When I had babies, we didn't know about the sunglasses, and often babies were in the sun. Sun hats were rare. Sun worship was in. Then I grew up and learned about cataracts. My daughter grew up and found the sunglasses for her baby.
Today I searched this topic on the web. The first doctors' articles mentioned babies born with vision problems, also lots of cures. NO mention of protection from the sun. There were plenty of ads for baby sunglasses.
Before I gave up, I found this:
December 18, 2012 Protecting Your Baby’s Eyes From the Sun
on a site called The Charlene Chronicles.
I urge you to see this blog and read this article, no matter what your age. It even mentions a feature in baby sunglasses that I have on my ultra-coverage ones.