Newborn babies can't see clearly at birth because:

Did you know your brain changes every day? The brain's ability to change is called plasticity. Every time you learn and experience new things, new connections form between neurons. And the more you do something, the stronger those connections become. The brain can also change if it's impaired or injured. It can "reorganize" itself, so healthy parts of the brain can take on new functions.
Flipping Experiment
Years ago, scientists created special goggles that flipped views upside down. Volunteers wore these goggles whenever they were awake.
At first, they were confused and dizzy because they saw everything upside-down. But after several days, something amazing happened. Even with the goggles, they started seeing things right-side-up. Their brains changed their mind's view!
Then the volunteers removed the glasses, but their brains had become used to the new view. Now they saw an upside-down world, even without the goggles. After just a few days, their brains once more adjusted and produced a right-side-up image.
Newborn babies can't see clearly at birth because:
their eyes are not fully developed
the seeing part of their brain is still developing
their pupils are still adjusting to light
Each day, the network of brain cells in the visual cortex becomes more complex. As the baby looks out at the world, neurons send a flurry of messages between the eyes and the brain. As the brain matures, the connections between neurons become stronger and the baby's vision improves.
As you grow up, your brain continues to change. It develops slowest as a:
child
teenager
adult
As we go through life, especially during childhood and the teenage years, we generate as many as 100 trillion connections! But unused connections weaken and fade away--a process called "pruning."
Your brain keeps changing as an adult. Everything you think, feel, and do:
changes the shape of your brain
makes your brain bigger
creates or strengthens connections between neurons
With every experience (reading a book, playing baseball), signals race down pathways from neuron to neuron. When you remember or repeat the experience, these signals retrace those pathways and reinforce them. A new experience forms new connections.
Braille is a communication system for blind people. It uses a pattern of raised dots to represent letters and numbers. When studying:
they use the "vision" part of their brain to read words
the areas of the brain that control their fingers expand
both of these
People rely on their sense of touch to read and write Braille. Their brain "reorganizes" itself so the part of their brain normally used for vision takes on the function of touch. They also rely on fine motor skills, so that area of the brain expands.
When stroke patients suffer brain damage, they might lose the ability to speak or move. But abilities that are lost can often come back.
With intensive training, a person can often regain these abilities by forming new connections in healthy parts of the brain.
Definition: the brain's ability to change
Examples of Brain Plasticity: when neurons form in young babies; when new neural connections are made throughout life; when brain reorganizes itself to compensate for injury
Cool Fact: Experienced Braille users can read as fast with their fingers as you're reading these words with your eyes!