The white of the eye isn’t simply white. Look closely and you will see many veins and subtle details across its surface. Recreating these is quite easy.
Load the current outer eye material into the painting application.
This image should still have the black circle we created earlier in its alpha channel. We need to duplicate this and bring it into our main RGB channels as a layer. Having the alpha visible will help to tell you which areas of the texture will be visible so you don’t accidentally paint on the cornea, which is transparent.
Start by painting broad strokes, each moving in toward the center. If possible, use a brush that will automatically fade as you paint to taper the line nicely.
Next, with a finer ...