Causes of Poor Vision.

Causes for one's poor vision can vary according to the person's age, health condition, prolonged exposure to poor lighting conditions, etc

For more information and details, I would recommend a notable resource in the form of an eBook published by Martin Sussman from Cambridge Institute for Better Vision, titled "10 Keys To Better Vision".

You can purchase the eBook here:

http://www.10keystobettervision.com/

Bert