One reason could be the increased amount of sunlight inducing the brown color in the sclera.
Sclera
It's the white part of the eyeball.
sclera.outer most layer of eye ball.it is the tough layer. it provides firmness to eyeball.
The white of the eye is called the Sclera.
Ok if you all think I'm stupid or dome an eyeball is a body part that looks like a meatball but not brown tho but it is a body part that makes you see.
There are a number of reasons why a dog would have brown in the white part of their eye. They might have a parasite.
No
gecko poop is part white and part brown and the white part can be gooey
9 tenth part white 1 tenth part brown
The Iris.
Sclera
iris