Color vision screening: a comparison of the AO H-R-R and Farnsworth F-2 tests

Vision screening tests should include a simple, reliable, and valid test of color vision defects. In this investigation the single plate Farnsworth F-2 test and the AO H-R-R pseudoisochromatic plates were compared as primary screening tests for red-green color defective vision. The tests were administered to 2827 children, kindergarten through high school grades. Both tests failed a higher percentage of children than expected in the lower grades (kindergarten through 3). In grades 4 through high school, however, 4.16% failed the F-2 test and 4.02% failed the AO H-R-R, compared to a predicted 4.2% of the general population with inherited red-green deficiencies. The failure rates of the F-2 test for 1171 high school boys and girls were 7.3 and 0.89%, respectively, very close to the expected incidence of red-green defects in males and females. Although the F-2 test passed a few pupils who failed the AO H-R-R test, their defects were categorized as mild or borderline on the AO H-R-R test and therefore not likely to be of practical significance. Less than 0.5% of the children in grades 4 through high school failed the F-2 test after passing the AO H-R-R. Some children with normal color vision, particularly very young children, may fail the F-2 test because of difficulty picking out the less obvious blue square. Nevertheless, for screening purposes the F-2 test is comparable to the AO H-R-R test and except for kindergarten and grade 1 pupils is an excellent single plate color vision screening test.(ABSTRACT TRUNCATED AT 250 WORDS)     

Evaluation of a new color vision test: "color vision testing made easy".

PURPOSE: A new pseudoisochromatic color plate test, "Color Vision Testing Made Easy" (CVTMET) has recently been introduced. Said to be designed for all age groups, including pre-school children, it uses the identification of simple shapes and objects to detect red-green color deficiencies. We evaluated the CVTMET to determine if the test is suitable for color vision screening of young children. METHODS: Forty-one adults predetermined to be color normal (n = 20) or to have hereditary red-green color deficiency (n = 21), served as subjects. A battery of color vision tests including the Ishihara, Panel D-15, and the anomaloscope were used for diagnosis and color deficiency classification. Subjects were then tested with Part I and Part II of the CVTMET test and results were compared to the Ishihara, Panel D-15, and anomaloscope. In addition, the CVTMET was used to screen for color vision deficiency in 152 kindergarten children 5 to 7 years of age. RESULTS: The pass/fail results for the adult subjects were the same for Parts I and II and compared favorably with the anomaloscope. There were no false positives (100% specificity) and only a few (2 of 21) false negatives (90.5% sensitivity). The two color-deficient subjects who passed the CVTMET had the mildest color deficiencies (simple deuteranomaly) and also passed the Ishihara test. Testability of kindergarten children was found to be 100%. Color vision deficiency occurred in 5.06% of the boys, which is about the same frequency found in older boys of similar ethnic background. CONCLUSION: This preliminary study indicates that the CVTMET appears to be an excellent screening instrument for red-green color deficiency in adults and has been shown to be useful for examining color vision in children 5 to 7 years of age.     

The Ishihara Test: on the prevention of job discrimination.

Experiments were carried out to answer questions relative to the use of the 24-plate edition of the Ishihara Test for Colour-Blindness as a screening instrument for detecting the presence of inherited color defective vision. Subjects and their numbers varied between some experiments. Some subjects had normal color vision and others had inherited color defectiveness as confirmed with a Nagel anomaloscope. Most of the 157 subjects who participated in the experiments were either young deaf college students or police recruits with normal hearing who did not pass the Ishihara Test during their respective visual screening processes. Some hearing faculty and staff participated as part of Experiment 2. Item analysis and statistics applied to test the significance of differences between group means were applied to derive the following results: (a) test-retest reliability for the Ishihara is high both for persons with inherited color defectiveness and normal color vision; (b) persons making fewer than five errors on the first 13 plates made common incidental (nontypical) errors not related to color defective vision; and (c) five (5) or more errors was identified with some degree of inherited color defective vision, and subsequent referral for additional color vision diagnostics is warranted. Failure to utilize the recommended "pass-fail" criterion and/or to allow clients who fail color vision screening recourse to additional testing to establish type and degree of color defective vision may unnecessarily lead to job discrimination and/or interfere in a negative manner with the career selection process.     

The validity of the University of Waterloo Colored Dot Test for Color Vision Testing in adults and preschool children.

PURPOSE: Most color vision tests require a high level of cognitive ability and as such are problematic for preschool children and multiply challenged individuals. Our goal was to design a color vision test for these groups and evaluate the clinical utility for preschool children. METHODS: The University of Waterloo Colored Dot Test (UWCDot) for Color Vision Testing requires the subject to distinguish a colored disc from seven gray discs. The target disc was a Munsell color along the deutan, protan, or tritan confusion line with gray. The first phase estimated the sensitivity and specificity of the test for adults. Thirty-one adults with normal color vision and 21 adults with congenital red-green defects participated. In the second phase, the utility of the UWCDot test for screening preschool children was determined. Subjects were 281 males and 269 females aged 2.5 to 5 years with normal vision. Their color vision was also assessed with the Standard Pseudoisochromatic Plates, Part 1 (SPP1). RESULTS: The sensitivity and specificity of UWCDot for adults approached the values for the desaturated D-15 when subjective responses were scored. Monitoring fixational eye movements produced sensitivity and specificity values that were similar to the anomaloscope. After adjusting the scoring criterion for the preschool children by using the females as a control, 2.9% of the males were identified as red-green deficient, 1.8% were blue-yellow deficient, and 3.2% had an unclassified deficiency. By definition, 1% of the females failed the test. Counting fixational eye movements was not a useful scoring method in the preschool children. Comparisons with SPP1 indicated that the UWCDot uncovers approximately 35% of the individuals with definite red-green color vision defects. CONCLUSIONS: Our results indicate that the UWCDot is capable of detecting approximately 35% of the preschool children who have a congenital red-green color vision defect. These individuals are likely to have a more severe deficiency.     

Performance of the standard pseudoisochromatic plate test

The Standard pseudoisochromatic Plate (SPP) test was administered to 346 normals, 55 anomalous trichromats, and 46 dichromats. Its ability to detect and classify congenital color defectives was assessed. The performance of each plate was assessed separately and compared with its colorimetric properties. The test as a whole achieves a high level of accuracy in separating normals from color vision defectives [Youden's Index (YI) = 92.4%] and a high reliability (71.3%) in classification of the congenital color vision defectives. The performance of individual plates in separating color normals and color vision defectives of individual plates varies (YI ranges from 69.8 to 86.1%). A set of three plates can be chosen, which achieves a performance similar to that of the whole test. The test is found to be a reliable clinical screening method for congenital red-green color vision defectives.     

Comparison of the Standard Pseudoisochromatic Plates to the Ishihara color vision test

The Standard Pseudoisochromatic Plates (SPP) color vision test was compared to the Ishihara color vision test with respect to screening validity, digit confusion errors, and individual plate efficiency. Results from 315 1st and 3rd grade males confirmed previous reports that the SPP is an effective screening test. Moreover, the SPP test was superior to the Ishihara test with respect to digit confusion errors. Color normal children made about 5 to 7 times as many errors on the Ishihara test as on the SPP. Screening inefficiency values of individual plates of both tests were calculated. A high inefficiency value of a SPP plate was usually caused by its inability to detect color defective subjects.     

Use of the mollon-reffin minimalist color vision test with young children

PURPOSE: We evaluated the Mollon-Reffin Minimalist (M-R M) color vision test to determine how successfully young children can perform the task and to compare success rates with the American Optical Hardy Rand Rittler (HRR) test and a preferential-looking type test based on the F2 plates (the Pease-Allen color test [PACT]). METHODS: Participants included 146 children (aged 3-10 years) and 32 older subjects (aged 11-39 years). The M-R M test uses 3 series of colored caps coinciding with protan, deutan, and tritan confusion axes, with 6 saturations along each axis. The observer must identify a single colored cap from gray caps of varying lightness. The PACT test consists of 2 cards with targets for detecting red-green and blue-yellow color deficiencies. The tester judges the location of the target on the basis of the child's looking and/or pointing responses. The HRR was performed according to standard instructions, although a more flexible scoring protocol was also used. RESULTS: A significant difference in the children's performance between the "test" item of the 3 tasks emerged (Cochran Q test, P<.001): all children successfully completed the M-R M, 90% successfully completed the PACT, and 88% successfully completed the HRR. Few errors were made on the M-R M red-green series, even among children aged 3 to 4 years, although errors were made with the least saturated blue-yellow cap at all ages. Recommendations are made for the use of the M-R M with children. CONCLUSIONS: The M-R M test can be performed by young children and may prove to be especially useful for detecting and monitoring acquired color vision defects.     

Screening of colour vision defects in diabetic patients

The colour vision of 50 diabetic patients was examined with two screening tests, Standard Pseudoisochromatic Plates part 2 (SPP 2) and Farnsworth Panel D 15 (Panel D 15) test and with two diagnostic tests, Nagel anomaloscope and Farnsworth-Munsell 100-hue test. The performance of the diabetic patients in colour vision tests was compared to their performance in colour dependent urine and blood glucose tests. Fourteen of the patients failed the glucose tests, and they failed both of the screening tests as well. The diagnostic tests showed that all of them had a blue-yellow defect and 10 of them also had a red-green defect. The rest of the patients, 36, read the glucose tests correctly, but 17 of them failed the SPP 2 screening test, and 5 failed the Panel D 15 screening test. In diagnostic tests there were 15 patients with normal colour vision, one patient with a red-green defect, 13 patients with a blue-yellow defect, and 7 patients with both a red-green and a blue-yellow defect. The colour vision defect in diabetic patients is most often a blue-yellow defect or a combined blue-yellow and red-green defect. Therefore, the usual pseudoisochromatic plates, e.g. the Ishihara test, are not sufficient in screening because they screen only red-green defects. The screening tests should contain both a red-green and a blue-yellow part.(ABSTRACT TRUNCATED AT 250 WORDS)     

Chromaticity co‐ordinates of Ishihara plates reveal that hidden digit plates can be read by S‐cones

Background: The Ishihara pseudoisochromatic plates constitute one of the most commonly used screening tools for red‐green colour vision deficiencies. Even though hidden digit plates are supposed to be read only by those who are colour vision defective, studies report that some normal trichromats can indeed read these plates. By measuring the chromaticity co‐ordinates of the dots used in Ishihara plates, the purpose of this study was to clarify the mechanism that enables normal trichromats and colour vision defectives to read the plates, particularly hidden digit plates. Methods: Spectrophotometric measurements were made for a 24‐plate version of the Ishihara pseudoisochromatic plates and chromaticity co‐ordinates of the dots were expressed in the MacLeod‐Boynton diagram. Results: As theoretically expected, reading of Ishihara plates by normal trichromats was mediated by the dot chromaticity differences along the L/(L + M) axis. On the other hand, reading by colour vision defective observers was made possible mainly by the dot chromaticity differences along the S/(L + M) axis. This would also explain why some normal trichromats can read hidden digit plates, the plates that are supposed to be read only by colour vision defective observers. Conclusion: Normal trichromats read Ishihara plates using their chromatic discrimination ability along the L/(L + M) axis. Red‐green colour vision defective observers rely on S‐cones in reading the plates. Some normal trichromats can read the hidden digit plates because they can extract S‐cone differences efficiently despite the distraction from the L/(L + M) axis.     

Prevalence of inherited color vision deficiency among male school teenagers in Nablus, Palestine

AIM: To find out the prevalence of inherited color vision deficiency (CVD) among Palestinian male-school children aged 14-18 and compare it with other eastern and western countries. METHODS: Six hundred and thirty-four male subjects (n=634) aged 14-18 from Palestinian Governorate of Nablus were randomly selected and screened using Ishihara pseudoisochromatic plates. Subjects who failed Ishihara screening were tested further with computer software of Farnsworth-Munsell 100 Hue test. RESULTS: Out of the 634 male participants, 597 were included in the study and 8.0% of them (48 males) demonstrated red-green CVD. 5.4%, 2.3% and 0.3% of the 48 males exhibited deutan, protan and total color vision deficiency (monochromacy), respectively. CONCLUSION: The results show that the prevalence of red-green CVD among the male school children from Palestinian Governorate of Nablus is not significantly different from that of male populations in nearby and Western countries.     

巴勒斯坦纳布卢斯地区男校学生遗传性色觉缺陷的患病率

目的:了解巴勒斯坦地区14~18岁男性学生遗传性色觉缺陷(CVD)的患病率,并与其他东西方国家进行比较。方法:从巴勒斯坦纳布卢斯省随机挑选634名年龄在14~18岁的男性受试者,并使用Ishihara假同色法进行筛选。Ishihara假同色法筛查不合格的受试者用Farnsworth-Munsell 100 Hue测试计算机软件进行进一步测试。结果:在634男性参与者中,597名被纳入研究,其中8.0%(48名男性)表现出红绿色觉缺陷。48名男性中,有5.4%、2.3%和0.3%分别表现出绿色觉异常、红色觉异常和总色觉缺陷(单色性)。结论:巴勒斯坦纳布卢斯省男校学生红绿色觉缺陷的患病率与周边及西方国家的男性无显著差异。     

Neurophysiological basis and clinical tests for assessment of X-linked color vision deficiencies in school children

Vision screening of school children at 5-6 years of age must include color vision screening. X-linked dyschromatopsia is the most frequent disorder affecting 8% of boys and 0.4% of girls. This paper presents the physiology of these deficiencies caused by an alteration of the spectral absorption properties of one of the cone pigments (protanomalous or deuteranomalous trichromats) or the absence of one of the pigments (protanopia or deuteranopia), the most frequent. Absence of two of the pigments (blue cone monochromacy) is very rare and differs from achromatopsia. The physiological basis of the main tests for easy clinical screening are presented. Testing methods designed for children are reviewed. The Ishihara test is the most widely used screening test specific for congenital color defects. If the plates are correctly read, the child has normal color vision. If not, arrangement tests such as Panel D 15 and desaturated Panel D 15 tests can be used to diagnose the type of the defect (protan or deutan) and grade the degree of color deficiency according to a strategy adapted to children. Examples of results are presented for each axis along which caps are confused, providing a quick and easy preliminary diagnosis. Early detection of color vision malfunction in children allows parents and teachers to make necessary adjustments to the teaching methods for appropriate learning.     

Evaluation of an updated HRR color vision test

The HRR pseudoisochromatic plate (pip) test was originally designed as a screening and diagnostic test for color vision deficiencies. The original HRR test is now long out of print. We evaluate here the new 4th edition of the HRR test, produced in 2002 by Richmond Products. The 2002 edition was compared to the original 1955 edition for a group of subjects with normal color vision and a group who had been previously diagnosed as having color vision deficiencies. The color deficient subjects spanned the range of severity among people with red-green deficiencies except for one individual who had a mild congenital tritan deficiency. The new test compared favorably with the original and in at least two areas, outperformed it. Among subjects with deutan defects the classification of severity correlated better with the anomaloscope results than the original; all the subjects who were classified as dichromats on the anomaloscope were rated as "severe" on the new HRR, while those diagnosed as anomalous trichromats were rated as mild or medium on the new test. Among those with moderate and severe defects the new test was highly accurate in correctly categorizing subjects as protan or deutan. In addition, a mild tritan subject made a tritan error on the new test whereas he was misdiagnosed as normal on the original.     

Standard Pseudoisochromatic Plates part 2

The Standard Pseudoisochromatic Plates part 2 are able to detect acquired blue-yellow color vision defects as well as acquired and congenital red-green color vision defects. One test plate might be age dependent. The value of 3 test plates is not clear.     

Color vision deficiencies in two cases of digoxin toxicity

Color vision deficiencies are a common sign of digoxin intoxication and color vision testing can be used to diagnose digoxin toxicity. We tested two patients, a 79-year-old man and a 61-year-old man, with digoxin toxicity by means of the Farnsworth-Munsell 100-hue test, AOH-R-R plates, and Ishihara plates. Initial testing disclosed both red-green and blue-yellow color vision deficiencies. These improved when digoxin levels diminished. The deficiencies were superimposed on preexisting acquired and congenital deficits. As serum digoxin levels decreased, the color vision deficiencies lessened on all three tests. The Farnsworth-Munsell 100-hue test gave the best quantifiable measure of color vision deficiencies, but proved difficult to use for routine bedside testing.     

Survey of the accuracy of new pseudoisochromatic plates

The accuracy of three new pseudoisochrometic tests for detecting red–green colour deficiency was assessed. These were the Ishihara plates, the Ishihara test for 'unlettered persons' and Ohkuma's lest cards. We examined 500 subjects; 471 normal trichromats and 29 colour-deficient people, Results obtained for the 1989 edition of the Ishiliara places were compared with the 9th edition and the most efficient plates identified. Although normal trichromats may be expected to make several interpretive misreadings, the Ishihara plates were found to be superior to the 9th edition and to the Ohkuma test (1986) for colour vision screening. The new symbol designs of the Ishihara plates for 'unlettered persons' (1990) were found to be very effective for colour vision screening, and a further study with young children is proposed. The 38 plate I9S9 edition of the Ishihara les; is recommended for use in clinical practice. The designs included in the concise 24 plate edition and the new abbreviated 14 plate edition are not selected from the point of view of accuracy and more reliable results are obtained if the full lest is given or if the practitioner shows only the most efficient designs.     

色觉定量测定的新方法

目的 探對色覺進行定量測定。方法 采用自行研制的色覺定量測定儀,對用假同色色盲表檢查為正常色絕者1000例(2000祗眼);紅绿色盲,紅、绿色弱各30例(60祗眼)進行色絕定性與定量測定。結果正常者紅色值為3.44±0.52,绿色值3.93±2.06;紅绿色盲者紅色值78.5±9.69,绿色值89.0±6.23;紅色弱者紅色值39.40±7.62;绿色弱者,绿色值43.60±11.25。結論 本測定法對正常色覺與色覺异常既能定性又能定量測定,優于假同色色盲表檢查法。     

Color vision

Many visual disorders produce acquired color vision defects. Color vision theory emphasizes several stages of visual processing: prereceptoral filters (lens, macular pigment, pupil), cone photopigments (L-, M-, and S-cones), and postreceptoral processes (red-green, S-cone, and luminance channels). Congenital color defects, which affect 8% to 10% of males and 0.4% to 0.5% of females, result from alterations in the photopigment absorption spectra or the absence of one or more photopigments. The most common defects are color vision deficiencies (protan and deutan defects), which are milder than the rarer achromatopsias (complete loss of color vision). Acquired color vision defects can be attributed to a number of different causes: alteration of prereceptoral filters, reduced cone photopigment optical density, greater loss of one cone type than the others, and disruption of postreceptoral processes. Acquired color vision defects have been divided into three classes: type 1, red-green defect with scotopization; type 2, red-green defect without scotopization; and type 3, blue defects (with or without pseudoprotanomaly). Blue defects are usually type 3 acquired defects because congenital tritan defects have an incidence of one in several tens of thousands. Red-green defects can be acquired or congenital, and ruling out acquired defects can require a battery of tests (plates and arrangement tests, anomaloscopy, perhaps genetic analysis). Color vision tests must be administered carefully (with a standard illuminant and protocol), and pupillary miosis or high lens density should be noted and their possible effects considered when interpreting test results. Plate tests provide a simple screening method but do not provide a diagnosis. Arrangement tests and anomaloscope testing take more time and make greater demands on the tester, but they provide a more thorough evaluation. When standard protocols are followed and results are interpreted in terms of prereceptoral filters, photopigment optical density, cone loss, and disruption of postreceptoral processes, a battery of color vision tests can be useful in the differential diagnosis, after progression of the disease, and for evaluating the effectiveness of treatment.     

Progressive peripheral cone dysfunction

A 22-year-old man had a three-year history of progressive day blindness, most notably peripherally, and denied difficulty with central vision or color vision. Visual function studies demonstrated a diffuse dysfunction of the photopic system and normal scotopic function. The central cone function, however, was essentially normal. Visual acuity was 20/20 in each eye, results on AO-HRR and Ishihara color plate testing were normal, color naming visual fields demonstrated color discrimination in the central 10 degrees, and foveal adaptation was normal.     

What do color blind children really see? Guidelines for clinical prescreening based on recent findings

Recent research on classical red-green blind observers has shown that complete dichromacy may be present only under conditions where the viewing angle is small. For viewing angles greater than about 4 degrees, both rods and an anomalous cone have been shown to underlie a weak form of trichromacy. The conditions for rod or anomalous cone mediation of this trichromacy have also been shown to depend on the overall viewing luminance. These data taken together prompt a rethinking of the classical view of red-green dichromacy and lead to new considerations of the color discrimination performance of dichromatic candidates. In this paper we review the recent research on the presence of trichromatic abilities in classical dichromats and we relate these findings to the needs of the clinician, especially in the screening of young children.