- 20/20 vision is a measurement of visual acuity. 20/20 visual acuity means that a person can see small detail from 20 feet away the same as a person with normal eyesight would see from 20 feet.
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What is 20/20 vision? The term "20/20" and similar fractions (such as 20/40, 20/60, etc.) are visual acuity measurements. They also are called Snellen fractions, named after Herman Snellen, the Dutch ophthalmologist who developed this measurement system in 1862.
20/20 vision meaning: 1. the ability to see perfectly, without needing to wear glasses or contact lenses: 2. the ability…. Learn more.
Visual acuity is a number that indicates the sharpness or clarity of vision. A visual acuity measurement of 20/70 means that a person with 20/70 vision who is 20 feet from an eye chart sees what a person with unimpaired (or 20/20) vision can see from 70 feet away.
20/20 vision isn't actually "defined" as what the average person sees at 20 feet, its just a nice way to describe it (since its more or less true). 20/20 has a precise mathematical definition, so if everyone in the world suddenly got 20/40 vision, we would just say 20/40 is average human eyesight.
Feb 01, 2017 · In other words, the 20-20-20 rule works. While many doctors suggest the 20-20-20 rule is a best line of defense, researchers explain that any break from repetitive computer work or screens is...
- Ashley Marcin
Jun 13, 2014 · Abstract With the promulgation of the 20/20: A Vision for the Future of Counseling consensus definition of counseling, there is finally profession‐wide clarity as to what it means to engage in professional counseling.
- David M. Kaplan, Vilia M. Tarvydas, Samuel T. Gladding
Normal" visual acuity (in central, i.e. foveal vision) is frequently considered to be what was defined by Herman Snellen as the ability to recognize an optotype when it subtended 5 minutes of arc, that is Snellen's chart 6/6-metre, 20/20 feet, 1.00 decimal or 0.0 logMAR.
- A Word from Verywell
To be considered legally blind, you would have to meet one of two criteria for visual acuity (sharpness of vision) and visual field (the entire scope of what you can see without moving your eyes).
An eye doctor will measure visual acuity and visual field to determine if a person is legally blind. A common test for visual acuity is the Snellen eye chart. Someone who is legally blind would be able to read only the top line of the chart, a capital E while wearing corrective lenses. The line below the big E is the line for 20/100. There are also tests that can measure in between 20/200 and 20/100. Someone who cannot view the line for 20/100 but sees somewhere between 20/100 and 20/200 would still meet the government's standard of legal blindness, which is why it is listed as "20/200 or less."8 Visual field testing often begins with a confrontational visual field test in which you an eye doctor has you cover one eye at a time and then holds up one or more fingers in different quadrants of the visual field to see if you can see them while keeping your eyes focused on a central point in front of you. There are also more comprehensive computerized tests that use flashing, flickering...
There are many conditions that can cause legal blindness, but the most common ones are age-related eye disease. Age-related eye diseases that are the leading causes of low vision and blindness are:6 1. Age-related macular degeneration 2. Cataracts(cloudiness of the clear lens of the eye) 3. Diabetic retinopathy 4. Glaucoma Eye trauma or injuries and genetic conditions, such as Usher syndrome, can also lead to legal blindness.
Treatments for legal blindness vary depending on the cause and the stage of the disease. For age-related eye diseases, it typically involves prescription medications or eye procedures to try to delay or keep the vision from worsening. For example, the goal of treatment for glaucoma is to reduce eye pressure. This can be achieved with prescription eye drops or oral medications, laser procedures, and, in severe cases, surgeries to try to prevent further damage. Careful monitoring of glaucoma and other age-related eye diseases is important for determining if treatment is working or needs to be adjusted. Cataracts are the exception in that vision can be restored with surgery to remove the clouded lens and, in most cases, replace it with an implant.
Low vision or legal blindness can be limiting to be sure, but there are many resources and assistive devices to help you live your life with the utmost independence. Depending on the cause of your vision loss, you may be able to benefit from eye exercises and strategies for participating in everyday activities. You also may find using a cane, talking calculator, special computer software, and other products designed to support people who are legally blind to be helpful.10
- related to: What is the definition of 20 - 20 Vision?