Research overview: tapetal reflectance and the color of cat eyeshine

The color of a cat's eyeshine, often green or yellow-green, reflects the wavelengths the tapetum returns most strongly. This overview surveys measurements of feline tapetal reflectance and discussion of how the layer is tuned to bounce back light in the range to which the retina is most sensitive. By matching reflectance to photoreceptor sensitivity, the tapetum maximizes the useful light recycled rather than wasting reflection on wavelengths the eye cannot exploit. The survey notes individual and developmental variation in eyeshine color, including the lighter or bluish glow sometimes seen in kittens whose tapetum is still maturing. Linking reflectance spectra to retinal sensitivity shows the tapetum is not a generic mirror but an optically matched component. The everyday observation of glowing cat eyes thus encodes real information about how the feline eye is engineered for dim light.