Cats are predominantly red-green blind. This is called deuteranomaly (green blindness) and protanomaly (red blindness). However, cats are more likely to have protanomaly – i.e. red blindness. This means that the colour spectrum in the orange and red range is primarily affected. However, they can probably recognise green at least a little. This type of colour blindness makes it difficult for your cat to distinguish between red, brown, orange and purple.
Your cat's photoreceptors are most sensitive to wavelengths between the blue-violet and green-yellow range.
This is also why your cat probably prefers blue and yellow toys. These colours are eye-catching to them, while different red toys, in particular, appear as similar shades of gray.
