Answer :
20/50 vision is a term used in vision testing that describes visual acuity. Visual acuity refers to the sharpness of vision, and it's typically measured by one's ability to discern letters or numbers at a given distance according to a fixed standard.
In the United States, the Snellen chart is often used to measure this ability. A vision of 20/50 means that what a person with normal vision can see at 50 feet, a person with this vision can only see at 20 feet.
When referring to minutes of arc, we are dealing with a concept in optics called 'angular resolution.' Angular resolution is the smallest angle of detail your eyes can distinguish. It's often measured in arc minutes, where 1 degree is 60 minutes of arc (arcmin).
The normal visual acuity, which is 20/20 vision, corresponds to resolving detail that subtends an angle of 1 arcminute. For 20/50 vision, the minimum angle of resolution (MAR) is calculated based on the ratio given in the vision score. It is calculated as follows:
[tex]\text{MAR} = \frac{50}{20} = 2.5 \text{ arcminutes}[/tex]
Therefore, 20/50 vision corresponds to approximately 2.5 minutes of arc. This means that a person with 20/50 vision requires about 2.5 times the normal angle to resolve details compared to someone with 20/20 vision.
