Ishihara Test Research Articles

Neural activation patterns and connectivity in visual attention during Number and Non-number processing: An ERP study using the Ishihara pseudoisochromatic plates.

Visual cognitive function is important to build up executive function in daily life. Perception of visual Number form (e.g., Arabic digit) and numerosity (magnitude of the Number) is of interest to cognitive neuroscientists. Neural correlates and the functional measurement of Number representations are complex occurrences when their semantic categories are assimilated with other concepts of shape and colour. Colour perception can be processed further to modulate visual cognition. The Ishihara pseudoisochromatic plates are one of the best and most common screening tools for basic red-green colour vision testing. However, there is a lack of study of visual cognitive function assessment using these pseudoisochromatic plates. We recruited 25 healthy normal trichromat volunteers and extended these studies using a 128-sensor net to record event-related EEG. Subjects were asked to respond by pressing Numbered buttons when they saw the Number and Non-number plates of the Ishihara colour vision test. Amplitudes and latencies of N100 and P300 event related potential (ERP) components were analysed from 19 electrode sites in the international 10-20 system. Abrain topographic map, cortical activation patterns and Granger causation (effective connectivity) were analysed from 128 electrode sites. No major significant differences between N100 ERP components in either stimulus indicate early selective attention processing was similar for Number and Non-number plate stimuli, but Non-number plate stimuli evoked significantly higher amplitudes, longer latencies of the P300 ERP component with a slower reaction time compared to Number plate stimuli imply the allocation of attentional load was more in Non-number plate processing. Adifferent pattern of asymmetric scalp voltage map was noticed for P300 components with a higher intensity in the left hemisphere for Number plate tasks and higher intensity in the right hemisphere for Non-number plate tasks. Asymmetric cortical activation and connectivity patterns revealed that Number recognition occurred in the occipital and left frontal areas where as the consequence was limited to the occipital area during the Non-number plate processing. Finally, the results displayed that the visual recognition of Numbers dissociates from the recognition of Non-numbers at the level of defined neural networks. Number recognition was not only a process of visual perception and attention, but it was also related to a higher level of cognitive function, that of language.

Illuminations that improve color discrimination ability of people with red-green color vision deficiency.

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.

Chiasmal syndrome: Clinical characteristics in patients attending an ophthalmological center

PurposeTo present the clinical characteristics of a group of patients with the diagnosis of chiasmal syndrome who attended a large ophthalmological institute. MethodsRetrospective, observational clinical study with the review of medical records of patients with a diagnosis of chiasmal syndrome. The following variables were assessed: demographic characteristics, chief complaint upon presentation, best-corrected visual acuity (BCVA), presence or absence of diplopia, pupillary responses, optic nerve head morphology, etiology, and results from the ancillary tests including Ishihara test, Goldmann visual field (GVF) perimetry and neuroimaging. ResultsA total of 104 met the inclusion criteria, with a median age of 52years (range 4–86years). Fifty-four patients (51.9%) were referred to our institution with a diagnosis of a causative etiology for chiasmal syndrome, while in 50 (48.1%) the diagnosis was performed at our center. The most common presenting symptom was low visual acuity in 57 patients (54.8%), and the most common GVF defect was bitemporal hemianopsia in 39 patients (78 eyes, 39.8%). Pupillary abnormalities were present in 58 patients (55.7%), the optic nerve revealed pallor at any degree in 67 patients (64.4%) and the Ishihara test was affected in 65 patients (62.5%). The most common diagnosis was pituitary macroadenoma. ConclusionThe ophthalmologist participates in the diagnosis and rehabilitation of patients with chiasmal syndrome. Low visual acuity is the most common symptom at presentation, and bitemporal hemianopia the most frequent GVF defect. Examination of the optic nerve head and pupillary responses, and ancillary tests including Ishihara test and neuroimaging are relevant for diagnosis.

Neuro‐retinal changes evaluation in multiple sclerosis patients: 10 years follow‐up

PurposeTo analyze functional and structural changes in the retina and optic nerve (ON) in patients with multiple sclerosis (MS) compared to healthy controls (C) and after 10 years of follow‐up.MethodsFifty eyes of patients with mild‐moderate MS were evaluated and compared to 50 eyes of C at a baseline visit and at 10 years of follow‐up. The following functional parameters were evaluated: best‐corrected visual acuity (BCVA), color vision examined with the Ishihara test, and mean deviation of visual field (VF) analyzed using the Humphrey perimetry. The structural parameters of the ON were also studied using the NSITE axonal application of the optical coherence tomograph (OCT) Heidelberg Spectralis.ResultsNo differences were found in the functional parameters in MS patients compared to C, neither at 10 years of follow‐up (p > 0.05). However a statistically significant decrease was observed in the structural parameters between C and MS patients at 10 years of follow‐up: mean, nasal‐inferior (NI), temporal‐inferior (TI), temporal (T), temporal‐superior (TS), papillomacular bundle and nasal/temporal (N/T) ratio thickness (p < 0.001), but also in the axonal thickness, specifically in the mean, TI, T, TS, papillomacular bundle and N/T ratio thickness (p < 0.001) measured with OCT in patients with MS after 10 years of disease progression. A higher functional disability using the Expanded Disability Status Scale was also recorded.ConclusionsAxonal damage can be analyzed and quantified in the retina and ON using the OCT in MS. Patients with MS showed significant decrease in the retina nerve fiber layer at 10 years of follow–up compared to C and a progressive axonal death (without outbreaks) that could be detected and quantified using the OCT, but not with the functional tests (BCVA, color and VF).

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Dynamic Color Displays Using Stepwise Cavity Resonators.

High-resolution multicolor printing based on pixelated optical nanostructures is of great importance for promoting advances in color display science. So far, most of the work in this field has been focused on achieving static colors, limiting many potential applications. This inevitably calls for the development of dynamic color displays with advanced and innovative functionalities. In this Letter, we demonstrate a novel dynamic color printing scheme using magnesium-based pixelated Fabry-Pérot cavities by gray scale nanolithography. With controlled hydrogenation and dehydrogenation, magnesium undergoes unique metal and dielectric transitions, enabling distinct blank and color states from the pixelated Fabry-Pérot resonators. Following such a scheme, we first demonstrate dynamic Ishihara plates, in which the encrypted images can only be read out using hydrogen as information decoding key. We also demonstrate a new type of dynamic color generation, which enables fascinating transformations between black/white printing and color printing with fine tonal tuning. Our work will find wide-ranging applications in full-color printing and displays, colorimetric sensing, information encryption and anticounterfeiting.

The “C test” for tritan discrimination

AbstractThe aim of this study was to develop and evaluate a clinical standard capable of generating ordinal measures of monocular tritan discrimination. A novel pseudoisochromatic plate test was developed, called the “C test.” It contains 10 progressively desaturated plates arranged in perceptually distinct steps that provide a standard for analyzing the threshold for tritan discrimination. The most difficult plate that can be detected is the “C score.” Relevant diagnostic findings including the C score, Logmar acuity, Pelli‐Robson score, and LOCS III lens grading were prospectively recorded in 568 eyes. A total of 355 normal eyes were selected for statistical analysis. The correlations between C score, Logmar acuity, and Pelli‐Robson score with LOCS III grading were analyzed with Spearman rank analysis. The strongest correlations were between the Logmar acuity with posterior subcapsular cataract (PSC) (0.68), the C score with nuclear colour (NC) (–0.58), and the Logmar acuity with NC (0.57). The lower normal limit for the C score was 9 in pseudophakes and phakic eyes with NC < 3, 7 for eyes with NC = 3, but undetermined for eyes with NC > 3. A comparison of C score distribution between three distinct age ranges of pseudophakic eyes (n = 136) showed no significant variation (P = .486). The Spearman rank correlation between C score and Logmar acuity was 0.028, and between C score and Pelli‐Robson score was 0.012. The normal limit for the C score used under 800 Lux is 9 when NC < 3 and 7 when NC = 3 in all age groups.

The Glare Effect Test and the Impact of Age on Luminosity Thresholds.

The glare effect (GE) is an illusion in which a white region appears self-luminous when surrounded by linearly decreasing luminance ramps. It has been shown that the magnitude of the luminosity effect can be modulated by manipulating the luminance range of the gradients. In the present study we tested the thresholds for the GE on two groups of adults: young (20–30 years old) and elderly (60–75 years old). Purpose of our perspective study was to test the possibility of transforming the GE into a test that could easily measure thresholds for luminosity and discomfort glare. The Glare Effect Test (GET) consisted in 101 printed cards that differed from each other for the range of luminance ramps. Participants were assessed with GET and a battery of visual tests: visual acuity, contrast sensitivity, illusion of length perception, and Ishihara test. Specifically in the GET, participants were required to classify cards on the basis of two reference cards (solid black-no gradient; full range black to white gradient). PSEs of the GE show no correlation with the other visual tests, revealing a divergent validity. A significant difference between young and elderly was found: contrary to our original expectations, luminosity thresholds of GE for elderly were higher than those for young, suggesting a non-direct relationship between luminosity perception and discomfort glare.

The Efficacy of Progesterone in Treatment of Traumatic Optic Neuropathy (Proton Study)

To evaluate the visual function improvement for treatment of indirect traumatic optic neuropathy Study design was comparative historical controlled trial. Seven patients newly diagnosed with indirect traumatic optic neuropathy Study design was comparative historical controlled trial. Seven newly diagnosed with indirect traumatic optic neuropathy (TON) were enrolled for progesterone group. Nineteen indirect Ton patients were reviewed medical records for steroid group (N= 12) and observation group (N= 7). Patients in progesterone group were given Depot medroxyprogesterone acetate (DMPA) 1 mg/kg. intramuscular injection every 12 hrs. for 5 days and observed for side effects. All patients were examined and reviewed for visual acuity by ETDRS chart, color vision test by Ishihara test, visual field testing by Humphrey automated perimetry, fundus and optic disc examination at baseline, follow-up 1 week, 1 month and 3 months. Demographic and clinical characteristic of patients in 3 groups were not different in terms of age, sex, underlying disease, side of eye, type of injury, baseline visual acuity, associated orbital fracture, history of amnesia, time to visit hospital and time to start treatment. Improvement in best-corrected visual acuity (BCVA) compared at 3 months from baseline showed no difference between 3 groups (p= 0.891). Analysis within steroid group showed statistically significant improvement of BCVA at 1 and 3 months (p= 0.015, 0.028 respectively). No improvement was shown in color vision and visual field in progesterone group. Only better baseline BCVA was the protective factor for better visual outcome (p= 0.027, Odds ratio = 0.004, 95%CI = 0.000 - 0.537). No side effects of progesterone were found in this study. Progesterone is a safe and promising neuroprotective agent that could be adjunctive or alternative to steroid in case of contraindication to corticosteroid treatment. This study showed no difference among choices of treatment therefor study in larger population is required. Steroid remains an effective option contrast with recent studies.

Performance of the Ishihara, D‐15, and City University colour vision test as a function of intraocular straylight

AbstractThree colour vision tests, the Ishihara test, the City University Test (CUT), and the D‐15 test were studied as a function of induced intraocular straylight, using a commercially available light‐scattering filter. Thirty young individuals (aged 17‐28 years) with no ocular abnormalities and normal colour vision participated in the study. Intraocular straylight was estimated in all individuals using a psychophysical compensation method with the C‐Quant straylight meter, with and without the light‐scattering filter which caused an increase in intraocular straylight typical of that found for cataract. Under normal viewing conditions all the subjects passed each of the 3 tests with no errors. When viewing the Ishihara test plates through the filter, 10 out of the 30 observers made at least 1 error. Three subjects also made errors on the desaturated CUT test plates, but all subjects still passed the D‐15 test with the filter. The errors in the Ishihara test correlated with the amount of intraocular straylight, as measured with the C‐Quant. This study indicates that interpretation of the Ishihara test in a clinical environment will be made more difficult in individuals with higher levels of straylight.

Validity of the Worth 4 Dot Test in Patients with Red-Green Color Vision Defect.

The Worth four dot test uses red and green glasses for binocular dissociation, and although it has been believed that patients with red-green color vision defects cannot accurately perform the Worth four dot test, this has not been validated. Therefore, the purpose of this study was to demonstrate the validity of the Worth four dot test in patients with congenital red-green color vision defects who have normal or abnormal binocular vision. A retrospective review of medical records was performed on 30 consecutive congenital red-green color vision defect patients who underwent the Worth four dot test. The type of color vision anomaly was determined by the Hardy Rand and Rittler (HRR) pseudoisochromatic plate test, Ishihara color test, anomaloscope, and/or the 100 hue test. All patients underwent a complete ophthalmologic examination. Binocular sensory status was evaluated with the Worth four dot test and Randot stereotest. The results were interpreted according to the presence of strabismus or amblyopia. Among the 30 patients, 24 had normal visual acuity without strabismus nor amblyopia and 6 patients had strabismus and/or amblyopia. The 24 patients without strabismus nor amblyopia all showed binocular fusional responses by seeing four dots of the Worth four dot test. Meanwhile, the six patients with strabismus or amblyopia showed various results of fusion, suppression, and diplopia. Congenital red-green color vision defect patients of different types and variable degree of binocularity could successfully perform the Worth four dot test. They showed reliable results that were in accordance with their estimated binocular sensory status.

Rejecting Similar Stimuli is Different from Rejecting Nonsimilar Stimuli in Item Recognition: Event-Related Potential Evidence

Two crucial elements are necessary to recognize an object: familiarity and recollection (Yonelinas, 2002). Familiarity is generally defined as a fast memory process that supports recognition without detailed information. Recollection refers to an all-or-none, recall-like process that retrieves detailed memories about individual items or episodes. Event-related potentials (ERPs) have largely contributed to distinguish these two memory processes (Rugg & Curran, 2007). A mid-frontal effect, known as the FN400 effect, is generally associated to familiarity because it consistently differs when comparing new items with studied items correctly recognized and new familiar items (i.e., lures) falsely recognized (Curran, 2000; Curran & Cleary, 2003). In contrast, recollection occurs later over parietal regions, and is reflected by greater positive amplitude for recognized studied items than for new items correctly rejected and lures falsely recognized (Curran, 2000).While it is reasonable to argue that familiarity contributes to the false recognition of lures, it is still unclear whether recollection contributes to their correct rejection. In contrast to new items, lures tend to be confounded with other studied or known items. To avoid this confusion, notice the novelty of the lures, and achieve their correct rejection, one must search for differences between the lures and the other items (Gallo, Bell, Beier, & Schacter, 2006). Such search requires a comparison between the perceived lures and the recollected representations from memory of the confounding items. According to a few studies (Johnson et al., 1997; Herzmann, Jin, Cordes, & Curran, 2012) this recall-to-reject (Rotello, Macmillan, & Van Tassel, 2000) or recollection rejection (Matzen, Taylor, & Benjamin, 2011) process is different from recollection leading to recognition of old items, and occurs mainly in frontal regions (Lepage, Brodeur, & Bourgouin, 2003; Gallo, McDonough, & Scimeca, 2009; Slotnick, Moo, Segal, & Hart Jr, 2003).Current studyThe goal of this study was to examine whether rejecting items that are similar to the studied ones differs from the recollection of previously presented items, and whether it activates frontal regions instead of parietal regions. Participants completed two experiments, one where the new items were unrelated to the studied items, thus were neither familiar nor linked to specific memories (Experiment 1), and one where the new items were lures similar to studied items (Experiment 2). The parietal old/new effect was expected to be comparable across experiments and greater old/new effect was expected in the frontal region when new items were lures. The FN400 was also examined.METHODParticipantsSeventeen healthy volunteers (10 female), aged between 20 and 35 years (Mage = 24.3), were recruited by means of classified advertising (e.g., Craigslist). Participants were right-handed, reported no current or previous history of neurologic disease or head trauma causing loss of consciousness, and had no first- degree family member having a history of mental health problems. All participants passed the Pseudoisochromatic Plates Ishihara Compatible Test, meaning that they had intact color perception. Written informed consent was obtained from all participants after a complete description of the study. The ethic review board of the Douglas Mental Health McGill University Institute approved the protocol and the consent form.Stimuli and procedureAll participants participated in two episodic memory experiments (see Figure 1). Eight participants started with Experiment 1 and nine started with Experiment 2. Each experiment comprised of a study phase with 200 stimuli, immediately followed by a recognition phase including 100 old stimuli and 100 new stimuli. Old stimuli were photos of objects presented in the study phase, but depicted from a different angle of view. New stimuli in Experiment 1 represented objects that were seen for the first time and which were unrelated to objects presented at study. …

Color perception differentiates Alzheimer's Disease (AD) from Vascular Dementia (VaD) patients.

Alzheimer's Disease (AD) and Vascular Dementia (VaD) are the most common causes of dementia in older people. Both diseases appear to have similar clinical symptoms, such as deficits in attention and executive function, but specific cognitive domains are affected. Current cohort studies have shown a close relationship between αβ deposits and age-related macular degeneration (Johnson et al., 2002; Ratnayaka et al., 2015). Additionally, a close link between the thinning of the retinal nerve fiber (RNFL) and AD patients has been described, while it has been proposed that AD patients suffer from a non-specific type of color blindness (Pache et al., 2003). Our study included 103 individuals divided into three groups: A healthy control group (n = 35), AD (n = 32) according to DSM-IV-TR, NINCDS-ADRDA criteria, and VaD (n = 36) based on ΝΙΝDS-AIREN, as well as Magnetic Resonance Imaging (MRI) results. The severity of patient's cognitive impairment, was measured with the Mini-Mental State Examination (MMSE) and was classified according to the Reisberg global deterioration scale (GDS). Visual perception was examined using the Ishihara plates: "Ishihara Color Vision Test - 38 Plate." The three groups were not statistically different for demographic data (age, gender, and education). The Ishihara color blindness test has a sensitivity of 80.6% and a specificity of 87.5% to discriminate AD and VaD patients when an optimal (32.5) cut-off value of performance is used. Ishihara Color Vision Test - 38 Plate is a promising potential method as an easy and not time-consuming screening test for the differential diagnosis of dementia between AD and VaD.

Hybrid imprinting process to fabricate a multi-layer compound eye for multispectral imaging.

We present a high-precision hybrid imprinting method to fabricate multi-layer micro-optical structures on nonplanar substrates using a custom-built vacuum imprinting system; with the application of kinematic couplings that align the flexible stamps in all six degrees of freedom, a cross-layer pattern registration precision of 400 nm has been achieved on nonplanar substrates. To demonstrate the precision and feasibility of the new process and instrument, we have designed and fabricated a multi-layer artificial compound eye (ACE) for multispectral imaging. The shapes and sizes of all 12 micro-lenses on the ACE are optimized and integrated with different color filers (red, green and blue) so that the light from different channels and of different spectral contents will focus to the same plane, where the photodetector is located. Next, the multi-layer ACE is installed in a portable optical system for simultaneous multispectral imaging, i.e., to perform pattern detection by looking at specific frequency windows. Imaging experiments are devised and performed on (1) color blindness test cards, (2) space image, and (3) breast and gastric tumor samples. The results confirm the system's capabilities of frequency separation, extraction of hidden information, and tumor identification.

Retinal and Optic Nerve Degeneration in Patients with Multiple Sclerosis Followed up for 5 Years

To quantify retinal nerve fiber layer (RNFL) changes in patients with multiple sclerosis (MS) and healthy controls with a 5-year follow-up and to analyze correlations between disability progression and RNFL degeneration. Observational and longitudinal study. One hundred patients with relapsing-remitting MS and 50 healthy controls. All participants underwent a complete ophthalmic and electrophysiologic exploration and were re-evaluated annually for 5 years. Visual acuity (Snellen chart), color vision (Ishihara pseudoisochromatic plates), visual field examination, optical coherence tomography (OCT), scanning laser polarimetry (SLP), and visual evoked potentials. Expanded Disability Status Scale (EDSS) scores, disease duration, treatments, prior optic neuritis episodes, and quality of life (QOL; based on the 54-item Multiple Sclerosis Quality of Life Scale score). Optical coherence tomography (OCT) revealed changes in all RNFL thicknesses in both groups. In the MS group, changes were detected in average thickness and in the mean deviation using the GDx-VCC nerve fiber analyzer (Laser Diagnostic Technologies, San Diego, CA) and in the P100 latency of visual evoked potentials; no changes were detected in visual acuity, color vision, or visual fields. Optical coherence tomography showed greater differences in the inferior and temporal RNFL thicknesses in both groups. In MS patients only, OCT revealed a moderate correlation between the increase in EDSS and temporal and superior RNFL thinning. Temporal RNFL thinning based on OCT results was correlated moderately with decreased QOL. Multiple sclerosis patients exhibit a progressive axonal loss in the optic nerve fiber layer. Retinal nerve fiber layer thinning based on OCT results is a useful marker for assessing MS progression and correlates with increased disability and reduced QOL.

Congenital and acquired colour vision deficiency among population in North Kordofan State of Sudan

Background: Congenital colour vision deficiency (CVD) is an x-linked chromosome disorders which, predominantly occurring in males. This disorder results from abnormalities in one or all three-cone type's photoreceptors. It is mainly affect long wavelength photopigments (red) and middle wavelength photopigments (green). However, the acquired CVD is due to ocular or general pathology as well as due to prolonged use of some medications, which is mostly affect short wavelength photopigments (blue). Objective: This study aimed to evaluate the prevalence of hereditary and acquired CVDs among Sudanese population in North Kordofan State. Materials and Methods: This is a population-based crossed-sectional study of 1100 subjects, their age ranged from 10 to 80 years, the mean age of subjects was 40.4 ± 16.6 (standard deviation) were selected from three districts and 110 subjects were selected from each set. Investigations included visual acuity using Snellen tumbling E-chart, refraction using retinoscopy, colour vision using Ishihara and City University colour vision tests, external eye using torch and magnifier and evaluation of internal eye and ocular media using direct ophthalmoscope. Results: A total of 1216 subjects were invited to participate in the study and 1100 were examined resulting in a participation rate of 91%. The findings revealed that 61 (5.5%) had CVD, 49 (9.0%) were males and 12 (2.2%) were females. The prevalence of congenital (red-green) CVD was 39 (3.5%) which was high in males 37 (6.8%) than females 2 (0.4%). The prevalence of congenital CVD was found associated with males (P

Wearable Improved Vision System for Color Vision Deficiency Correction.

Color vision deficiency (CVD) is an extremely frequent vision impairment that compromises the ability to recognize colors. In order to improve color vision in a subject with CVD, we designed and developed a wearable improved vision system based on an augmented reality device. The system was validated in a clinical pilot study on 24 subjects with CVD (18 males and 6 females, aged 37.4 ± 14.2 years). The primary outcome was the improvement in the Ishihara Vision Test score with the correction proposed by our system. The Ishihara test score significantly improved (n}{}p = 0.03n) from 5.8 ± 3.0 without correction to 14.8 ± 5.0 with correction. Almost all patients showed an improvement in color vision, as shown by the increased test scores. Moreover, with our system, 12 subjects (50%) passed the vision color test as normal vision subjects. The development and preliminary validation of the proposed platform confirm that a wearable augmented-reality device could be an effective aid to improve color vision in subjects with CVD.

A New Computerized Test for Colour Deficiency

10% percent of today's population suffers from colour vision deficiency. There are many tests to diagnose colour blindness in related literature. Ishihara pseudoisochromatic plates which have almost one-century background are being used widespread to diagnose if a subject is colour blind. In this study, a novel computerized test based on Ishihara tests has been designed. The new test has been applied on 12 individuals having colour deficiency and 50 individuals having normal colour vision. We have achieved 100% sensitivity and 100% specificity from the new test though Ishihara test results.

Light wavelengths of LEDs to improve the color discrimination in Ishihara test and Farnsworth Panel D‐15 test for deutans

AbstractThis study was performed to determine significant light wavelengths to improve color discrimination ability of subjects with deutan. We conducted both the Ishihara test and the Farnsworth Panel D‐15 test for subjects with deutan and normal color vision. Seven different LED lights from 450 to 660 nm and an additional D65 white lamp were utilized to change the lighting conditions, including the wavelength and intensity. The results of the Ishihara test and D‐15 test showed that color identification of deutans was markedly improved with the longer wavelength LEDs regardless of the intensity of the additional D65 lamp. Notably, the error rates of deutans in the Ishihara test were <25% for LED wavelengths of 630 and 660 nm. In the case of subjects with normal color vision, the D65 lamp abolished the errors in the Ishihara test, regardless of the LED wavelength. Addition of the D65 lamp also decreased the number of crossings in the D‐15 test. These results suggested that illumination by LED light with longer wavelengths, such as 630 and 660 nm, may provide deutans with greater red‐green discrimination ability in both the Ishihara test and the Farnsworth Panel D‐15 test. © 2016 Wiley Periodicals, Inc. Col Res Appl, 42, 424–430, 2017

Historical Development of the Wool and Colour Plate Tests for Screening for Colour Vision Deficiencies in German Speaking Countries

Colour vision is a complex visual function that can be affected by congenital and/or acquired disorders. The frequency of congenital colour vision deficiencies has been investigated in rail and navy staff since the 1870s. Various test methods have been developed. Wool tests, flor contrast tests and colour plate tests have been used. A published colour plate test, based on Stilling's pseudo-isochromatic plates in combination with a flor contrast test, has been a common screening method for colour vision testing in German-speaking countries. This test is intended to detect congenital and acquired colour vision deficiencies in a simple and safe manner. More modern options, such as Internet and tablet PC have technical limitations, but will increasingly be used for screening for colour vision deficiencies.