Ask HN: Do your eyes bug you even though your prescription is "correct"?

The solution for me to eliminate headaches when working at computer screens was getting an extra set of intermediate distance glasses specifically for computer work. The "computer screen distance" of 3 ft is in between book-reading distance of 1 feet and driving distance 20'+ feet. I also avoid progressive lenses or high-index lenses for computer work. I commented about how arrived at this solution previously: https://news.ycombinator.com/item?id=15375221

Reading glasses work fine when the screen is very close to your face such as a laptop screen. However if it's a separate monitor that's ~30 inches away, reading glasses are slightly blurry which can lead to eyestrain and headaches.

https://www.warbyparker.com/learn/wp-content/uploads/2023/04...

Look into it if you suspect it's a contributor to headaches: https://www.google.com/search?q=computer+glasses+%22intermed...

> I also avoid […] high-index lenses for computer work.

Yes! You're the first to mention this.

It's not refractive index itself that's the problem, it's dispersion (roughly, the degree to which refractive index varies across the visual spectrum, described by ‘Abbe number’). We've all seen pictures of a prism splitting a beam of white light into a rainbow — for visual purposes, the less split the better.

Higher-index materials tend to have poorer dispersion, but especially in the mid-range 1.6ish, there are wide variations in quality at the same index. Glass tends to be best, if your prescription is light enough that you can handle the weight. Polycarbonate and acrylic are awful. MR-8 is in the middle, and what I've settled on for recent computer glasses.

Hear, hear!

Here's a good way to test your glass's refraction index. On your desktop find a small red icon with something white in the center. Stare directly at it. Now turn your head until the icon is at the edge of your vision. If your lenses are cheap polycarbonate, the white part of the icon will appear to move towards the edge of the icon or even out of it.

Most non-cheapo glasses today in the US use Trivex. It's a polymer, not glass, but its Abbe number is 43, which is perfectly adequate.

Crown glass, with its Abbe number of 59, is superior, but the eyeball can discern differences only up to 45-50, so most of Crown glass's improvement over Trivex is imperceptible.

This is partly why it's not offered in glasses (again, in the US, at least according to my optometrist). It is also twice as heavy, shatters (polymers like Trivex don't), and scratches more easily.

Among non-glass options, CR-39 is a good choice for computer glasses with prescriptions weaker than -5:

  - high (58) Abbe number
  - thick (1.5 index)
  - cheapest

Thickness and weight can be mitigated with a smaller frame, e.g. vintage options.

Actually buying CR-39 lens might require solving a dark pattern maze of online or offline options, since the cost is so low.