What is the cause of my dirty looking sclera and how can I make it whiter?

This is what my eyes look like. Though for some strange reason in this picture they look quite white but to be honest Im looking at myself into the mirror right now and they don’t look that white. They look more like a dirty white-y colour. I don’t remember if I had whiter sclera before but this sure kinda bothers me and I think that it doesn’t really bring out my eye colour as gorgeous as its supposed to be.
What can I do to make them whiter?