Hacker News Reader

Comment by Ericson2314 | Hacker News Reader

Nice website. I got a 27" 5K UHD LG monitor at 90 PPD, so I'll never be able to use these things. So sharp I have to wear glasses not contacts.

View on HN

That's my kind of monitor. :) It's not wasted either. Foveal cone angular density is actually around 12,000 cones/deg^2, or 110 PPD, so anything up to that is achievable with perfectly corrected vision. That's a lot higher than the 60 PPD typically claimed for retina PPD, which is at an imperfect 20/20. 110 PPD is more than 3x the PPD of the AVP...

Good to hear! I wonder how many people kinda need glasses and don't get them, making the popular opinion of what the retina is capable of much too low.

Has anyone done studies showing how much people notice the difference between 60 and 110 PPD photos for example? There are many people who have a hard time articulating 30 vs 60 PPD as it is with computer monitors. How much of a diminishing return is it to go beyond 60 PPD?

I don't know about studies, but I'm pretty sure there is a large difference between very high contrast edges (worst case: text rendered without anti-aliasing) and photos or even videos, where there usually aren't any high-contrast high-frequency edges (black pixel next to white pixel). Since anti-aliasing is standard in font rendering and pretty common in computer games, I don't think very high PPD content would often be noticable.

On the monitor I mentioned, this text is about 15-20 pixels tall mostly-white on mostly-black, and I can read it from ~4 feet away.

(website says that is ~186 PPD)

That makes sense. Given that the smallest legible fonts are around 5 pixels tall, that's 3-4x less PPD than your monitor offers at 4 feet, so you'd need ~46-62 PPD eyesight to be able to read the text. 20/20 at 60 would be more than sufficient.

This study popped up: https://www.techhive.com/article/578376/8k-vs-4k-tvs-most-co...

In summary, with an 88" screen at a distance of 5 feet, some viewers rated 8K content (118 PPD) higher on average than equivalent 4K content (59 PPD), particularly those with better than 20/20 vision (~60 PPD). Most would not notice. It wasn't directly tested but I'd guess most people do notice the difference between 30 and 60 PPD, but only those with above average eyesight will see improvements beyond that.

Nice find. TV image quality is usually so imprecise (compression, lack of text), I would suspected computer displays to be more noticeable.

I use a 27" 5K display as well, only with contacts. I'm short sighted at -6.75 in each eye. Why would I be unable to wear contacts when using it? If anything its an improved experience as my lenses significantly shrink whatever i'm looking at which the contacts do significantly less.

At -6.75, the impact of the shrinkage caused by eyeglasses would very likely exceed any slight visual imperfections caused by contacts (glare, halos, instability, rotation misalignment for astigmatism, etc.) I'm at -4 and prefer contacts for computer use, but it's right on the point of almost indifference for me.

-2.5 (IIRC, I'm long overdue for a new prescription) for me

Maybe I had bad contacts, but I found that my vision was just worse with them. Couldn't really explain it or describe it. It wasn't like the fuzziness of near-sitedness.

At -2.5, you probably don't get much shrinkage or aberration with your glasses, so they work better for you. For me, at -4 plus strong astigmatism, wearing glasses makes everything look tiny, and circles look like ovals... contacts are a better experience. That said I have tried over a dozen types of contacts over the years and it took me many many attempts to find both a product and a set of lens parameters that worked well enough for my eyes to want to switch from specs. Now I found that, I don't even own spectacles any more.

What brand/models of contacts ended up working well with your astigmatism? I find that one of my eyes has issues with the contact losing alignment too frequently, and so I’m always looking for other options. Thanks!

I've been wearing lenses since the 90s. These days I wear 1-Day Acuvue Moist for Astigmatism for the most part, released in 2006, and they continue to be my overall favorite.

I keep trying newer lens technologies as they come out, but mostly it's been a bust. However I do also like Precision1 for Astigmatism water gradient lenses, which came out in 2021. They are thicker and more stable overall, with slightly higher vision quality, but prone to drying up if I don't blink.

Occasionally for a change I'll wear Acuvue Oasys 1-Day for Astigmatism, which came out in 2017.

All three work well for me but the Acuvue Moist are the ones I tend to reach for the most often. It depends a lot on the individual and the fit, I think.

I do have some astigmatism so I'll keep this in mind.

I hate that at -6.75 that my glasses shrink things so much that a 27" monitor almost looks more like a 24" monitor and so on. I'd wear contacts more but I can't wear them often or for long due to dry eye issues caused by something else.

Reply on news.ycombinator.com