I work in accessibility and see lots of posts like this one — cautioning the reader from every doing X because it creates accessibility problems for me.

It may be possible to follow most/all such advice when building an app or website, but surely it is not possible for presentations (which have to be consumed in the same format by everyone present). Some may hate dark text on a light background; others may find that the only suitable format.[1] So when I read posts like these, I don't view them as imperatives ("never do X") but rather as data points to be factored into decision-making processes.

This is easiest when the post explains the problem and gives various alternatives and explains why they provide a better experience. When they just leave it at "never do X", I'm left wondering whether Y is better than Z or vice-versa. I wish the author had given more context about why this is bad for astigmatism, or what sorts of things are better than others (in terms of ranking alternatives).

1: I hear from people who say that the only decent color scheme for BeeLine Reader (my text accessibility startup) is bright red and bright blue. But other people tell me that color scheme is terrible and shouldn't be the default on my website because it is so bad. You literally cannot please all of the people all of the time! [edited]

Speaking from my own disability I'd say I'd much prefer if people used white on dark text over any use of light background. But this is because my own issue is with photosensitivity which affects a large number of low vision users.

In fact I often create white on black content because it is easy for me to author and read. I also have significant color blindness and am totally unsure which color combinations are hard for others to read, may not show up on a projector, may be a faux pas or may be gaurish.

And this is the profound difficulty of creating accessible content. What is accessible for one is often not accessible for others with a different disability. Simply saying don't do this or don't do that has long ceased to be considered a good method of creating accessible content. This has been abandoned in favor of using a broad suite of tools to validate content meets a wide array of accessibility needs.

Edit: I have never looked into whether such a tool exists for common slide presentation apps.

I really don't get it... I have severe astygmatism (which caused amblyopia in infancy) among other visual defects. My glasses do the best they can but my corrected vision still has a lot of visual defects. My poor vision causes me trouble with a lot of day-to-day things, but white text on black background is not one of them. I experimented without my glasses and I still don't have a preference for black-on-white over white-on-black - they are equal.

Not really a fan of the ranty style without a solution.

On top of that, like another commentor mentioned, people with astygmatism typically wear glasses or contacts?

I didn't think this was a problem as I assumed most people with astigmatism (myself included) wear corrective lenses or glasses.

What’s the alternative? Hopefully not black text on white slides. That’s terrible for me and others.

Perhaps building an app that synchronizes conference slides to a phone and allows users to customize the contrast/appearance of the slides would help in this case?

I'm surprised the author didn't show examples of what would be preferred for comparison.

This describes my own personal experience with dark themes, difficult to read.

I have astigmatism. White on black or black on white both halo. I think both are equally clear.

It would be somewhat surprising otherwise-- the relevant part of vision for this is linear and should work the same in both directions. Though if the room is so dark that my puples will be dilated then that is obviously going to cause a loss of acuity ... but if that is what the author is going for then the advice should be to not present in a pitch black room.

In a dimmer room I have a small preference for white (or green/amber) on black so that the overall brightness isn't blowing out my vision.

Blue focuses noticeably worse, so I have serious trouble reading things like blue on black or black on blue... esp if the blue is some fancy LED sign or something that uses a shorter wavelength.

I think articles like this that don't support their advice with some kind of study of many people ... is pretty low value because it's too likely to just be repeating the author's own personal preferences and disguising them as research supported Truths.

Safer advice would be: Some people have poor vision, make your text extra big and clear even if you could read something less legible.

Maybe this is victim-blaming, but my suggestion to the post’s author is to update her prescription. I have astigmatism. This solution worked for me.

White text on black is my second favorite. Only thing better is green text on black.

The reason is very simple: There's less light coming from the screen into my eye.

Every monitor I've ever owned I reduce the brightness to the lowest setting possible, and they are still too bright.

Green is best because the high resolution parts of your eye only see green. So the blue and red components of white are just unnecessary extra light.

Being unable to stand both white text on black and black text on white, I have found setting the foreground to black and the background to gray60 (in emacs and the terminal) is what allows me to look at a screen for hours without pain.

(Interestingly enough, I too have an astigmatism in one eye, but I don't know if that's the sole cause of my discomfort.)

that's a bit disappointing, seeing as this format is by far my favourite because of it being very simple and aesthetically pleasing.

any suggestions? my intuitive response to this would be black on brightly hued navy blue, but i worry that is also low-contrast, which also causes issues.

can't please everyone!

As a person with astigmatism and very familiar with halation, I always felt like white on black was almost equivalent to black on white. It seemed to just come down to personal preference or mood...

I see the white on black ok for a few moments, but soon my eyes can't see anything (or rather, can't discern shapes and text and such).

The worst are websites with white text on black backgrounds. Arstechnica used to do this, and I was unable to read more than a paragraph or two. Then when I would leave and go back to normal sites, I would have all kinds of weird ghost blocks in my vision (character sized).

Ouch. Don’t read the NZ Herald’s front page today then!

https://www.smh.com.au/sport/rugby-union/mourning-has-broken...

I have significant astigmatism and I prefer light text on a dark background. When I used a Mac, I found the best solution to get everything dark enough was to use a light theme and used Mac’s Accessibility Menu to invert the screen colors. I spend 7-8 hours a day on a dark terminal with light letters.

It's even worse for people with multifocal intraocular lenses implanted after cataract surgery: they see strong glares and halos around light objects on dark background (including text), and unlike astigmatism this cannot be corrected with glasses or contacts

With DLP projectors, white on black also causes way worse rainbow effect for people that are sensitive to that.

On mobile, this site has a “toggle high contrast” widget on the left side that seems to directly contravene the points made in the article.

I have astigmatism and I have no idea what the author's talking about. I stare at white on black terminal text all day without issue (maybe it's different for presentations?). I've also made presentations with white on black text before and had no problem reading the slides.