Normally a child should be able to recognize mother and have a social smile by 6-8 weeks of age. If the child has poor vision in both the eyes, then he/she may not recognize the mother or may not respond to the visual stimuli. Once the child starts walking, he/she may frequently bump into objects.
If the child has poor vision in only one eye then it may be difficult to notice it. The eye with poor vision may not be aligned properly with the other eye, thus causing squint (strabismus). The child may also have rhythmic jiggling movements of the eyes (nystagmus).
Sometimes the cause of poor vision may be visible as a whiteness of the cornea or whiteness behind the pupil. In some cases the eyes of child with glaucoma may be watering and very sensitive to light.
The poor vision may also be noticed incidentally when the child is being examined by a doctor or during vision screening in the school.