with CVD. Cambridge Color Test was used to categorize their color vision phenotype, and those with a phenotype suggestive of color vision deficiency had their L- and M-opsin genes genotyped. Pseudoisochromatic stimuli were shown with target chromaticity in 20 vectors radiating from the background chromaticity and saturation of 0.06, 0.04, 0.03, 0.02, 0.01, and 0.005 u’v' units. Each stimulus condition appeared in four trials. The number of errors for each stimulus condition was considered an indicator of the participant's performance. At high chromatic saturation, there were fewer errors from both phenotypes. The errors of the normal trichromats had no systematic variation for high saturated stimuli, but below 0.02 u’v' units, there was a discrete prevalence of tritan errors. For participants with CVD, the errors happened mainly in red-green chromatic vectors. A three-way ANOVA showed that all factors (color vision phenotype, stimulus saturation, and chromatic vector) had statistically significant effects on the number of errors and that stimulus saturation was the most important main effect. ROC analysis indicated that the performance of the fixed saturation levels to identify CVD was better between 0.02 and 0.06 u’v’ units reaching 100%, while saturation of 0.01 and 0.005 u’v’ units decreased the accuracy of the screening of the test. We concluded that the color discrimination task using high saturated stimuli separated normal trichromats and participants with red-green color vision deficiencies with high performance, which can be considered a promising method for new color vision tests based in frequency of errors.

I read with interest the correspondence from Jayakrishnan and Al-Rawas on the use of universal dots to colour code and identify asthma inhalers.1 I appreciate the authors’ desire to ensure a universal and consistent system but, unfortunately, the interpretation of colours is fraught with complication. The problem of colour vision deficiency has been known since John Dalton first described the condition in 1798.2 Some 8% of men and 0.5% of women have some degree of a problem, that is an estimated 2.4 million men in the UK alone. Red–green colour vision deficiency is the most common and brown is a colour where particular difficulty is encountered. The problems with colour vision deficiency have been documented but continue to be generally under-appreciated in the medical environment, for example, there is good evidence that doctors and patients can struggle to spot red rashes.3 Those with colour vision deficiency can also fail to recognise blood in bodily fluids4 and this has translated into evidence that those with colour vision deficiencies are more likely to present with late stage bladder cancer.5 I would plead the case on behalf of those of us who are colour blind and I would resist the use of colour in the identification of medicines. In the diagram1 I was unable to differentiate between the brown, green, or red universal dots. It is particularly challenging to identify small dots or bands of colour, and great care needs to be taken in assigning surface colour codes as those with colour vision deficiencies are prone to error, particularly under lower levels of illumination.6

Background: Normal human beings can appreciate color in all three of it’s attributes; Hue, intensity, and saturation. Human beings can perceive three primary colors, that is, red, green, and blue. Any defect in appreciation of colors is known as color vision deficiency (CVD). Complete inability to appreciate color is known as color blindness. The genes for red and green cone pigments are found in the q arm of the X chromosome. Hence, red and green CVD are inherited as X-linked recessive diseases. Blue CVD is autosomaly inherited. Blood groups are genetically inherited as well. Although it is a known fact that there is a preponderance of genetic diseases in subjects belonging to a specific blood group, no such study was available in Western Odisha as per our knowledge. This becomes more relevant as consanguineous marriages are a serious social problem in that part of Odisha. Aim and Objectives: Therefore, the study was undertaken to find out the prevalence of CVD among Medical students in Western Odisha and to find out it’s relation, if any, with ABO blood groups, as these two entities are genetically inherited. Record should be kept for future use, especially for counseling at the time of marriage and if necessary, to choose a subject for further study, where color detection does not play an important part. Materials and Methods: Prior permission was taken from the Institutional Ethics Committee to carry out this study. The study was carried out among the 1st–4th year medical students of V.S.S. Medical College and Hospital (n = 690) from August 2022 to October 2022. Ishihara test plates for color vision and agglutination method for ABO blood grouping were employed to get the prevalence of CVD and to get the percentage of subjects belonging to each blood group among those having CVD. The observations were noted carefully. Results: After careful screening, it was seen that 647 (93.76%) were normal, 42 (6.08%) had CVD, and 1 (0.14%) subject was completely color blind. All those affected were males. Distribution of blood group in CVD subjects showed 7 (16.27%) numbers belonging to blood group A, 22 (51.16%) belonging to blood group B, 1 (2.3%) belonging to blood group AB, and 12 (27.9%) belonging to blood group O. The only color blind student belonged to blood group B (2.3%). Conclusion: As medical students have to deal with colors throughout their career, the study helps the subjects to be aware of their condition early in their professional life. It also tried to find out the percentage distribution into ABO blood groups. A larger population should be included to get more accurate results.

Background Recent survey data indicate that some people report long-term improvement in color vision deficiency (CVD), also known as color blindness, following use of psychedelics such as lysergic acid diethylamide (LSD) and psilocybin. However, there are no objective data reported in the medical literature quantifying the degree or duration of CVD improvement associated with psychedelic use. Case presentation Here we present the case of a subject with red-green CVD (mild deuteranomalia) who self-administered the Ishihara Test to quantify the degree and duration of CVD improvement following the use of 5 g of dried psilocybin mushrooms. Self-reported Ishihara Test data from the subject revealed partial improvement in CVD peaking at 8 days and persisting for at least 16 days post-psilocybin administration. This improvement may have lasted longer, though the subsequent observations are confounded by additional substance use. Conclusion A single use of psilocybin may produce partial improvements in CVD extending beyond the period of acute effect, despite this condition typically resulting from a genetic defect. Systematic exploration of this possible phenomenon is needed to confirm our findings, gauge their generalizability, and determine the mechanism of action.

Color Vision Deficiences in Two Cases of Digoxin Toxicity

In this research, three illuminants that improve color discrimination ability of people with red-green color vision deficiency were developed. The illuminants are close to daylight-colored and were produced by using spectral optimization. Deutans were the focus of this research, but a few protans were also tested for reference. The illuminants were produced by combining different types of LEDs, and their effects were tested with several test subjects with and without color vision deficiency using the Ishihara color vision test and the Farnsworth Panel D-15 test. The illuminant with the most powerful effect provided near perfect results with the Ishihara test for deutans, while the other two illuminants produced smaller improvements. The Farnsworth Panel D-15 test produced results that were similar to the Ishihara test though generally the color discrimination of blue hues was weaker under the most powerful illuminant.

Objectives:This study was designed to evaluate the thickness of the central macula, the retinal nerve fiber layer (RNFL), and the ganglion cell complex (GCC) in individuals with congenital red-green color vision deficiency (CVD) using spectral-domain optical coherence tomography (SD-OCT).Methods:This study included 22 males with a red-green CVD (Group 1) and 22 males with normal color vision (Group 2). The Ishihara test was used to determine CVD. SD-OCT was used to evaluate the central macula, RNFL, and GCC measurements of all of the study participants. The quantitative data of the 2 groups were compared. The Kruskal-Wallis test was used for the statistical analysis and a p value <0.05 was considered significant.Results:The mean central macula thickness observed in Group 1 and 2 was 255.00±25.50 µm and 248.95±24.70 µm, respectively. The mean RNFL thickness of Group 1 and 2 was 110.66±14.70 µm and 109.49±9.90 µm, respectively, and the mean GCC thickness of Group 1 and 2 was 97.70±10.80 µm and 97.56±5.10 µm, respectively. There were no significant differences between the groups in the assessment of the central macula, RNFL, or GCC thickness (p=0.20, p=0.34, p=0.37).Conclusion:The results of this study suggested that congenital red-green CVD does not affect the thickness of the central macula, RNFL, or GCC. To the best of our knowledge, this is the first study to evaluate the thickness of the GCC in individuals with congenital red-green CVD.