Odd-eyed Cat - Eyeshine and Red-eye Effect

Eyeshine and Red-eye Effect

In flash photographs, odd-eyed cats typically show a red-eye effect in the blue eye, but not in the other eye. This is due to the combined effect of the (normal) presence of a tapetum lucidum in both eyes and the absence of melanin in the blue eye. The tapetum lucidum produces eyeshine in both eyes, but in the non-blue eye a layer of melanin over the tapetum lucidum selectively removes some colors of light.