RESUMO
Primary congenital glaucoma is a rare disease that occurs in early birth and can lead to low vision. Evaluating affected children is challenging and there is a lack of studies regarding color vision in pediatric glaucoma patients. This cross-sectional study included 21 eyes of 13 children with primary congenital glaucoma who were assessed using the Farnsworth D-15 test to evaluate color vision discrimination and by spectral domain optical coherence tomography to measure retinal fiber layer thickness. Age, visual acuity, cup-to-disc ratio and spherical equivalent data were also collected. Global and sectional circumpapillary and macular retinal fiber layer thicknesses were measured and compared based on color vision test performance. Four eyes (19%) failed the color vision test with diffuse dyschromatopsia patterns. Only age showed statistical significance in color vision test performance. Global and sectional circumpapillary and macular retinal fiber layer thicknesses were similar between the color test outcomes dyschromatopsia and normal. While the color vision test could play a role in assessing children with primary congenital glaucoma, further studies are needed to correlate it with damage to retinal fiber layer thickness.
Assuntos
Visão de Cores , Glaucoma , Tomografia de Coerência Óptica , Humanos , Feminino , Masculino , Criança , Estudos Transversais , Tomografia de Coerência Óptica/métodos , Glaucoma/congênito , Glaucoma/diagnóstico por imagem , Glaucoma/fisiopatologia , Glaucoma/patologia , Glaucoma/diagnóstico , Pré-Escolar , Visão de Cores/fisiologia , Acuidade Visual , Adolescente , Defeitos da Visão Cromática/fisiopatologia , Defeitos da Visão Cromática/congênito , Percepção de Cores/fisiologia , Retina/diagnóstico por imagem , Retina/patologia , Retina/fisiopatologia , Testes de Percepção de CoresRESUMO
Many studies have examined how color and luminance information are processed in the visual system. It has been observed that chromatic noise masked luminance discrimination in trichromats and that luminance thresholds increased as a function of noise saturation. Here, we aimed to compare chromatic noise inhibition on the luminance thresholds of trichromats and subjects with severe deutan or protan losses. Twenty-two age-matched subjects were evaluated, 12 trichromats and 10 with congenital color vision impairment: 5 protanopes/protanomalous, and 5 deuteranopes/deuteranomalous. We used a mosaic of circles containing chromatic noise consisting of 8 chromaticities around protan, deutan, and tritan confusion lines. A subset of the circles differed in the remaining circles by the luminance arising from a C-shaped central target. All the participants were tested in 4 chromatic noise saturation conditions (0.04, 0.02, 0.01, 0.005 u'v' units) and 1 condition without chromatic noise. We observed that trichromats had an increasing luminance threshold as a function of chromatic noise saturation under all chromatic noise conditions. The subjects with color vision deficiencies displayed no changes in the luminance threshold across the different chromatic noise saturations when the noise was composed of chromaticities close to their color confusion lines (protan and deutan chromatic noise). However, for tritan chromatic noise, they were found to have similar results to the trichromats. The use of chromatic noise masking on luminance threshold estimates could help to simultaneously examine the processing of luminance and color information. A comparison between luminance contrast discrimination obtained from no chromatic and high-saturated chromatic noise conditions could be initially undertaken in this double-duty test.
Assuntos
Percepção de Cores/fisiologia , Defeitos da Visão Cromática/fisiopatologia , Defeitos da Visão Cromática/psicologia , Visão de Cores/fisiologia , Sensibilidades de Contraste/fisiologia , Discriminação Psicológica/fisiologia , Reconhecimento Visual de Modelos/fisiologia , Fenótipo , Adulto , Feminino , Humanos , Masculino , Estimulação Luminosa , Limiar Sensorial/fisiologia , Adulto JovemRESUMO
PURPOSE: Visual evoked cortical potentials (VECPs) are useful for investigating the mechanisms and dysfunctions of color vision. Chromatic sinusoidal gratings are generally used to elicit VECPs, but they require long psychophysical measurements to match the perceptual luminance between their stripes. An alternative method is to use pseudoisochromatic stimuli, which makes use of luminance noise to mask luminance clues and force the target perception to be dependent on chromatic contrast. In this study, we compared VECPs generated by sinusoidal gratings and pseudoisochromatic gratings. Contrary to chromatic sinusoidal gratings, pseudoisochromatic stimuli do not require the use of previous methods to find the equiluminance of the stimulus. METHODS: Normal trichromats were recruited to be tested with red-green chromatic sinusoidal gratings and pseudoisochromatic gratings presented by pattern onset-offset and pattern reversal modes in five spatial frequencies. In addition, we also tested four different chromatic contrast pairs in pattern onset-offset mode presentation in five trichromats and one colorblind subject (deuteranope). RESULTS: Pattern onset-offset VECPs elicited by sinusoidal gratings had a larger amplitude than those obtained with pseudoisochromatic stimuli, whereas pattern reversal VECPs elicited by pseudoisochromatic gratings had similar amplitudes compared to those elicited by sinusoidal gratings. We found no difference between the VECP amplitudes elicited by sinusoidal and pseudoisochromatic gratings containing different chromatic contrast. Color-blind subjects displayed absent or small responses to the stimuli. CONCLUSION: Pseudoisochromatic stimulus can be an alternative stimulus to generate VECPs dominated by the chromatic mechanism.
Assuntos
Percepção de Cores/fisiologia , Defeitos da Visão Cromática/fisiopatologia , Potenciais Evocados Visuais/fisiologia , Estimulação Luminosa , Córtex Visual/fisiologia , Adulto , Defeitos da Visão Cromática/diagnóstico , Sensibilidades de Contraste/fisiologia , Eletrorretinografia , Feminino , Humanos , Masculino , Reconhecimento Visual de Modelos , Psicofísica , Adulto JovemRESUMO
L and M cones send their signals to the cortex using two chromatic (parvocellular and blue-yellow koniocellular) and one luminance (magnocellular) pathways. These pathways contain ON and OFF subpathways that respond to excitation increments and decrements respectively. Here, we report on visually evoked potentials (VEP) recordings that reflect L- and M-cone driven increment (LI and MI) and decrement (LD and MD) activity. VEP recordings were performed on 12 trichromats and four dichromats (two protanopes and two deuteranopes). We found that the responses to LI strongly resembled those to MD, and that LD and MI responses were very similar. Moreover, the lack of a photoreceptor type (L or M) in the dichromats led to a dominance of the ON pathway of the remaining photoreceptor type. These results provide electrophysiological evidence that antagonistic L/M signal processing, already present in the retina and the lateral geniculate nucleus (LGN), is also observed at the visual cortex. These data are in agreement with results from human psychophysics where MI stimuli lead to a perceived brightness decrease whereas LI stimuli resulted in perceived brightness increases. VEP recording is a noninvasive tool that can be easily and painlessly applied. We propose that the technique may provide information in the diagnosis of color vision deficiencies.
Assuntos
Percepção de Cores/fisiologia , Defeitos da Visão Cromática/fisiopatologia , Potenciais Evocados Visuais/fisiologia , Corpos Geniculados/fisiologia , Células Fotorreceptoras Retinianas Cones/fisiologia , Córtex Visual/fisiologia , Adolescente , Adulto , Humanos , Estimulação Luminosa/métodos , Vias Visuais/fisiologia , Adulto JovemRESUMO
We have used the Farnsworth-Munsell 100-hue (FM 100) test and Mollon-Reffin (MR) test to evaluate the colour vision of 93 subjects, 30.4 ± 9.7 years old, who had red-green congenital colour vision deficiencies. All subjects lived in Belém (State of Pará, Brazil) and were selected by the State of Pará Traffic Department. Selection criteria comprised the absence of visual dysfunctions other than Daltonism and no history of systemic diseases that could impair the visual system performance. Results from colour vision deficient were compared with those from 127 normal trichromats, 29.3 ± 10.3 years old. For the MR test, measurements were taken around five points of the CIE 1976 colour space, along 20 directions irradiating from each point, in order to determine with high-resolution the corresponding colour discrimination ellipses (MacAdam ellipses). Three parameters were used to compare results obtained from different subjects: diameter of circle with same ellipse area, ratio between ellipse's long and short axes, and ellipse long axis angle. For the FM 100 test, the parameters were: logarithm of the total number of mistakes and positions of mistakes in the FM diagram. Data were also simultaneously analysed in two or three dimensions as well as by using multidimensional cluster analysis. For the MR test, Mollon-Reffin Ellipse #3 (u' = 0.225, v' = 0.415) discriminated more efficiently than the other four ellipses between protans and deutans once it provided larger angular difference in the colour space between protan and deutan confusion lines. The MR test was more sensitive than the FM 100 test. It separated individuals by dysfunctional groups with greater precision, provided a more sophisticated quantitative analysis, and its use is appropriate for a more refined evaluation of different phenotypes of red-green colour vision deficiencies.
Assuntos
Defeitos da Visão Cromática/fisiopatologia , Visão de Cores/fisiologia , Adolescente , Adulto , Brasil , Cor , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Psicofísica/métodos , Adulto JovemRESUMO
Alcohol consumption among young adults is widely accepted in modern society and may be the starting point for abusive use of alcohol at later stages of life. Chronic alcohol exposure can lead to visual function impairment. In the present study, we investigated the spatial luminance contrast sensitivity, colour arrangement ability, and colour discrimination thresholds on young adults that weekly consume alcoholic beverages without clinical concerns. Twenty-four young adults were evaluated by an ophthalmologist and performed three psychophysical tests to evaluate their vision functions. We estimated the spatial luminance contrast sensitivity function at 11 spatial frequencies ranging from 0.1 to 30 cycles/degree. No difference in contrast sensitivity was observed comparing alcohol consumers and control subjects. For the evaluation of colour vision, we used the Farnsworth-Munsell 100 hue test (FM 100 test) to test subject's ability to perform a colour arrangement task and the Mollon-Reffin test (MR test) to measure subject's colour discrimination thresholds. Alcohol consumers made more mistakes than controls in the FM100 test, and their mistakes were diffusely distributed in the FM colour space without any colour axis preference. Alcohol consumers also performed worse than controls in the MR test and had higher colour discrimination thresholds compared to controls around three different reference points of a perceptually homogeneous colour space, the CIE 1976 chromaticity diagram. There was no colour axis preference in the threshold elevation observed among alcoholic subjects. Young adult weekly alcohol consumers showed subclinical colour vision losses with preservation of spatial luminance contrast sensitivity. Adolescence and young adult age are periods of important neurological development and alcohol exposure during this period of life might be responsible for deficits in visual functions, especially colour vision that is very sensitive to neurotoxicants.
Assuntos
Consumo de Bebidas Alcoólicas/fisiopatologia , Defeitos da Visão Cromática/fisiopatologia , Visão de Cores/efeitos dos fármacos , Adolescente , Adulto , Álcoois/toxicidade , Defeitos da Visão Cromática/induzido quimicamente , Sensibilidades de Contraste/fisiologia , Feminino , Humanos , Masculino , Adulto JovemRESUMO
We assessed chromatic discrimination in multiple sclerosis (MS) patients both with (ON) and without (no ON) a history of optic neuritis using the Cambridge color test (CCT). Our goal was to determine the magnitude and chromatic axes of any color vision losses in both patient groups, and to evaluate age-related changes in chromatic discrimination in both patient groups compared to normals. Using the CCT, we measured chromatic discrimination along the protan, deutan and tritan axes in 35 patients with MS (17 ON eyes) and 74 age matched controls. Color thresholds for both patient groups were significantly higher than controls' along the protan and tritan axes (p < 0.001). In addition, the ON and no-ON groups differed significantly along all three-color axes (p < 0.001). MS patients presented a progressive color discrimination impairment with age (along the deutan and tritan axes) that was almost two times faster than controls, even in the absence of ON. These findings suggest that demyelinating diseases reduce sensitivity to color vision in both red-green and blue-yellow axes, implying impairment in both parvocellular and koniocellular visual pathways. The CCT is a useful tool to help characterize vision losses in MS, and the relationship between these losses and degree of optic nerve involvement.
Assuntos
Testes de Percepção de Cores , Defeitos da Visão Cromática/etiologia , Defeitos da Visão Cromática/fisiopatologia , Esclerose Múltipla/complicações , Neurite Óptica/etiologia , Limiar Sensorial/fisiologia , Adolescente , Adulto , Idade de Início , Calibragem , Criança , Percepção de Cores , Discriminação Psicológica , Feminino , Lateralidade Funcional/fisiologia , Humanos , Masculino , Pessoa de Meia-Idade , Neurite Óptica/fisiopatologia , Estimulação LuminosaRESUMO
PURPOSE: To determine whether colour vision improves following reduction of intraocular pressure (IOP) in glaucoma patients. METHODS: The medical records of 29 glaucoma patients (41 eyes) were reviewed. Inclusion criteria required subjects to have made more than four visits to the Glaucoma Service Laboratory and to undergo a thorough eye examination including a Farnsworth-Munsell 100-hue colour vision test and Goldmann tonometry before and after pressure lowering. Colour vision parameters of total error score (TES), yellow-blue score (YBS) and red-green score (RGS) were measured. The study group consisted of 21 eyes of glaucoma patients who underwent uncomplicated trabeculectomy with an IOP reduction of >/= 20% from baseline. The control group consisted of 21 eyes of glaucoma patients matched for age and colour vision, who received medication and/or underwent surgery with a post-intervention IOP reduction of < 20% from baseline. The primary outcome was a comparison of pre- and post-intervention colour vision parameters between the two groups. RESULTS: There was a statistically significant improvement in TES (43 +/- 44, p < 0.001), RGS (19 +/- 27, p = 0.0077) and YBS (23 +/- 29, p = 0.0007) in the study group compared with the control group. The improvement in TES (r = 0.52, p < 0.001), RGS (r = 0.55, p < 0.001) and YBS (r = 0.40, p = 0.008) was correlated with the percentage of IOP reduction. There was no statistically significant difference between improvement in Y-B and R-G scores in the study group. CONCLUSION: Intraocular pressure reduction of >/= 20% post-trabeculectomy was associated with an improvement in colour vision. Colour vision tests may be useful as an adjunctive outcome measure for therapeutic interventions.