how to sprite small eyes

Anyone have any advice/ help on spriting eyes, on human characters,

when working with small sprites, ie. 8-bit or 16-bit era

Here's a few attempts.
1.


My problem is you can barely see them..

2.


This ones a little better but I still don't think the eyes are great.... they look pretty basic


If anyone has any advice or just better examples feel free to throw them in.