Why do most black cats have yellow eyes?
ANSWER: Black cats have a high content level of melanin (pigment). Melanin comes in two varieties: brown-black eumelanin and red-yellow pheomelanin.
Where there is little pigment in the iris, the eyes are blue due to the refraction of light and not pigmentation. However, if the iris contains a predominance of phenomelanin the eye is yellow. A predominance of eumelanin makes the eye darker (copper).
The high melanin content in black cats results in a high phenomelanin content in their eyes making them yellow.
I don’t know why there is more phenomelanin than eumelanin in the eyes of black cats.
I welcome any alternative thoughts on this topic.