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Comment by crdrost | Hacker News Reader

I'm not sure you're right. At night both I and my wife have reported difficulty reading glowing blue signs compared to glowing red/green signs at the same font size, brightness, and distance.

I'm also not sure that the author is correct; the wrong-focal-distance explanation seems rather weak simply because our focal length is adjustable.

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You have astigmatism. I have a similar issue with blue when not wearing my glasses. I have 20/20 vision, but my astigmatism makes it difficult to focus on certain things. A computer being a big one. Blue light blockers help, but with proper astigmatism correction I don’t need them.

20/10 vision in one eye, 20/13 in another, no astigmatism.

Blue LEDs in clocks when viewed at night look completely fucked up.

I’ve never met anyone without some astigmatism; especially, people with other vision impairment. Astigmatism is the number one cause of night blindness which is what you described.

I don't think it's night blindness. I have the same problem, with and without glasses (I have astigmatism).

HN is so funny. 'I have no astigmatism.' -- 'Sure you do!'

Because nearly every person has some amount of astigmatism.

Sure, but presumably the parent has been checked by their eye doctor and indeed, not everyone has it.

Signed, a dude with very slight astigmatism :)

There were three people involved in that exchange, not two, assuming nobody's using multiple aliases...

crdrost described their vision problems, jbluepolarbear said "you have astigmatism", techrat popped in and said "[I have] no astigmatism" and jbluepolarbear made a more general statement that most people do.

I'd assume techrat doesn't know anything about crdrost's vision either.

It's right up there with 'I've been clinically diagnosed with ADHD by a qualified psychiatrist and this medication has improved my life tremendously' -- 'There's no such thing, the medication doesn't do anything and you just need to mediate more, have you tried mindfulness?'

You're precious. Why don't you tell me what else my eye doctor has never diagnosed me with?

9 in 10 people have some affliction of astigmatism. Astigmatism is just that your eye isn’t perfectly spherical. What does your eye prescription say in the cyl and axis fields, that’s your astigmatism correction.

'eye prescription'?

Bruh. Read the comment of mine you replied to. 20/10 and 20/13 vision. I don't need prescriptions.

That's like saying you can run a 3 minute mile so you don't have a shoe size.

This whole thread is silly.

Shoe size is an inherent byproduct of having feet of a certain dimension. A prescription has to be prescribed.

If we're doing dumb analogies, it's like you're trying to insist a homeless man must have an address.

...Actually, that's a real problem in the financial services sector. You can't satisfy KYC requirements without an address of record.

Off topic, but I'm jumping around a bit tonight.

i'm imagining a homeless man receiving his begging money via a bitcoin QR code on his phone.. i hope he has a bitcoin atm nearby.

Aren't those numbers about your ability to focus on distance objects, though?

I could totally believe the someone might have "perfect" vision that doesn't require correction, but still have a slight astigmatism that impacts their vision under certain specific scenarios such as when viewing blue LEDs in low light.

I'm not necessarily saying that's what you have, but more just that to the extent your eyes have been evaluated, it was likely "yeah they look great as far as your ability to perceive the brightly lit eye chart, no need to do the more detailed analysis where we figure out the other parameters that will never be used because you're fine, bye."

I think more than one person has confused you with the person a couple levels up thread, i.e. https://news.ycombinator.com/item?id=27859324

20/10 and 20/13 means much better than average good vision. It would be bad if they were e.g. 20/30. Funny that you're LARPing an eye doctor without knowing this.

You can still have 20/10 vision with Astigmatism. I guess my years of research into astigmatism because of my own affliction and years of optics study visual effects means I’m larping. Never said I was a doctor, I’m just intimately familiar with how corneal distortion.

> About one in three people has some degree of astigmatism.

https://my.clevelandclinic.org/health/diseases/8576-astigmat...

> about 9 in 10 people have some degree of Astigmatism

https://patient.info/eye-care/astigmatism

I wonder why there's such a big degree in difference between the two claims.

The 30-60% is most likely for those affected by their astigmatism. Astigmatism is when the eye isn’t a perfect sphere. Many people have very slight astigmatism and don’t require correction.

pro tip: don't tell other people about their own experiences unless they ask you, and you're a professional.

Pro tip: nope

> In Europe and Asia, astigmatism affects between 30 and 60% of adults.

https://en.wikipedia.org/wiki/Astigmatism

I can’t actually verify that number presented in that paper. I’ve looked and that stat is attributed to that paper, but there’s no evidence that the paper said that. Plus the paper is pay walled so unverified.

Considering the obvious inability for anyone to reliably know the astigmatism status of everyone they meet, not only is your anecdata unverifiable it's completely absurd.

Astigmatism is easy to self-detect, and it's quite different from the light focusing to the wrong plane. Astigmatism will noticeably warp the entire shape of the distant point object, rather than just make it "fuzzy" in an isotropic manner.

Source? Astigmatism can blur and distort.

https://patient.info/eye-care/astigmatism

for me, it's mainly the difference in looking up and down compared to looking left and right.

You're not alone. I normally have excellent night vision but seeing things in glowing blue, such as the clock on the coffee maker or the microwave, causes the digits to split like double vision and become blurry while everything else remains the same.

I have the exact same thing. It always makes me wonder why companies choose to have blue neon lights on their buildings because it's nearly impossible to read them when it's a thin font.

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