What does 20/20 mean

The term 20/20 is used to describe someone with perfect vision, but what do the numbers mean?

Everything optically is measured at a twenty foot distance(20 feet is considered optical infinity). However, exam rooms typically are not 20 feet long, but with the use of mirrors and certain types of charts, the same effect as a 20 foot distance in achieved.

20/20 means that what someone with perfect vision sees at 20 feet is the same as what you would see. 20/40 vision means that an object a person with perfect vision sees at 40 feet, you would have to walk up to 20 feet away to see the same object. The same is said for 20/50, 20/100, etc.

Most people have the potential to see 20/20 either unaided or with the help of glasses or contacts. However, some conditions are not correctable even with help. Macular degeneration, cataracts, retinitis pigmentosis, and many other conditions may cause a loss of vision that may lead to non 20/20 vision.

Legal blindness describes a condition that a person cannot achieve 20/200 vision or better in their best eye, even with glasses. Also, someone whose visual field is smaller than 20 degrees- this is applicable to conditions that impair your peripheral vision, such as glaucoma.

To make certain you are seeing as clearly as possible, schedule a yearly eye exam.