An optical parameter imaging system with profile information fusion / 生物医学工程学杂志

There is a shared problem in current optical imaging technologies of how to obtain the optical parameters of biological tissues with complex profiles. In this work, an imaging system for obtaining the optical parameters of biological tissues with complex profile was presented. Firstly, Fourier transformation profilometry was used for obtaining the profile information of biological tissues, and then the difference of incident light intensity at different positions on biological tissue surface was corrected with the laws of illumination, and lastly the optical parameters of biological tissues were achieved with the spatial frequency domain imaging technique. Experimental results indicated the proposed imaging system could obtain the profile information and the optical parameters of biological tissues accurately and quickly. For the slab phantoms with height variation less than 30 mm and angle variation less than 40º, the maximum relative errors of the profile uncorrected optical parameters were 46.27% and 72.18%, while the maximum relative errors of the profile corrected optical parameters were 6.89% and 10.26%. Imaging experiments of a face-like phantom and a human's prefrontal lobe were performed respectively, which demonstrated the proposed imaging system possesses clinical application value for the achievement of the optical parameters of biological tissues with complex profiles. Besides, the proposed profile corrected method can be used to combine with the current optical imaging technologies to reduce the influence of the profile information of biological tissues on imaging quality.

A controlled clinical study on the effect of PVEP-CD comprehensive therapy for children amblyopia / 国际眼科杂志(Guoji Yanke Zazhi)

@#AIM: To evaluate the therapeutic effect of the PVEP-CD comprehensive therapy \〖a multimedia visual training system uses the individualized PVEP(pattern visual evoked potential)sensitive spatial frequency parameters\〗 in children with amblyopia by comparing the differences in visual acuity and stereo acuity enhancement between the PVEP-CD comprehensive therapy and traditional therapy. <p>METHODS: A total of 38 children(54 eyes)with amblyopia who were treated in our hospital from April 2018 to January 2019 were randomly divided into two groups. Traditional therapy group(19 cases, 27 eyes; therapeutic methods contain refractive correction, patching/optical or drug suppress and precision eyesight training); PVEP-CD comprehensive therapy group(19 cases, 27 eyes; therapeutic methods contain refractive correction, patching/optical or drug suppress and a multimedia visual training using the individualized P-VEP sensitive spatial frequency parameters). To study the clinic therapeutic effect, the best distance corrected visual acuity(BCVA)and near stereo acuity were measured at the enrollment visit and the final visit after 6mo treatment.<p>RESULTS: After 6mo treatment, both groups had an apparent BCVA improvement(both therapy effective rate≥85%). PVEP-CD comprehensive therapy group were significantly better than traditional therapy group in BCVA lines improvement \〖3(2, 3)lines\〗, near stereo acuity therapy effective rate(89%)and near stereo acuity level improvement \〖2(1, 4)levels\〗(all<i> P</i><0.05). In amblyopic children older than 6y, PVEP-CD comprehensive therapy group showed a significantly greater BCVA lines improvement(<i>P</i>=0.018). In mild amblyopia cases, PVEP-CD comprehensive therapy group showed a significantly better clinical efficacy in near stereo acuity(<i>P</i>=0.048)and greater improvement in near stereo acuity level(<i>P</i>=0.029). In moderate amblyopia cases,the BCVA lines improvement(<i>P</i>=0.003)was significantly greater in PVEP-CD comprehensive therapy group. <p>CONCLUSION:Both PVEP-CD comprehensive and traditional therapy can improve the BCVA in children with amblyopia and have a good clinical efficacy. Furthermore, the PVEP-CD comprehensive therapy could improve the BCVA and near stereo acuity level more obviously and help amblyopic children get a better binocular vision.

A controlled clinical study on the effect of PVEP-CD comprehensive therapy for children amblyopia / 国际眼科杂志(Guoji Yanke Zazhi)

@#AIM: To evaluate the therapeutic effect of the PVEP-CD comprehensive therapy \〖a multimedia visual training system uses the individualized PVEP(pattern visual evoked potential)sensitive spatial frequency parameters\〗 in children with amblyopia by comparing the differences in visual acuity and stereo acuity enhancement between the PVEP-CD comprehensive therapy and traditional therapy. <p>METHODS: A total of 38 children(54 eyes)with amblyopia who were treated in our hospital from April 2018 to January 2019 were randomly divided into two groups. Traditional therapy group(19 cases, 27 eyes; therapeutic methods contain refractive correction, patching/optical or drug suppress and precision eyesight training); PVEP-CD comprehensive therapy group(19 cases, 27 eyes; therapeutic methods contain refractive correction, patching/optical or drug suppress and a multimedia visual training using the individualized P-VEP sensitive spatial frequency parameters). To study the clinic therapeutic effect, the best distance corrected visual acuity(BCVA)and near stereo acuity were measured at the enrollment visit and the final visit after 6mo treatment.<p>RESULTS: After 6mo treatment, both groups had an apparent BCVA improvement(both therapy effective rate≥85%). PVEP-CD comprehensive therapy group were significantly better than traditional therapy group in BCVA lines improvement \〖3(2, 3)lines\〗, near stereo acuity therapy effective rate(89%)and near stereo acuity level improvement \〖2(1, 4)levels\〗(all<i> P</i><0.05). In amblyopic children older than 6y, PVEP-CD comprehensive therapy group showed a significantly greater BCVA lines improvement(<i>P</i>=0.018). In mild amblyopia cases, PVEP-CD comprehensive therapy group showed a significantly better clinical efficacy in near stereo acuity(<i>P</i>=0.048)and greater improvement in near stereo acuity level(<i>P</i>=0.029). In moderate amblyopia cases,the BCVA lines improvement(<i>P</i>=0.003)was significantly greater in PVEP-CD comprehensive therapy group. <p>CONCLUSION:Both PVEP-CD comprehensive and traditional therapy can improve the BCVA in children with amblyopia and have a good clinical efficacy. Furthermore, the PVEP-CD comprehensive therapy could improve the BCVA and near stereo acuity level more obviously and help amblyopic children get a better binocular vision.

Measurement of Contrast Sensitivity in Patients with Behçet's Disease without Ocular Involvement

PURPOSE: To evaluate contrast sensitivity in patients with Behçet's disease (BD) without ocular involvement. METHODS: The study group was composed of 47 BD patients (20 to 50 years of age) who did not have ocular involvement. The control group was composed of 47 normal volunteers who were similar to the study group in terms of age and gender. No participants in this study had any ocular or systemic pathologies except for BD. The contrast sensitivity measurements were performed using the Functional Acuity Contrast Test under photopic conditions, and the results were compared between the two groups. RESULTS: The mean age of the BD patients and control subjects was 34.5 ± 9.7 and 33.2 ± 7.6 years, respectively. The mean disease duration of the BD patients was 5.5 ± 6.4 years. There was a statistically significant decrease at five spatial frequencies (A, 1.5; B, 3; C, 6; D, 2; and E, 18 cycles per degree) in patients with BD compared with control subjects (p < 0.001, p = 0.004, p = 0.002, p < 0.001, and p = 0.001, respectively). CONCLUSIONS: The contrast sensitivity of BD patients without ocular involvement was lower than that of the control group. Further studies seem mandatory to confirm our results.

Estimating Response Time in Spatial Frequency Band Experiments involving Visual Perception / Estimación del tiempo de respuesta en los experimentos de banda de frecuencia espacial que implican percepción visual

ABSTRACT The present study aimed to determine the optimum response time (RT) needed to identify images of everyday objects when filtered using different spatial frequency bands. Subjects were randomly presented with different images of familiar objects that were both serialized and progressive in their spatial frequencies. The time needed to recognize them was then measured. The results showed that the optimum RT for identifying an image filtered in different spatial frequency bands was approximately 2000 ms of exposure. Specifically, stimuli presented using spatial frequency bands with Gaussian filters of variance V26-V32, which were familiar and of medium size to the viewer, were recognized in a mean time of 2126 ms.

RESUMEN El presente estudio tiene como objetivo determinar el tiempo de respuesta óptimo (RT) necesario para identificar imágenes de objetos cotidianos cuando se filtran utilizando diferentes bandas de frecuencias espaciales. A los sujetos se les presentaba aleatoriamente diferentes imágenes de objetos familiares cuyas bandas de frecuencia eran progresivamente serializadas. Se midió el tiempo necesario para reconocerlos. Los resultados mostraron que la RT óptima para identificar una imagen filtrada en diferentes bandas de frecuencias espaciales fue de aproximadamente 2000 ms de exposición. En concreto, los estímulos presentados utilizando bandas de frecuencias espaciales con filtros gaussianos de varianza V26-V32, que eran familiares y de tamaño medio para el espectador, se reconocieron en un tiempo medio de 2126 ms.

Influence of multiple sclerosis, age and degree of disability, in the position of the contrast sensitivity curve peak.

Context: Contrast sensitivity (CS) function is one of the most important tests available for evaluating visual impairment. Multiple sclerosis (MS) can produce highly selective losses in visual function and psychophysical studies have demonstrated CS deficits for some spatial frequencies. Aims: This work studies the differences in CS between a group of controls and a group of MS patients, focusing on the location of the maximum sensitivity peak, shape of the curve, and determination of the most affected spatial frequencies. Materials and Methods: Using a sinusoidal stimulus the authors assessed CS function in 28 subjects with definitive relapsing remitting MS, and in 50 controls with acuities of 20/25 or better. The peaks of the CS curves were studied by fitting third degree polynomials to individual sets of data. Results: Compared with the control group, the CS function curve for MS subjects showed more deficits in extreme points (low‑ and high‑spatial frequencies). Our results display significant CS losses, at the high‑frequencies band level, in the beginning of the disease. When the disease progresses and the disabilities appear, there are greater losses at the low‑frequencies band level. In average, the CS curve peaks for the MS group were shifted in relation to the control group. Conclusions: CS losses in the MS group suggest an association with ageing and disability level in the expanded disability status scale. The position of the CS function peak is influenced by MS, age, and degree of disability.

Pacientes com depressão maior têm menor sensibilidade a contraste visual que indivíduos saudáveis / Patients with major depression have visual contrast sensitivity less than healthy subjects

O objetivo foi medir a sensibilidade ao contraste, SC, visual de grades senoidais circulares concêntricas com frequências espaciais de 0,25; 4 e 8 cpg, ciclos por grau de ângulo visual, em adultos saudáveis e com depressão maior. Foram estimadas a SC de 20 participantes, 10 saudáveis e 10 participantes com depressão maior, utilizando o método psicofísico da escolha forçada e luminância média de 0,7 cd/m². Todos os participantes apresentavam acuidade visual normal ou corrigida e estavam livres de doenças identificáveis. Os resultados mostraram que a SC visual máxima ocorreu na faixa de 0,25 cpg para os dois grupos. Os resultados demonstraram ainda que a SC visual dos participantes com depressão maior foi mais baixa do que a dos participantes saudáveis (p < 0,05), pois os participantes com transtorno precisaram de mais contraste para detectar as frequências espaciais testadas. Estes resultados sugerem alterações na percepção visual relacionadas à depressão maior.

The aim of this study was to measure visual contrast sensitivity, CS, for concentric circular sine-wave gratings with spatial frequencies of 0.25, 4 and 8 cpd, cycles per degree of visual angle, in adults without and with major depression disorder. We measured the visual CS for 20 participants, ten without and ten with major depression disorder medicated, using a temporal two-alternative forced-choice psychophysical method with mean luminance of 0.7 cd/m². All volunteers were free from identifiable ocular disease and had normal acuity. The results showed maximum contrast sensitivity to spatial frequency occurred in the range of 0.25 cpd for both groups. The results also showed that the visual CS for major depression was lower than those of adults without depression (p < 0.05). These results showed alterations in the visual perception related the major depression.

Development of spatiotemporal frequency turning in rat lateral geniculate neuron / 中华实验眼科杂志

BackgroundRecent researches suggested that properties of neurons in the lateral geniculate neuron (LGN) may represent an important neural limitation on the development of basic spatial and temporal vision,and even binocular rivalry.However,previous studies on the properties of spatiotemporal frequency tuning of LGN were rather concentrated on a monkey or cat,whereas little is known about rat.ObjectiveThis study was to examine the development of spatiotemporal frequency tuning in rats LGN.MethodsTwenty Wistar rats were collected and divided into 14-16 day,20-22 day,27-30 day and 60 day groups according to the different ages after their eyes opened and 5 rats were assigned for each group.Extracellular single neuron recording was carried out in the rats to study the spatio-temporal receptive field properties of neurons in LGN by sinusoidal gratings visual stimuli.Dynamic changes of the spatio-temporal receptive field properties of neurons in LGN with the development of Wistar rats were evaluated.ResultsThe differences between band-pass and low-pass distribution of temporal frequency or spatial frequency of rat LGN were not statistically significant (x2 =0.68,0.47,P＞0.05 ).The optimal temporal frequency of receptive field in rat LGN went up to the maximum value until 60 day in Wistar rats.The mean optimal temporal frequencies of neurons in the four different age groups were ( 2.5 ± 1.3 ),( 2.6± 1.2),(2.6± 1.1 ) and ( 3.6± 1.1 ) Hz with significant differences among the 4 groups (F=4.53,P＜0.05 ),and those in the 14-16 day group,20-22 day group,27- 30 day group were significantly lower than in the 60 days group ( q =4.43,4.10,4.03,P ＜ 0.05 ).No significant differences were seen among the 14-16 day group,20-22 day group and 27-30 day group ( P＞0.05 ).The optimal spatial frequency values in the four groups were ( 0.04 ± 0.04 ),( 0.04 ± 0.03 ),( 0.05 ± 0.03 ),( 0.05 ± 0.04 ) cpd,respectively without statistical difference among them ( F =0.58,P ＞ 0.05 ).The temporal and spatial bandwidth values in the various age groups were not statistically significant among the four groups ( F =0.37,1.22,P＞0.05). Conclusions The development of temporal and spatial frequency characteristics of the rat LGN receptive field may be related to its functional visual pathway.

Variance analysis of contrast sensitivity for amblyopia and normal eye based on spatial frequency channels / 中华实验眼科杂志

Background Contrast sensitivity (CS) of amblyopia has been extensively studied,but its relationship with spatial frequency channels needs further research. Objective The purpose of this study was to investigate the reasons of the CS deficits in amblyopia through comparing the differences in CS between amblyopic and normal eyes from the point of view of spatial frequency channels. MethodsThe CS values of 166 normal children eyes and 143 amblyopic children abnormal eyes were measured by adopting OPTEC 6500.Then,spatial frequency channels' tuning curves were derived via principal component analysis and non-orthogonal rotation.Also,numbers and bandwidths of channels were calculated using the method of full width at half maximum ( FWHM ).All of these were used to analyze the variations of CS between amblyopia and normal eyes by comparing the numbers and the bandwidths of the channels.The reliability of spatial frequency channel was verified by a cross-validation study of 43 amblyopic children. ResultAt spatial frequency of 1.5,3.0,6.0,12.0,18.0 cpd,the mean of CS of amblyopia were 36.35±21.40,50.33 ± 33.46,46.88 ± 41.72,16.24 ± 17.26,4.67 ± 5.79,and the mean of CS of normal eyes were 49.49±24.69,87.23±40.87,93.18±51.99.36.63±24.72,15.70±13.87,with the rank-sum test results were H =27.83,66.61,68.34,78.23,89.88,P＜0.05.There existed three spatial frequency channels in both amblyopia and normal eyes.At the peaks of 3.0,6.0 and 12.0 cpd,the bandwidths of normal eyes were 1.03,1.02 and 0.99 octaves,and the bandwidths of amblyopia were 1.04,1.01and 0.73 octaves.Conclusions The reduction in bandwidths of the corresponding spatial frequency channels may cause the CS deficits in amblyopia.

Diferenças na detecção de frequências espaciais e radiais em crianças / Differences in detection of spatial and radial frequencies in children

O objetivo deste estudo foi comparar curvas de sensibilidade ao contraste para estímulos radiais (FSCr) e grades senoidais (FSC) de 0,25, 0,5, 1 e 2 cpg em crianças de 6 a 13 anos. Foram mensurados limiares de contraste para 40 crianças, utilizando o método psicofísico da escolha forçada e níveis baixos de luminância. Todas estavam livres de doenças oculares e tinham acuidade visual normal. Os resultados mostraram que a sensibilidade das crianças foi maior para grades senoidais (FSC) do que para estímulos radiais (FSCr). Esses resultados sugerem que esses estímulos podem ser processados por áreas visuais distintas.

The aim of this work was to compare contrast sensitivity curves for radial (rCSF) and sine-wave gratings (CSF) stimuli of 0.25, 0.5, 1 and 2 cpd in 6 to 13 year-old-children. It was measured the contrast thresholds of 40 children using the psychophysical forced-choice method and low luminance levels. All children were free of identifiable ocular diseases and had normal acuity. The results showed that contrast sensitivity of the children was higher for spatial frequencies (CSF) than radial frequencies (rCSF). The results suggest that these stimuli can be processed by different visual cortical areas.

The Jitter Spatial Frequency Sweep VEP: a new paradigm to study spatiotemporal development of pattern - and motion - processing mechanisms in human infants

We introduce a new VEP paradigm - the Jitter Spatial Frequency (JSF) Sweep VEP - that permits efficient mapping of the spatiotemporal tuning of the developmental motion asymmetry (DMA). Vertical sinewave gratings undergoing 90º horizontal oscillatory displacements (6 or 10 Hz) were presented while their SF was swept over 2 to 5 octaves during each VEP trial. JSF sweep VEPs were recorded from 28 infants (8-43 weeks), and symmetric (second-harmonic, F2) and asymmetric (F1) components of the VEP were measured. JSF sweeps can provide four useful estimates: (1,2) the high-SF cutoff of F1 and F2 responses estimates the spatial resolution of direction-selective (DS) and non-DS mechanisms, respectively; (3) the low-SF cutoff for F1 estimate the SF-boundary between mature (F1 absent) and immature (F1 present) DS mechanisms; and (4) the F1 high-SF cutoff estimates the lower velocity limit of cortical DS cells. For 6 Hz, the low-SF F1 cutoffs increased two times faster than traditional (contrast-reversal) VEP grating acuity (0.5 vs ~0.25 octaves/month), and twice that of the high-SF F1 and F2 cutoffs. This implies that no single mechanism can account for the DMA at both low and high SFs. At 10 Hz, the DMA exhibited no significant development, consistent with slower maturation of DS mechanisms at higher ST frequencies. The F2 high-SF cutoffs were higher than F1 at both 6 and 10 Hz, suggesting higher spatial resolution for non-DS (pattern) vs DS (motion) mechanisms. Finally, the lower velocity limit of the DS mechanisms decreased from ~2 deg/sec at 8 weeks, to 0.75 deg/sec at 33 weeks, similar to analogous limits for direction-of-motion identification in adults (~0.5 - 1 deg/sec), and close to prior VEP estimates in infants (0.6 deg/sec).

Contrast sensitivity function of sine-wave gratings in children with acute malnutrition

The aim of this study was to determine the contrast sensitivity curves of sine-wave gratings with spatial frequencies of 0.25, 1.0, 2.0 and 8.0 cycles per degree (cpd) of visual angle in 16 female subjects aged 7 to 9 years old, eight well-nourished and eight with acute protein-energy malnutrition (PEM). All participants had normal visual acuity and were free of identifiable ocular illness. Contrast threshold was measured using a temporal two-alternative forced-choice psychophysical method, at a distance of 150 cm of the stimuli, binocularly, with mean luminance of 40.1 cd/m2. We detected a general decline in contrast sensitivity for children with acute malnutrition at all spatial frequencies compared to well-nourished children. The malnourished group needed in average 1.37 times more contrast to detect the stimulus in comparison with the well-nourished one. Differences between the groups were statistically significant at all spatial frequencies (p < .001). These results suggest that acute PEM changes the visual perception for sine-wave gratings.

Sensibilidade ao contraste mesópica de crianças surdas para estímulos radiais e grades senoidais / La sensibilidad al contraste mesópica de los niños sordos para estímulos radiales y rejillas sinusoidales / Mesopic contrast sensitivity of deaf children for radial and sine-wave grating stimuli

O objetivo deste estudo foi medir e comparar as curvas de sensibilidade ao contraste mesópicas para estímulos radiais (FSCr) e grades senoidais (FSC) de 0,25; 0,5; 1 e 2 cpg em crianças surdas de 7 a 12 anos. Mensuramos limiares de contraste para 10 crianças, utilizando o método psicofísico da escolha forçada e luminância média de 0,7 cd/m2. Todos os participantes estavam livres de doenças oculares e apresentavam acuidade visual normal. Os resultados mostraram que a sensibilidade das crianças surdas foi maior para grades senoidais (FSC) do que para estímulos radiais (FSCr). Estes resultados sugerem que os dois estímulos podem ser processados por áreas visuais corticais distintas.

The aim of this work was to measure and compare mesopic contrast sensitivity curves for radial (rCSF) and sine-wave gratings (CSF) stimuli of 0.25, 0.5, 1 and 2 cpd in deaf children between the ages of 7 to 12 years. We measured the contrast thresholds of 10 children using the psychophysical forced-choice method and mean luminance of 0.7 cd/m2. All participants were free of ocular diseases and had normal acuity. The results showed that contrast sensitivity of the deaf children was higher for sine-wave gratings (CSF) than radial stimuli (rCSF). These results suggest that these two stimuli can be processed by different visual cortical areas.

El objetivo de este estudio fue medir y comparar las curvas de sensibilidad al contraste mesópicas para estímulos radiales (FSCr) y rejillas sinusoidales (FSC) de 0,25; 0,5; 1 y 2 cpg en niños sordos de 7 a 12 años. Medimos los umbrales de contraste en 10 niños, con el método psicofísico de la elección forzada y la luminancia media de 0,7 cd/m2. Todos los participantes estaban libres de enfermedades oculares y presentaban acuidad visual normal. Los resultados mostraron que la sensibilidad de los niños sordos fue mayor para frecuencias espaciales (FSC) que para los estímulos radiales (FSCr). Estos resultados sugieren que los estímulos pueden ser procesados en distintas areas corticales visuales.

Sensibilidade ao contraste de crianças surdas e ouvintes para grades senoidais em condições mesópicas / Contrast sensitivity of deaf and hearing children for sine-wave gratings in mesopic conditions

O objetivo deste trabalho foi comparar a sensibilidade ao contraste (FSC) de crianças surdas e crianças ouvintes para freqüências espaciais de 0,25 a 2,0 cpg (ciclos por grau de ângulo visual) em nível de luminância mesópica (0,7 cd/m²), utilizando o método psicofísico da escolha forçada. Vinte crianças (7-12 anos) participaram desta pesquisa, dez com surdez pré-lingual e dez ouvintes. Todos os participantes apresentavam acuidade visual normal ou corrigida. A ANOVA mostrou diferença significante entre os grupos [F(1, 238) = 15,487; p < 0,001], porém a análise com o teste post-hoc Tukey HSD não revelou diferença significante na comparação freqüência a freqüência entre os dois grupos (p > 0,05). Os resultados sugerem alterações na FSC para estímulos de grade senoidal das crianças surdas em níveis de luminância mesópica.

The aim of this study was to compare the contrast sensitivity (CSF) of deaf children and hearing children to spatial frequency of 0.25 to 2.0 cpd (cycles per degree of visual angle) at mesopic luminance level (0.7 cd/m²), using the psychophysical forced-choice method. Twenty children (7-12 years old) participated in this research, ten with prelingual deafness and ten with normal hearing. All participants had normal or corrected visual acuity. The ANOVA showed significant difference between the two groups [F(1, 238) = 15.487; p < 0.001], but the post-hoc Tukey HSD test analysis did not reveal significant difference in frequency to frequency comparison between the two groups (p > 0.05). The results suggest alterations in CSF to sine-wave gratings stimuli of deaf children at mesopic luminance level.

Alterações na sensibilidade ao contraste relacionadas à ingestão de álcool / Changes in the contrast sensitivity related to the alcohol ingestion

O objetivo deste trabalho foi caracterizar a função de sensibilidade ao contraste (FSC) para freqüências espaciais de 0,25, 1,0 e 4,0 cpg (ciclos por grau de ângulo visual) na ausência (Grupo Controle-GC) e após a ingestão moderada de álcool (Grupo Experimental-GE). Para tanto, foi utilizado o método psicofísico da escolha forçada. Participaram do estudo quatro mulheres, de 21 a 30 anos, com acuidade visual normal ou corrigida. Os resultados mostraram diferenças significativas entre os grupos na freqüência de 4,0 cpg (p = 0,039), sendo o GE mais sensível ao contraste do que o GC. Estes resultados sugerem alterações na FSC relacionadas à ingestão moderada de álcool.

The purpose of this paper was to characterize the contrast sensitivity function (CSF) for spatial frequencies equal to 0.25, 1.0 and 4.0 cpd (cycles per degree) in the absence (Control Group-CG) and after moderate alcohol ingestion (Experimental Group-EG). For such, the forced choice psychophysical method was used. The participants were four 21 to 30 year-old-women with normal or corrected visual acuity. The results showed a significant difference between groups at the spatial frequency of 4.0 cpd (p= 0.039), such that the EG was more sensitive to contrast than the CG. These results suggest alcohol-related alterations in the CSF.

Detecção de estímulos radiais e espaciais em adultos e idosos / Detection of spatial and radial stimuli in young and older adults

O objetivo deste estudo foi comparar curvas de sensibilidade ao contraste para estímulos radiais (FSCr) e grades senoidais (FSC) de 0,25, 0,5, 1 e 2 cpg em adultos e idosos. Mensuramos limiares de contraste para seis adultos jovens e seis idosos utilizando o método psicofísico da escolha forçada. Todos estavam livres de doenças oculares e tinham acuidade visual normal. Os idosos apresentaram prejuízos na FSC e FSCr se comparados aos adultos jovens. A sensibilidade dos adultos e idosos foi maior para grades senoidais (FSC) do que para estímulos radiais (FSCr). Esses resultados sugerem que esses estímulos podem ser processados por áreas visuais distintas.

A sensibilidade ao contraste em crianças pré-escolares para padrões distintos / The contrast sensitivity to distincts patterns in pre-school children

Em termos gerais, a FSC tem sido usada para caracterizar o desenvolvimento da percepção visual da forma de crianças. O objetivo do presente estudo foi mensurar e comparar curvas de sensibilidade ao contraste para estímulos radiais (FSCr) e grades senoidais (FSC) em crianças pré-escolares com o método psicofísico da escolha forçada- senoidais de 0,25; 0,5; 1 e 2 cpg em crianças pré-escolares (4 e 5 anos) e adultos jovens com o método psicofísico da escolha forçada. Participaram 15 voluntários com a acuidade visual normal ou corrigida distribuídos igualmente nas três faixas etárias. Os resultados mostraram que a sensibilidade melhora com o desenvolvimento e que a sensibilidade de todos os participantes foi maior para as grades senoidais do que para as freqüências radiais. Estes resultados sugerem que os estímulos radiais e as grades senoidais são processados por áreas visuais diferentes.

In general the FSC is used to characterise the development of the visual perception of material by children. The aim of the present work was to mensure and compare contrast the sensitivity curves to differ then of the radical stimuly (FSCr) and sine-wave gratings (FSC) in pré-school children, usind the psychophysical method of choice-forced for radial and sine-wave gratings stimuli of 0.25; 0.5; 1 and 2 cpd in 4-5 yearold preschool children and young adults using the psychophysical forced-choice staircase method. Fifteen volunteers with corrected-to-normal visual acuity, five in each age range, participated in the experiments. The results showed that the sensitivity improves with the development and that in for all participants the sensitivity was higher for sine-wave gratings than the radial frequencies. These results suggest that the radial and the sine-wave gratings stimuli are processed by different visual areas.

A Comparison of Contrast Sensitivity Between Strabismic and Anisometropic Amblyopia

Contrast sensitivity was measured by MCT 8000(R)(Vistech Consultant INC, U.S.A.) in two groups: 23 strabismic amblyopes and 10 anisometropic amblyopes. In general, the amblyopic eyes exhibited a statistically significant loss of contrast sensitivty in both day and night vision. When visual acuity was equated between groups, the anisometropic group had a greater loss of contrast sensitivity at the high spatiaI frequencies and the strabismic group exchibited a similar loss of contrast at all spatial frequencies. Test-retest correlations(average 0.76) were statistically significant, which demonstrated that the test using MCT 8000(R) was reliable.