Prevalence Of Congenital Colour Vision Deficiency Among Secondary School Male Students In Almadina Almunawara (Saudi Arabia)

@#The aim of this cross-sectional study is to determine the prevalence of congenital colour vision defects among male secondary school students in Al-Madinah Al-Munawara city, Saudi Arabia. A total of 1154 male secondary school students were selected randomly through a multi-stage sampling method. Ishihara 24-plates was used to screen for colour blindness. The overall prevalence of congenital colour vision defects was 3.3% with 1% protanopes and 2.3% deuteranopes. The prevalence of congenital colour vision defect among Saudis was 2.48% and (5.48%) among non-Saudis. In conclusion, the prevalence of congenital colour vision defect among male secondary school students of Al-Madinah Al-Munawara city is comparable to previously reported in central Saudi Arabia, but lower than for Caucasian.

OCT determined macular thickness in diabetic retinopathy and relation to colour vision deficiency patterns.

Background: Diabetic retinopathy is the most common cause of blindness in industrialised nations and the incidence of diabetes is expected to rise over the next 10 years. Early treatment of proliferative diabetic retinopathy and diabetic maculopathy improves visual outcome and with effective screening, blindness could be reduced. Patients suffering from diabetes mellitus show alterations in their colour perception. Colour vision testing provides a sensitive, non-invasive method to assess macular damage in diabetic retinopathy and any deterioration in colour vision often precedes changes in other clinical measures such as visual acuity and morphological changes. Optical coherence tomography (OCT) provides cross-sectional images of the retina, information concerning internal retinal structure as well as reproducible measurements of retinal thickness. Aims & Objective: This study was intended to examine the relationship between macular thickness on OCT (Optical coherence tomography) and colour vision deficiency patterns in diabetics. Material and Methods: A total of 100 patients with established diabetic retinopathy visiting hospital were examined and a detailed history of diabetes, duration and inability to differentiate colours was taken. Retinal examination for evidence of diabetic retinopathy and colour vision patterns on Ishihara colour vision chart were noted. OCT was performed on these patients. Results: 21% (21 out of 100) of patients under study showed a gross deficiency of red green pattern of colour blindness. The colour vision deficiency increased with increasing macular thickness. Macula thickness on OCT in subjects varied from 188 to 462 microns. The average macular thickness of patients with total colour vision deficiency was 290 microns that with red green was 274 micron and those without any colour vision deficiency was 228. Prevalence of colour vision deficiency increased with duration of diabetes and severity of retinopathy. Conclusion: Higher prevalence of red green colour blindness was observed in patients of diabetes with macular oedema. Impaired colour vision was more in patients with macular thickness above 228 micron.

Serum homocysteine as a risk factor in diabetic with colour vision deficiency and for developing retinopathy.

Background: Diabetic retinopathy causes vascular complications of retina causing blindness. Macular edema is the crucial cause of visual impairment and may occur at any stage of diabetic retinopathy. Patients suffering from diabetes mellitus can show alterations in their colour perception. Colour vision testing provides a sensitive method to assess macular damage. Deterioration in colour vision often precedes changes in other clinical measures such as visual acuity and morphological changes. Elevated homocysteine levels play a causative role in inducing vascular endothelial cell damage and causing retinopathy in diabetics. Aims & Objective: This observational study was intended to examine if serum homocysteine is a risk factor for developing colour vision defects in diabetes and worsening of retinopathy. Material and Methods: A total of 92 patients with established diabetic retinopathy and having colour vision defects visiting hospital were examined and a detailed history of duration of diabetes was taken. Retinal examination for evidence of diabetic retinopathy and colour vision patterns on Ishihara colour vision chart were noted. OCT was performed on these patients. Results: 92 of patients with diabetic retinopathy under study had a gross colour vision deficiency. The average macular thickness on OCT of patients with total colour vision deficiency was 279 microns. Prevalence of colour vision deficiency increased with duration of diabetes and severity of retinopathy. The average serum homocysteine level in these patients was 21.98 μM/L which was above the normal range. Serum homocysteine levels ranged from 11.0 μM/L to 30.2 among males and 11.1to 41.0 in females. Conclusion: Higher prevalence of colour blindness was observed in patients of diabetes with macular oedema and high circulating serum homocysteine levels. Impaired colour vision was more in patients with average macular thickness of 228 micron and raised homocysteine levels thus suggesting it could be a possible risk factor.

Colour preference and light sensitivity in trilobite larvae of mangrove horseshoe crab, Carcinoscopius rotundicauda (Latreille, 1802).

The trilobite larvae of C. rotundicauda were tested to determine their colour preference and light sensitivity until their first moulting (25 days post hatching) under laboratory conditions. Maximum congregation size of the trilobite larvae was found in the white zone respectively where (n= 12) followed by yellow (n= 8) and orange (n= 8), which showed the larval preference for lighter zones. Morisita’s index calculation showed a clumped/aggregated distribution (yellow, blue, orange and white) and uniform/hyper dispersed distribution (green, red and black) for various colours tested. Trilobite larvae showed least preference for brighter regions while tested in the experiment [black; (n=4) and red; (n=5)]. Experiments done to determine the light sensitivity of trilobite larvae showed that the larvae had more preference towards ultraviolet lights. The maximum congregation size of 38.8 and 40.7% of the larvae was encountered under ultraviolet light, when the light sources were kept horizontal and vertical, respectively. Overall, results suggested that the trilobite larvae of C. rotundicauda, preferred light source of shorter wavelengths (UV light) and colours of lighter zone (white, yellow, orange), which might be due to their adaptation to their natural habitat for predator avoidance, prey selection and water quality.

Practical Assessment of Colour Vision to Certify Fitness for Driving

A patient with red-green colour blindness came to the polyclinic for a medical examination for the purpose of applying for a vocational driving license. He had been driving a private vehicle for years. As he could not read all the plates in the Ishihara, the attending doctor decided not to certify him fit, but referred him to an ophthalmologist. This upset the patient. A review of the guidelines suggests that for colour-blind patients, the Ishihara should not be the standard to assess a patient’s fitness to drive. We propose a simple colour chart that is more practical for this purpose.

EFFECTIVENESS OF COMPUTERIZED VISUAL SCREENING TOOL USED IN DRIVING SCHOOLS IN MALAYSIA

Purpose: A survey on new Malaysian drivers was conducted in Malaysia between year 2006-2009. The objective of this study was to look at the effectiveness of the present computerized visual screening tool and to compare it with the conventional testing method. Methods: A total of 3717 drivers aged 19±6 years, who had passed in the computerized visual screening, participated in this study. Results: 250 subjects achieved less than 0.3 LogMAR with their best eye and 83 subjects failed the Ishihara Test after retested using the conventional tool. Conclusion: These finding showed the computerized visual screening test failed to filter some subjects according to the standards set.

Effect of Illumination on Colour Vision Testing with Farnsworth-Munsell 100 Hue Test: Customized Colour Vision Booth versus Room Illumination

PURPOSE: To evaluate a customized, portable Farnsworth-Munsell 100 (FM 100) hue viewing booth for compliance with colour vision testing standards and to compare it with room illumination in subjects with normal colour vision (trichromats), subjects with acquired colour vision defects (secondary to diabetes mellitus), and subjects with congenital colour vision defects (dichromats). METHODS: Discrete wavelengths of the tube in the customized booth were measured using a spectrometer using the normal incident method and were compared with the spectral distribution of sunlight. Forty-eight subjects were recruited for the study and were divided into 3 groups: Group 1, Normal Trichromats (30 eyes); Group 2, Congenital Colour Vision Defects (16 eyes); and Group 3, Diabetes Mellitus (20 eyes). The FM 100 hue test performance was compared using two illumination conditions, booth illumination and room illumination. RESULTS: Total error scores of the classical method in Group 2 as mean+/-SD for room and booth illumination was 243.05+/-85.96 and 149.85+/-54.50 respectively (p=0.0001). Group 2 demonstrated lesser correlation (r=0.50, 0.55), lesser reliability (Cronbach's alpha, 0.625, 0.662) and greater variability (Bland & Altman value, 10.5) in total error scores for the classical method and the moment of inertia method between the two illumination conditions when compared to the other two groups. CONCLUSIONS: The customized booth demonstrated illumination meeting CIE standards. The total error scores were overestimated by the classical and moment of inertia methods in all groups for room illumination compared with booth illumination, however overestimation was more significant in the diabetes group.

Computer adapted Ishihara test in 104 students / 国际眼科杂志(Guoji Yanke Zazhi)

AIM: To investigate the validity of computer-adapted Ishihara test and the concordance with classic Ishihara test for the diagnosis of colour blindness. The sensitivity and the specificity of computer-adapted Ishihara test and potential usefulness of the test for detecting congenital colour blindness or colour vision deficiency were discussed.METHODS: Colour vision of 104 university students aged between 20 and 23 (median 21) years was evaluated by two methods. These methods are: 1) Individual test method based on computer-adapted Ishihara colour plates; 2) Individual test method based on classic method of exposing Ishihara colour printed plates. The capabilities of students perceiving colours were evaluated by these two different methods. The specificity, concordance and validity for the computer adapted Ishihara test method were investigated.RESULTS: There were 6 male and 1 female colour blind students. The pedigree of the female student proved to have a carrier mother and colour blind father. The incidence of colour blindness was 13.6 % (6/44) among males and 1.7%(1/60) for females. The incidence of colour blindness in whole population was 6.7 % (7/104). These students had not been aware that they have colour vision deficiency before our examination tests. Test results of students with normal colour vision and the students with colour blindness were compared as well as the two test methods in terms of concordance. The sensitivity and the specificity were both found to be 100 %and concordance was also found 100 %.CONCLUSION: Computer-adapted Ishihara test is digitally mastered, and remains true with respect to the basic concepts of color vision testing. It has obvious advantages over manual testing because its total test time and its error scores are standardized. It has been found 100% in agreement with the golden standard of classic Ishihara test. These features make this test original and dependable one.

High myopia associated with colour vision deficiency:a family report / 国际眼科杂志(Guoji Yanke Zazhi)

AIM: To evaluate genetic characteristics and clinical findings in a family with high myopia and colour vision deficiency (CVD).METHOD: Eight affected subjects of 42 members in four generations of the same family underwent a complete ophthalmic examination. Classical and computer adapted Ishihara Plates and Farnsworth-Munsell 100 Hue (FM100H)tests were used for determining the red-green CVD and full-field electroretinography (ERG) was performed to evaluate retinal function.RESULTS: Eight affected subjects had subnormal visual acuity due to high myopia. The results of colour vision tests were consistent with red-green CVD in six of these affected subjects. Fundus examination showed degenerative myopic changes characterized with generalized chorioretinal atrophy.Abnormal cone and rod dark-adaptation and diminished cone response in ERG were found in two subjects. According to family pedigree, it has been suggested that red-green CVD has X-linked recessive inheritance.CONCLUSION: The concurrence of high myopia with CVD in the members of this family may show a possible evidence for an associate genetic basis on different disorders.

Situation on colour vision deficiencies because recessives in chromosome X of first year students at Hai Phong Medical College from 2000 to 2002

In 409 students were tested with Ishihasa chromatic plates for distinguishing subjects with color vision deficiencies (CVD) at Hai Phong Medical College from 2000 to 2002. 57.7% male and 42.3% female. Frequency of CVD: 8.05 ± 0.25% male, female 0%. All people with CVD, among them deuteranopia was 68.42%, frequency: 5.51 ± 0.19. All people with CVD, among them red - green were 21.05%, frequency: 1.70 ± 0.11%. All people with CVD, among them red and total color was 5.26%, frequency of red: 0.37 ± 0.05%, frequency of total color: 0.37 ± 0.05%

A Computerized Scoring Method of The Hahn Double 15 Hue Test / 예방의학회지

The Hahn double 15 hue test is used for social and vacational aptitude test to separate strongly and mildly affected subjects among the colour vision defective persons, detected using colour vision test. However, the assessment of colour vision defect type and severity is based on the hue confusions which are represented diagrammatically on Hahn double 15 hue score sheet, this qualitative assessment of the test results have not provide a numerical score suitable for mathematical analysis. This paper presented a new proposal for quantitatively scoring the Hahn double 15 hue test based on those hue confusions made by the subject. With this program large numbers of double 15 hue test results can be processed easily and rapidly, and program helps to compare the severity of specific type colour vision defect and monitor acquired colour vision defect which has various disease process, continuously.

Evaluation of congenital colour vision deficiencies

Three hundred patients who have congenital colour vision deficiencies were examined at the author's eye clinic for 3 years (1987-1990) using 5 types of colour vision tests: Hahn's, TMC's, Okuma's (new), H-R-R's colour vision tests and Double 15 Hue Test (Hahn). The results obtained from each test were quite different in type and grade, and the summarized results were considered to be the best: Type: protan 23.3%, deutan 76.0%, unclassified 0.7% Grade: mild 20.3%, medium 25.3%, strong 54.4% The frequency of coincidence both in type and grade between the summarized results and those of each test were compared, and the highest was 62.3% in Double 15 Hue Test. The efficiency of the author's colour vision test and Double 15 Hue Test were evaluated with the data in this clinical trial, and they were found to be useful for classifying the type and estimating the grade of the congenital and also acquired colour vision deficiencies.