Can we see the white of their eyes?
How white? How bright? Color doesn’t exist in a void. It’s always in context with other colors, other tones, other light. The quality and quantity (and temperature) of falling light will determine the kind of white.
We need to take care when selecting white. What exact white are we looking for? A fragile pearl of porcelain? Cotton, chiffon or alabaster?
A warmer eggshell, ivory or parchment? A darker linen or bone?
Maybe a cool snow or frost? A tinged lace?
Colors have depth and greater meaning. Before we decide on an exact color, we should be clear about the exact meaning we want to express.