Having good eyesight is typically associated with 20/20 vision. But the issue is more complicated. Understanding how vision is evaluated -- and how to support your own eye health -- is important whether you need glasses or not.
How Vision Develops
Contrary to what you might think, you are not born with normal vision. In fact, you only see in shades of gray when you first enter the world. You're also not able to focus on objects because the nerves in the eyes and brain involved in vision are not fully developed after birth. Being able to see some colors, such as red, orange and green, occurs during the first week of life. During the first year of your life, your eyes' ability to focus and judge distance improves as you continue to grow and develop.
20/20 Vision
Having 20/20 vision is what is commonly considered as good eyesight. You are able to clearly see certain letters at a distance of 20 feet. The Snellen eye chart is typically used to assess this standard. Although 20/20 is normal, you may have even better vision such as 20/15 or 20/10. If you can't read the chart's letters at the 20-foot distance, your visual acuity, or sharpness, is compromised. If the only letter you can clearly see is the chart's big "E," your vision is 20/200 and is considered poor.
Other Vision Evaluation Methods
Good eyesight goes beyond reading letters on the Snellen eye chart. Optometrists and ophthalmologists assess your vision in other ways to get a thorough understanding of how well you see. Depth perception, peripheral vision and color perception are all important to have evaluated. The visual field test, for example, checks peripheral vision. It helps the eye care professional assess whether you have blind spots in your vision. Although not a vision test, checking your intraocular pressure is essential during eye exams because having high pressure can be a sign of the vision-affecting disease glaucoma.
Supporting Eye Health
Whether an eye exam shows your vision is normal or compromised, protecting your eyes is vital. In addition to getting exams at least every two years, protect your eyes from cigarette smoke and the sun's UV light. Both may increase your risk of developing cataracts, according to optometrist Gary Heiting. Healthy lifestyle changes also benefit the eyes. Regular exercise may reduce age-related eye damage. In addition, eating a diet rich in veggies, fruits and fish like salmon and tuna provide nutrients for eye health. Such nutrients include essential fatty acids, vitamin E, vitamin C, zinc and lutein, according to the American Optometric Association.
References
- KidsHealth.org: Vision Facts and Myths
- AllAboutVision.com; Your Infant's Vision Development; Gary Heiting, OD
- AllAboutVision.com; The Eye Chart and 20/20 Vision; Liz Segre
- AllAboutVision.com; What to Expect During a Comprehensive Eye Exam; Jennifer Palombi, OD & Gary Heiting, OD
- AllAboutVision.com; Eight Ways to Protect Your Eyesight; Gary Heiting, OD
- American Optometric Association; Open Your Eyes to Healthy Eating Habits; February 2009
