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OP
Black Hole

Black Hole

May contain traces of nut
Pheeeew. Great news about your sight. For my twenty twenty vision sd channels feel like looking through the glass darkly sic.
Where do I queue? I hope they come in a choice of uniform!
Perhaps better not then, you know what they say about making you go blind!

mihaid got me wondering exactly what counts as "twenty twenty vision", so the results of googling:

https://www.allaboutvision.com/eye-exam/2020-vision.htm said:
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.

In the Snellen visual acuity system, the top number of the Snellen fraction is the viewing distance between the patient and the eye chart. In the United States, this distance typically is 20 feet; in other countries, it is 6 meters.

At this testing distance, the size of the letters on one of the smaller lines near the bottom of the eye chart has been standardized to correspond to "normal" visual acuity — this is the "20/20" line. If you can identify the letters on this line but none smaller, you have normal (20/20) visual acuity.

The increasingly larger letter sizes on the lines on the Snellen chart above the 20/20 line correspond to worse visual acuity measurements (20/40, 20/60, etc.); the lines with smaller letters below the 20/20 line on the chart correspond to visual acuity measurements that are even better than 20/20 vision (e.g., 20/15, 20/12, 20/10).

The single big "E" at the top of most Snellen eye charts corresponds to 20/200 visual acuity. If this is the smallest letter size you can discern with your best corrective lenses in front of your eyes, you are legally blind.

On most Snellen charts, the smallest letters correspond to 20/10 visual acuity. If you have 20/10 visual acuity, your eyesight is twice as sharp as that of a person with normal (20/20) vision.

So, actually, 20/20 isn't all that great. I know I can read the bottom line at the opticians (with my glasses), in fact I don't even bother with the larger lines and go straight for that... it's only when they start mucking about with the optical gantry I have trouble! I can read a car number plate easily at 50m, and just about make it out at 75m.
 

EEPhil

Number 28
:roflmao: I knew the Kiwis had a problem with pronunciation (you try and find the "f" in Whangarei - Yes, OK, find the "f" in Loughborough) but, unless the dust is from someone's scab, I think they cocked up the spelling as well.
 
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