A newborn can see, but only within a narrow band of distance and contrast. The limits come from three separate immature systems, and each resolves on its own timetable.
The eye itself is still growing
A newborn eye is shorter than an adult eye, which changes where light comes to focus relative to the retina. The optics are not yet matched to the shape of the organ.
The retina is also immature at its centre, the region responsible for fine detail. Peripheral vision is comparatively better developed at birth than central vision.
Growth in the first months brings these into alignment, which is why acuity improves steadily rather than switching on. The change is structural and gradual.
Focusing muscles have limited range early on
The lens changes shape to focus at different distances, and the muscle controlling it starts with a restricted working range. Newborns are effectively fixed at a short focal distance.
That distance corresponds roughly to the gap between a feeding baby's eyes and the face of the person holding them. Objects much beyond it are not resolved.
The range widens over the early months as control develops. This is also when parents notice a baby tracking objects across a room rather than only in front of them.
The visual brain has to be trained by input
Much of what counts as seeing happens after the eye. The regions that interpret edges, motion and depth develop in response to the input they receive.
Depth perception depends on the two eyes working together, and that coordination is not present at birth. Eyes that occasionally drift out of alignment in the first weeks are common as a result.
Because these regions are shaped by use, sustained interruption of clear input in early life affects development. This is the reasoning behind screening for conditions that block or blur one eye.
Contrast matters more than detail at this stage
Newborns respond strongly to high-contrast boundaries and much less to fine or pastel patterns. Sharp light and dark edges are what the immature system can resolve.
Faces are unusually effective stimuli, combining contrast, movement and repetition at exactly the right distance. Preference for face-like patterns appears very early.
Colour discrimination develops over the following months, with strong saturated colours registering before subtle ones. Early preference for bold patterns follows from the same limitation.
What is checked and when
Routine newborn examinations include a check of the eyes, looking for the reflection from the back of the eye and for structural problems, rather than measuring what the baby can see.
Later checks in the preschool years assess acuity once a child can cooperate. The staging reflects what can be measured at each age rather than when problems begin.
Persistent misalignment beyond the early weeks, an eye that consistently turns, or an absent or unusual reflection warrants prompt review by a health professional rather than waiting for a scheduled check.