Combined influence of illness duration and medication type on visual sensitivity in schizophrenia

Objective: Patients with schizophrenia have visual processing impairments. The main findings from the literature indicate that these deficits may be related to differences in paradigms, medications, and illness duration. This study is part of a large-scale study investigating visual sensitivity in schizophrenia. Here we aimed to investigate the combined effects of illness duration and antipsychotic use on contrast sensitivity function. Methods: Data were collected from 50 healthy controls and 50 outpatients with schizophrenia (classified according to illness duration and medication type) aged 20-45 years old. The contrast sensitivity function was measured for spatial frequencies ranging from 0.2 to 20 cycles per degree using linear sine-wave gratings. Results: Patients with an illness duration > 5 years had more pronounced deficits. Differences in the combined effects of illness duration and antipsychotic use were marked in patients on typical antipsychotics who had been ill > 10 years. No significant differences were found between typical and atypical antipsychotics in patients with an illness duration < 5 years. Conclusion: Visual impairment was related to both long illness duration and medication type. These results should be tested in further studies to investigate pharmacological mechanisms.

Organic solvent exposure and contrast sensitivity: comparing men and women

The goal of this study was to compare the visual contrast sensitivity (CS) of men and women exposed and not exposed to organic solvents. Forty-six volunteers of both genders aged between 18 and 41 years (mean±SD=27.72±6.28) participated. Gas station attendants were exposed to gas containing 46.30 ppm of solvents at a temperature of 304±274.39 K, humidity of 62.25±7.59% and ventilation of 0.69±0.46 m/s (a passive gas chromatography-based sampling method was used considering the microclimate variables). Visual CS was measured via the psychophysical method of two-alternative forced choice using vertical sinusoidal gratings with spatial frequencies of 0.2, 0.5, 1.0, 2.0, 5.0, 10.0, and 16.0 cpd (cycles per degree) and an average luminance of 34.4 cd/m2. The results showed that visual CS was significantly lower (P<0.05) in the following groups: i) exposed men compared to unexposed men at frequencies of 0.2, 0.5, 1.0, and 2.0 cpd; ii) exposed women compared to unexposed women at a frequency of 5.0 cpd; and iii) exposed women compared to exposed men at a frequency of 0.5 cpd, even at exposures below the tolerance limit (300 ppm). These results suggest that the visual CS of exposed men was impaired over a wider range of spatial frequencies than that of exposed women. This difference may have been due to the higher body fat content of women compared to that of men, suggesting that body fat in women can serve as a protective factor against neurotoxic effects.

Acute effect of alcohol intake on sine-wave Cartesian and polar contrast sensitivity functions

The aim of this study was to assess contrast sensitivity for angular frequency stimuli as well as for sine-wave gratings in adults under the effect of acute ingestion of alcohol. We measured the contrast sensitivity function (CSF) for gratings of 0.25, 1.25, 2.5, 4, 10, and 20 cycles per degree of visual angle (cpd) as well as for angular frequency stimuli of 1, 2, 4, 24, 48, and 96 cycles/360°. Twenty adults free of ocular diseases, with normal or corrected-to-normal visual acuity, and no history of alcoholism were enrolled in two experimental groups: 1) no alcohol intake (control group) and 2) alcohol ingestion (experimental group). The average concentration of alcohol in the experimental group was set to about 0.08%. We used a paradigm involving a forced-choice method. Maximum sensitivity to contrast for sine-wave gratings in the two groups occurred at 4 cpd sine-wave gratings and at 24 and 48 cycles/360° for angular frequency stimuli. Significant changes in contrast sensitivity were observed after alcohol intake compared with the control condition at spatial frequency of 4 cpd and 1, 24, and 48 cycles/360° for angular frequency stimuli. Alcohol intake seems to affect the processing of sine-wave gratings at maximum sensitivity and at the low and high frequency ends for angular frequency stimuli, both under photopic luminance conditions.

Single intravitreal bevacizumab injection effects on contrast sensitivity in macular edema from branch retinal vein occlusion / Efeito de uma única injeção intravítrea de bevacizumabe sobre a sensibilidade ao contraste no edema macular causado por oclusão de ramo venoso da retina

PURPOSE: To evaluate the effect of a single intravitreal bevacizumab injection on visual acuity, contrast sensitivity and optical coherence tomography-measured central macular thickness in eyes with macular edema from branch retinal vein occlusion. METHODS: Seventeen eyes of 17 patients with macular edema from unilateral branch retinal vein occlusion were treated with a single bevacizumab injection. Patients were submitted to a complete evaluation including best corrected visual acuity, contrast sensitivity and optical coherence tomography measurements before treatment and one and three months after injection. Visual acuity, contrast sensitivity and optical coherence tomography measurements were compared to baseline values. RESULTS: Mean visual acuity measurement improved from 0.77 logMAR at baseline to 0.613 logMAR one month after injection (P=0.0001) but worsened to 0.75 logMAR after three months. Contrast sensitivity test demonstrated significant improvement at spatial frequencies of 3, 6, 12 and 18 cycles/degree one month after injection and at the spatial frequency of 12 cycles/degree three months after treatment. Mean ± standard deviation baseline central macular thickness (552 ± 150 µm) reduced significantly one month (322 ± 127 µm, P=0.0001) and three months (439 ± 179 µm, P=0.01) after treatment. CONCLUSIONS: Bevacizumab injection improves visual acuity and contrast sensitivity and reduces central macular thickness one month after treatment. Visual acuity returns to baseline levels at the 3-month follow-up, but some beneficial effect of the treatment is still present at that time, as evidenced by optical coherence tomography-measured central macular thickness and contrast sensitivity measurements.

OBJETIVO: Avaliar o efeito de uma única injeção intravítrea de bevacizumabe na função visual, sensibilidade ao contraste, em olhos com edema macular causado por oclusão de ramo venoso retiniano. MÉTODOS: Dezessete olhos de 17 pacientes com edema macular unilateral causado por oclusão de ramo venoso retiniano foram tratados com uma única injeção intravítrea de bevacizumabe. Pacientes previamente foram submetidos a exame ocular completo, sensibilidade ao contraste, variável de maior interesse, melhor acuidade visual corrigida e tomografia de coerência óptica e foram reavaliados no 1º e 3º mês de seguimento. RESULTADOS: O teste de sensibilidade ao contraste demonstrou melhora significante nas frequências espaciais 3, 6, 12 e 18 ciclos/grau (c/g) no primeiro mês de seguimento e na frequência espacial 12 c/g após o 3º mês de tratamento. A média da acuidade visual melhorou de 0,77 no pré-tratamento para 0,61 logMAR no 1º mês de seguimento (P=0,0001), com piora ao final do 3º mês, 0,75 logMAR. A média da espessura foveal central (552 ± 150 µm) reduziu significantemente no 1º (322 ± 127 µm, P=0,0001) e 3º (439 ± 179 µm, P=0,01) mês de seguimento. CONCLUSÃO: No edema macular causado por oclusão de ramo venoso retiniano, uma única injeção intravítrea de bevacizumabe melhora a sensibilidade ao contraste, acuidade visual e reduz a espessura foveal central após 1 mês de tratamento. Após 3 meses de seguimento, ainda é possível observar benefício com o tratamento, como foi evidenciado pela sensibilidade ao contraste e a medida da espessura foveal central à tomografia de coerência óptica.

Mercury toxicity in the Amazon: contrast sensitivity and color discrimination of subjects exposed to mercury

We measured visual performance in achromatic and chromatic spatial tasks of mercury-exposed subjects and compared the results with norms obtained from healthy individuals of similar age. Data were obtained for a group of 28 mercury-exposed subjects, comprising 20 Amazonian gold miners, 2 inhabitants of Amazonian riverside communities, and 6 laboratory technicians, who asked for medical care. Statistical norms were generated by testing healthy control subjects divided into three age groups. The performance of a substantial proportion of the mercury-exposed subjects was below the norms in all of these tasks. Eleven of 20 subjects (55 percent) performed below the norms in the achromatic contrast sensitivity task. The mercury-exposed subjects also had lower red-green contrast sensitivity deficits at all tested spatial frequencies (9/11 subjects; 81 percent). Three gold miners and 1 riverine (4/19 subjects, 21 percent) performed worse than normal subjects making more mistakes in the color arrangement test. Five of 10 subjects tested (50 percent), comprising 2 gold miners, 2 technicians, and 1 riverine, performed worse than normal in the color discrimination test, having areas of one or more MacAdam ellipse larger than normal subjects and high color discrimination thresholds at least in one color locus. These data indicate that psychophysical assessment can be used to quantify the degree of visual impairment of mercury-exposed subjects. They also suggest that some spatial tests such as the measurement of red-green chromatic contrast are sufficiently sensitive to detect visual dysfunction caused by mercury toxicity.

Estudio comparativo de sensibilidad macular en pacientes tratados con metotrexate y cloroquina, en artritis reumatoide / Comparative study of macular sensibility in subjects with theumatoid arthritis in pharmacological treatment with methotrexate and chloroquine

El metotrexate (MTX) es una droga de uso reciente en el tratamiento de artritis reumatoide (AR) a dosis de 10-15 mg/m2/semana, por su rápido efecto antiinflamatorio. En la actualidad los reportes sobre efectos secundarios a nivel ocular son escasos. Este es un estudio donde se han incluido pacientes de ambos sexos, con antecedentes de AR, colaboradores, orientados, con agudeza visual de 20/40 o mejor, sin otra enfermedad sistémica.