1) Poor visual efficiency: This is how your child’s brain interprets information. Visual efficiency does not mean the clarity of our vision, but how our eyes interpret things and move left and right and up and down. It includes how they come together as a team to see one clear image, a concept known as convergence. For balance, convergence is very important.
2) Low core strength: If your child tires easily, fatigues easily and doesn’t like to engage in physical activities, than that might indicate why she has poor balance. Decreased muscle strength can even affect something as simple as her ability to balance and sit in a chair.
3) Poor midline development: The “midline” represents the two sides of the brain and two sides of the body. It runs exactly down the center of the body and children have to be able to operate around that middle. So if your child’s brain doesn’t know where the middle of her body is, it’s really hard for her to coordinate movement around it.
To read more please follow : http://actg.org/blog/five-reasons-your-child-may-have-poor-balance