When we check your vision, we are measuring your visual acuity. We are testing how sharp or clear your vision is. 20/20 is a standard of good and normal vision. When we denote in 20/20 form, we are speaking in measurements of feet. When measuring in meters, the notation becomes 6/6. Many countries actually use the 6/6 notation! This notation is known as the Snellen fraction. There are other many ways to report visual acuity!
Let's split this ratio into two parts: the first "20" refers to how far you (the test subject) is standing away from an eye chart. The second number in the ratio refers to where someone with healthy, normal vision stands away from the eye chart - in comparison to you. If your visual acuity is 20/40, it means that you are standing 20 feet away from the eye chart, and someone with normal vision can stand at 40 feet and still see what you are seeing. Therefore, 20/40 is worse vision than 20/20. In contrast, if your visual acuity is 20/15, that means that while you can see the eye chart at 20 feet, someone with normal vision has to walk up to 15 feet, to see the same target that you are seeing. Thus, 20/15 is better vision than 20/20.
If your eyes and your visual pathways are free from any disease or pathology, you should be able to obtain 20/20 vision. You can have 20/20, but that does not mean that your eyes are perfectly healthy! There are many eye diseases that exist, that may not affect the vision early in the disease process. Cataracts, retinal diseases, hereditary eye diseases, glaucoma, and so on, can exist in someone with 20/20 vision!
See your eye doc annually to ensure that your vision and your eyes are the best that they can be!
Cheers!
My video is at DLive
Great quality post Dr Cynthia!
Thanks for your support @jennyy!
Informative post! How do I schedule an appointment?! =P
Haha! Let me know when you happen to be in town! LOL
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