Lantern Test Research Articles

Color Vision Testing, Standards, and Visual Performance of the U.S. Military.

Color vision deficiency (CVD) is a disqualifying condition for military special duty occupations. Color vision testing and standards vary slightly among the U.S. military branches. Paper-based pseudoisochromatic plates (PIPs) remain a screening tool. Computer-based color vision tests (CVTs), i.e., the Cone Contrast Test (CCT), the Colour Assessment and Diagnosis (CAD) test, and the Waggoner Computerized Color Vision Test (WCCVT), are now replacing the Farnsworth Lantern Test (FALANT) and its variants to serve as a primary or secondary test in the U.S. Armed Forces. To maintain consistency in recruitment, performance, and safety, the study objectives were to examine military color vision testing, passing criteria, and color discrimination performance. Study participants were 191 (17% female) students, faculty, and staff of the U.S. Air Force Academy and the Naval Aerospace Medical Institute. All subjects performed six CVTs, and 141 participants completed two additional military relevant color discrimination tasks. Friedman non-parametric test and Wilcoxon signed-rank post hoc test with Bonferroni adjusted P values were used to compare CVTs and standards. Analysis of variance and Bonferroni adjusted post hoc test were used to describe effects on color discrimination performance. The Heidelberg Multicolor-Moreland and Rayleigh (HMC-MR) anomaloscope diagnosed 58 CVD (30.4%). There were no statistically significant differences in identifying red-green CVD by the HMC-MR, CCT, CAD, WCCVT, and PIP tests (P = .18), or classifying deutan, protan, and normal color vision (CVN) by the HMC-MR and the CVT (P = .25). Classification of tritan CVD was significantly different depending on which CVT was used (P < .001). Second, overall passing rates were 79.1% on the CAD (≤6 standard normal unit (SNU)), 78.5% on the combined PIP/FALANT, 78.0% on the CCT (≥55%), and 75.4% on the WCCVT (mild) military standards. The CVTs and the PIP/FALANT standards were not significantly different in number of personnel selected, but CAD and CCT passed significantly more individuals than WCCVT (P = .011 and P = .004, respectively). The previous U.S. Air Force standard (CCT score ≥75%) passed significantly fewer individuals relative the U.S. Navy pre-2017 PIP/FALANT or the current CVT standards (P ≤ .001). Furthermore, for those who failed the PIP (<12/14), the FALANT (9/9 or ≥16/18) agreed with the CVTs on passing the same CVN (n = 5); however, it also passed moderate-to-severe CVD who did not pass WCCVT (n = 6), CCT (n = 3), and CAD (n = 1). Lastly, moderate/severe CVD were significantly slower and less accurate than the "mild" CVD or CVN in the two color discrimination tasks (P < .001). In comparison to CVN in the in-cockpit display color discrimination task, mild CVD (CCT ≥55% and <75%) were significantly slower by 1,424 ± 290 milliseconds in reaction time (P < .001) while maintaining accuracy. CVTs are superior to paper-based PIP in diagnosing, classifying, and grading CVD. Relative to the PIP/FALANT standard in personnel selection, the current U.S. military CVT passing criteria offer comparable passing rates but are more accurate in selecting mild CVD. Nevertheless, military commanders should also consider specific operational requirements in selecting mild CVD for duty as reduced job performance may occur in a complex color critical environment.

Predicting the CN Lantern Test for Railways with Clinical Color-vision Tests.

This research will help clinicians in advising their color-vision-defective patients regarding their career options. In Canadian railways, individuals with a color-vision-defect (CVD) may qualify for positions at shorter sighting distance from signal lights. The railway companies' medical units use the CN Lantern (CNLan) test, and there is little information available as to whether clinical color-vision tests (CCVTs) can predict the CNLan results. This study determines the ability of some CCVTs to predict the CNLan performance to assist clinicians in advising their CVD patients regarding career options. The CNLan viewing distance was varied between 4.6 and 0.57 m using a geometric progression. The CCVTs were the Hardy, Rand, and Rittler; Ishihara; ColorDx pseudoisochromatic plate (PIP); the Rabin Cone Contrast Test; Color Assessment and Diagnosis; Cambridge Color Vision Test; U.S. Air Force Operational Based Vision Assessment Cone Contrast Test; Farnsworth Munsell D15; and ColorDx D15. Fifty-six normal-color-vision and 63 CVD subjects participated in this study. Failure of either the Farnsworth Munsell D15 or ColorDx D15 essentially guarantees failure on the CNLan at the 4.6-m distance. The agreement values decreased as the viewing distance decreased. To counsel patients regarding a career as a locomotive engineer, clinicians should have either the Hardy, Rand, and Rittler or ColorDx PIP and a D15 test. For patients applying for a position in the yard, a mild-to-moderate classification CVD on HRR or ColorDx PIP indicates a high probability of passing CNLan.

Efficacy of red contact lens in improving color vision test performance based on Ishihara, Farnsworth D15, and Martin Lantern Test

BackgroundThe aim of this study was to evaluate the efficacy of red contact lens in improving color vision test performance based on Ishihara, Farnsworth D15, and Martin Lantern Test (MLT). MethodsThirty subjects with a known color vision defect were enrolled after consent. The color vision was assessed using Ishihara test, D15 test, and MLT. The error scores were recorded. The test was repeated after using a red contact lens. ResultsThe mean error scores were 7.87 (±1.00), 3.33 (±3.15), and 5.67 (±2.52) on Ishihara, MLT, and D15 test, respectively. The error scores reduced to 3.93 (±3.78), 1.33 (±1.34), and 2.77 (±2.12) Ishihara, MLT, and D15 test, respectively (P value < 0.05, Wilcoxon rank test). None of the subjects were in color perception (CP) II at presentation but 47.5% became CP II with the lens on Ishihara test. Ninety percent could pass the MLT CP III standard. ConclusionThis study shows that red lens reduced error scores and subjects could pass the color vision tests. Notwithstanding the improvement in performance on color vision tests, lens is not recommended for personnel on active combat duty. The recruiting medical officer needs to be aware of the fact that a subject with defective color vision can pass various tests with a red contact lens.

Novel Classification of the Degree of Color Vision Defects in General Practice: Simulations of Cap Number and Saturation of the Farnsworth Dichotomous Test D-15

Objective: In most eye clinics, while severe to moderate color vision defects are diagnosed with the Farnsworth dichotomous test D-15 (D-15 test), moderate to mild color vision defects are detected with the Farnsworth lantern test. This study aims to propose a new classification of the degree of color vision defects in general practice by simulations of the cap number and saturation of the D-15 test. Methods: We performed the simulation of the modified D-15 tests with a reduced number of test caps (9 and 6 caps) to compress a hue circle based on the color confusion lines for the hypothetical participant. In addition, we performed another simulation of the modified D-15 test with modified chroma test caps (chroma 6 and 2). Results: The color confusion along the confusion lines was more likely to occur as the number of caps decreased in our simulation model. The modified chroma D-15 test did not affect the results of this study. Conclusion: The results of this study reveal that the D-15 test with a reduced number of test caps has possibilities to classify patients with moderate or mild color vision defects.

Color Vision and the Railways

There are two currently available lantern tests that have their design based solely on the practices of the rail industry. These are the CN Lantern (CNLAN) used on the Canadian Railways and the Railway LED Lantern Tests (RLLT). In the same way that the signaling practices differ in the two jurisdictions, the design of the lanterns also differ. The CIE (Commission Internationale de l'Éclairage)-recommended color vision standards for transport predate both lanterns. The study was undertaken to assess the appropriateness of these lanterns in CIE Color Vision Standard 1. CIE Standard 1 is called "Normal color vision" but some very mild anomalous trichromats may pass the specified "lantern test that presents a high level of difficulty." The lantern tests were undertaken by 46 color vision-normal and 37 color vision-deficient subjects. Subjects made more errors on the RLLT, and the pattern of errors is different, partly because there are blank presentations in the RLLT and "no light" is an acceptable response. The two lanterns showed agreement on the pass/fail categorization of 73 of the 83 subjects. The RLLT fails more color vision-normal subjects. Despite the different construction principles, the RLLT and CNLAN have pass/fail levels that are comparable with the Holmes-Wright Type B lantern, which is nominated in CIE Color Vision Standard 1 but is no longer commercially available. The higher failure rate of color vision-normal subjects on the RLLT has been addressed by changing the intensities of the two darkest red lights.

Color Vision and the Railways: Part 1. The Railway LED Lantern Test.

Lantern tests and practical tests are often used in the assessment of prospective railway employees. The lantern tests rarely embody the actual colors used in signaling on the railways. Practical tests have a number of problems, most notably consistency of application and practicability. This work was carried out to provide the Railway LED Lantern Test (RLLT) as a validated method of assessing the color vision of railway workers. The RLLT, a simulated practical test using the same LEDs (light-emitting diodes) as are used in modern railway signals, was developed. It was tested on 46 color vision-normal (CVN) and 37 color vision-deficient (CVD) subjects. A modified prototype was then tested on 106 CVN subjects. All 106 CVN subjects and most mildly affected CVD subjects passed the modified lantern at 3 m. At 6 m, 1 of the 106 normal color vision subjects failed by missing a single red light. All the CVD subjects failed. The RLLT carried out at 3 m allowed mildly affected CVD subjects to pass and demonstrate adequate color vision for the less demanding railway tasks. Carried out at 6 m, it essentially reinforced normal color vision as the standard. The RLLT is a simply administered test that has a direct link to the actual visual task of the rail worker. The RLLT lantern has been adopted as an approved test in the Australian National Standard for Health Assessment of Rail Safety Workers in place of a practical test. It has the potential to be a valid part of any railway color vision standard.

New Genetic Technology May Help Pilots, Aviation Employees, and Color Vision Researchers

Color vision research is not new for the Federal Aviation Administration (FAA); the Civil Aerospace Medical Institute has been conducting color vision research and publishing the results since 1967 ( 3 ). The FAA originally initiated color vision research because of the emerging use of color coding in the airport environment and the FAA has continued a line of color vision research because of the increasing use of color coding resulting from changing technology inside the cockpit, on air traffic control displays, and in the airport environment. Color can be used to convey meaning without supplemental signage such as the ubiquitous traffic signal that alerts drivers to proceed with caution via a yellow flashing light or to stop via a red flashing light. However, that meaning is only conveyed if the driver can distinguish between the yellow and the red colors. Approximately 8 to 10% of the male population ( 5 ) has a congenital color vision deficiency and, depending upon the type and severity of that deficiency, that task of interpreting the meaning of color coding may be difficult or impossible. Consequently, the FAA has long maintained a color vision standard for aero-medical screening to ensure that pilots and air traffic controllers can perform safety-related tasks without adverse consequences. Throughout the past few years, the FAA has explored a variety of color vision tests, searching for a valid screening test that has high sensitivity and specificity, meaning the ability to detect the presence or absence of the deficiency, respectively. Basically, color vision tests can be categorized as diagnostic, screening, or occupational tests. Diagnostic tests are designed to specifically diagnose the type and degree of deficiency, the screening tests focus on differentiating between normal or deficient color vision, and the occupational tests seek to separate those capable versus incapable of certain tasks such as identifying colors of wires or lights (e.g., the Farnsworth Lantern test that was developed to assess the ability of potential Navy signalmen for identifying red, green, and white lights). A few tests have been developed for the purpose of precisely diagnosing and classifying color vision; however, when color vision test scores are compared to performance on occupational tasks such as identifying or discriminating colors used in signal lights, precision approach path indicator (PAPI) lights, colored navigation lights, color coded map reading tasks, color coded air traffic control displays, and cockpit displays, a specific cut-point on those selection tests has not been found that can fully separate those who can from those who cannot accurately perform the color-coded pilot or air traffic control tasks. Some tests, including new computerized instruments, have been designed to differentiate defects involving the long wavelength sensitive cones (protan-type), middle wavelength sensitive cones (deutan-type), and short wavelength sensitive cones (tritan-type). Congenital protan and deutan deficiencies are, collectively, extremely common, affecting 1 in 12 men and 1 in 230 women; however, recent evidence indicates that tritan defects are virtually never present at birth (e.g., congenital) and the inherited forms involve S cone photoreceptor degeneration that develops later in life with the exact onset depending upon the specific mutation ( 1, 4 ). Thus, the exact frequency of inherited tritan defects is uncertain; however, it is probably less than 1 in 500. In part, because the underlying pathophysiology has not been well understood, few tests have been available that are capable of detecting tritan deficiencies. In the past, those tests included the single Farnsworth F2 pseudoisochromatic plate (PIP), the Moreland anomaloscope, the Hardy, Rand, Rittler PIP test, and, most recently, the Oculus anomaloscope. Consequently, the occupational color vision tests used by most agencies only screen for the most common (protan and deutan) types of defects. The newly developed computerized color vision tests, including the Colour Assessment and Diagnostic Test, the Cambridge Colour Test, the Cone Contrast Test, and the Computerized Color Vision Test, are all designed to detect tritan defects. However, tritan weaknesses have been noted in several of the FAA ‘ s recent studies in much higher than the traditionally expected numbers and diagnostic agreement is low among those tests when tritan deficiencies are involved. In the past, the FAA and other regulatory organizations have not, or have rarely, required tritan color vision screening in their occupational screening because of the following three factors: the rarity of the congenital defect, the unknown number of individuals affected by acquired deficiencies, and the lack of effective, reliable, valid, and affordable equipment with which to diagnose the deficiency.

Development of computerized color vision testing as a replacement for Martin Lantern

BackgroundDevelopment and standardization of computerized color vision testing as a replacement for Martin Lantern test. Non-randomized comparative trial. MethodsAll candidates of SSB, Allahabad, reporting for SMB underwent color vision testing at the eye dept by computerized eye test and currently available tests. ResultsAll candidates were subjected to Ishihara chart testing and those found to be CP III were subjected to the confirmatory test on Martin Lantern and the Software. Candidates requiring CP I standards for eligibility were tested on the same on Martin Lantern and on the new software method. On comparison between the Standard Martin Lantern and the Software, the results were consistent and comparable with 82 patients testing CP I on the Martin Lantern and 81 on the software. Of the CP III patients, 253 tested positive on the Standard lantern test as compared to 251 on the software and of the CP IV group, 147 tested positive on the Standard lantern and 149 by the software method. ConclusionIt was found that the software replicated the existing Martin Lantern accurately and consistently. The Martin Lantern Software can be used as a replacement for existing old Lanterns which are not in production since the early 20th century.

Comparison of color perception after tinted blue light–filtering and clear ultraviolet-filtering intraocular lens implantation

To compare color perception after implantation of clear and yellow-tinted intraocular lenses (IOLs). Dr. Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi, India. Comparative case series. This study evaluated eyes that had implantation of an Acrysof IQ SN60WF yellow-tinted IOL or an Acrysof SA60AT clear IOL. All eyes were evaluated postoperatively at 1 month and 3 months. The uncorrected distance visual acuity, intraocular pressure, and color vision (Ishihara pseudoisochromatic test, Edridge-Green lantern test, Heidelberg anomaloscope, and Farnsworth-Munsell (FM) 100-hue test) were evaluated. Both IOL groups comprised 50 eyes. There were no significant differences between the 2 groups in color vision on any of the 4 tests (P≥.05). Plotting the error scores on the polarity graph of the FM 100-hue test showed that eyes with a yellow-tinted IOL did not have a specific axis of confusion. There was no difference in color perception between the 2 IOLs irrespective of the color vision test used.

Repeatability of the Holmes-Wright Type A Lantern Color Vision Test

Recent studies showing a lack of internal consistency for the Holmes-Wright Type A Lantern (HWA) raise the issue as to whether the lantern test is repeatable. This study determines the HWA repeatability for several scoring criteria. There were 78 individuals with normal color vision (NCV) and 80 individuals with defective color vision (DCV) who were tested during two separate visits. Three runs of the test lights were always presented in dim room illumination. An additional dark-adapted run was presented during both visits for a subset of 61 subjects. Repeatability was evaluated for the following pass/fail criteria: the Joint Aviation Requirements, Farnsworth's criterion, the Commission Internationale de l'Eclairage criterion for the HWA, a perfect performance, and the 99th and 100th percentile scores of the NCV sample. The NCV agreement for passing both sessions was high, with 96% having a perfect score at both sessions. The DCV agreement for passing both sessions was lower, ranging from 0.62 to 0.80. Criteria which stopped the test after a perfect performance on the first run had the lowest values. The DCV agreement for failing both sessions was high, ranging from 0.97 to 0.99. Stopping the test after a perfect performance on the first run should be abandoned. Presenting three runs of the nine test lights and allowing no more than two errors is repeatable, passes all the NCV, and minimizes the number of individuals who pass the lantern at the first session and fail at a later session.

Color Vision Testing by Farnsworth Lantern and Ability to Identify Approach-Path Signal Colors

It is presumed that pilots with abnormal color vision who pass the Farnsworth lantern test can distinguish aviation signal lights including the red and white lights of the Precision Approach Path Indicator (PAPI). The investigation of the FedEx Flight 1478 crash at Tallahassee airport in 2002 raises doubts about this presumption. It found a contributory factor was that the pilot had difficulty distinguishing the PAPI signals because of his deficient color vision (DCV) even though he had passed the Farnsworth lantern. This paper reports on the ability of subjects with DCV who pass the Farnsworth lantern to distinguish PAPI signal colors. Under a good visibility and a marginal visibility condition, 52 DCV subjects and 52 with normal color vision (NCV) named the colors of simulated PAPI signal lights observed in the dark. Subjects were tested with the Farnsworth lantern and a comprehensive battery of other color vision tests. The 10 DCV subjects who passed the Farnsworth lantern made significantly more errors naming PAPI signals than the NCV subjects and 80% made more errors than the worst performing NCV subject. Some confused the red and white signals on more than 10% of occasions. Passing the Farnsworth lantern test does not ensure that DCV pilots can distinguish PAPI signal colors. The criterion for passing the lantern test should be made more stringent. In addition the design of PAPI signals can be improved by a better choice of the white color and by providing a redundant non-color cue. abnormal color vision, aviation color vision standard, aviation signal lights, color vision tests, PAPI.

Color Vision Assessment by Farnsworth Lantern: Results Using Alternative Pass-Fail Criteria

The Farnsworth lantern is used in the United States and Australia to assess pilot applicants who have deficient color vision (DCV). Its efficacy was questioned following a crash in July 2002 because the DCV pilot confused the red and white approach path signals, despite having passed the Farnsworth test. The Farnsworth lights are larger and brighter than many aviation signals and it has a higher pass rate than the lantern tests used in other countries. Moreover, applicants can pass by making no errors on 1 run of 18 lights, which is too small a sample. There were 3 runs of the Farnsworth lantern given to 100 male subjects with DCV. The effect on pass rate of changing the number of runs and the pass criterion was assessed. There were 20 subjects who passed the Farnsworth lantern test. Their average error rate over three runs was 3.9%; two had an error rate of 13% and five confused red and white signals, the colors used in approach path signals. One subject passed by having zero errors on run 1 but made 13% errors on the next two runs. If all subjects are given two runs after a practice run, 15% pass if the pass criterion is < or = 1 error and 11% pass if it is zero errors. No subject made red-white color confusions with the zero error pass criterion. A practice run and two test runs should always be given. The pass criterion should be < or = 1 error in total on the two test runs.

Color Vision and Fatigue: An Incidental Finding

Because there is little information available as to how fatigue and color vision interact, we present some incidental findings on how a protanope and a color-normal perform on several color vision tests after 1 night of sleep deprivation. A series of clinically and occupationally based color vision tests were administered to a protanope and a color-normal subject after they had stayed awake all night and after a regular night's sleep. There was essentially no change in their performance on the clinical color vision tests; however, both did worse on the occupationally based color vision tests after 1 night of sleep deprivation. The color-normal made numerous errors in identifying colors displayed on a video display terminal, whereas the protanope had a large increase in errors on the CN Lantern Test. Both subjects passed these respective tests after a regular night's sleep. The primary reason for color-normal's poor performance on the video display terminal test was probably due to a decrement in his visuo-motor control rather than a loss in color discrimination. In contrast, the protanope's poor performance on the lantern test was probably due to the additive effects of the inherent limitations of his visual system and fatigue.

The ChromaGen contact lens system: colour vision test results and subjective responses

The ChromaGen lens system is designed to enhance colour perception in colour vision deficiency (CVD). To investigate its efficacy, 14 CVD subjects were prescribed ChromaGen contact lenses. Colour vision tests (Ishihara, Farnsworth Munsell D-15, Farnsworth Lantern) were administered at baseline, lens dispensing, and after a 2-week lens-wearing trial during which subjective responses were recorded daily using visual analogue scales. ChromaGen lenses significantly reduced Ishihara error rates (p<0.001; ANOVA), particularly for deutan subjects. There was also a significant reduction in errors (p<0.005) on the D-15 test. Conversely, lens wear had no significant effect on Farnsworth Lantern test performance. Subjectively, subjects reported enhanced colour perception, but poor vision in dim light. Judgement of distance and motion were only slightly affected. We conclude that ChromaGen lenses may enhance subjective colour experience and assist in certain colour-related tasks, but are not indicated as an aid for CVD in occupations with colour vision-related restrictions.

A lantern color vision test for the rail industry

Correct identification of wayside signal colors is critical for safe operation of railway equipment. However, evaluating color discrimination using just a screening test may not be occupationally relevant. A lantern test (CNLAN) was designed to provide a functional assessment of color discrimination for the rail industry. It was validated against a simulated field trial. 81 individuals with normal color vision and 74 individuals with congenital red-green defects participated. Color vision was classified using the Nagel Anomaloscope. Using a criterion based on the worst-normal performance, 97% of the individuals with a color vision defect failed both the CNLAN and simulation trial. This value is slightly lower than the 100% who failed both the Ishihara test and simulation. However, the Ishihara test also failed 3.7% of the color-normals who passed both the simulation and lantern, whereas by definition none of the color-normals failed the lantern. This lantern test provides a reasonable functional assessment of one's ability to identify rail signal colors; especially when a strict failing criterion is applied to screening tests.

A family with protanomaly and deuteranomaly

A family with protanomaly and deuteranomaly is reported. It consists of four members: two parents, a daughter, and a son. The father and the daughter are deuteranomalous, the son is protanomalous, and the mother is color normal. Clinical color vision tests including pseudo-isochromatic plates, Farnsworth's dichotomous test, lantern test, and anomaloscope were performed. PCR was done using primers to amplify exon 4 and 5 of X-linked visual pigment genes. The father and the daughter had LWS and MWS/LWS (exon4/5) hybrid genes. The son had MWS and LWS/MWS (exon4/5) hybrid genes. The mother had LWS, MWS, and LWS/MWS (exon4/5) hybrid genes. She is considered to have MWS and LWS/MWS hybrid genes on one X chromosome, which was passed to her son and an LWS gene on the other X-chromosome, which was passed to her daughter. © 2000 John Wiley & Sons, Inc. Col Res Appl, 26, S93–S95, 2001

Can clinical colour vision tests be used to predict the results of the Farnsworth lantern test?

Clinicians usually do not have access to a lantern test when making an occupational assessment of the ability of a person with defective colour vision to recognise signal light colours: they must rely on the results of ordinary clinical tests. While all colour vision defectives fail the Holmes Wright Type B lantern test and most fail the Holmes Wright Type A lantern, 35% of colour vision defectives pass the Farnsworth lantern. Can clinical tests predict who will pass and fail the Farnsworth lantern? We find that a pass (less than two or more diametrical crossings) at the Farnsworth Panel D 15 Dichotomous test has a sensitivity of 0.67 and specificity of 0.94 in predicting a pass or fail at the Farnsworth lantern test; a Nagel range of >10 has a sensitivity of 0.87 and a specificity of 0.57. We conclude that neither the D 15 nor the Nagel Anomaloscope matching range are satisfactory predictors of performance on the Farnsworth Lantern.

Pre-employment colour vision testing.

Male candidates (1020) for employment in occupations that required discrimination of colour were subjected to the Ishihara test and two trade tests of colour perception, the Giles Archer Lantern test and the Electricity Supply Industry (ESI) wire test. One hundred candidates failed the Ishihara test, 61 of the 100 passed both trade tests; 16 of the 100 passed the wire test alone and 7 of the 100 passed the lantern test alone but only 16 failed all 3 tests. Seventy-seven of the 84 who passed some part of their colour perception assessment were offered employment appropriate to their colour vision ability. Eleven of the 16 who passed the wire test alone and 3 of the 6 who passed the lantern test alone successfully entered employment. The Ishihara test, whilst being a useful screening test, is not sufficient on its own as a test of suitability for employment; one or more trade tests should be administered before rejecting candidates who fail it.

Electronic Flight Information System displays and colour defective observers

The use of colour in the Electronic Flight Information System (EFIS) displays of modern commercial airliners has created an environment for pilots in which colour coding is used more extensively than previously. Therefore, more thorough diagnostic analysis of pilots' colour vision, before a full commercial licence is granted, has been proposed. The aim of the experiments reported here is to determine whether a reliable battery of diagnostic colour vision tests is able to predict the colour naming perforniarice of colour defective subjects when using Boeing 747–400 EFIS displays. Results show that observers with normal colour vision and those identified as hiing. mild deuteranomaly made significantly fewer errors than those with other types of defective colour vision. As protanomals, protanopes and more severe deitteranomals can only be identified reliably with a battery of colour vision tests, we propose that the lantern test be supplemented by other tests for aircrew colour vision testing.

The Boström-Kugelberg pseudo-isochromatic plates. How efficient is the third edition?

The third edition of the Boström-Kugelberg pseudo-isochromatic plates was printed to the best possible visual match with the second edition. Slight colour differences between the 2 editions initiated this study where 72 colour defectives and 57 normal trichromats were tested with the plates and classified with the aid of Nagel's anomaloscope. Of the defectives, the plate test disclosed all but two anomalous trichromats. One normal subject was falsely classified as defective. The plates had to be shown twice according to the instructions since otherwise 13 of the 53 normals were misclassified. Three plates were shown to have low sensitivity; one is best used as a demonstration plate, and the other two can be deleted without lost efficiency. Forty-eight of the colour defectives were also studied with Farnsworth's lantern. The correlation between the numbers of plate and signal errors was weak. All subjects who failed the lantern test made several plate errors, but 15 subjects who passed the lantern test, made two or more errors on the plate test. The outcome of the plate test does not give evidence of the subject's lantern test performance.