Hi Tatiana,
For my daughter, we had no clear sign that her eye sight was bad. It was completely out of fluke that her pediatrician sent us to an eye specialist. I noticed that she would tilt her head to one side when making a cute face and that was it. She didn't bump into anything or have cross eyes.
When we took her to an eye doctor, we were shocked to hear that her eye sight was very bad. We monitored it for 2 years and saw 2 different eye specialist. Her eye sight improved but when she was almost 3 years old, the eye doctor decided that she needed glasses to make sure her brain development wouldn't be affected.
After seeing what my daughter went through, I recommend all moms to get their babies' eyes checked. It's never too early. If we didn't have our daughter's eyes checked back then, we still wouldn't have noticed anything because she doesn't show any signs.
Julia