An ethologically relevant paradigm to assess defensive response to looming visual contrast stimuli.

In the animal kingdom, threat information is perceived mainly through vision. The subcortical visual pathway plays a critical role in the rapid processing of visual information-induced fear, and triggers a response. Looming-evoked behavior in rodents, mimicking response to aerial predators, allowed identify the neural circuitry underlying instinctive defensive behaviors; however, the influence of disk/background contrast on the looming-induced behavioral response has not been examined, either in rats or mice. We studied the influence of the dark disk/gray background contrast in the type of rat and mouse defensive behavior in the looming arena, and we showed that rat and mouse response as a function of disk/background contrast adjusted to a sigmoid-like relationship. Both sex and age biased the contrast-dependent response, which was dampened in rats submitted to retinal unilateral or bilateral ischemia. Moreover, using genetically manipulated mice, we showed that the three type of photoresponsive retinal cells (i.e., cones, rods, and intrinsically photoresponsive retinal ganglion cells (ipRGCs)), participate in the contrast-dependent response, following this hierarchy: cones > > rods > > > ipRGCs. The cone and rod involvement was confirmed using a mouse model of unilateral non-exudative age-related macular degeneration, which only damages canonical photoreceptors and significantly decreased the contrast sensitivity in the looming arena.

Efectividad del tratamiento con atropina versus oclusiones en pacientes con ambliopía refractiva moderada unilateral / Effectiveness of Atropine Treatment Versus Occlusions in Patients with Unilateral Moderate Refractive Amblyopia

Objetivo: Comparar la efectividad del tratamiento de atropina versus oclusión ocular en pacientes con ambliopía refractiva moderada unilateral. Métodos: Se realizó un estudio descriptivo, longitudinal y prospectivo de una serie de casos que acudieron a la consulta de Oftalmología Pediátrica del Instituto Cubano de Oftalmología Ramón Pando Ferrer durante el período comprendido de septiembre del 2019 a septiembre de 2021. La muestra quedó conformada por 44 pacientes, los cuales se dividieron de forma aleatoria en dos grupos de estudio, 22 casos al grupo de oclusiones e igual número al grupo de atropina, que cumplían los criterios de inclusión. Se analizaron las variables edad, sexo, defecto refractivo, agudeza visual mejor corregida, sensibilidad al contraste y estereopsis. Resultados: Predominó el astigmatismo hipermetrópico en ambos grupos de estudio. La media de la agudeza visual mejor corregida inicial en ambos grupos fue de 0,4 LogMAR y mejoró a 0,1 LogMAR al finalizar el tratamiento. La media de la sensibilidad al contraste inicial fue de 1,48 (±19,75) para el grupo de oclusiones y de 1,47 (±20,5) para el grupo atropina, al finalizar alcanzaron 1,59 (±10,1) y 1,57 (±10,0) por orden de mención. La estereopsis inicial fue subnormal en ambos grupos, al finalizar el tratamiento fue normal en el 77,3 por ciento grupo oclusión y el 68,2 por ciento grupo atropina. Conclusiones: La efectividad del tratamiento en pacientes con ambliopía refractiva moderada unilateral con atropina es similar a la que se alcanza con la aplicación de la oclusión ocular(AU)

Objective: To compare the effectiveness of atropine treatment versus ocular occlusion in patients with unilateral moderate refractive amblyopia. Methods: A descriptive, longitudinal and prospective study of a series of cases that attended the Pediatric Ophthalmology office of the Ramón Pando Ferrer Cuban Institute of Ophthalmology during the period from September 2019 to September 2021 was carried out. The sample consisted of 44 patients, who were randomly divided into two study groups, 22 cases to the occlusion group and the same number to the atropine group, who met the inclusion criteria. The variables age, gender, refractive defect, best corrected visual acuity, contrast sensitivity and stereopsis were analyzed. Results: Hypermetropic astigmatism predominated in both study groups. Average initial best-corrected visual acuity in both groups was 0.4 LogMAR and improved to 0.1 LogMAR at the end of treatment. Average initial contrast sensitivity was 1.48 (±19.75) for the occlusion group and 1.47 (±20.5) for the atropine group, at completion reaching 1.59 (±10.1) and 1.57 (±10.0) in order of mention. Initial stereopsis was subnormal in both groups, at the end of treatment it was normal in 77.3 percent occlusion group and 68.2 percent atropine group. Conclusions: The effectiveness of treatment in patients with unilateral moderate refractive amblyopia with atropine is similar to that achieved with the application of ocular occlusion(AU)

Dual visual impairment and contrast sensitivity among community-dwelling older adults: a cross-sectional study from the PrevQuedas Brazil trial / Duplo déficit visual e sensibilidade ao contraste em idosos da comunidade: estudo transversal do PrevQuedas Brasil

OBJECTIVE: To investigate the importance of improving visual assessment for community-dwelling older adult fallers. METHODS: Cross-sectional study with eligible older adults (> 60 years old) living in the community and who suffered at least one fall in the last 12 months from the PrevQuedas Brasil clinical trial. Sociodemographic data, information on previous falls, physical and functional assessment (BOMFAQ and FES-I) were collected. We evaluated impairments in visual acuity and contrast sensitivity using the Snellen E chart and low-contrast visual acuity tests, respectively. Dual visual impairment refers to the presence of both impairments. For statistical analysis we compared the participants in relation to the number of falls (single fallers or recurrent fallers) using Chi-square or Fisher's exact test and the significance level was <0.05 for all analyses. RESULTS: Visual acuity, low contrast sensitivity, and dual visual impairment were associated with recurrent falls (OR 1.85); visual impairment was more prevalent among the oldest old. Approximately 90% of the participants reported using glasses, and 63.80% used multifocal lenses. Dual impairment was identified in 143 (20.30%) participants. In multivariate logistic regression, the predictive variables for recurrent falls were low contrast sensitivity (95%CI 1.15­2.47), dual visual impairment (95%CI 1.16­2.83), and self-perceived fall risk (95%CI 1.16­2.46) which was measured using the Falls Efficacy Scale-International. CONCLUSION: Older adults with dual visual impairment are more likely to suffer recurrent falls. Low contrast sensitivity is crucial for fall risk assessment

OBJETIVO: Este estudo investiga a importância de avaliar a visão de idosos caidores na comunidade. METODOLOGIA: Estudo transversal com idosos elegíveis (> 60 anos) residentes na comunidade e que sofreram pelo menos uma queda nos últimos 12 meses do ensaio clínico PrevQuedas Brasil. Foram coletados dados sociodemográficos, informações sobre quedas pregressas, exames físicos e funcionais (BOMFAQ e FES-I). Avaliamos os comprometimentos da acuidade visual e da sensibilidade ao contraste por meio da Tabela E de Snellen e testes de acuidade visual de baixo contraste, respectivamente. O duplo déficit visual refere-se à presença de ambas as deficiências. Para análise estatística comparamos os idosos com relação ao número de quedas (caidores únicos ou caidores recorrentes) usando Qui-quadrado ou Teste exato de Fisher e o nível de significância foi <0.05 para todas as análises. RESULTADOS: Baixa acuidade visual, baixa sensibilidade ao contraste e duplo déficit visual foram associados a quedas recorrentes com odds ratio ­ OR 1,85, frequentemente mais prevalente entre os idosos longevos. Cerca de 90,00% dos idosos relataram usar óculos e 63,80% usavam lentes multifocais. O duplo déficit visual foi identificado em 143 (20,30%) participantes. Nos modelos de regressão logística multivariados, verificamos que as variáveis preditoras para queda recorrente foram a baixa sensibilidade ao contraste (intervalo de confiança ­ IC95% 1,15­2,47), duplo déficit (IC95% 1,16­2,83) e a autopercepção do risco de cair (IC95% 1,16­2,46) medido pela Falls Efficacy Scale-International. CONCLUSÃO: Idosos com baixa sensibilidade ao contraste e duplo déficit visual têm maiores chances de sofrerem múltiplas quedas quando comparados com idosos que possuem apenas baixa acuidade visual. Assim, a baixa sensibilidade ao contraste é essencial na avaliação do risco de quedas dos idosos

Sensibilidad al contraste y aberrometría ocular en pacientes operados de miopía con técnicas de superficie / Contrast Sensitivity and Ocular Aberrometry in Patients Operated on for Myopia with Surface Techniques

Objetivo: Determinar el cambio de la sensibilidad al contraste en pacientes operados de miopía con técnicas de superficie y su relación con la aberrometría ocular. Métodos: Se realizó un estudio experimental con 324 ojos de 162 pacientes miopes atendidos en la consulta de Cirugía Refractiva del Instituto Cubano de Oftalmología "Ramón Pando Ferrer" en el período de enero 2019 y marzo de 2020 y que fueron operados de cirugía refractiva con láser de excímero, técnicas de superficie y perfil de ablación asférico. La sensibilidad al contraste fue la variable principal de comparación entre ambas técnicas quirúrgicas. Se formaron dos grupos de pacientes, cuya asignación fue secuencial, al primer grupo, se le realizó la técnica quirúrgica PRK-MMC (81) y al segundo LASEK-MMC (81) con un seguimiento de 3 meses. Resultados: Predominaron las mujeres con miopía leve y edades entre 21 y 28 años. A los tres meses la sensibilidad al contraste, agudeza visual sin corrección, equivalente esférico y el valor cuadrático medio total mejoraron de manera significativa, mostrando una relación positiva con la sensibilidad al contraste en ambos grupos, sin diferencias entre ellos. Conclusiones: La sensibilidad al contraste mejora con técnicas de superficie y posee una relación positiva y significativa con los resultados visuales, refractivos y aberrométricos. El estudio de las aberraciones oculares proporciona un arma fundamental para valorar la calidad óptica del ojo humano, información que permite conocer la calidad visual que se puede esperar en los pacientes evaluados(AU)

Objective: To determine the change in contrast sensitivity in patients operated on for myopia with surface techniques and its relationship with ocular aberrometry. Methods: An experimental study was carried out with 324 eyes of 162 myopic patients treated at the Refractive Surgery Clinic of the Cuban Institute of Ophthalmology "Ramón Pando Ferrer" between January 2019 and March 2020 who underwent refractive surgery with excimer laser and surface techniques and aspheric ablation profile. Contrast sensitivity was the main variable of comparison between both surgical techniques. Two groups of patients were sequentially assigned, the first group underwent PRK-MMC (81) and the second LASEK-MMC (81) with a 3-month follow-up. Results: Women with mild myopia and ages between 21 and 28 years predominated. After 3 months contrast sensitivity, uncorrected visual acuity, spherical equivalent and total average square value improved significantly, showing a positive relationship with contrast sensitivity in both groups, with no differences between them. Conclusions: Contrast sensitivity improves with surface techniques and has a positive and significant relationship with visual, refractive and aberrometric outcomes. The study of ocular aberrations provides a fundamental tool to assess the optical quality of the human eye, information that allows us to know the vision quality that can be expected in the patients evaluated(AU)

Improvement in visual performance after nicotine gum administration in tobacco use disorder: a case report.

Chronic tobacco consumption, identified as Tobacco Use Disorder (TUD), is a public health problem. We present a case report of a 37-year-old Brazilian male diagnosed with TUD at age 26, with no comorbidities, that presented visual improvements (i.e., lower thresholds and better discrimination) after nicotine gum administration. Here, we assessed contrast sensitivity and chromatic discrimination using the Metropsis and the Cambridge Colour Test, respectively. Results showed lower thresholds for both visual tasks after the use of nicotine gum. Even considering this is a single case report, our intent is to open new avenues for research involving smoking, addiction and the use of nicotine gum as a replacement tool or adjuvant tool for improvement of visual and/or cognitive processing. It is well known that nicotine gum has protective effects for some diseases, and improves some cognitive functions. However, unclear were its effects on visual processing of people with TUD.

Development of a Spatio-temporal Contrast Sensitivity Test for Clinical Use.

PURPOSE: We developed a contrast sensitivity test that considers an integrative approach of spatial and temporal frequencies to evaluate the psychophysical channels in processing two-dimensional stimulus for clinical use. Our new procedure provides a more efficient isolation of the magnocellular and parvocellular visual pathways supporting spatiotemporal contrast sensitivity processing. METHODS: We evaluated 36 participants of both sexes aged 18-30 years with 20/20 or better best-corrected visual acuity. Two spatial frequencies (0.5 cycles per degree [cpd] and 10 cpd), being in one of the three temporal frequencies (0.5 cycle per second [cps], 7.5 cps, and 15 cps), were presented in a high-resolution gamma corrected monitor. A two-alternative forced-choice procedure was conducted, and the staircase method was used to calculate the contrast sensitivity. Reliability was assessed using a retest procedure within a month ( ± 5 days) under the same conditions. RESULTS: Results showed statistical significance in 0.5 cpd and 10 cpd spatial frequencies for 0.5 cps (F = 77.36; p < 0.001), 7.5 cps (F = 778.37; p < 0.001), and 15 cps (F = 827.23; p < 0.001) with a very high (η ² = 0.89) effect size. No statistical differences were found between the first and second sessions for all spatial frequencies. For reliability, a significantly high correlation and high internal consistency were found in all spatiotemporal conditions. The limits were calculated for normality. CONCLUSION: We developed an approach to investigate the spatiotemporal integration of contrast sensitivity designed for clinical purposes. The relative contribution of the low spatial frequencies/high temporal frequencies and the high spatial frequencies/low temporal frequencies of the psychophysical channels can also be evaluated separately.

Evaluation of contrast sensitivity in non-high-risk proliferative diabetic retinopathy treated with panretinal photocoagulation with and without intravitreal injections of ranibizumab / Avaliação da sensibilidade ao contraste em retinopatia diabética proliferativa de não alto risco tratada com panfotocoagulação retiniana com ou sem injeções intravítrea de ranibizumabe

ABSTRACT Purpose: To evaluate contrast sensitivity in non-high-risk, treatment-naïve proliferative diabetic retinopathy patients treated with panretinal photocoagulation and intravitreal injections of ranibizumab) versus panretinal photocoagulation alone. Methods: Sixty eyes of 30 patients with bilateral proliferative diabetic retinopathy were randomized into two groups: one received panretinal photocoagulation and ranibizumab injections (study group), while the other received panretinal photocoagulation alone (control group). All eyes were treated with panretinal photocoagulation in three sessions according to the Early Treatment Diabetic Retinopathy Study guidelines. Contrast sensitivity measurements were performed under photopic conditions (85 cd/m2) with the Visual Contrast Test Sensitivity 6500 chart, allowing for the evaluation of five spatial frequencies with sine wave grating charts: 1.5, 3.0, 6.0, 12.0, and 18.0 cycles per degree (cpd). Outcomes were measured in contrast sensitivity threshold scores among and within groups, from baseline to 1, 3, and 6 months. Results: Fifty-eight eyes (28 in the study group and 30 in the control group) reached the study endpoint. A comparative analysis of changes in contrast sensitivity between the groups showed significant differences mainly in low frequencies as follows: at month 1 in 1.5 cpd (p=0.001) and 3.0 cpd (p=0.04); at month 3 in 1.5 cpd (p=0.016), and at month 6 in 1.5 cpd (p=0.001) and 3.0 cpd (p=0.026) in favor of the study group. Conclusions: In eyes of patients with non-high-risk proliferative diabetic retinopathy, panretinal photocoagulation treatment with ranibizumab appears to cause less damage to contrast sensitivity compared with panretinal photocoagulation treatment alone. Thus, our evaluation of contrast sensitivity may support the use of ranabizumab as an adjuvant to panretinal photocoagulation for the treatment of proliferative diabetic retinopathy.

RESUMO Objetivos: Avaliar a sensibilidade ao contraste em pacientes virgens de tratamento com retinopatia diabética proliferativa de não alto risco, submetidos a panfotocoagulação retiniana com injeções intravítreas de ranibizumabe versus pan­fotocoagulação isolada. Métodos: Sessenta olhos de 30 pa­cientes foram randomizados em dois grupos: um submetido a panfotocoagulação com injeções de ranibizumabe (grupo estudo), e o outro submetimedo a panfotocoagulação isolada (grupo controle). Todos olhos foram tratados em 3 sessões de laser, seguindo recomendação do Early Treatment Diabetic Retinopathy Study (ETDRS). Avaliação da sensibilidade ao contraste foi realizada sob condições fotópicas (85 cd/m2) com tabela Visual Contrast Test Sensitivity 6500, permitindo avaliação de cinco frequências espaciais medidas com redes senoidais: 1.5, 3.0, 6.0, 12.0 e 18.0 ciclos por grau de ângulo visual (cpd). Foram realizadas medidas dos limiares de sensibilidade ao contraste intra e entre grupos na visita inicial, no 1º, 3º, e 6º mês de seguimento. Resultados: Cinquenta e oito olhos, 28 do grupo estudo e 30 do grupo controle, atingiram o término do estudo. Análise comparativa da SC entre os grupos mostrou diferença estatisticamente significante, nas baixas frequências espaciais, no 1º mês em 1.5 cpd (p=0,001) e 3.0 cpd (p=0,04), no 3º mês em 1.5 cpd (p=0,016) e no 6º mês em 3.0 cpd (p=0,026) a favor do grupo estudo. Conclusão: O tratamento com panfotocoagulação associada a injeção de ranibizumabe parece causar menos danos a sensibilidade ao contraste quando comparada com panfotocoagulação isolada em olhos com retinopatia diabética proliferativa de não alto risco. Dessa forma, os resultados apresentados podem justificar a associação do ranibizumabe à panfotocoagulação nestes pacientes.

Do automotive window films affect drivers' safety by decreasing vision sensitivity? A Cross-sectional study / Películas automotivas e perda de acuidade visual? Estudo transversal

ABSTRACT Objective: To measure visual acuity in high contrast and low contrast sensitivities in different grades of visible light transmission films in three different positions (front, lateral and rear windows). Methods: Forty-four healthy volunteers between 30-75 y-o, with BCVA better than 0,5, were tested in the 5 following vehicles with different grades of visible light transmission films. Vehicle 1: 75% in the front and 70% in the lateral and rear windows; Vehicle 2: 70% in the front and lateral windows and 28% in the rear; Vehicle 3: 70% in the front, 28% in the lateral and 15% rear; Vehicle 4: 35% in all 3 windows; Vehicle 5: 50% in the front, 20% in the lateral and 15% in the rear. Descriptive statistics were used and the average of the 3 measurements of VA was considered. Wilcoxon Test was applied to compare the average visual acuity in each vehicle and position. P value<0.05 was considered statistically significant. Results: According to the Brazilian Traffic Regulations for driving in categories C/D/E, when low contrast was tested in the front window, all visible light transmissions were borderline, in the lateral window they were all outside the limit, while in the rear window for both low and high contrast, all visible light transmissions tested were outside the limit and also borderline for driving in categories A/B, with the exception of the vehicle with visible light transmission of 35%. Conclusion: Visual acuity is affected, especially in the rear window, by the use of automotive films. The study is an alert that window films is a possible cause of accidents and may contribute to the revision of traffic regulations worldwide.

RESUMO Objetivo: Medir a acuidade visual em alto e baixo contraste nas diversas graduações de transparência de filmes em três janelas de veículos: frontal, lateral e traseira. Métodos: Foram avaliados 44 voluntários saudáveis entre 30 e 75 anos, com acuidade visual melhor corrigida acima de 0,5, em cinco veículos, sendo: veículo 1, com 75% de transparência frontal e 70% na lateral e traseira; veículo 2, com 70% na frontal e na lateral e 28% na traseira; veículo 3, com 70% na frontal, 28% na lateral e 15% na traseira; veículo 4, com 35% nas três janelas; e veículo 5, com 50% na frontal, 20% na lateral e 15% na traseira. Foi realizada estatística descritiva utilizando a média de três medidas consecutivas, com teste de Wilcoxon para comparar a média de acuidade visual em cada janela, e foi considerado estatisticamente significativo quando valor de p<0,05. Resultados: Todas as transparências testadas nos vidros reduziram a acuidade visual em situação de baixo contraste para níveis limítrofes na janela frontal e níveis ilegais na lateral para conduzir veículos nas categorias C/D/E. Na janela traseira, tanto em alto quanto em baixo contraste, todas as transparências mostraram redução da acuidade visual para níveis ilegais para categorias C/D/E e limítrofes para as categorias A/B, exceto na transparência de 35%. Conclusão: A acuidade visual é reduzida pelo uso dos filmes automotivos, especialmente na janela traseira. Condutores de veículos com filmes devem ser alertados pelo risco aumentado de acidentes. Esse dado científico propõe revisões nas regulações de tráfego mundiais.

Sensibilidad al contraste en edad pediátrica / Contrast sensitivity in pediatric ages

La sensibilidad al contraste es considerada como la capacidad de discriminar diferencias de iluminación entre áreas adyacentes, cuyo umbral se estima como la menor cantidad de contraste que se necesita para lograr esta distinción. La medida de la agudeza visual cuantifica la visión en alto contraste; sin embargo, los objetos que nos encontramos en la vida real no son solo de alto contraste, sino que presentan diferentes niveles de contraste y tamaño, lo cual puede ser determinado con el estudio de la sensibilidad al contraste, ya sea a través de cartillas de bajo contraste o de las pruebas que evalúan las frecuencias espaciales, que serán utilizadas según la edad del paciente pediátrico. Con este trabajo se pretende mostrar los diferentes criterios relacionados con la sensibilidad al contraste en edades pediátricas, para lo cual se realizó una búsqueda en diferentes publicaciones y textos de la especialidad. Existe controversia relacionada con la edad pediátrica en la cual se alcanza la sensibilidad al contraste al nivel del adulto, así como los valores normativos en la infancia con las diferentes pruebas empleadas. La valoración de la sensibilidad al contraste constituye una herramienta más para evaluar la función visual conjuntamente con la determinación de la agudeza visual y la visión de colores. Se necesitan más estudios sobre este tema para unificar criterios con el fin de perfeccionar la atención a la población pediátrica(AU)

Contrast sensitivity is the ability to distinguish differences in luminance between adjacent areas. Its threshold is estimated as the smallest amount of contrast needed to achieve such a distinction. Visual acuity measurement quantifies high contrast vision. However, the objects around us are not only characterized by high contrast: they display different levels of contrast and size, which may be determined through the study of contrast sensitivity, either with low contrast charts or spatial frequency tests, to be used according to the pediatric patient's age. The purpose of the study was to present various criteria about contrast sensitivity in pediatric ages. To achieve this end, a search was conducted in different publications and texts from the specialty. A debate is currently in progress about the pediatric age in which adult contrast sensitivity is achieved and the standard values to be verified with the different tests applied in childhood. Contrast sensitivity assessment is one more tool to evaluate visual function and determine visual acuity and color vision. Further studies are required about the subject aimed at unifying criteria so as to improve the care of the pediatric population(AU)

Interventions to Improve Reading Performance in Glaucoma.

PURPOSE: To evaluate whether changes to contrast, line spacing, or font size can improve reading performance in patients with glaucoma. DESIGN: Cross-sectional study. PARTICIPANTS: Thirty-five patients with glaucoma and 32 healthy control participants. METHODS: A comprehensive ophthalmologic examination was performed followed by reading speed assessment using the Minnesota Low Vision Reading (MNREAD) test under a range of contrasts (10%, 20%, 30%, 40%, and 50%), line spacings (1.0, 1.5, 2.0, 2.5, and 3.0 lines), and font sizes (0.8, 0.9, 1.0, 1.1, and 1.2 logarithm of the minimum angle of resolution), for a total of 15 tests. Regression analyses were performed to examine the effect of varying test conditions on reading speed (measured in words per minute [wpm]). RESULTS: Participants' mean age was 63.0 ± 12.6 years. Patients with glaucoma showed a visual field mean deviation in the better eye of -6.29 ± 6.35 dB. Reading speeds were significantly slower in patients with glaucoma versus control participants for 14 of the 15 MNREAD tests, despite no significant differences in age, gender, or education between groups. Increased contrast (from 10% to 50%) was associated with faster reading speed in patients with glaucoma (10.6-wpm increase per 10% increase in contrast; 95% confidence interval, 7.4-13.8 wpm; P < 0.001; R2 = 0.211). No significant improvement was found in reading speed with increase in font size or line spacing. CONCLUSIONS: Patients with glaucoma showed significantly slower reading speeds than similarly aged control participants. Reading speed was improved by increasing contrast, but not by increases in line spacing or font size.

Nicotine gum enhances visual processing in healthy nonsmokers.

OBJECTIVE: The main purpose of this study was to investigate the isolated effects of nicotine on visual processing, namely contrast processing. METHODS: Thirteen participants, aged 18-40 years, were enrolled in this double blind, randomized and pilot controlled trial involving nicotine gum administration (placebo, 2-mg and 4-mg doses). The participants' instruction was to detect the location of vertical gratings (0.2; 1.0; 3.3; 5.7; 8.8; 13.2 and 15.9 cycles per degree) when it was presented either left or right on the monitor screen. A repeated multivariate analysis of variance was conducted to analyse the results for the visual processing tasks. Bayesian analyses were also carried out considering maximum robustness to avoid bias. RESULTS: The findings that nicotine gum administration resulted in better contrast discrimination when compared to placebo gum (p < .001). More specifically, the 4-mg resulted in better visual sensitivity when compared to the 2-mg (p < .01) and the placebo (p < .001) gum. Demographic data were not related to the outcomes. CONCLUSIONS: These data bring the need for support the findings. If proved, it is possible that nicotine, in small doses, can have a potential therapeutic use for those populations with low vision. TRIAL REGISTRATION NUMBER: RBR-46tjy3.

Standard Results and Contrast Sensitivity Reestablishment after Implantation of a Trifocal Intraocular Lens.

PURPOSE/AIM: To assess, following the standards, the results of safety, efficacy and predictability for a trifocal intraocular lens and to evaluate contrast sensitivity and visual acuity defocus curve. MATERIALS AND METHODS: Fifty subjects operated on cataract surgery or refractive lens exchange with a trifocal intraocular lens have been recruited for the study. The monocular uncorrected visual acuity (VA) at far, intermediate (67 cm) and near (40 cm) distances in addition to corrected VA at far and near distances was evaluated at 1 week, 1 month and 3 months after surgery. Postoperative refraction, binocular contrast sensitivity function (CSF) and binocular defocus curves were also collected at the 3-month follow-up visit. RESULTS: Mean uncorrected VA was 0.10, 0.07 and 0.05 logMAR at far, intermediate and near distances. Corrected distance VA at far and near distances was 0.04 and 0.02 logMAR. Ninety percent and 100% achieved a spherical equivalent in ±0.50 D and ±1.00 D, respectively. CSF was above normal range for 12 and 18 cycles per degree (cpd) in all the conditions, inside the normal range in 1.5, 3 and 6 cpd and only decreased below normal range for 1.5 and 3 cpd in mesopic vision without glare. CONCLUSIONS: The procedure achieved a safety, efficacy and predictability similar to those reported by previous studies. The CSF was generally enhanced after the procedure in comparison to those reported in non-operated subjects above 60 years old. Previous studies might underestimate the effective distance of the intermediate and near foci.

Sensibilidad al contraste en un grupo de diabéticos mexicanos / Contrast sensitivity in a group of Mexican diabetics

RESUMEN Objetivo: Comparar la sensibilidad al contraste evaluada en un grupo de mexicanos con diabetes mellitus contra uno sin diabetes como control. Métodos: Un total de 31 voluntarios, 14 participantes con DM con un tiempo de diagnóstico entre 2 y 20 años (sin retinopatía diabética), y 17 en el grupo control iniciaron el estudio; 4 diabéticos y 5 no diabéticos fueron excluidos por no cumplir con los criterios de inclusión. Por lo tanto, los datos analizados fueron de un grupo de 10 diabéticos (52 ± 10 años) y otro de 12 no diabéticos (52 ± 6 años). Se evaluó la sensibilidad al contraste con la cartilla Vector Vision CSV1000E a una distancia de 2,5 metros con una iluminación de 85 cd/m2. Resultados: Un mayor porcentaje de ojos diabéticos alcanzaron un mejor umbral de contraste en 3, 6 y 18 ciclos por grado en comparación con el grupo control. En 12 ciclos por grado solamente en los umbrales 1 y 5. Conclusiones: La sensibilidad al contraste de la población mexicana con diabetes mellitus presenta mejor percepción de contraste en las frecuencias evaluadas que el grupo control(AU)

ABSTRACT Objective: Compare contrast sensitivity as measured in a group of Mexican diabetes mellitus patients versus a control non-diabetic group. Methods: A group of 31 volunteers, 14 participants with DM with a diagnosis time between 2 and 20 years (without diabetic retinopathy), and 17 in the control group started the study; 4 diabetics and 5 non-diabetics were excluded because they did not meet the inclusion criteria. Therefore, the data analyzed were from a group of 10 diabetics (52 ± 10 years) and another of 12 non-diabetics (52 ± 6 years). Contrast sensitivity was evaluated with a Vector Vision CSV1000E chart at a distance of 2.5 meters and a luminance of 85 cd/m2. Results: A higher percentage of diabetic eyes reached a better contrast threshold at 3, 6 and 18 cycles per degree in comparison with the control group. At 12 cycles per degree only at thresholds 1 and 5. Conclusions: Contrast sensitivity in the Mexican population with diabetes mellitus displays better contrast perception at the frequencies evaluated than the control group(AU)

Visual processing of color and shape in people with leprosy : Visual processing in people with leprosy.

The aim of this study was to analyze the contrast sensitivity of spatial luminance and the color discrimination thresholds of the protan, deutan, and tritan axes of people with leprosy. This study included 8 subjects with leprosy (M = 4, W = 4, M = 33.38 ± 8.7) and 8 healthy subjects (M = 4, W = 4, M = 30.89 ± 5.8). The contrast sensitivity was evaluated by the Metropsis software version 11.0 with vertical sinusoidal grids of frequencies of 0.2, 0.5, 1, 5, 10, and 16 cycles per degree of visual angle (cpd) and color vision by the desaturated Lanthony D15 tests and the trivector and ellipse protocols of the Cambridge Color Test. The results showed significant differences between the groups in the processing of spatial frequencies of 0.2 (U = 14; p = .018); 5.0 (U = 45.0; p = .001); 10.0 (U = 45.0; p = .001), and 16.0 (U = 45.0; p = .001) cpd. The difference in color recognition through D15d (U = 4.0; p = .002). Ellipse 2 (U = 10.0; p = .012) and ellipse 3 (U = 9.0; p = .009) were discriminated against. Overall, the results indicate that leprosy changes the visual processing of low, medium, and high spatial frequencies, as well as the sensitivity of the short wavelength (tritan line of confusion) and long (protan line of confusion) cones.

Fellow eye comparison between alcohol-assisted and single-step transepithelial photorefractive keratectomy: late mid-term outcomes.

Objective: To compare late mid-term results of two different surgical approaches of surface excimer laser ablation for myopic and astigmatic errors in contralateral eyes of the same patients. Methods: Prospective cohort study. A photorefractive keratectomy technique was performed on the right eye and single-step transepithelial photorefractive keratectomy on the left eye of the same patient, in 2012. Postoperative uncorrected and corrected visual acuities, manifest refraction, contrast sensitivity, objective scatter index, tear film stability assessed by serial measurements of objective scatter index and aberrometry as well as occurrence of haze, were compared between groups of eyes. Results: Thirty-two eyes of 16 patients with a mean time of follow-up of 35.2 +/ - 5.0 months (range 30-46 months) were evaluated. No significant differences were observed in postoperative results (visual acuity, spherical equivalent, defocus equivalent, higher-order aberrations, objective scatter index, tear film stability and contrast sensitivity). Contrast sensitivity tended to be better in transepithelial photorefractive keratectomy technique, under photopic lighting conditions without glare and mesopic conditions both with glare and without glare, however, no statistically significant differences were found. No eye presented corneal haze at the last examination. Conclusion: No statistically significant differences in visual acuity, refractive results, contrast sensitivity, objective scatter index, tear film stability or ocular aberrometry were observed between the two surface ablation techniques.

Visual contrast sensitivity in school-age Guadeloupean children exposed to chlordecone.

Recent evidence suggests that prenatal exposure to chlordecone, a persistent organochlorine pesticide that was used intensively in the French West Indies, affects infant neurodevelopment. The aim of the present study was to evaluate the association between prenatal and postnatal chlordecone exposures on visual contrast sensitivity in 285 children aged from 7.1 to 8 years old (mean age = 7.68 ±â€¯0.21 years; sex ratio = 54 % girls) in a Guadeloupean prospective birth cohort (TIMOUN). The Freiburg Visual Acuity and Contrast Test (FrAcT) was used to assess visual contrast sensitivity. Chlordecone concentrations were measured in blood samples at birth (cord blood) and in children at testing time to estimate pre- and postnatal exposure, respectively. Exposures were categorized into three groups and were also log-transformed and considered as continuous variables. Multiple linear regression models were performed on all children taking into account various potential confounders, including maternal characteristics (age, education, intellectual functioning, alcohol and tobacco use during pregnancy). Potential moderation effect of sex was also examined. Results showed that higher cord plasma chlordecone levels were associated with lower contrast sensitivity. Although child chlordecone levels was not associated with the FrAcT, sex-specific stratified analyses revealed significant associations in boys. Associations between postnatal exposure and FrACT scores in girls were null. This study indicates that exposure to chlordecone in utero and during childhood may impair visual contrast sensitivity at school age, particularly in boys.

Refractive and Visual Outcomes After Bilateral Implantation of a Trifocal Intraocular Lens in a Large Population.

PURPOSE: To review refractive, visual acuity, defocus curve and contrast sensitivity results after bilateral implantation of a trifocal intraocular lens (IOL) in a large population. SETTING: One site in Santiago, Chile. DESIGN: Single arm, non-randomized retrospective chart review. METHODS: This was a single-arm retrospective chart review of clinical outcomes after bilateral implantation of a trifocal IOL (Panoptix®), both toric and non-toric versions. Binocular visual acuity at 4 m, 60 cm and 40 cm was tested. Other tests included refraction, mesopic and photopic contrast sensitivity, and defocus curve measurement. RESULTS: The review included 500 eyes of 250 patients implanted with the trifocal IOL and 200 eyes of 100 patients implanted with the trifocal toric IOL, with no clinically significant differences between groups. Ninety-six percent of all eyes were within 0.50D of the intended spherical equivalent correction. In the toric group, 94% of eyes (187/200) had a residual refractive cylinder ≤0.50D, compared to 81% of eyes (406/500) in the non-toric group. Four out of five patients (80.6%, 282/350) had a binocular uncorrected VA of 0.1 logMAR (20/25) at all test distances. Mean defocus was 0.1 logMAR or better from vergences from 0.00 to -3.00 D (corresponding to vision from distance to about 33 cm). With a cutoff of 0.2 logMAR, 96% of patients had a range of vision 2.5 D or greater. Contrast sensitivity was similar between the toric and non-toric lenses, and similar to age-matched normal results. CONCLUSION: The non-toric and toric trifocal IOLs provided good distance, intermediate and near vision to patients, with a wide range of vision and good contrast sensitivity.

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.

Desenvolvimento e validação de medidas psicofísicas de sensibilidade ao contraste de segunda-ordem / Development and validation of second-order psychophysical contrast sensitivity measures / Desarrollo y validación de medidas de sensibilidad al contraste psicofísico de segundo-orden

A medida de Sensibilidade ao Contraste (SC) de primeira ordem é frequentemente utilizada para avaliação da percepção espacial. Nosso objetivo foi desenvolver e validar um teste de SC de segunda ordem para aplicação clínica. Modificações metodológicas foram realizadas na rotina psicofísica para redução do tempo de testagem em um primeiro experimento, validamos a nova metodologia. Em um segundo experimento, valores de normalidade foram derivados do resultado de 16 participantes e foram testados nas mesmas condições do primeiro experimento. As medidas de validade foram obtidas por meio do Spearman-Brown Split-Half Reliability Coefficient para todas as frequências espaciais testadas (r> 0,90). O desenvolvimento e a validação deste novo experimento para as medidas de SC de segunda ordem permitirão avançar nos estudos dos mecanismos básicos da percepção de espaço para estímulos complexos, assim como a aplicação clínica em diversas doenças.

The first-order Contrast Sensitivity (SC) measure is often used to assess spatial perception. Our goal was to develop and validate a second-order SC test for clinical application. Methodological changes were made in the psychophysical routine to reduce testing time and in the first experiment we validated the new methodology. In a second experiment, normal values were derived from the result of sixteen participants who were tested under the same conditions as the first experiment. Validity measures were obtained using Spearman-Brown Split-Half Reliability Coefficient for all tested spatial frequencies (r> 0.90). The development and validation of this new experiment for second-order SC measures will allow to advance in the studies of the basic mechanisms of the perception of space for complex stimuli, as well as the clinical application in several diseases.

La medida de sensibilidad al contraste (SC) de primer orden se utiliza a menudo para evaluar la percepción espacial. Nuestro objetivo era desarrollar y validar una prueba SC de segundo orden para aplicación clínica. Se realizaron cambios metodológicos en la rutina psicofísica para reducir el tiempo de prueba y en el primer experimento validamos la nueva metodología. En un segundo experimento, los valores normales se derivaron del resultado de dieciséis participantes que fueron evaluados en las mismas condiciones que el primer experimento. Las medidas de validez se obtuvieron utilizando el coeficiente de confiabilidad de la mitad dividida de Spear-man-Brown para todas las frecuencias espaciales probadas (r> 0.90). El desarrollo y validación de este nuevo experimento para medidas CS de segundo orden permitirá avanzar en los estudios de los mecanismos básicos de percepción del espacio para estímulos complejos, así como la aplicación clínica en diversas enfermedades.