Colour perception deficits after posterior stroke: Not so rare after all?

Cerebral achromatopsia is an acquired colour perception impairment caused by brain injury, and is generally considered to be rare. Both hemispheres are thought to contribute to colour perception, but most published cases have had bilateral or right hemisphere lesions. In contrast to congenital colour blindness that affects the discrimination between specific hues, cerebral achromatopsia is often described as affecting perception across all colours. Most studies of cerebral achromatopsia have been single cases or case series of patients with colour perception deficits. Here, we explore colour perception deficits in an unbiased sample of patients with stroke affecting the posterior cerebral artery (N = 63) from the Back of the Brain project. Patients were selected based on lesion location only, and not on the presence of a given symptom. All patients were tested with the Farnsworth D-15 Dichotomous Colour Blindness Test and performance compared to matched controls (N = 45) using single case statistics. In patients with abnormal performance, the patterns of colour difficulties were qualitatively analysed. 22% of the patients showed significant problems with colour discrimination (44% of patients with bilateral lesions, 28% with left hemisphere lesions and 5% with right hemisphere lesions). Lesion analyses identified two regions in ventral occipital temporal areas in the left hemisphere as particularly strongly related to impaired performance in colour perception, but also indicated that bilateral lesions are more strongly associated with impaired performance that unilateral lesions. While some patients only had mild deficits, colour perception impairments were in many cases severe. Many patients had selective deficits only affecting the perception of some hues. The results suggest that colour perception difficulties following PCA stroke are common, and that they vary in severity and expression. In addition, the results point towards bilateral processing of colour perception with a left hemispheric domination, contradicting previous reports.

Association between cognition and color discrimination among Lebanese patients with schizophrenia.

BACKGROUND: Patients with schizophrenia (SCZ) exhibit poorer color discrimination than normal individuals. Although retinal abnormalities, as well as cortical and subcortical alterations, found in patients with SCZ have been suggested to cause this poor color discrimination, the impact of cognitive impairment remains to be determined. Dopamine (DA) and glutamate (Glu), known to be disrupted in SCZ, are also suggested to play a role in color discrimination. Our objective was to investigate the contribution of cognitive impairment to color discrimination deficits in SCZ and to examine if these deficits are correlated to SCZ symptoms. METHODS: This study includes 127 patients with SCZ between July and September 2021. The participants completed several questionnaires, specifically the Positive and Negative Syndrome Scale (PANSS), the Montreal Cognitive Assessment (MoCA) test, and the Farnsworth D-15 test, to assess the extent of SCZ symptoms, cognition, and color discrimination respectively. RESULTS: Higher cognition (Beta = - 0.279) was significantly associated with a lower total error score (TES). Moreover, a higher positive PANSS score (Beta = 0.217) was significantly associated with a higher TES. A multinomial regression analysis taking the type of color blindness as the dependent variable showed that female sex (ORa = 5.46) was significantly associated with a certain type of color blindness. CONCLUSION: Color discrimination deficits in patients with SCZ may be due to the effect of cognitive impairment and/or SCZ itself.

Ametropia and Emmetropization in CNGB3 Achromatopsia.

Purpose: Emmetropization is the process of adjusting ocular growth to the focal plane in order to achieve a clear image. Chromatic light may be involved as a cue to guide this process. Achromats are color blind and lack normal cone function; they are often described as being hyperopic, indicating a failure to emmetropize. We aim to describe the refraction and refractive development in a population of genetically characterized achromats. Methods: Refractive error data were collected retrospectively from 28 medical records of CNGB3 c.1148delC homozygous achromats. The distribution of spherical equivalent refractive error (SER) and spherical error was analyzed in adults. The refractive development in children was analyzed by documenting astigmatic refractive error and calculating median SER in 1-year age groups and by analyzing the individual development when possible. Results: The distribution of SER and spherical error resembled a Gaussian distribution, indicating that emmetropization was disturbed in achromats, but we found indication of some decrease in SER during the first years of childhood. The prevalence of refractive errors was high and broadly distributed. Astigmatic refractive errors were frequent but did not seem to increase with age. Conclusions: Refractive development in achromats is more complicated than a complete failure to emmetropize. The spread of refractive errors is larger than previously documented. Results presented here support the theory that chromatic cues and cone photoreceptors may play a role in emmetropization in humans but that it is not essential.

Clinical and Imaging Characteristics Associated with Color Vision Impairment in Lewy Body Disease.

BACKGROUND: Color vision impairment (CVI) has been reported in dementia with Lewy bodies (DLB) and prodromal Lewy body disease (pro-LBD). OBJECTIVE: In order to better characterize the diagnostic value of CVI testing, we compared the prevalence of CVI in patients with with Lewy body disease compared to Alzheimer's disease (AD), and we examined clinical and imaging characteristics associated with CVI in patients with DLB and suspected pro-LBD. METHODS: We retrospectively reviewed medical records, dopamine transporter (DaT-SPECT) imaging, and volumetric MRI from patients with AD, DLB, and suspected pro-LBD who underwent an online Farnsworth D-15 color vision test. RESULTS: 111 patients (62 DLB, 25 pro-LBD, and 24 AD) were included with a median age of 75 years. Newly diagnosed CVI was present in 67% of patients with DLB, 44% of patients with pro-LBD, and 18% of patients with AD. In patients with DLB, CVI was associated with lower Montreal Cognitive Assessment (MoCA) scores and lower sub-scores in visuospatial/executive function, naming, and language. In a multivariable logistic regression model, a diagnosis of DLB or pro-LBD compared to AD, and a lower composite MoCA score in visuospatial/executive function, naming, and language were associated with CVI controlling for age and gender. Among 17 DLB patients who underwent volumetric MRI, patients with CVI (n = 9) demonstrated lower normative volumetric percentiles in the right transverse superior temporal lobe. CONCLUSION: We provide further evidence that CVI can help differentiate DLB from AD, and we suggest that CVI may be an indicator of cognitive decline and disease progression in DLB.

Blind to the risk: an analysis into the guidance offered to doctors and medical students with colour vision deficiency.

BACKGROUND/OBJECTIVES: Doctors and medical students with colour vision deficiency (CVD) are less capable and less confident at identifying colour in a wide range of clinical scenarios, some of which could be potentially life-threatening. There have been numerous calls for screening and counselling over the last 25 years. SUBJECTS/METHODS: Surveys were sent to all 33 UK medical schools and 154 acute trusts, to ascertain what screening and support exists for doctors with CVD. The response rate was 95%. RESULTS: 1.4% of acute trusts and 16.7% of medical schools screen for CVD. 3.4% of trusts and 10.0% of medical schools had CVD-specific advice which they give to medical professionals. Guidance and advice given varied widely between different schools and trusts. DISCUSSIONS: Despite research showing a clear problem and lack of support for doctors with CVD, there has been a failure to respond by the medical profession. Screening, national guidance, counselling, and further research is needed to provide full support for practitioners with CVD and ensure patient safety.

The impacts of abnormal color vision on people's life: an integrative review.

BACKGROUND: This article shows an integrative review on the impact that abnormal color vision may have on the daily routine of individuals. PURPOSE: We followed the PRISMA guidelines for reviews and carried out researches in four databases (Pubmed, Lilacs, Scopus, and Web of Science) using keywords related to the impact of abnormal color vision. METHOD: Initially, 805 articles were retrieved and after a first filtering stage, we selected 74 articles for a detailed analysis of the abstracts in which it was found that a total of 20 studies were in fact related to the topic of this review. We then read the selected studies in full and those included in the final selection were analyzed and categorized into specific topic groups of findings. Seven categories were created in total: "impact on daily routine activities", "occupational impact", "impact on product choice motivation", "emotional impact", "impact on school or professional qualification", "impact on self-care and health", and "advantages". RESULTS: From the definition of these categories we could understand that people with some degree of color vision loss face challenges in different aspects of their daily life, especially in their work activities. Still, the amount of research and hence technical support which could be offered to this population is restricted. Additionally, the scarce availability of publications on the topic and the fact that they include very specific groups of people, such as drivers and medical students, allow us to draw only partial conclusions about the all possible impacts yield by such perceptual difference since they observe the impact of the color-vision deficiency in their daily routine from a specific and precise point of view. CONCLUSIONS: A broader view of the impact of this problem on the daily life of its carriers is fundamental for implementing strategies that allow such people to be included in all sorts of activities or for the impact of this sensory change to be decreased or treated in a way that would reduce the detrimental impacts.

Macular maldevelopment in ATF6-mediated retinal dysfunction.

Background: Achromatopsia has been previously associated with mutations in the ATF6 gene. Rod-monochromatism, foveal hypoplasia, and disruption of the subfoveal photoreceptor layer are described as phenotypical features. We report detailed structural and electrophysiological assessment of two patients from two families, one manifesting severe macular maldevelopment and one with foveal hypoplasia.Materials and methods: The patients underwent a complete ophthalmic examination including electroretinography (ERG), spectral-domain optical coherence tomography (SD-OCT), fundus autofluorescence, and fundus photography. Genetic testing was performed by next-generation sequencing.Results: In one patient, fundoscopy and SD-OCT revealed well-demarcated coloboma-like excavated lesions at the central macula of both eyes. Genetic analysis identified a novel homozygous p.Asp140Ter mutation in the ATF6 gene. The second patient had foveal hypoplasia in association with a homozygous ATF6 mutation affecting a splice donor site (c.1187 + 5G>C). In both patients, electrophysiological assessment showed normal rod-specific (DA 0.01) and dark-adapted bright white-flash ERGs (DA 10.0). 30 Hz flicker ERGs were undetectable. There were low-amplitude single-flash photopic ERGs (LA 3.0) with timing and shape suggesting S-cone origin.Conclusions: The findings, particularly a case with severe macular maldevelopment, may expand on the phenotype previously associated with ATF6-mediated achromatopsia. In addition, the comprehensive electrophysiological assessment suggests that preserved S-cone activity can be detected in this particular molecular sub-type of cone dysfunction.

Preparing medical students with congenital colour vision deficiency for safe practice.

BACKGROUND: Colour vision of candidates is tested in many medical colleges in India at the time of admission to undergraduate courses; however, there are no guidelines, and therefore no counselling, on how students with congenital colour vision deficiency (CCVD) should negotiate the medical course, and how best they can practise safely after graduation. Problems in interpreting coloured signs may lead to misdiagnosis. This study aimed to explore difficulties during clinical work that requires colour discrimination, and to offer suggestions on safe practice based on the findings and a review of the literature. METHODS: We did a cross-sectional study after obtaining institutional ethical clearance and written informed consent. Thirty volunteer medical students with CCVD (≥3 errors on Ishihara chart) were matched with 30 volunteers from their own batch who made no errors. All participants interpreted colour-dependent clinical and laboratory photographs. RESULTS: Students with CCVD made more errors (range 5-26; mean [SD] 13.17 [5.873] out of 75 items in 35 colour-dependent photographs) than colour-normal students (range 2-13; mean [SD] 5.53 [3.037], p<0.001). The nature of the errors suggested that medical students with CCVD could have problems in learning histology, pathology, haematology, microbiology, dermatology, paediatrics, medicine, biochemistry and during ophthalmoscopy. CONCLUSIONS: Screening at the time of admission will make students aware of their CCVD status and, through conscious practice thereafter, they may understand their limitations. Faculty could guide and prepare such students for safe practice.

Localization and patterns of Cerebral dyschromatopsia: A study of subjects with prospagnosia.

OBJECTIVE: Cerebral dyschromatopsia is sometimes associated with acquired prosopagnosia. Given the variability in structural lesions that cause acquired prosopagnosia, this study aimed to investigate the structural correlates of prosopagnosia-associated dyschromatopsia, and to determine if such colour processing deficits could also accompany developmental prosopagnosia. In addition, we studied whether cerebral dyschromatopsia is typified by a consistent pattern of hue impairments. METHODS: We investigated hue discrimination in a cohort of 12 subjects with acquired prosopagnosia and 9 with developmental prosopagnosia, along with 42 matched controls, using the Farnsworth-Munsell 100-hue test. RESULTS: We found impaired hue discrimination in six subjects with acquired prosopagnosia, five with bilateral and one with a unilateral occipitotemporal lesion. Structural MRI analysis showed maximum overlap of lesions in the right and left lingual and fusiform gyri. Fourier analysis of their error scores showed tritanopic-like deficits and blue-green impairments, similar to tendencies displayed by the healthy controls. Three subjects also showed a novel fourth Fourier component, indicating additional peak deficits in purple and green-yellow regions. No subject with developmental prosopagnosia had impaired hue discrimination. CONCLUSIONS: In our subjects with prosopagnosia, dyschromatopsia occurred in those with acquired lesions of the fusiform gyri, usually bilateral but sometimes unilateral. The dyschromatopsic deficit shows mainly an accentuation of normal tritatanopic-like tendencies. These are sometimes accompanied by additional deficits, although these could represent artifacts of the testing procedure.

Agnosias visuales / Visual agnosia

Las agnosias visuales se definen como una alteración en la capacidad de reconocer objetos con la vista, en ausencia de pérdida de agudeza visual o disfunción cognitiva que explique esta alteración. Están producidas por lesiones de la corteza visual asociativa, respetando la corteza visual primaria. Existen 2 vías principales de procesamiento de la información visual: la vía ventral, encargada del reconocimiento de objetos, y la vía dorsal, encargada de su localización en el espacio. Las agnosias visuales pueden, por tanto, dividirse en 2 grandes grupos dependiendo de cuál de las 2 vías esté lesionada. El objetivo de este artículo es realizar una revisión narrativa sobre los diferentes síndromes agnósicos visuales, incluyendo los últimos avances realizados en algunos de ellos (AU)

Visual agnosia is defined as an impairment of object recognition, in the absence of visual acuity or cognitive dysfunction that would explain this impairment. This condition is caused by lesions in the visual association cortex, sparing primary visual cortex. There are 2 main pathways that process visual information: the ventral stream, tasked with object recognition, and the dorsal stream, in charge of locating objects in space. Visual agnosia can therefore be divided into 2 major groups depending on which of the two streams is damaged. The aim of this article is to conduct a narrative review of the various visual agnosia syndromes, including recent developments in a number of these syndromes (AU)

Is Male Migraine Associated With Color Vision Deficiency? Findings Among Israeli Adolescents Between 2007 and 2013.

OBJECTIVE: Accumulating clinical and experimental evidence has shown that migraine patients tend to suffer from color vision abnormalities. The aim of this study was to examine whether color vision deficiency is associated with male migraine in a large population of adolescents. METHODS: The study population included all Israeli male adolescents who underwent medical and cognitive examinations as part of their recruiting process between the years 2007 and 2013. Migraine prevalence among patients with color vision deficiency was compared to that of males without substantial color vision abnormalities. RESULTS: The study population included 305 964 male adolescents at the age of 17 ± 0.6, of whom 7584 (2.5%) had color vision deficiency, as determined by the Farnsworth Panel D-15 color blindness test. Males with color vision deficiency had a 32% increased prevalence of migraine as compared with the control group (odds ratio 1.32, 95% confidence interval 1.18-1.48, P < .001), after adjusting for multiple variables. CONCLUSIONS: The authors found an association between color vision deficiency and migraine in male adolescents. The study results lay the basis for further research into male migraine, as well as the visual aspects of migraine.

Os "daltônicos" e suas dificuldades: condição negligenciada no Brasil? / Colorblind individuals and their difficulties: a neglected condition in Brazil?

O termo "discromatopsia congênita" ("daltonismo") designa os defeitos de visão cromática, cuja taxa de prevalência entre homens é de 6% a 10%. Este estudo investigou as percepções de discromatópsicos quanto ao diagnóstico, suas dificuldades e mecanismos de enfrentamento do problema. Foi realizada pesquisa com metodologia clínica-qualitativa, na qual participaram 13 homens universitários, compondo uma amostra intencional, fechada por saturação teórica. Os dados foram coletados por meio de entrevistas individuais semiestruturadas. Os relatos foram gravados, transcritos e compuseram um corpus investigado pela técnica de análise de conteúdo categorial temática. Os participantes relataram dificuldades objetivas e subjetivas com materiais didáticos, práticas de ensino, interações com colegas e professores, já a partir do início da socialização secundária. Posteriormente, foram referidas, sobretudo, dificuldades relacionadas à decodificação de sinais de trânsito. Os participantes desenvolveram algumas habilidades de enfrentamento dessas dificuldades, mas aguardam ações a serem desencadeadas pelos poderes públicos, dirigidas ao atendimento das suas necessidades sociais, educacionais e trabalhistas...

The term congenital dyschromatopsia (colorblindness) refers to color vision genetic deficiency, whose prevalence rate is 6 to 10% among men. This study investigated the perceptions of subjects with congenital dyschromatopsia regarding diagnosis, their difficulties and coping mechanisms of the condition. This research was carried out using a clinical-qualitative methodology, in which 13 male university students took part, consisting of a purposeful sample concluded by theoretical saturation. Data were collected by conducting semi-structured individual interviews. Reports were recorded, transcribed and a corpus was made investigated by the technique of thematic categorical content. Participants reported objective and subjective difficulties with didactic material, teaching practice, interactions with colleagues and teachers, already from the beginning of their secondary socialization. Subsequently, difficulties in decoding traffic lights were mainly reported. Participants developed some coping skills to face these challenges, but await actions to be initiated by the Brazilian government to meet their social, education and labor needs...

Suppressing thyroid hormone signaling preserves cone photoreceptors in mouse models of retinal degeneration.

Cone phototransduction and survival of cones in the human macula is essential for color vision and for visual acuity. Progressive cone degeneration in age-related macular degeneration, Stargardt disease, and recessive cone dystrophies is a major cause of blindness. Thyroid hormone (TH) signaling, which regulates cell proliferation, differentiation, and apoptosis, plays a central role in cone opsin expression and patterning in the retina. Here, we investigated whether TH signaling affects cone viability in inherited retinal degeneration mouse models. Retinol isomerase RPE65-deficient mice [a model of Leber congenital amaurosis (LCA) with rapid cone loss] and cone photoreceptor function loss type 1 mice (severe recessive achromatopsia) were used to determine whether suppressing TH signaling with antithyroid treatment reduces cone death. Further, cone cyclic nucleotide-gated channel B subunit-deficient mice (moderate achromatopsia) and guanylate cyclase 2e-deficient mice (LCA with slower cone loss) were used to determine whether triiodothyronine (T3) treatment (stimulating TH signaling) causes deterioration of cones. We found that cone density in retinol isomerase RPE65-deficient and cone photoreceptor function loss type 1 mice increased about sixfold following antithyroid treatment. Cone density in cone cyclic nucleotide-gated channel B subunit-deficient and guanylate cyclase 2e-deficient mice decreased about 40% following T3 treatment. The effect of TH signaling on cone viability appears to be independent of its regulation on cone opsin expression. This work demonstrates that suppressing TH signaling in retina dystrophy mouse models is protective of cones, providing insights into cone preservation and therapeutic interventions.

Colour discrimination and categorisation in Williams syndrome.

Individuals with Williams syndrome (WS) present with impaired functioning of the dorsal visual stream relative to the ventral visual stream. As such, little attention has been given to ventral stream functions in WS. We investigated colour processing, a predominantly ventral stream function, for the first time in nineteen individuals with Williams syndrome. Colour discrimination was assessed using the Farnsworth-Munsell 100 hue test. Colour categorisation was assessed using a match-to-sample test and a colour naming task. A visual search task was also included as a measure of sensitivity to the size of perceptual colour difference. Results showed that individuals with WS have reduced colour discrimination relative to typically developing participants matched for chronological age; performance was commensurate with a typically developing group matched for non-verbal ability. In contrast, categorisation was typical in WS, although there was some evidence that sensitivity to the size of perceptual colour differences was reduced in this group.

Variations in opsin coding sequences cause x-linked cone dysfunction syndrome with myopia and dichromacy.

PURPOSE: To determine the role of variant L opsin haplotypes in seven families with Bornholm Eye Disease (BED), a cone dysfunction syndrome with dichromacy and myopia. METHODS: Analysis of the opsin genes within the L/M opsin array at Xq28 included cloning and sequencing of an exon 3-5 gene fragment, long range PCR to establish gene order, and quantitative PCR to establish gene copy number. In vitro expression of normal and variant opsins was performed to examine cellular trafficking and spectral sensitivity of pigments. RESULTS: All except one of the BED families possessed L opsin genes that contained a rare exon 3 haplotype. The exception was a family with the deleterious Cys203Arg substitution. Two rare exon 3 haplotypes were found and, where determined, these variant opsin genes were in the first position in the array. In vitro expression in transfected cultured neuronal cells showed that the variant opsins formed functional pigments, which trafficked to the cell membranes. The variant opsins were, however, less stable than wild type. CONCLUSIONS: It is concluded that the variant L opsin haplotypes underlie BED. The reduction in the amount of variant opsin produced in vitro compared with wild type indicates a possible disease mechanism. Alternatively, the recently identified defective splicing of exon 3 of the variant opsin transcript may be involved. Both mechanisms explain the presence of dichromacy and cone dystrophy. Abnormal pigment may also underlie the myopia that is invariably present in BED subjects.

Hypoxia, color vision deficiencies, and blood oxygen saturation.

Chromatic thresholds were measured using the Cambridge Colour Test (CCT), the Colour Assessment and Diagnosis (CAD) test, and the Cone Specific Contrast Test (CSCT) at ground and 3780 m (12,400 ft) for subjects with normal color vision and red-green color vision defects. The CAD revealed a small (~10%) increase in the red-green thresholds for the trichromatic subjects and a similar increase in the blue-yellow thresholds for the dichromats. The other two color vision tests did not reveal any significant change in chromatic thresholds. The CAD results for the trichromats were consistent with a rotation of the discrimination ellipse counterclockwise with little change in the elliptical area. This alteration in the color discrimination ellipse can occur when retinal illumination is lowered.

Un caso de eritropsia / A case of erythropsia

La eritropsia o visión roja (del griego erythros=rojo, y opsis=vista) es una alteración en la percepción de los colores de carácter temporal. Este fenómeno es una cromatopsia o visión alterada. Consiste en la aparición de un tinte rojizo, de presentación uniforme que parece colorear todos los objetos. Este síntoma visual suele alarmar al paciente. Se trata de un proceso poco conocido y que suele ser transitorio. Puede deberse a procesos benignos como el post-operatorio de las cataratas y por toxicidad farmacológica ó ser consecuencia de procesos más graves como la hemorragia vítrea (AU)

Erythropsia or red vision (from the Greek erythros=red, and opsis=sight) is a temporary distortion of colour vision. This phenomenon is a chromatopsia or impaired vision. It consists of seeing all objects with a uniform reddish tint. This vision symptom usually alarms the patient. It is a little known process and is usually transient. It may be due to benign processes such as post-operative cataracts and drug toxicity or to be a consequence of more serious processes such as vitreous haemorrhage (AU)