RESUMEN
A computer-controlled test of colour vision is described, in which luminance noise and masking contours are used to ensure that the subject's responses depend on chromatic signals. The test avoids the need--common to most computer-controlled tests--to define equiluminance for the individual subject before the colour test itself can be administered. The test achieves a good separation of protan and deutan subjects and reveals the large range of chromatic sensibilities among anomalous trichromats. As a population, dichromats had higher thresholds on the tritan axis of the test than did normals. In an extension of the test, full discrimination ellipses were measured for normal and colour-deficient observers. The nature of anomalous trichromacy is discussed and the possibility is raised that hybrid genes, resulting from genetic recombination, may code for incorrectly labelled or functionally impaired molecules.
Asunto(s)
Pruebas de Percepción de Colores/métodos , Defectos de la Visión Cromática/fisiopatología , Adolescente , Adulto , Anciano , Gráficos por Computador , Sensibilidad de Contraste/fisiología , Discriminación en Psicología/fisiología , Femenino , Humanos , Luz , Masculino , Persona de Mediana Edad , Umbral Sensorial/fisiologíaRESUMEN
We have developed and extensively assessed an automated chromatic discrimination test which can be used to screen effectively a diabetic population for sight threatening diabetic eye disease. Equiluminant, sinusoidal, low spatial frequency, chromatic gratings are produced along a tritan confusion axis under computer software control on a high resolution CRT. The correct position of the tritan axis in colour space was calibrated using subjects whilst they were transiently tritanopic. The minimum amplitude about a neutral "grey point" along the tritan confusion axis at which a subject can just distinguish a grating is found using a double staircase reversal algorithm. This measure is taken as the Tritan Discrimination Sensitivity and it is this that we use to flag those diabetics with severe diabetic retinopathy. This computerised tritan discrimination test is quick, non-invasive, easy to operate, inexpensive and reliable. The test-retest reliability coefficient (rho) is 0.92. The tritan discrimination test effectively identifies those diabetics who have or are most at risk of developing severe diabetic retinopathy. The sensitivity of the test for the detection of maculopathy, ischaemic retinopathy (pre-proliferative), and proliferative retinopathy is 97%, 65%, and 93%, respectively. The corrected specificity of the test is 83%. We conclude that the tritan discrimination test has potential for use as a valuable screening tool for the early detection and treatment of severe diabetic retinopathy.
Asunto(s)
Percepción de Color/fisiología , Retinopatía Diabética/diagnóstico , Discriminación en Psicología/fisiología , Selección Visual/métodos , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Envejecimiento/fisiología , Retinopatía Diabética/clasificación , Retinopatía Diabética/fisiopatología , Humanos , Persona de Mediana Edad , Psicofísica/instrumentación , RiesgoRESUMEN
A study comparing the macular function of both eyes of 130 urological surgeons was carried out to investigate whether the increased light exposure to the endoscoping eye caused any deterioration of macular function. The non-endoscoping eye was used as a control. A sophisticated computer test of colour contrast sensitivity was used. The computer assesses the degree of brightness at which the subject is just able to detect a coloured grating, and for each eye this is expressed as a threshold for the red/green axis and the blue/yellow (tritan) axis. The subjects also completed a questionnaire about their working patterns and their general and ophthalmic history and had a brief examination of the fundus. The results do not suggest that urologists are suffering any significant macular damage as a result of their work with endoscopes.