I don't think it's impolite to ask a clarification question. Parents with their first child often have unrealistic expectations of development milestones. We want to get that out of the way first. Crucially, the OP has not provided a diagnosis (source of blindness), which one would get after soliciting medical advice and conducting tests.
I have a friend who got his first daughter a hearing test. The audiologist delayed the test twice until he finally gave up.
His daughter was able to hear instructions like “go get your socks” but since she was two and not talking, they leapt to the conclusion that it was probably hearing related.
Three years later, I still make fun of him for it but at the time I tried to keep a straight face.
Ironically, he’s a medical doctor himself.
> Parents with their first child often have unrealistic expectations of development milestones.
This is a great point. There were several instances when either me or my wife (or both of us) thought something was wrong with our baby, until we consulted with our pediatrician, who would laugh and then calmly explain why we were jumping the gun. Haha.
The comment read to me as disrespectfully implying to check with a pediatrician as if OP hadn't already. But ironically... perhaps that was my own disrespectful reading of the comment.