It is hypothesized that colour vision and opponent processing of colour signals in the visual system evolved as a means of overcoming the extremely unfavourable lighting conditions in the natural environment of early vertebrates. The significant flicker of illumination inherent in the shallow-water environment complicated the visual process in the achromatic case, in particular preventing early...

Common variation in colour vision exists among both colour normal and colour deficient subjects. Differences at a few amino acid positions that influence the spectra of the L and M cone pigments account for most of this variation. The genes encoding the L and M photopigments are arranged in head-to-tail arrays on the X-chromosome, beginning with the L and followed by one or more M pigment genes...

The intensity threshold of colour vision has been behaviourally tested in birds; the results show that parrots lose colour vision in brighter light than humans.

following nest exits. Every 2 to 3 days, nest position was changed in the horizontal plane on a 4 m long platform to make positional cues unreliable. The choice criterion for a returning bee was defined as the first colour landmark that the bee hovered in front of, or landed on. Thus, if the bee chose the training colour landmark, the response was considered correct. Data from all bees were poo...

Background/aims: Disturbances of colour vision are a frequently reported sign of digoxin toxicity. The aim of this study was to investigate the incidence of acquired colour vision deficiency in elderly hospitalised patients receiving maintenance digoxin therapy. Methods: 30 patients (mean age 81.3 (SD 6.1) years) receiving digoxin were tested using a battery of colour vision tests (Ishihara, AO...

If the photoreceptors of a colour vision system are polarization sensitive, the system detects polarization-induced false colours. Based on the functional similarities between polarization vision and colour vision, earlier it was believed that a uniformly polarization-sensitive (insect) retina (UPSR)-in which receptors of all spectral types have the same polarization sensitivity ratio and micro...

BACKGROUND/AIMS Disturbances of colour vision are a frequently reported sign of digoxin toxicity. The aim of this study was to investigate the incidence of acquired colour vision deficiency in elderly hospitalised patients receiving maintenance digoxin therapy. METHODS 30 patients (mean age 81.3 (SD 6.1) years) receiving digoxin were tested using a battery of colour vision tests (Ishihara, AO...

Objective: Colour vision is a function of three types of cone pigments present in retina. Any abnormality in the cone pigments may cause deficiency of colour vision which is called as colour blindness. The incidence of Colour vision deficiency varies from race to race and different in different geographical areas. Colour is very important sign used in medical profession, but there is no effecti...

In this paper we present a method for automatically evaluating the amount of colour changes images undergo when perceived by individuals with colour deficient vision. This measure enables the classification of images based on the extent images visually change when viewed by people with one of the three classes of dichromatic (protanopia, deuteranopia, and tritanopia) colour vision. By measuring...

The dual retina of humans and most vertebrates consists of multiple types of cone for colour vision in bright light and one single type of rod, leaving these animals colour-blind at night. Instead of comparing the signals from different spectral types of photoreceptors, they use one highly sensitive receptor, thus improving the signal-to-noise ratio. However, nocturnal moths and geckos can disc...