Visit an eye care practitioner regularly.

These are trained professionals who specialize in looking after the health of your eyes. They can be ophthalmologists (eye doctors) or optometrists. To keep your eyes in good health, have your eyes checked regularly or when you are having problems with your vision. Learn more about your eyes and ask your eye doctor questions when you have them. Learning more about your eyes and how to prevent eye diseases will help you to feel more in control of your health.

• If you don't have any vision problems, you should visit an eye care practitioner every 5-10 years during your 20s and 30s.
• If you don't have any vision problems, you should visit an eye care practitioner every 2-4 years between the ages of 40 and 65.
• If you don't have any vision problems, you should visit an eye care practitioner every 1-2 years after the age of 65.

Source : http://www.wikihow.com/Take-Care-of-Your-Eyes#Eating_for_Good_Eye_Health_sub