The baby will respond to light when it is still inside the belly. You can take a flashlight with not too much light and shine it on the belly about 1-2 meters apart and move it slowly, and you will find that the fetus will move with the light. So newborns can see things as soon as they are born, it’s just that at this time the newborn’s eyes are less sensitive to things, and it’s easy for people to mistakenly think that newborns can’t see things. Newborns have just come from the dark world to the bright world, early on the visual focus adjustment ability is poor, the object distance is too far, too close, too small, or moving too fast, can not be well captured by the baby. Some studies show that newborn babies only use about 45 degrees of visual field, and can only follow people or objects within 18-38cm forward. Power retinoscopy tests have found that the optimal visual focal length for newborns is 19 centimeters. Because of the lack of understanding of the visual characteristics of newborns, adults are always accustomed to using adult standards to determine whether the baby can see things, and naturally assume that newborns can not see things. If you want to test whether your newborn can see or not, you have to choose the right time. Newborns are interested in seeing only when they are in a state of quiet awakening, which lasts for a very short time, only 1∕10 of the day, usually about an hour after feeding, when babies tend to be the most relaxed and in the best spirits. In this case, you will notice that your baby’s eyes are wide open and bright.