When Do Kittens' Eyes Change Colour? Why Are Kittens Born with Blue Eyes?

Posted by
Jennifer Copley
Oct 1, 2009

How Old Are Kittens When Their Eyes Change Colour?

All kittens are born with blue eyes. Except for breeds that naturally have blue eyes, eye colour usually begins changing to the permanent adult colour at around 6 weeks of age, though this process may begin a little earlier or later. The change should be complete by around 12 weeks.

Why Are All Kittens Born with Blue Eyes?

According to Anne Marie Helmenstine, Ph.D., melanin, the pigment that colours hair, skin, and eyes, is not yet fully deposited into the irises of a newborn's eyes or darkened as a result of exposure to ultraviolet light. Melanin production increases during the early weeks of a kitten's life, causing its eyes to change colour.

A cat is genetically programmed to develop its adult eye colour and will produce the right amount of melanin to do so. Larger amounts create brown or black irises and lower amounts cause them to be light brown, green, or gray. Very small amounts create blue or light gray eyes. Albinos, having no melanin, have pink eyes due to light reflecting off the blood vessels in their eyes.

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