RE: Acuity for 400% zoom

My understanding is that acuity as measured with uncorrected myopia is different from corrected myopic at the same acuity.   Myopia scatters the light creating blurry vision because the image is not focused.  Decreased acuity that is corrected isn’t blurry for most--- it’s more of a lack of detail – like looking at text far in the distance perhaps for others.    Certainly different visual conditions may cause vision to be seem cloudy such as cataracts and some people might see things blurred such as those that cannot wear correction for certain reasons.  I also wear contacts with high myopia and experience both uncorrected and correct states with decreased acuity so I am personally familiar with both.

There are many other factors such as the screen resolution, monitor, platform dpi, etc. distance from monitor, etc. that play a part of this.  In my experience many people with low vision prefer to hold things more closely thus increasing their effective acuity.

Jonathan

From: Glenda Sims <glenda.sims@deque.com>
Sent: Tuesday, May 29, 2018 7:50 PM
To: Wayne Dick <wayneedick@gmail.com>
Cc: Shawn Henry <shawn@w3.org>; public-low-vision-a11y-tf <public-low-vision-a11y-tf@w3.org>
Subject: Re: Acuity for 400% zoom

Hey Shawn,

My left eye (uncorrected) is 20/550.  So I just tried an experiment.  I opened word.  copied the text of your email, pasted it into word.  set font to Arial, size to 12 point.  Then I increased magnification (in Word) to 400%.

I can't read that text (on my laptop) at a normal viewing distance of 22" (the laptop screen is 22" inches from my eyeballs...yes, I did just measure with a tape measure).

As I bring the laptop closer to my face...I can read this same text...when the laptop is 15" from my eyes.

So...I wonder if someone on this list has something in the vicinity of 20/400 or 20/300 and can conduct a similar experiment.

G

glenda sims<mailto:glenda.sims@deque.com>, cpacc<http://www.accessibilityassociation.org/certification>   | team a11y lead | 512.963.3773

        deque systems<http://www.deque.com>  accessibility for good

On Mon, May 28, 2018 at 7:56 PM, Wayne Dick <wayneedick@gmail.com<mailto:wayneedick@gmail.com>> wrote:
Dear Shawn,
We all read differently. You bring up a good research point.
I am right eyed. My right eye is so much better than the left that I barely know how to read with my left. Also, only parts of my macula can actually see well enough to read. So, I bounce my head as I read and only pick up a few in a visual capture.

My visual acuity is 20/80. So 400% is nice. I do move my head a few times to read a line. I compensate with a little narrower reading line (increased margins) and scroll vertically a little more. Overall, I do a lot less thinking about scrolling and more thinking about the content.

Wayne

On Mon, May 28, 2018 at 1:20 PM Shawn Henry <shawn@w3.org<mailto:shawn@w3.org>> wrote:
Hi LVTF folks,

Generally at what acuity -- 20/??? -- would a person be able to read well at 400% zoom, but not under 400% zoom?
(I know "It depends." on a whole bunch of factors! I'm wanting a reasonable number *generally*.)

Currently I have 20/500. I'd like more perspectives.

Context: The persona quote here:
<https://w3c.github.io/wai-intro-wcag/standards-guidelines/wcag/new-in-21/#1410-reflow-aa>
says:
[[
Problem: "It's nearly impossible to read text if I have to scroll right and left to read each line. It's disorienting and I lose my place. It makes it hard to understand what I'm reading."
Works well: "I increase the text size 400% and it reflowed within the width of the window. I can read it easily without scrolling back and forth."
]]

It's attributed to: "Parent with low vision – 20/500"

Thanks for input.

Best,
~Shawn