What Exactly Is 20/20 Vision?

1. 67

   PhoenixVposted 12 years ago

   What Exactly Is 20/20 Vision?
   
   What Exactly Is 20/20 Vision? How is vision measured exactly? How can some people have 20/10 vision?

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2. 70

   Bretsukiposted 12 years ago

   20/20 vision is a measure of average visual acuity. the first number describes the equivalent distance that you can see letters or objects on a standard eye chart. the second number describes the equivalent distance as measured by an average number of viewers. Normal vision 20/20 can are letters oor objects projected at the equivallent distance of 20 feet. So you record 20.20 for each eye if both have the same visual acquity.
   
   Someone who sees 20/10 can see a letter at a size of the equvalent of 20 feet distance but would need to vbe ten feet away to see it. They are therefore short sighted in that eye.
   
   Anyone with a visual acquity of 20/250 over a large proportion of their vision in either eye is defined as legally blind.
   
   Medical blindness is lack of the ability to detect light in either or both eyes/.

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3. 70

   Dr Pran Ranganposted 12 years ago

   20/20 vision is an expression of normal visual clarity. if a person has 20/20 vision, it means that he can see an object clearly at 20 feet, which should normally be seen at that distance. If a person has 20/100 vision, it means that he must be close to 20 feet to see an object which a person with normal vision can see at 100 feet.
   
   20/20 vision doesn't mean perfect vision. It only represents visual acuity. if a person can see well at a distance but is unable to see a nearer object, the condition is called hypermetropia (farsightedness). If a person can see a nearer object clearly but is unable to see an object at a distance, the condition is called myopia (nearsightedness).
   
   A visual acuity corrected to 20/40 is normally acceptable. But a vision corrected to 20/200 or worse is considered legally blind in some countries.
   
   The metric equivalent of 20/20 vision is 6/6 vision as 20 feet is equal to 6 meters. Metric measurement is followed in some countries including India.
   
   20 feet or 6 meters is considered infinity from an optical perspective.

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