How to train babies eyes?

What to you mean by "train"? Help strengthen them? If so, make sure your baby sees a wide array of colours after they are around a month. Green is a soothing colour for the eyes and taking baby outdoors so they can feast their eyes on all nature's colours is great for the eyes. Its best not to introduce screen time to your baby too early. Limit it for when you absolutely need it.

When babies are newborn, they can't see very well. At this age, it's best to show them things in bright, contrasting colours like black, white and red. But after about 4 months, you can help his eyesight develop by getting books and toys in bright, beautiful colours.

moving rattles around them, giving them toys that move and books are good!