8 research outputs found
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Occupational color vision standards: new prospects
Occupational color vision standards in transport have been implemented for 100 years. A review of these standards has taken place early this century prompted by antidiscrimination laws in the workplace and several transport accidents. The Australian and Canadian Railways have developed new lanterns to address their occupational medical requirements. The Civil Aviation Authority in the UK has adopted the Color Assessment and Diagnosis (CAD) test as the standard for assessing color vision for professional flight crews. The methodology employed using the CAD test ensures that color deficient pilot applicants able to complete the most safety-critical task with the same accuracy as normal trichromats can be accepted for pilot training. This methodology can be extended for setting new color vision standards in other work environments
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Changes in color vision with decreasing light level: separating the effects of normal aging from disease.
The purpose of this study was to obtain additional information about the health of the retina (HR) by measuring the rate of loss of chromatic sensitivity with decreasing light level. The HR(index) is introduced to separate the effects of normal aging from early stage disease. For normal subjects the HR(index is largely independent of age (r(2)~0.1), but ~11% of clinically normal, asymptomatic, older subjects exhibit values below the 2σ limit. The HR(index provides a single number that captures how light level affects chromatic sensitivity irrespective of age and can be used to screen for preclinical signs of retinal disease
Discrimination thresholds of normal and anomalous trichromats: Model of senescent changes in ocular media density on the Cambridge Colour Test
Age-related changes in chromatic discrimination along dichromatic confusion lines were measured with the Cambridge Colour Test (CCT). One hundred and sixty-two individuals (16 to 88 years old) with normal Rayleigh matches were the major focus of this paper. An additional 32 anomalous trichromats classified by their Rayleigh matches were also tested. All subjects were screened to rule out abnormalities of the anterior and posterior segments. Thresholds on all three chromatic vectors measured with the CCT showed age-related increases. Protan and deutan vector thresholds increased linearly with age while the tritan vector threshold was described with a bilinear model. Analysis and modeling demonstrated that the nominal vectors of the CCT are shifted by senescent changes in ocular media density, and a method for correcting the CCT vectors is demonstrated. A correction for these shifts indicates that classification among individuals of different ages is unaffected. New vector thresholds for elderly observers and for all age groups are suggested based on calculated tolerance limits