The purpose of this paper was to evaluate achromatic and chromatic vision of workers chronically exposed to organic solvents through psychophysical methods. Thirty-one gas station workers (31.5 ± 8.4 years old) were evaluated. Psychophysical tests were achromatic tests (Snellen chart, spatial and temporal contrast sensitivity, and visual perimetry) and chromatic tests (Ishihara's test, color discrimination ellipses, and Farnsworth-Munsell 100 hue test—FM100). Spatial contrast sensitivities of exposed workers were lower than the control at spatial frequencies of 20 and 30 cpd whilst the temporal contrast sensitivity was preserved. Visual field losses were found in 10–30 degrees of eccentricity in the solvent exposed workers. The exposed workers group had higher error values of FM100 and wider color discrimination ellipses area compared to the controls. Workers occupationally exposed to organic solvents had abnormal visual functions, mainly color vision losses and visual field constriction.
The present study investigated the visual perimetry and color vision of two Amazonian populations differently exposed to mercury. Ten riverines environmentally exposed to mercury by fish eating and 34 gold-miners occupationally exposed to mercury vapor. The visual perimetry was estimated using the Förster perimeter and the color vision was evaluated using a computerized version of Farnsworth-Munsell test. Riverine and gold-miners' hair mercury concentrations were quantified. Mercury hair concentration of the riverines was significantly higher than that from gold-miners. Riverines had lower perimetric area than the gold-miners. The errors in the hue ordering test of both Amazonian populations were larger than the controls (non-exposed subjects), but there was no difference between themselves. Riverines had significant multiple association between the visual function and hair mercury concentration, while the gold-miners has no significant association with the exposure. We concluded that the different ways of mercury exposure led to similar visual outcomes, with greater impairment in riverines (organic mercury exposed subjects).
We describe a 7-year-old child with multisystemic inflammatory syndrome that was temporarily associated with the novel coronavirus disease which evolved into serious illness, with coronary aneurysm, using human immunoglobulin and acetylsalicylic acid, in which clinical manifestations including hepatitis, convulsions, and coma were aggravated with Reye's syndrome. To date, there has been no report of the association of multisystemic inflammatory syndrome that is temporarily associated with the novel coronavirus disease and Reye's syndrome.
The purpose of this study was to compare contrast sensitivity estimated from transient visual evoked potentials (VEPs) elicited by achromatic pattern-reversal and pattern-onset/offset modes. The stimuli were 2-cpd, achromatic horizontal gratings presented either as a 1 Hz pattern reversal or a 300 ms onset/700 ms offset stimulus. Contrast thresholds were estimated by linear regression to amplitudes of VEP components vs. the logarithm of the stimulus contrasts, and these regressions were extrapolated to the zero amplitude level. Contrast sensitivity was defined as the inverse of contrast threshold. For pattern reversal, the relation between the P100 amplitude and log of the stimulus contrast was best described by two separate linear regressions. For the N135 component, a single straight line was sufficient. In the case of pattern onset/offset for both the C1 and C2 components, single straight lines described their amplitude vs. log contrast relations in the medium-to-low contrast range. Some saturation was observed for C2 components. The contrast sensitivity estimated from the low-contrast limb of the P100, from the N135, and from the C2 were all similar but higher than those obtained from the high-contrast limb of the P100 and C1 data, which were also similar to each other. With 2 cpd stimuli, a mechanism possibly driven by the M pathway appeared to contribute to the P100 component at medium-to-low contrasts and to the N135 and C2 components at all contrast levels, whereas another mechanism, possibly driven by the P and M pathways, appeared to contribute to the P100 component at high contrast and C1 component at all contrast levels.
O processamento visual de contrastes s radiações eletromagnéticas dentro da faixa de comprimentos de ondas entre aproximadamente 380 nm e 760 nm vindas do ambiente entram em contato com fotorreceptores na retina e podem ser convertidas em sinais eletroquímicos (Luo, 1999). Esses sinais são transmitidos e codificados através de redes neuronais que levam, entre outros efeitos, à geração da percepção visual consciente. Desde a recepção da energia eletromagnética até a geração da percepção consciente, ocorrem diversos processos de codificação da informação cuja compreensão é fundamental para entender-se como a visão funciona. Os processos mais distais são mais bem entendidos, enquanto aqueles que ocorrem progressivamente mais centralmente são da mesma forma progressivamente menos entendidos.Nos fotorreceptores, a codificação da informação luminosa ocorre através da transdução da quantidade de fótons absorvidos pelos fotopigmentos em amplitudes de alterações graduadas do potencial de membrana da célula fotorreceptora Pugh Jr., 1992;2006). As respostas elétricas dos fotorreceptores aos estímulos luminosos são hiperpolarizantes (Naka; Rushton, 1966). Em síntese, os fotorreceptores funcionam como contadores dos fótons absorvidos, em outras palavras, do número de eventos de absorção de fótons pelos fotopigmentos que levam a fotoisomerizações desses fotopigmentos e ativação da cascata de fototransdução Pugh Jr., 1992; Yau, 1994).A partir da próxima etapa do processamento visual, a sinapse entre fotorreceptores e células bipolares, inicia-se uma transformação da informação luminosa. As células bipolares comparam as informações oriundas de diferentes fotorreceptores, fazendo surgir pela primeira vez dentro do processamento visual a informação de contraste (Werblin; Dowling, 1969; Zhang; Wu, 2009). As células bipolares fazem a codificação de contraste graças à organização de seus campos receptivos com diferentes propriedades de ativação / inibição entre as áreas centrais e periféricas desses campos. A estrutura do campo receptivo com antagonismo funcional entre seu centro e periferia é o circuito básico para o processamento da informação espacial no sistema visual. A geração da oponência entre centro e periferia dos campos receptivos das células bipolares tem origem em acoplamentos entre células bipolares e na combinação de várias vias sinápticas mediadas por células horizontais e amácrinas (para maiores detalhes
Objective Ishihara test is a color vision test, whose results consider that all plates of the test have the same weighting. Rodriguez-Carmona et al. (Aviat Space Environ Med 83:19–29, 2012 ) proposed an equation to quantify the Ishihara test results (severity index), which took an account the rate of hits from the different plates of the test considering the performance of trichromat or colorblind population. We proposed a correction in Rodiguez-Carmona’s equation for the severity index. We evaluated 60 normal trichromats and 107 subjects with congenital color deficiency. We calculated three indexes to quantify the results of each subject: a non-weighted index, a weighted index similar to the Rodriguez-Carmona et al., and a weighted index modified which combined the hit frequency for each plate in a trichromat population and of the error reading frequency for each plate in color-blind populations. Results Compared to the non-weighted evaluation, the weighted index was reduced by 22.95%, 32.92%, and 35.38% from trichromats, protan and deutan groups, respectively. Receiver Operating Characteristics (ROC) analysis showed perfect performance of the classifier for all metrics to measure the Ishihara test results. The proposal correction changed significantly the value of the index, but the overall benefits were small. Electronic supplementary material The online version of this article (10.1186/s13104-019-4320-2) contains supplementary material, which is available to authorized users.
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