Digital asthenopia: blue-blocking lenses and + 0,40D additional power in the near zone, for eye strain, accommodation and convergence functions / Astenopia digital: avaliação de lentes com filtro de luz azul e poder adicional de +0,40D na zona de perto, para fadiga visual e nas funções de convergência e acomodação

ABSTRACT Purpose Evaluate blue-violet light filter and additional power of +0.40 D in the near zone ophthalmic lenses, on convergence, accommodative functions, and symptoms of digital asthenopia (DA). Methods Randomized study in cross-over design conducted on 49 volunteers (age, 29 ± 5.5 years; male: female, 18:31). Each subject wore test (+0.40 D in the near zone) and control lenses (regular single vision) for 4 weeks in randomized order. Both lenses had a selective blue-violet light filter. A baseline measurement was taken with the subjects' current updated glasses. Accommodation amplitude (AA) and near point of convergence (NPC) were measured binocularly with the RAF ruler. DA was evaluated by a questionnaire. Results No significant difference (p=.52) was found for AA comparing baseline (11.50±1.88 D), test (11.61± 1.62 D), and control SV lenses (11.88±1.50 D). No significant difference was found for NPC (p=.94), between baseline (6.50 ± 2.89cm), test (6.71± 3.49) and control SV lenses (6.82± 3.50 cm). No significant difference was found comparing test and control SV lenses in symptoms of DA (p=0.20). Conclusions The +0.40 D lenses have no negative impact on convergence or loss of accommodation power. The +0.40 D and control SV lenses had a similar impact on attenuating symptoms of DA.

RESUMO Objetivo Avaliar os efeitos do uso de lentes oftálmicas com filtro seletivo de luz azul-violeta, sem e com poder adicional de + 0,4D na zona de perto nas funções de acomodação e convergência e para sintomas de astenopia digital (AD). Métodos Ensaio clínico controlado, randomizado e mascarado, com 49 voluntários (idade, 29 ± 5,5 anos; masculino: feminino, 18: 31). Cada participante usou lentes de teste (+0,40 D na zona de perto) e controle (visão simples), por 4 semanas de forma randomizada. Ambas as lentes tinham filtro seletivo de luz azul-violeta. A medição inicial (baseline) foi feita com os óculos atualizados de cada participante. A amplitude de acomodação (AA) e o ponto de convergência próximo (PPC) foram medidos binocularmente com a régua RAF. A AD foi avaliada por um questionário. Resultados Não houve diferença estatisticamente significante (p=0,52) para as medidas de AA comparando as lentes baseline (11,50±1,88 D), teste (11,61±1,62 D) e controle VS (11,88±1,50 D). Nenhuma diferença significativa foi encontrada para a medida do PPC (p=0,94), entre as lentes baseline (6,50 ± 2,89cm), teste (6,71±3,49) e controle VS (6,82±3,50 cm). Nenhuma diferença significativa foi encontrada comparando lentes teste de VS e controle nos sintomas de AD (p=0,20). Conclusões As lentes com +0,40 D não têm impacto negativo na convergência ou na perda de acomodação. As lentes +0,40 D e controle VS, tiveram impacto semelhante na redução dos sintomas de AD.

Asthenopia in bankers: identification and analysis of risk factors / Astenopia em bancários: identificação e análise dos fatores de risco

Abstract Objective: To evaluate the prevalence of asthenopia in a cohort of bank employees and identify possible associated risk factors. Methods: Cross-sectional study based on information supplied by bankers in response to a standardized electronic questionnaire. Results: The questionnaire was responded by 945 bankers. The frequency of asthenopic symptoms was positively associated with female gender, age over 50 years, and reading or using the computer >6 hours a day. Conclusion: Asthenopic symptoms were found to be significantly associated with gender, age and time spent reading. The most frequently reported symptoms were headache and sore eyes.

Resumo Objetivo: Avaliar a presença de astenopia em bancários e identificar possíveis fatores de risco associados. Metodos: Estudo transversal realizado por meio de informações obtidas em um questionário padronizado, aplicado eletronicamente à trabalhadores da categoria de bancários. Resultados: Responderam ao questionário 945 trabalhadores. Observou-se que a frequência dos sintomas de astenopia foi maior nos grupos que declararam usar computador ou ler por mais de 6 horas por dia. As queixas de astenopia foram significativamente maiores nos trabalhadores com mais de 50 anos e do sexo feminino. Conclusão: Este trabalho identificou uma associação positiva de queixas de astenopia em bancários em relação ao tempo de leitura, sexo e idade. Dentre os sintomas oculares associados à astenopia, foi encontrada uma maior prevalência de dor de cabeça e dor nos olhos.

Factors leading to the Computer Vision Syndrome: an issue at the contemporary workplace

INTRODUCTION: Vision and eye related problems are common among computer users, and have been collectively called the Computer Vision Syndrome (CVS). METHODS: An observational study in order to identify the risk factors leading to the CVS was done. Twenty-eight participants answered a validated questionnaire, and had their workstations examined. The questionnaire evaluated personal, environmental, ergonomic factors, and physiologic response of computer users. The distance from the eye to the computers' monitor (A), the computers' monitor height (B), and visual axis height (C) were measured. The difference between B and C was calculated and labeled as D. Angles of gaze to the computer monitor were calculated using the formula: angle=tan(-1)(D/ A). Angles were divided into two groups: participants with angles of gaze ranging from 0 degrees to 13.9 degrees were included in Group 1; and participants gazing at angles larger than 14 degrees were included in Group 2. Statistical analysis of the evaluated variables was made. RESULTS: Computer users in both groups used more tear supplements (as part of the syndrome) than expected. This association was statistically significant (p<0.10). Participants in Group 1 reported more pain than participants in Group 2. Associations between the CVS and other personal or ergonomic variables were not statistically significant. CONCLUSIONS: Our findings show that most important factor leading to the syndrome is the angle of gaze at the computer monitor. Pain in computer users is diminished when gazing downwards at angles of 14 degrees or more. The CVS remains an under estimated and poorly understood issue at the workplace. The general public, health professionals, the government, and private industries need to be educated about the CVS

Reduced blinking rate as a cause for computer vision syndrome

To correlate between eye complaints of computer users and reduced blinking rate. This study was carried on 20 subjects .all were computer complaining of one or more symptom of computer vision syndrome. Rate of blinking was calculated using digital web camera during work and during casual conversation. Tear break up time and Schirmer`s test was done for all patients during work and at rest. Marked reduction in blinking rate/min from 16.5 to 4.8. Mean tear break up time changes during work was 10.85sec and at rest was 11.2 sec the mean Schirrner's test was 13.5mm during work and 12.9 at rest. Blinking rate is markedly reduced during computer using giving an interpretation for the computer vision syndrome complaints

Estudio de la función visual en el trabajo con computadoras / [Visual function study in work with computer]

This investigation searched for the relationship between amount of nearwork, asthenopic symptoms and visual function, in a group of office workers engaged in telemarketing. Phoria, monocular accommodative facility with +/- 2 lens flippers and near point of convergence were measured in 100 office workers (mean age 21 +/- 2.6 years) whose uncorrected visual acuity was 20/30 or better. Daily hours of reading hard-copy and of computer use, and the level of asthenopic symptoms, were measured using a questionnaire. In this sample, telemarketers were involved 5.84 +/- 2.02 daily hours in computer use, and 2.87 +/- 2.13 daily hours in reading. The following asthenopic symptoms were present twice or more times in a week: headaches 16

, pain in the eyes 17

. An association was found between the amount of hours using computers and red eyes (chi 2 = 4.4, p = 0.0359) or blurred vision (chi 2 = 8.35, p = 0.0038). And also between deficit of convergence and headaches (chi 2 = 4.3313, p = 0.0374) or red eyes (chi 2 = 3.6416, p = 0.0564). No other associations could be found between the accommodative facility test results, the near point phoria, and the amount of nearwork or the asthenopic symptoms. In conclusion, computer use in telemarketing is associated with few asthenopic symptoms. Near point of convergence should be routinely measured, as it is associated with some asthenopic symptoms.

Factores de riesgo para la astenopía en operadores de terminales de computadoras / Risk factors for asthenopia among video display terminal operators

Objetivo. Establecer si la incidencia de astenopía (fatiga visual) es mayor en operadores de terminales de computadoras que en trabajadores administrativos no expuestos, así como identificar los factores de riesgo asociados. Material y métodos. Se estudió una muestra de 35 operadores de terminales de computadoras y 70 trabajadores administrativos no expuestos, de ocho centros de cómputo de una institución educativa. Se analizaron los siguientes factores: iluminación, contraste, tipo de luz, de pantalla, campo electrostático, distancia de observación, tipo y horas de trabajo, edad, uso de lentes correctivos, antigüedad y trabajo extra. La astenopía se identificó clínicamente por la presencia de por lo menos un signo y un síntoma durante la jornada de trabajo. Se utilizó la prueba chi cuadrada con corrección de Yates para evaluar la diferencia entre grupos, y un modelo de regresión logística para el análisis de los factores de riesgo. Resultados. Se determinó astenopía en el 68.5 por ciento de los operadores a diferencia del 47.7 por ciento de los no expuestos (p< 0.05). De los factores analizados, únicamente el correspondiente a las más de cuatro horas de trabajo continuo frente a la terminal demostró una asociación significativa con la astenopía (p< 0.05). Conclusiones. Se sugiere establecer pausas durante el trabajo con terminales a fin de evitar la fatiga visual. Por otra parte, es recomendable realizar estudios más extensos en la población mexicana para establecer criterios de seguridad y normar el trabajo con terminales de computadoras

Objective. To study the incidence of asthenopia among computer terminal operators as compared to unexposed administrative workers and to identify the risk factors associated with this condition. Material and methods. A sample of 35 computer terminal operators and 70 unexposed administrative workers from eight computing centers at an educational institution were included in the study. The risk factors studied were: lighting, contrast, type of lighting, screen type, electrostatic field, eye to monitor distance, time and number of hours worked, age, use of corrective lenses, seniority and overtime. Asthenopia was clinically identified as the presence of at least one sign and symptom present in a given workday. Results. Asthenopia was found in 68.5% of the exposed group and in 47.7% of the unexposed group (p< 0.05). Among the risk factors studied, working for more than four hours at the video display terminal was shown to have a significant association with asthenopia (p< 0.05). Conclusions. A recommedation is made to take breaks during the workday at computer terminals in order to avoid visual fatigue. Also, more extensive studies should be carried out in our population to establish safety criteria and to standardize work activities using computer terminals.

Computer eyestrain

Se discuten en este trabajo los mecanismos oculares probablemente mas importantes de los síntomas de astenipia en usuarios de computadoras: reducción del volumen de la secreción lacrimal, fatiga de los músculos extraoculares, fatiga al color y reducción de la amplitud de acomodación inducida por la luz monocromática. Sobre esta base se derivan algunas reglas prácticas para evitar o reducir la astenopia