There are several ways to protect your children's eyes:
1. When your child is reading, make sure the room has good, even lighting and discourage them from lying on the floor and reading.
2. When using a computer, make sure the room has even room lighting and that your child takes a break every few minutes and looks around the room. When playing computer games, sit as far back as the leads allows.
3. When watching television, make sure your child has a small light on in the room - the room shouldn't be totally dark - and position the TV set at eye level, or just slightly below.
4. Ensure your child is eating well. Nutrients such as Vitamin A help support visual function, Omega 3 help support brain and eye development and Lutein, an antioxidant, help support developing eyes.
Source: http://www.kidspot.com.au/familyhealth/Injuries-&-Safety-Safety-How-to-protect-your-childs-eyes+2810+219+article.htm