How do I get rid of the corners on my refraction material?

It won’t seem to go away no matter how many LERPs or multiplys I include. Just trying to make it circular with a faded edge.

no refraction is a value of 1. not black (which is zero)
water is close to 1.05 if im correct, and that distorts quite a lot already.
so your circle could be a value higher than 1, and the corners should be 1.