RESUMEN
Clinicians usually do not have access to a lantern test when making an occupational assessment of the ability of a person with defective colour vision to recognise signal light colours: they must rely on the results of ordinary clinical tests. While all colour vision defectives fail the Holmes Wright Type B lantern test and most fail the Holmes Wright Type A lantern, 35% of colour vision defectives pass the Farnsworth lantern. Can clinical tests predict who will pass and fail the Farnsworth lantern? We find that a pass (less than two or more diametrical crossings) at the Farnsworth Panel D 15 Dichotomous test has a sensitivity of 0.67 and specificity of 0.94 in predicting a pass or fail at the Farnsworth lantern test: a Nagel range of > 10 has a sensitivity of 0.87 and a specificity of 0.57. We conclude that neither the D 15 nor the Nagel Anomaloscope matching range are satisfactory predictors of performance on the Farnsworth Lantern.
Asunto(s)
Pruebas de Percepción de Colores/métodos , Defectos de la Visión Cromática/diagnóstico , Humanos , Ocupaciones , Sensibilidad y EspecificidadRESUMEN
One thousand, three hundred and sixteen office workers [692 visual display unit (VDU) users, 624 controls in the first year] were examined once each year over a 6-year period to establish whether or not VDU work was a factor in the occurrence of visual symptoms, ocular abnormalities, or ocular disease. Statistical analysis showed that although there were differences between VDU users and nonusers in the amount of myopia, the prevalence of some symptoms, and the prevalence of signs of fundal or vitreal disease, the differences were small and there were no clear trends or patterns to lend convincing support to the hypothesis that VDU work may be a risk factor. There were no significant differences in the prevalence and incidence of cataract.
Asunto(s)
Terminales de Computador , Oftalmopatías/epidemiología , Trastornos de la Visión/epidemiología , Adulto , Australia/epidemiología , Oftalmopatías/etiología , Oftalmopatías/fisiopatología , Femenino , Humanos , Incidencia , Presión Intraocular , Masculino , Persona de Mediana Edad , Prevalencia , Análisis de Regresión , Factores de Riesgo , Trastornos de la Visión/etiología , Trastornos de la Visión/fisiopatología , Agudeza Visual/fisiología , Campos Visuales/fisiologíaRESUMEN
The optics of the NAP prism are described. This is a prism that is produced commercially in "NAP glasses," which are marketed by the Sakura Company of Japan. It deflects a beam through about 90 degrees while keeping the image erect. Rays are both reflected and refracted, leading to some color fringing. The condition for zero color fringing is explored and the corresponding angle of deviation is calculated. The effects of prism apex angles on beam deviation angle and field of view are also investigated. The results show that the requirement for zero color fringing gives a small field of view but if some color fringing is tolerated, a larger field of view can be obtained.
Asunto(s)
Anteojos , Óptica y Fotónica , MatemáticaRESUMEN
The ability to recognize and discriminate colors under full-moon light was measured Color naming was performed at three sizes (0.5°, 2°, and 4°) by the use of one white and six colored chips that spanned the spectrum at two levels of saturation. The results show that correct color recognition is possible under full-moon light. However, the recognition rate depends on a complex interaction between hue, level of saturation, and size of test field. For small fields and desaturated colors, the recognition rate is low. However, for saturated colors, most hues can be recognized at better than chance levels, with red being recognized very accurately.