Not that it actually matters to many people, but when the limbus area is white, or a milky/light grayish color, it is called arcus conealis or arcus senilis. It is most frequent in older people. If one wants to simulate an aged eye, the color change between the pale color of the limbus area and the iris should not be sharp.

LMK

Probably edited for spelling, grammer, punctuation, or typos.