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Comment by mindslight | Hacker News Reader

Zenni requires you to do a bit of your own research, like every other new-economy self-service approach. But it's worth it.

Switching to Zenni has allowed me to move to cheap CR-39 lenses rather than expensive high index material. CR-39 is soft, and if I'm paying a lot for frames then the lenses getting scratched is a Big Deal. Then pile on further costs for coatings etc. But if the frames and lenses are both inexpensive, then needing to get a new pair sooner is not really a big deal.

(polycarb is right out due to its horrible chromatic aberration. If you don't know what that is, and you're perfectly content with the clarify of things you're seeing, don't look it up lest you sensitize yourself to it!)

I still need to find a decent sunglass frame on Zenni. Their basic aviators are way too small.

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Chromatic aberration drives me nuts, especially when driving at night or using a computer. LED headlights are particularly irritating; if I don't look through the centre of the lenses, the way they separate into distinct blue and white lights creates a visually chaotic scene.

The last time I got new glasses (from Costco), I specifically requested lenses that would minimise chromatic aberration. But they didn't have anything better than the high index lenses I already had. I have very bad eyes (rx of -8.25 and -8.00), which makes my lenses quite thick.

Are there other lens materials that do a better job of minimising chromatic aberration? I've tried researching this, but wasn't able to find anything.

The measure you're looking for is the Abbe number. Many opticians won't know what you're talking about, but if you push and/or research materials yourself this number is readily available. I remember comparing materials with (IoR-1)/Abbe as my "badness" score, but don't cite me on that.

A while ago I surveyed the materials that were available. The usual 1.6 proprietary materials (Sola/Hoya/Shamir/Signet) have Abbe of 42. The 1.67's are 31 or 32. I did see a reference to a single Zeiss material with an IoR of 1.67 and Abbe of 42, which you would be interested in. I'm sure it's going to be expensive though.

I know exactly what you're talking about. The Microsoft logo drives me nuts, in that I know the colored squares are equally separated from each other, but I don't see them that way. They actually move towards and away from each other as they move around my field of view.

Yeah, this effect really screws with my head sometimes. Sitting at a traffic signal and seeing the coloured light floating off to side is a bit weird too.

What you mention about polycarbonate is interesting. I just got my first pair of glasses (well, the first in about 35 years) and I can't quite put my finger on it but they bother me. Clarity is better, but there's something about the colors of things, especially where things contrast, that is bothersome. I end up taking them off (they are only really for computer use at this point, my vision isn't all that bad yet) just to see normally, if less clear.

Off to do some research...

Also got my first pair of glasses a few week ago when visiting home!

I love them, everything is so clear, it's almost like switching to 4k! But something is off when I read my computer screen. Also they cause eye strain after a while if I am reading.

Several people mentioned having separate pair of glasses. I have started reading about lenses and all that, very interesting. I'm considering getting extra pairs for cheap to test if I can get something better to use with a computer.

I've seen many recommendations about regular glass (non polycarbonate): heavier, but harder to scratch, and with fewer aberrations.

Also, I've been reading about how some lens maker can go with very precise steps in dioptry, also for the angular degrees of astigmatism instead of rounding. Maybe that would help too?

I recently purchased glasses online for the first time, from EyeBuyDirect. I got a pair specifically for computer use, with a weaker prescription, smaller pupil distance, and lower index of refraction to cut down on chromatic aberration. For $45 I'm fairly satisfied, even though I haven't quite got the frames adjusted for a perfect fit yet. The chromatic aberration is still noticeable when I look for it, but definitely smaller than my regular glasses, and I'm hoping that in the long run it will be less distracting with the new pair.

How did you adjust the correction to get focus at say 3 ft / 1 m for computer use?

Why a smaller PD?? I thought it was fixed by your skull anatomy?

I asked for this as a reglaze and they called it a "Snooker lens" even though it was for a regular frame

Almost ungooglable, but I get the concept

I'm not sure I understand.

The spherical correction was weakened by half a dioptre, leaving the cylindrical correction unchanged. So for my bad eye, the computer prescription's SPH is -4.75 instead of -5.25. This roughly agrees with the calculator at http://www.computerglassesrx.com/

The PD for near vision is only slightly smaller than for distance vision: 60mm instead of 63mm for me, less than 5% reduction. I doubt it is all that important since I've been using distance vision glasses to read with for decades, but it is a fact that you have to go a little bit cross-eyed to properly focus on something close to you. I think it might help a bit for looking at very small objects just a few inches away, but ditching the glasses entirely works even better for me when I need to read eg. markings on a 4mm IC.

My first order with Zenni I got probably 5 different frames, using a coupon code, and that helped me figure out what kinds of frames I liked and what didn't work. With that, I was able to dial in on what frames fit me best, and over the years I've mostly settled on one very-uncool but so-comfortable-I-forget-I-wear-glasses frame that goes in and out of stock. I order two every time and have extras at work, in my car, at my parents' house, etc.

Years ago I got some huge aviator sunglasses from them, but they aren't in stock anymore. I just have one of my aforementioned extras in my car with the nerdy clip-on.

Zenni really needs a "very large lenses" section for sunglasses, most of them are just not large enough to block peripheral sunlight. I had one pair that I bought from them and loved, but after getting a new prescription I went to reorder them to find they had been discontinued.

I wear frame #1116325 from Zenni for prescription sunglasses.

My hat size is 7 3/4ths (EU: 62) and my pupillary distance is 72. In other words, I have a pumpkin head. My mother says my head is so big because of my big brains and my wife says it's due to my thick skull.

#1116325 seems to fit just fine and the frame is $29.95. They can handle PDs up to 79, according to the website.

I get fancy-pants prescription lenses though so the total price is around $90.

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