To understand how certain problems can affect your child's vision, it’s important to know how normal vision happens. For children with normal vision, the following things happen in this order: 
    
      - 
        
Light enters the eye through the cornea. This is the clear, dome-shaped surface that covers the front of the eye. 
       
      - 
        
From the cornea, the light passes through the pupil. The iris, or the colored part of your eye, controls the amount of light passing through. 
       
      - 
        
From there, it then hits the lens. This is the clear structure inside the eye that focuses light rays onto the retina. 
       
      - 
        
Next, light passes through the vitreous humor. This is the clear, jelly-like substance that fills the center of the eye. It helps to keep the eye round in shape. 
       
      - 
        
Finally, the light reaches the retina. This is the light-sensitive nerve layer that lines the back of the eye. 
       
      - 
        
The optic nerve is then responsible for carrying the signals to the visual cortex of the brain. The visual cortex turns the signals into images.