Abstract: Introduction: In some Amazonian river basins, hair mercury concentration is above the recommended levels. We evaluated the influence of birth geographical location in the hair mercury level of Amazonian riverine children. Materials and Methods: Hair mercury concentration was measured in 219 children living in four Amazonian riverine communities: Tapajós River (São Luiz do Tapajós and Barreiras villages, n = 110), Tocantins River (Limoeiro do Ajurú village, n = 61), and Caeté River (Caratateua village, n = 48). We used Poisson regression analysis to evaluate the association between native and non-native children from each village and its hair mercury concentration. Results: Higher mercury exposure was found in native children from São Luiz do Tapajós (range = 0.81-22.38 µg/g) followed by native children from Barreiras (range = 0.48-13.46 µg/g), non-native children from São Luiz do Tapajós (range = 0.26-22.18 µg/g), non-native children from Barreiras (range = 0.43-20.76 µg/g), followed by the children from Caeté and Tocantins river basins. We observed that Tapajós villages’ native children had higher prevalence of mercury exposure children than other children (p < 0.05). Conclusions: Birth geographical location has association to mercury levels in the hair of children who lived in a same community with history of mercury exposure.

Objetivo: Avaliar a morfologia e função da retina em pacientes com doença macular relacionada à idade (DMRI), neovascular avançada, antes, durante e após o tratamento com ranibizumabe. Métodos: Vinte e um olhos com diagnóstico de DMRI avançada foram avaliados pela tomografia de coerência óptica (OCT) e eletrorretinografia multifocal (mfERG). Três injeções intravítreas de ranibizumabe foram administradas em intervalos de 1 mês. As avaliações foram realizadas antes da primeira injeção (D0) e aos 30 (D30), 60 (D60), e 90 dias (D90) após a primeira injeção e comparados com um grupo controle (n=21 olhos). Resultados: A espessura macular estava aumentada antes do tratamento devido à presença de fluido intrarretiniano, e o aumento da espessura do complexo EPR-CC foi compatível com a presença de membrana neovascular coroidal. O edema intrarretiniano diminuiu após o tratamento (P<0,01). Três diferentes áreas retinianas anulares (do centro para a periferia: anéis R1, R2 e R3) foram consideradas no mfERG. A amplitude do componente N1 diminuiu nos anéis R1, R2 e R3 em D30, D60 e D90 comparados com o grupo controle (P<0,05); e o tempo implícito de N1 aumentou no anel R3 em D30 (P<0,05). A amplitude do componente P1 diminuiu em R1 e R2 nos dias D30, D60 e D90 comparados com os controles (P<0,01); o tempo implícito de N1 aumentou no anel R1 em D0 e D60 (P<0,05), no anel R2 em D0, D30 e D90 (P<0,01) e no anel R3 em D30 e D60 (P<0,05). Conclusão: O ranibizumabe reduziu o edema intrarretiniano, mesmo em casos avançados. A atividade central macular parece aumentar após o início do tratamento e melhorar ao longo do tempo.

Purpose: To evaluate retinal morphology and function of patients with advanced neovascular age-related macular degeneration (AMD) before, during, and after treatment with ranibizumab. Methods: Twenty-one eyes diagnosed with advanced AMD were studied with optical coherence tomography (OCT) and multifocal electroretinography (mfERG). Three intravitreal injections of ranibizumab were administered at 1-month intervals. Evaluations were performed before the first injection (D0) and at 30 (D30), 60 (D60), and 90 days (D90) after the first injection and compared to an age-matched control group (n=21 eyes). Results: The thickness of macular retinal layers increased before treatment due to the presence of intraretinal fluid. A thick retinal pigment epithelium-choriocapillaris complex (RPE-CC) suggested the presence of choroidal neovascular membrane. Intraretinal edema decreased after treatment (P<0.01), but persisting RPE-CC thickness resulted in a subretinal scar. Three different annular retinal areas were studied with mfERG (from center to periphery: rings R1, R2, and R3). The amplitude of the first negative component (N1) decreased in R1, R2, and R3 at D30, D60, and D90 when compared with that in controls (P<0.05); the N1 implicit time was delayed in R3 at D30 (P<0.05). The amplitude of the first positive component (P1) was reduced in R1 and R2 at D30, D60, and D90 when compared with that in controls (P<0.01); the P1 implicit time was delayed in R1 at D0 and D60 (P<0.05), in R2 at D0, D30, and D90 (P<0.01), and in R3 at D30 and D60 (P<0.05). Conclusion: Ranibizumab reduces intraretinal edema, even in advanced cases. Central macular activity appeared to increase after the initiation of treatment, improving over time.

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.

This paper reports the results that are part of a series of experiments designed to evaluate aspects of the spatial resolution of the visual system of the opossum, Didelphis marsupialis aurita. This nocturnal marsupial presents a well-developed eye, displaying features that reflect specialization for operation at low levels of luminosity. The species was shown to be slightly myopic, a feature that may prove to be valuable because of the increased depth of field. Opossum visual acuity has been previously evaluated by means of determining the Contrast Sensitivity Function (CSF). The results indicate rather poor visual acuity compared with other nocturnal animals. In this paper, we describe the results obtained for the optical quality of the opossum's eye using a single-pass method. The results suggest that the opossum's optical system is capable of forming images that can be resolved when separated by an angular distance on the order of 6 minutes of arc.

The luminance contrast sensitivity function has been investigated using behavioral and electrophysiological methods in many vertebrate species. Some features are conserved across species as a shape of the function, but other features, such as the contrast sensitivity peak value, spatial frequency contrast sensitivity peak, and visual acuity have changed. Here, we review contrast sensitivity across different classes of vertebrates, with an emphasis on the frequency contrast sensitivity peak and visual acuity. We also correlate the data obtained from the literature to test the power of the association between visual acuity and the spatial frequency of the contrast sensitivity function peak.

The aim of this work was to isolate and investigate subcortical and cortical lateral interactions involved in flicker perception. We quantified the perceived flicker strength (PFS) in the center of a test stimulus which was simultaneously modulated with a surround stimulus (50% Michelson contrast in both stimuli). Subjects were requested to adjust the modulation depth of a separate matching stimulus that was physically identical to the center of the test stimulus but without the surround. Using LCD goggles, synchronized to the frame rate of a CRT screen, the center and surround could be presented monoptically or dichoptically. In the monoptic condition, center-surround interactions can have both subcortical and cortical origins. In the dichoptic condition, center-surround interactions cannot occur in the retina and the LGN, therefore isolating a cortical mechanism. Results revealed both a strong monoptic (subcortical plus cortical) lateral interaction and a weaker dichoptic (cortical) lateral interaction. Subtraction of the dichoptic from the monoptic data revealed a subcortical mechanism of the lateral interaction. While the modulation of the cortical PFS component showed a low-pass temporal-frequency tuning, the modulation of the subcortical PFS component was maximal at 6 Hz. These findings are consistent with two separate temporal channels influencing the monoptic PFS, each with distinct lateral interactions strength and frequency tuning characteristics. We conclude that both subcortical and cortical lateral interactions modulate flicker perception.

In the present investigation we mapped the primary visual area of the South American diurnal rodent, Dasyprocta aguti, by standardized electrophysiological mapping techniques. In particular, we performed a series of mapping experiments of the visual streak in the primary visual cortex. We found that the representation of the visual streak in V1 is greatly expanded, the nasal 10 degrees of the visual streak representation occupies ten times more cortical area than equivalent areas in the central or temporal representation. Comparison of these data with those on the density of ganglion cells in the retina at corresponding locations in the visual field reveal a significant mismatch between these two variables. The nasal representation is greatly expanded along the horizontal meridian in V1 as compared to the central and temporal regions whereas the density of ganglion cells decreases with progression along the visual streak from central region towards the nasal or temporal visual field. A review of the available data reveals that all lateral-eyed mammals exhibit a similar mismatch between the retinal and cortical representation of the visual field, and this mismatches is greater in those species with well defined visual streaks such as rabbit and agouti.

Pacientes que fazem uso de cloroquina ou hidróxi-cloroquina, drogas que são freqüentemente administradas para o tratamento de artrite reumatóide, lúpus eritrematoso ou malária, podem sofrer alterações na visão de cores e na sensibilidade de contraste. O presente estudo avaliou a função visual destes pacientes em um estudo conjunto da Universidade de São Paulo (USP), em São Paulo, e da Universidade Federal do Pará (UFPA), em Belém. Trinta e dois pacientes usuários de cloroquina sem alterações no exame de fundo de olho foram avaliados em São Paulo (n=10, 38 a 71 anos, média=55,8 anos) e em Belém (n=22, 20 a 67 anos, média=40 anos). A dose acumulada de cloroquina prescrita foi de 45 a 430 g (média=213 g; dp=152 g) para o grupo de São Paulo, e de 36 a 540 g (média=174 g; dp=183 g) para o grupo de Belém. Os testes foram realizados monocularmente com o estado refracional corrigido. A discriminação de cor foi avaliada utilizando o Teste de Cor de Cambridge (CCT): o limiar de discriminação de cor foi mensurado primeiro nos eixos protano, deutano e tritano, e em seqüência, três elipses de MacAdam foram determinadas. A visão de cores dos pacientes também foi avaliada com testes de arranjo de cores: o teste de 100 matizes de Farnsworth-Munsell (FM100), o D15 de Farnsworth-Munsell, e o teste Lanthony Dessaturado (D15d). A sensibilidade de contraste foi também medida com grades senoidais preto-e-brancas em 22 pacientes. Os resultados foram comparados com controles sem patologias oftalmológicasou neuro-oftalomológicas. 24 pacientes apresentaram discromatopsia adquirida, com perdas seletivas (11 pessoas) ou difusas (13 pessoas). Embora as perdas estivessem presentes no FM100, não houve correlação entre o escore de erro do FM100 e a área elíptica medida pelo CCT. Além disso, três pacientes que tiveram escores normais no FM100 falharam para alcançar limiares normais no CCT. O teste de Lanthony foi menos sensível do que os outros dois testes, tal que falhou em indicar perda em cerca de metade dos pacientes afetados, e o D15 foi o teste menos sensível, deixando de indicar déficits em 9 de 10 pacientes. A sensibilidade de contraste esteve dentro dos valores normais para pacientes submetidos a este teste. A extensão das perdas na discriminação de cores foi positivamente correlacionada com a dose acumulada. O CCT é recomendado para o acompanhamento destes pacientes, pois forneceu dados quantitativos que podem ser diretamente interpretados no espaço cromático da CIE (Commission Internationelle d'Éclairage).

Patients that make use of chloroquine or hydroxychloroquine, drugs which are frequently administered for treatment of rheumatoid arthritis, lupus erithromatosus or malaria, may suffer alterations in color vision and in contrast sensitivity. The present work evaluates the visual function of these patients in a joint study of the University of São Paulo (USP), in São Paulo, and of the Federal University of Pará (UFPA), in Belém. Thirty two chloroquine user patients without alterations in the eye fundus exam were evaluated in São Paulo (n=10; aged 38 to 71 years; mean=55,8 years) and in Belém (n=22; aged 20 to 67; mean=40 years). The prescribed accumulated chloroquine dose was 45 to 430 g (mean=213 g; sd = 152 g) for the São Paulo group, and 36 to 540 g (mean=174 g; sd=183 g) for the Belém group. Tests were performed monocularly with corrected eye refractive state. Color discrimination was evaluated using the Cambridge Colour Test (CCT): the color discrimination threshold was measured first in the protan, deutan and tritan axes and, in succession, three MacAdam's ellipses were determined. The patient's color vision was also evaluated with color arrangement tests: the Farnsworth-Munsell 100 Hue (FM100), the Farnsworth-Munsell D15, and the Lanthony Desaturated (D15d) tests. We also measured the contrast sensitivity for black-and-white sine wave grating of twenty two patients. The results were compared with controls without ophthalmologic or neuro-ophthalmologic pathologies. Twenty four patients presented acquired dyschromatopsia. There were cases of selective loss (11 patients) and of diffuse loss (13 patients). Although losses were present in the FM100 there was no correlation between the FM100 error score and the ellipse area measured by the CCT. Moreover, three patients that scored normal in the FM100, failed to reach normal threshold in the CCT. The Lanthony test was less sensitive than the other two tests, since it failed to indicate loss in about half the patients, and the D15 was the least sensitive test, having failed to indicate loss in 9 out of 10 patients. Contrast sensitivity was within normal values for patients submitted to this test. The extent of losses in color discrimination was positively correlated with the accumulated dose. The CCT is recommended for follow up since it provides quantitative data that can be directly interpreted in CIE (Commission Internationalle d'Éclairage) color space.