The phrase comes from the American system that denotes what an average person can see on an eye chart when they are standing 20 feet away. Outside the US, vision is measured in metres and the standard is expressed as 6/6 (Doesn�t have as nice of a ring).
However, 20/20 vision does not necessarily mean you have perfect vision.
According to the American Optometric Association �20/20 indicates the sharpness or clarity of vision only for distance. Other visual skills such as close vision, depth perception, eye movements, colour vision and focusing ability all play into your overall visual ability�
On top of this, early eye diseases usually have no symptoms. These include diseases such as cataracts, glaucoma and macula degeneration. This can lead people to neglect their eyes until they become symptomatic, sometimes being too late
Take Home Message
A comprehensive check up of your vision should be performed even if you believe you have perfect vision. We recommend: every 2 years for patient�s under 65 and every year over 65. The optometrist will let you know if they would like to see you more regularly.