Research overview: variation in eyeshine color among cats

Not all cat eyes glow the same color, and the variation carries clues about the tapetum and pigmentation. This overview surveys reports that eyeshine color can differ with age, coat and eye pigmentation, and tapetal development, with kittens sometimes showing a bluish glow that shifts toward green or yellow as they mature. In some cats with reduced pigmentation, the reflection may appear reddish because the underlying blood vessels of the choroid show through where the tapetum is absent or thin. The survey discusses how observers can read eyeshine as a rough indicator of tapetal presence and condition. While usually a curiosity, eyeshine color can occasionally flag developmental or pigmentary differences. Documenting this variation links a familiar nighttime phenomenon to the anatomy and pigmentation of the individual cat's eye.