Blue eyes are caused by the Tyndall effect.

Determine whether it is true or false.

Tyndall effect is the scattering of a beam of light by a medium containing small suspended particles.

The amount of melanin in one of the layers of the iris is the main distinction between blue, brown, and black-coloured irises. 

When compared to a black iris, the layer in a blue iris contains relatively less melanin, which makes it translucent. The Tyndall effect causes light to be scattered when it strikes this translucent layer. 

Blue light is more widely scattered than red light because it has a shorter wavelength. Unscattered light is absorbed by a deeper layer in the iris. These irises acquire their distinctive blue colour because the majority of the scattered light is blue.