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Color vision tests use estimative of threshold color discrimination or number of correct responses to evaluate performance in chromatic discrimination tasks. Both approaches have advantages and disadvantages. In the present investigation, we compared the number of errors during color discrimination task in normal trichromats and participants with color vision deficiency (CVD) using pseudoisochromatic stimuli at fixed saturation levels. We recruited 28 normal trichromats and eight participants with CVD. Cambridge Color Test was used to categorize their color vision phenotype, and those with a phenotype suggestive of color vision deficiency had their L- and M-opsin genes genotyped. Pseudoisochromatic stimuli were shown with target chromaticity in 20 vectors radiating from the background chromaticity and saturation of 0.06, 0.04, 0.03, 0.02, 0.01, and 0.005 u’v' units. Each stimulus condition appeared in four trials. The number of errors for each stimulus condition was considered an indicator of the participant's performance. At high chromatic saturation, there were fewer errors from both phenotypes. The errors of the normal trichromats had no systematic variation for high saturated stimuli, but below 0.02 u’v' units, there was a discrete prevalence of tritan errors. For participants with CVD, the errors happened mainly in red-green chromatic vectors. A three-way ANOVA showed that all factors (color vision phenotype, stimulus saturation, and chromatic vector) had statistically significant effects on the number of errors and that stimulus saturation was the most important main effect. ROC analysis indicated that the performance of the fixed saturation levels to identify CVD was better between 0.02 and 0.06 u’v’ units reaching 100%, while saturation of 0.01 and 0.005 u’v’ units decreased the accuracy of the screening of the test. We concluded that the color discrimination task using high saturated stimuli separated normal trichromats and participants with red-green color vision deficiencies with high performance, which can be considered a promising method for new color vision tests based in frequency of errors.

LDH: Funda??o de Amparo ? Pesquisa do Estado de S?o Paulo (FAPESP) post-doctoral fellowship 2019/14606-4 and Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES) doctoral scholarship; EH: FAPESP post-doctoral fellowships 2014/25743-9 and 2018/09321-8; BSWC: Natural Sciences and Engineering Research Council (NSERC) Discovery grant; OFG: Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico (CNPq) Research Productivity Fellowship; PRKG: CNPq grant 484228/2011-0; DFV: FAPESP grant 2014/26818-2, CAPES ProAmazonia 3263/2013-19 and CNPq 309409/2015-2. Universidade de S?o Paulo. Instituto de Psicologia. Departamento de Psicologia Experimental. S?o Paulo, SP, Brazil. Universidade de S?o Paulo. Instituto de Psicologia. Departamento de Psicologia Experimental. S?o Paulo, SP, Brazil / Hospital Israelita Albert Einstein. Instituto de Ensino e Pesquisa. S?o Paulo, SP, Brazil. Universidade de S?o Paulo. Instituto de Psicologia. Departamento de Psicologia Experimental. S?o Paulo, SP, Brazil. University of Toronto. Department of Cell and System Biology. Toronto, Canada. Minist?rio da Sa?de. Secretaria de Vigil?ncia em Sa?de. Instituto Evandro Chagas. Centro Nacional de Primatas. Ananindeua, PA, Brasil. Universidade Federal do Par?. N?cleo de Medicina Tropical. Bel?m, PA, Brazil / Universidade Federal do Par?. Instituto de Ci?ncias Biol?gicas. Bel?m, PA, Brazil. Universidade Federal do Par?. N?cleo de Medicina Tropical. Bel?m, PA, Brazil / Universidade Federal do Par?. Instituto de Ci?ncias Biol?gicas. Bel?m, PA, Brazil. Universidade Federal do Par?. N?cleo de Teoria e Pesquisa do Comportamento. Bel?m, PA, Brazil Universidade Federal do Par?. N?cleo de Teoria e Pesquisa do Comportamento. Bel?m, PA, Brazil Universidade de S?o Paulo. Instituto de Psicologia. Departamento de Psicologia Experimental. S?o Paulo, SP, Brazil / Hospital Israelita Albert Einstein. Instituto de Ensino e Pesquisa. S?o Paulo, SP, Brazil. Primate colour vision depends on a matrix of photoreceptors, a neuronal post receptoral structure and a combination of genes that culminate in different sensitivity through the visual spectrum. Along with a common cone opsin gene for short wavelengths (sws1), Neotropical primates (Platyrrhini) have only one cone opsin gene for medium-long wavelengths (mws/lws) per X chromosome while Paleotropical primates (Catarrhini), including humans, have two active genes. Therefore, while female platyrrhines may be trichromats, males are always dichromats. The genus Alouatta is inferred to be an exception to this rule, as electrophysiological, behavioural and molecular analyses indicated a potential for male trichromacy in this genus. However, it is very important to ascertain by a combination of genetic and behavioural analyses whether this potential translates in terms of colour discrimination capability. We evaluated two howler monkeys (Alouatta spp.), one male A. caraya and one female A. seniculus, using a combination of genetic analysis of the opsin gene sequences and a behavioral colour discrimination test not previously used in this genus. Both individuals completed the behavioural test with performances typical of trichromatic colour vision and the genetic analysis of the swsl, mws, and Iws opsin genes revealed three different opsin sequences in both subjects. These results are consistent with uniform trichromacy in both male and female, with presumed spectral sensitivity peaks similar to Catarrhini, at similar to 430 nm, 532 nm, and 563 nm for S-, M- and L-cones, respectively.

Purpose: We developed a contrast sensitivity test that considers an integrative approach of spatial and temporal frequencies to evaluate the psychophysical channels in processing two-dimensional stimulus for clinical use. Our new procedure provides a more efficient isolation of the magnocellular and parvocellular visual pathways supporting spatiotemporal contrast sensitivity processing. Methods: We evaluated 36 participants of both sexes aged 18–30 years with 20/20 or better best-corrected visual acuity. Two spatial frequencies (0.5 cycles per degree [cpd] and 10 cpd), being in one of the three temporal frequencies (0.5 cycle per second [cps], 7.5 cps, and 15 cps), were presented in a high-resolution gamma corrected monitor. A two-alternative forced-choice procedure was conducted, and the staircase method was used to calculate the contrast sensitivity. Reliability was assessed using a retest procedure within a month (±5 days) under the same conditions. Results: Results showed statistical significance in 0.5 cpd and 10 cpd spatial frequencies for 0.5 cps (F = 77.36; p < 0.001), 7.5 cps (F = 778.37; p < 0.001), and 15 cps (F = 827.23; p < 0.001) with a very high (η2 = 0.89) effect size. No statistical differences were found between the first and second sessions for all spatial frequencies. For reliability, a significantly high correlation and high internal consistency were found in all spatiotemporal conditions. The limits were calculated for normality. Conclusion: We developed an approach to investigate the spatiotemporal integration of contrast sensitivity designed for clinical purposes. The relative contribution of the low spatial frequencies/high temporal frequencies and the high spatial frequencies/low temporal frequencies of the psychophysical channels can also be evaluated separately.

Albinism is a rare phenotype that affects the pigmentation in eyes, hair, and skin. The effects of albinism in color vision are still unclear. Our study aimed to evaluate the color vision phenotype and genotype of an albino capuchin monkey. An adult albino male capuchin monkey (Sapajus apella) had the L and M opsin gene analyzed, and was trained in a behavioral task of color discrimination. Color discrimination thresholds were determined along 20 chromatic axes around the background chromaticity. A color discrimination ellipse was drawn by interpolation among these thresholds. The albino monkey’s behavioral color discrimination ellipse showed poor discrimination along the red–green axis indicating a deutan phenotype. Genetic analysis revealed only the presence of the L gene in the albino monkey. This result did not differ from that obtained with ten previously tested non-albino monkeys. Behavioral and molecular analyses agreed that the albino capuchin monkey had color vision similar to that of non-albino dichromat monkeys, suggesting no influence of albinism on color discrimination.

We investigated the impact of visual impairment on balance control. We measured the center of pressure (COP) between the two feet and plantar surface pressures on each foot in 18 normal-sighted participants and compared their data with measures from 18 legally blind participants, either acquired or congenital. Pressures were measured in open- and closed-eye conditions using a baropodometric resistive plate. In the eyes-open condition, there were no differences between the sighted and legally blind groups in COP displacement. However, participants with visual loss had significantly increased pressures in two metatarsal regions (M1 and M2 zones) of the plantar surface in both viewing conditions (p < 0.05). The differences in pressure measures between the normally sighted and legally blind groups could be attributed mainly to the subgroup of subjects with acquired impairment. Our findings suggest that subjects with visual impairment present increased metatarsal pressures (i.e. forefoot), not yet associated to anterior displacement of COP or impaired balance control.

A visão de cores apresenta um papel muito importante para a sobrevivência e desenvolvimento de primatas. A capacidade de discriminar, visualmente, o alvo de um fundo apenas pela diferença de matiz pode ser o diferencial tanto para a busca de alimentos, como para a fuga de predadores. Estudos sobre a visão de cores auxiliam a fazer inferências sobre suas bases biológicas e utilidade funcional. O presente estudo buscou avaliar a discriminação de cores em primatas do gênero Alouatta (Bugio), por meio de uma adaptação do teste computadorizado Cambridge Colour Test (CCT) e do sequenciamento dos genes que codificam as opsinas, uma vez que por estudos anteriores inferia-se que eles pudessem apresentar visão tricromática, diferenciando-os dos outros platirrinos. Para este estudo foram utilizados 6 indivíduos do Centro Nacional de Primatas (CENP, Ananindeua, Pará, Brasil). O experimento comportamental objetivava determinar elipses de discriminação de cor para três fundos de diferentes cromaticidades do diagrama CIE 1976 uv, as quais serviram de parâmetro para a determinação do fenótipo dos indivíduos. A análise genética buscou identificar as variedades de opsinas. Dois indivíduos concluíram o teste comportamental com sucesso, um macho de Alouatta caraya e uma fêmea de Alouatta seniculus, ambos apresentando visão de cores tricromática. A análise molecular identificou a presença de dois alelos para comprimentos médios/longos da opsina. O potencial de tricromacia demonstrado na análise genética foi compatível com os resultados da análise comportamental que mostraram capacidade discriminativa tricromática. Neste trabalho abordamos os diversos aspectos desse estudo, tanto na modelagem dos animais quanto na importância desse achado Color vision has a very important role in the survival and development of primates. The ability to visually discriminate the target of a background only by hue difference may be the difference for both search of food or escape from predators. Studies on color vision help to make inferences about their biological bases and functional utility. This study sought to evaluate the color discrimination in primates of the genus Alouatta (Howler monkey), through an adaptation of the computerized test Cambridge Colour Test (CCT) and the sequencing of the genes coding opsins. Through previous studies have inferred that they could present trichromatic vision, distinguishing them from other platyrrhines. Six subjects from the National Primate Center (CENP, Ananindeua, Pará, Brazil) were tested. The behavioral experiment aimed to determine color discrimination ellipses to three backgrounds of different chromaticity at CIE 1976 u\'v\' diagram, which served as a parameter for determining the phenotype of individuals and the genetic analysis sought to identify the varieties of opsins. Two individuals completed the test successfully one male and one female, both featuring trichromatic color vision. Two individuals successfully completed the behavioral test, one Alouatta caraya male and one Alouatta seniculus female, both presenting trichromatic color vision. Molecular analysis identified the presence of two alleles for medium/long lengths of opsin compatible with behavioral analysis. In this work we approach the various aspects of this study, both in the modeling of the animals and in the importance of this finding

Background Oculocutaneous Albinism (OCA) is an autosomal recessive inherited condition that affects the pigmentation of eyes, hair and skin. The OCA phenotype may be caused by mutations in the tyrosinase gene (TYR), which expresses the tyrosinase enzyme and has an important role in the synthesis of melanin pigment. The aim of this study was to identify the genetic mutation responsible for the albinism in a captive capuchin monkey, and to describe the TYR gene of normal phenotype individuals. In addition, we identified the subject’s species. Results A homozygous nonsense mutation was identified in exon 1 of the TYR gene, with the substitution of a cytosine for a thymine nucleotide (C64T) at codon 22, leading to a premature stop codon (R22X) in the albino robust capuchin monkey. The albino and five non-albino robust capuchin monkeys were identified as Sapajus apella, based on phylogenetic analyses, pelage pattern and geographic provenance. One individual was identified as S. macrocephalus. Conclusion We conclude that the point mutation C64T in the TYR gene is responsible for the OCA1 albino phenotype in the capuchin monkey, classified as Sapajus apella. Electronic supplementary material The online version of this article (doi:10.1186/s12863-017-0504-8) contains supplementary material, which is available to authorized users.

The identification of color vision types in primates is fundamental to understanding the evolution and biological function of color perception. The Hard, Randy, and Rittler (HRR) pseudoisochromatic test categorizes human color vision types successfully. Here we provide an experimental setup to employ HRR in a nonhuman primate, the capuchin (Cebus libidinosus), a platyrrhine with polymorphic color vision. The HRR test consists of plates with a matrix composed of gray circles that vary in size and brightness. Differently colored circles form a geometric shape (X, O, or Δ) that is discriminated visually from the gray background pattern. The ability to identify these shapes determines the type of dyschromatopsy (deficiency in color vision). We tested six capuchins in their own cages under natural sunlight. The subjects chose between two HRR plates in each trial: one with the gray pattern only and the other with a colored shape, presented on the left or right side at random. We presented the test 40 times and calculated the 95 % confidence limits for chance performance based on the binomial test. We also genotyped all subjects for exons 3 and 5 of the X-linked opsin genes. The HRR test diagnosed two subjects as protan dichromats (missing or defective L-cone), three as deutan dichromats (missing or defective M-cone), and one female as trichromat. Genetic analysis supported the behavioral data for all subjects. These findings show that the HRR test can be applied to diagnose color vision in nonhuman primates.

O albinismo é um conjunto de alterações fenotípicas caracterizadas pela incapacidade de produzir melanina, fazendo com que a pigmentação de alguns órgãos seja reduzida ou ausente. Discutem-se quais efeitos esta redução ou ausência de pigmentação, na retina, poderia ter sobre a capacidade visual do indivíduo. A visão de cores apresenta um papel muito importante para a sobrevivência e desenvolvimento de primatas. A capacidade de discriminar visualmente o alvo de um fundo apenas pela diferença de matiz pode ser o diferencial tanto para a busca de alimentos, como para a fuga de predadores. Estudos sobre a visão de cores auxiliam a fazer inferências sobre suas bases biológicas e utilidade funcional. Pretendeu-se com esse estudo elucidar a discriminação de cores de um indivíduo albino de Sapajus sp, por meio de uma avaliação psicofísica utilizando-se de uma versão modificada do teste computadorizado Cambridge Colour Test (CCT), e uma análise genética de DNA, para identificar os genes que codificam as opsinas. Os arranjos genótipo/fenótipo inferidos do indivíduo a partir das elipses foram comparados à composição dos genes que codificam opsina, obtida por análise independente de DNA. Buscou-se, assim, identificar possíveis prejuízos à visão de cores causados pelo albinismo, em relação a Sapajus normais. Apesar dos vários problemas decorrentes do albinismo, o sujeito experimental aprendeu a tarefa com sucesso e apresentou, nos testes, limiares de discriminação de cores característicos de dicromacia do tipo deuterânope com valores dentro dos esperados para o gênero Sapajus. Os resultados comportamentais foram condizentes com o fenótipo inferido a partir da análise genética São Paulo Albinism is a set of phenotypic traits, characterized by the inability to produce melanin, that way the pigmentation of some organs are either reduced or absent. There is no consent on what effects this lower or none pigmentation on retina could lead on subject vision. The color vision represents a major role on primates survival and development. The capacity of visually discriminate targets only by hue differences from the background can be used either to search for food or to avoid predators. Studies on color vision help to make inference on their biological bases and functional utility. This study aimed to elucidate the color vision discrimination of an albino subject of Sapajus sp, through a psychophysical evaluation using a modified version of Cambridge Colour Test (CCT) and a genetic analyses of DNA in order to identify genes that codify the opsin. The correlation between genotype and phenotype were inferred by comparison between discrimination ellipses and genetic composition of genes that code opsin. Thus seeking to identify possible color vision losses caused by albinism comparing those analyses with healthy Sapajus. Despite many problems associated to albinism, the test subject successfully learn the task and his test showed color discrimination thresholds of a deuteranope dichromacy with values within the expected to subjects of Sapajus genera. Those behavioral results where consistent with the phenotype predicted by the genetic analyses

Aproximadamente 2.2 bilhões de pessoas no mundo, segundo a Organização Mundial da Saúde (2020), apresentam alguma deficiência visual para perto ou para longe e a maior parte delas, encontra-se com baixa visão. Pessoas com deficiências visuais, comumente apresentam muitas dificuldades para se mover e realizar tarefas da vida diária devido às condições de iluminação desfavoráveis existentes nos ambientes. Portanto, o objetivo deste trabalho foi investigar os efeitos da iluminação na mobilidade e nas atividades da vida diária de pessoas com baixa visão, e identificar quais patologias se beneficiam dessa pesquisa. Para isso, uma revisão sistemática da literatura foi realizada e diretrizes do método PRISMA (2009) foram consideradas. As buscas na literatura conduziram-se em 8 bases de dados eletrônicas, sendo 6 convencionais (PubMed, Web of Science, Scopus, Cochrane Library, PsycINFO e Lighting Research and Technology) e 2 da literatura cinzenta (Google Scholar e ProQuest). Os termos low vision e sinônimos combinados com lighting e seus sinônimos foram usados para as buscas realizadas até maio de 2020. Para a inclusão e exclusão dos estudos, critérios de elegibilidade foram definidos antes do início das buscas. O Jadad Scale foi utilizado para avaliar a qualidade dos estudos individuais. A revisão sistemática da literatura resultou em 11 artigos totalmente relevantes para a presente pesquisa: 6 para atividades da vida diária (AVD) e 5 para mobilidade. Todos os artigos mostraram, tanto de forma quantitativa quanto qualitativa, a importância e o impacto da iluminação artificial e natural na vida de pessoas com baixa visão. 189 indivíduos, predominantemente femininos, foram investigados na questão AVD, e 512, predominantemente masculinos, na questão Mobilidade. Altos níveis de iluminação beneficiaram idosos com baixa visão e degeneração macular relacionada à idade em suas atividades da vida diária, principalmente na cozinha. Baixos níveis reduziram o desempenho da mobilidade dos indivíduos com meia-idade e baixa visão. Conclui-se que, apesar de moderados os efeitos dos altos níveis de iluminação nas atividades da vida diária e mobilidade, a qualidade de vida melhorou significativamente para essa população. E como a maior parte dos estudos relacionados à baixa visão e à iluminação englobava diversas doenças, houve dificuldade para apontar quais níveis de iluminação seriam os ideais para cada patologia, indicando a necessidade de mais pesquisas nessa área Aproximately 2.2 billion people in the world, according to World Health Organixaton (2020), have some near or far visual impairment and most them, with low vision. People with visual loss, commonly have many difficulties in moving and performing routine tasks, due to adverse lighting conditions existing in the environments. Therefore, the aim of this work was to investigate the effects of lighting on mobility and daily living activities of people with low vision and to identify which pathologies are benefited from this research. For this, a systematic literature review was carried out and PRISMA Statement guidelines (2009) were considered. Database searches conducted in 8 electronic databases, 6 from conventional (PubMed, Web of Science, Scopus, Cochrane Library, PsycINFO and Lighting Research and Technology) and 2 from gray literature (Google Scholar and ProQuest). The terms low vision and its synonyms combined with lighting and its synonyms were used for searches that were carried out until May 2020. For inclusion and exclusion of records, eligibility criteria were defined before the beginning of database searches. The Jadad Scale was used to assess the quality of individual studies. The systematic review of literature resulted in 11 articles totally relevant: 6 for daily living activities (ADL) and 5 for mobility. All articles showed, either quantitatively or qualitatively, the importance and impact of artificial light and daylight in the lives of people with low vision. 189 predominantly female individuals were investigated in ADL question and 512 predominantly male in the Mobility question. High levels of lighting benefited elderly with low vision and age-related macular degeneration in their daily activities, especially in the kitchen. Low levels of lighting reduced the mobility performance of individuals with middle age and low vision. In conclusion, despite the moderate effects of high levels of lighting on activities of daily living and mobility, the quality of life improved significantly for this population. And as most studies related to low vision and lighting encompassed several diseases, it was difficult to point out which lighting levels would be ideal for each pathology, indicating a need for more research in this issue

Albinismo em humanos é uma doença autossômica recessiva caracterizada pela redução ou ausência de melanina. Predominam dois tipos principais: o albinismo ocular (OA, do inglês, Ocular Albinism), que manifesta alterações oculares, e o albinismo óculo-cutâneo (OCA, do inglês, Oculocutaneous Albinism) no qual encontramos alterações na pele, olhos e cabelos. Dentre os tipos de OCA, destacam-se: OCA1, causado por mutações em homozigose ou heterozigose composta no gene TYR e OCA2, causado também por mutações em homozigose ou heterozigose composta no gene OCA2. São diagnosticados a partir de uma análise dermatológica combinada a uma análise oftalmológica, que contribuem mas não determinam exatamente o tipo de albinismo, sem uma análise genética para confirmação do diagnóstico clínico. No albinismo ocorrem alterações oftalmológicas importantes causando desconforto para esses indivíduos, como hipopigmentação da íris e do epitélio pigmentado da retina, nistagmo e fotofobia. O objetivo deste trabalho foi diagnosticar geneticamente 21 albinos acompanhados na Santa Casa de Misericórdia de São Paulo e comparar seu diagnóstico dermatológico prévio e alterações oftalmológicas (diagnosticadas pelos exames de biomicroscopia por lâmpada de fenda com foto; teste de acuidade visual; exame de transiluminação da íris; e retinografia) aos resultados moleculares, identificados através do sequenciamento dos genes TYR e OCA2. Os resultados obtidos foram: a) três participantes foram classificados como OCA1 e 18 como OCA2; oito apresentaram mutações em heterozigose; também foram encontradas quatro mutações no gene TYR e seis no gene OCA2, uma delas do gene OCA2 ainda não descrita na literatura; b) de acordo com a avaliação dermatológica, seis participantes foram classificados como OCA1 e 15 como OCA2; c) em relação à avaliação oftalmológica, nos 21 albinos, a retinografia mostrou que o grau de transparência da retina variou de 2, 3 e 4, enquanto que a foto da íris, resultou nos graus 1 até 4 e acuidade visual, este último resultou em 8 variantes. Em conclusão, o diagnóstico genético se mostrou de extrema importância para a confirmação e identificação do tipo de albinismo sugerido dermatologicamente e não houve uma correlação entre os achados genéticos e oftalmológicos Albinism in humans is an inheritance autosomal recessive disease, characterized by reduced or absent of melanin. There are two main types: Ocular Albinism (OA) that shows ocular changes, and the Oculocutaneous Albinism (OCA) that shows changes in the skin, eyes and hair. Among the types of OCA, stand outs: OCA1, that is caused by homozygous or compound heterozygous mutations in the TYR gene; and OCA2, that is also caused by homozygous or compound heterozygous mutations in the OCA2 gene. Subjects are diagnosed from a dermatological analysis combined with an ophthalmological analysis, that contribute, but do not determine exactly the type of albinism present in the subject, without a genetic analysis to confirm the clinical diagnostic. In the albinism there are important ophthalmological changes, that causes discomfort, such as photophobia, for these individuals, as hypopigmentation of the iris and retina and nystagmus. The aim of this study was to accomplish the genetical diagnose in 21 albinos accompanied at \"Santa Casa de Misericórdia de São Paulo\" and to compare with the preliminary dermatological diagnose and the ophthalmological changes (diagnosed by the exams slit lamp biomicroscopy with iris photo; visual acuity from Snellen test; retinography (3D CT 1000, Topcon) and iris transillumination) to molecular results, identified through sequencing of TYR and OCA2 genes. The results were: a) three individuals classified as OCA1 and 18 as OCA2; eight subjects shown mutation in heterozygosis; were found four mutations for TYR gene and six for OCA2 gene, one of those OCA2 mutations was not described in any literature; b) according with dermatological analysis, six subjects were classified as OCA1 and 15 as OCA2; c) regarding the ophthalmological changes, in all subjects were evaluated the retinography, which varied from 2 to 4, photo of iris which varied from 1 to 4 and visual acuity, the last resulted in 8 variants. In conclusion, the genetical diagnosis showed itself of extreme importance to the confirmation and identification of the type of albinism dermatologically suggested, once there are different genes for each type of albinism and there was no correlation between genetic and ophthalmologic findings

Serpentes habitam grande diversidade de habitats na maior parte do planeta. Tamanha variedade ambiental implica o desempenho de distintos nichos ecológicos e padrões comportamentais, muitas vezes relacionados a diferentes adaptações de seus sistemas visuais. Não apenas a dispersão destes animais oferece oportunidades privilegiadas de investigação, os diversos e particulares históricos evolutivos neste grupo demarcam transições ambientais convenientes para esclarecer a influência da cena visual sobre a organização de sistemas visuais, comportamentos e a filogenia. A análise comparativa da retina destes animais traz informações a respeito de adaptações comportamentais e ecológicas relativas ao ambiente e padrões circadianos de atividade. Neste trabalho foi realizada a análise dos genes de fotopigmentos visuais e da morfologia dos fotorreceptores de duas espécies de serpentes da família Viperidae, Bothrops jararaca e Crotalus durissus terrificus. Três indivíduos de cada espécie foram obtidos junto ao laboratório de Herpetologia do Instituto Butantan. O RNA total foi extraído a partir de retinas homogeneizadas e convertido em cDNA por meio da reação de transcriptase reversa. Os genes de interesse foram amplificados com uso de primers específicos por meio de reação em cadeia de polimerase (PCR). Após purificação dos produtos de PCR foi realizado o sequenciamento dos genes de opsinas visuais expressos nas retinas das duas espécies, lws, rh1 e sws1. Cada opsina, maximamente sensível a uma banda espectral específica e presente em diferentes populações de fotorreceptores da retina, teve o seu pico de absorção estimado com base na estrutura proteica revelada. Adicionalmente, foi conduzida análise dos tipos celulares de células fotorreceptoras da retina das duas espécies de viperídeos, por meio da técnica de imunohistoquímica, visando caracterização morfológica dos fotorreceptores em que estão compreendidas cada classe de opsina. Os resultados obtidos apontam para os mesmos grupos morfológicos de fotorreceptores e a mesma sensibilidade espectral dos respectivos pigmentos visuais, das duas espécies analisadas: cones simples e cones duplos com o fotopigmento LWS, e pico de sensibilidade espectral (max) estimado em ~555nm; cones simples com o fotopigmento SWS1, e max estimado em ~360nm; e bastonetes, com o fotopigmento RH1, com max de ~500nm. Desta forma conclui-se similaridade do nicho ecológico e do histórico natural das duas espécies, que apontam para adaptações ao habito noturno. Isto demonstra o sucesso evolutivo e a versatilidade proporcionada pela disposição de retina duplex dominada por bastonetes. Em B. jararaca e C. d. terrificus, serpentes da subfamília Crotalinae, estas características de organização do sistema visual são somadas à capacidade de detecção de comprimentos de onda infravermelhos, o que aponta para similaridades em relação a serpentes do grupo Henophidia, consideradas evolutivamente mais primitivas, e consagra novamente a vantagens obtidas na manutenção deste padrão sensorial Serpents inhabit a great diversity of habitats around the planet. Such environmental variability implies the performance of distinct ecological niches and behavior patterns that are related to different visual system adaptations. The diversity of environments inhabited by snakes and their evolutionary history provides a privileged investigative opportunity on the adaptive organization of the visual systems, specific behaviors and phylogeny. The comparative analysis of the retina of those animals provide many information concerning behavior and ecological adaptations related to their respective environment and circadian rhythm patterns. In this study, we performed genetic analysis of the opsin genes and morphological analysis of the photoreceptors of two snakes from the Viperidae family, Bothrops jararaca and Crotalus durissus terrificus. Three subjects of each species were collected at the Butantan Institute. Total RNA was extracted from homogenized retinas, and mRNA was converted to cDNA by reverse transcriptase reaction. The opsin genes lws, rh1 and sws1 were amplified by polymerase chain reactions (PCR), using specific primers. Each opsin is expressed in a different photoreceptor population and is maximally responsive to a determined spectral absorption peak (max) that was inferred according to the protein structure. Additionally, photorreceptor cell populations were analyzed using immunohistochemistry technique. Results point out to the same morphological cell populations and the same absorption peak in their respective opsins in the two species: double and single cones with the LWS photopigment and estimated max at ~555nm; single cones with the SWS1 photopigment and max at ~360nm; and rods with the rhodopsin RH1 photopigment and max at ~500nm. In this way, great similarity of ecological niche and natural history was concluded for both species, which present adaptations to the nocturnal habit. This should demonstrate the great evolutionary success and versatility attained by the rod-domminated duplex retina. In B. jararaca and C. d. terrificus, snakes from the Crotalinae subfamily, those retinal features are summed to the capability of infra-red detection, which point out to similarity with snakes from the basal Henophidia group