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Optical engineer here. This is what they don't tell you about continuous/transition/progressive bifocals: optically they don't work. The lens design is an overconstrained optimization problem and the solutions they come up with end up compromising a lot on everything, to the point that it is practically useless.

Aren't the bifocals just a convenience over quality? It's inconvenient to wear two sets of glasses, but why would one wear bifocals while driving? This convenience can come at a high price!

Bifocals in general are quite useful. It's nice to be able to see the road and the speedometer using the same lenses.

Traditional bifocals and progressives are different beasts. The hard outline on traditional bifocals means you get essentially two different lenses, both able to function as intended. The soft blend on progressives means you get essentially one big blurry lens that does not have well defined properties anywhere.

> The soft blend on progressives means you get essentially one big blurry lens that does not have well defined properties anywhere.

That seems to be exactly my experience with them, stated very succinctly. I've had these about 9 months and I'm still struggling with the ergonomics daily. I think I made the wrong choice.

I used the wrong term, sorry. My concern applies to both bifocals and progressive lenses, though: aren't drivers trading off convenience over safety? Shouldn't we have at least two pairs of glasses - one for driving, and another for everything else?

When driving, I need to see things far away (mostly) but also on my dash/instrument cluster.

I am near-sighted overall and have needed distance glasses all my driving life. I got progressives last year and driving is safer now as I have a small area that I can use to clearly (and quickly!) read the instruments, the radio (read: map), defroster controls, etc.

In my case, not having multi-focal lenses was prioritizing convenience/laziness/cost over safety.

No worries, I understood your intent!

The impact is a lot less than you may expect. Brains are ridiculously good at filling in incomplete information. For example, did you know that you have a roughly sun-sized blind spot slightly off center in each eye (where the optic nerve attaches)?

Now imagine needing to switch glasses to read your dash. Inconvenient and unsafe!

> This is what they don't tell you about continuous/transition/progressive bifocals: optically they don't work.

I'll defer to your judgement re optical properties, but I want to offer a counter-anecdote about practicality.

I've had myopia and have been wearing negative diopter glasses for over half my life. I've never needed vision correction for reading. This is not an unusual combination, and if you want a celebrity example, watch some old Apple keynote videos with the late Steve Jobs, who would repeatedly lift his glasses to read something on the phone in his hand. This "works", but can be inconvenient in some situations.

A while ago, I started thinking about progressive bifocals. Cursory web searches told me that my particular combo was impractical. My optician didn't see a problem, so I decided to trust him and got a pair made. The TLDR is that they work for me much better than the old ones. There was a period of adaptation. Going downstairs and looking at the floor/ground were a bit disorienting for a while, but i don't notice it any more. Switching between the monitor and the phone or paper in front of me works, which is why I wanted the bifocals in the first place. I only use the old glasses for watching TV, probably meaning that my TV-watching posture sucks, but fortunately I don't watch a lot of TV. I still take off the glasses for sustained book reading.

What's your lay of the land when it comes to different glass qualities and glass thickness options? Stores here (nordics) have around 4 different glass qualities for progressives, with varying and opaque names like "better" and "supreme". Thickness starts with 1.6 but store people push for 1.67 or 1.74. I get strong upselling vibes, but hard to say. (Is the "supreme plus" noticeably better than "supreme" or merely there for upsell anchoring effect, to make people pick "supreme" without feeling they overspent?) Are there high quality information resources for consumers on what the underlying lens material and processing technologies are?

Search HN for "ABBE". The very cheapest material has the highest optical quality. Thinner ones are for weight, which matters if you have strong prescriptions. Weight can also be countered with a smaller frame height/width, which might require a vintage or designer frame, but that's a one time cost that can used with cheaper and higher optical quality lens replacements.

I got my first set of progressive lenses in safety glasses earlier this year as a way to try them out. Based on that experience, I switched my daily glasses to progressives in May and love them.

Once or twice a day, I notice a visual artifact that I perceive to be in my left peripheral vision, and of course I sometimes need to move my head slightly to see something, but being able to see clearly at all distances with relative ease is the exact opposite of “practically useless” IMO.

>to the point that it is practically useless.

And yet I know many people who use them and love them. So?

The human brain mostly adapts. Big Optical makes $$$$ billions. A small percentage of human brains have persistent dizziness and depth perception errors, which can lead to physical injury and reduced quality of life. We don't have yet have a test funded by disablity insurance, which can determine which brains might fail to adapt.

The good news is that multiple glasses have never been cheaper or more accessible, so progressives are entirely a choice.

>The human brain mostly adapts. A small percentage of human brains have persistent dizziness and depth perception errors, which can lead to physical injury and reduced quality of life

That's a fine argument, which I accept. Not the same as "practically useless", which was the original argument.

But for actual use, especially screens and reading, the tradeoff can be pretty bad

Search for "Chemistrie" magnetic lens attachment in +0.5 increments. They can even stack for different focal lengths, e.g. reading vs computer screen at 36". Magnets embed in primary glasses. Expensive via local opticians, they will retrofit via mail order and buychemistrie dot com.

Oh so much.

Progressives here. The very bottom irritates me to no end during the day. If I drive in the morning or walk around I feel absolutely horrible. Like I'm drunk.

Sure, if I need to read something really really close on my phone in the evening, when the eyes have gone tired it's kinda OK. I do need to focus on the bottom of the glasses.

But I still (after months) usually just look straight ahead (sometimes that "mid section" is not right for what I'm looking at) or I need to intentionally look down, in order to actually look through the top of my glasses.

I think the progressives are worse than getting two pairs, but I can't tell for sure yet, since this is the first time for me and I believed the optometrist who recommended progressives (from own experience, being a little older than myself).

I will have to try the other way soon I guess.

Like right now, evening, I can't read this screen on the bottom of the glasses. The laptop is too far away. To look through the top, I have to look down. Like "double chin territory".

At normal cell phone distance, I can't use the bottom part. It's sorta blurry. I need to try and find the middle. Which is the smallest sections (I don't have huge glasses. Maybe an inch top to bottom, which all the progression has to fit into.

I'm trying progressive lenses again after throwing them in the trash a few years ago. The distortion is the worst part for me. Moving my head around makes the world warped as it moves between zones. Maybe I'd get used to it if I forced myself to wear them all the time but I spend most of my day WFH and wearing a weak version of my distance prescription that lets me focus on my monitor yet see reasonably well around the house without too much eyestrain.

Knew a friend who was a doctor. Said your brain is very malleable and adaptive.

If you wear them for a week, you will probably adapt and stop noticing the progressives, even walking around and going up/down stairs.

I've had progressives for years. They suck, universally.

I've had mine about 9 months and I definitely still notice the distortion. I'm glad to see my opinion validated here. My doctor talked the progressives up, and maybe a lot of people do like them, but I'm definitely ready to try the traditional split lens.

Yeah they told me the same.

But it doesn't work that way. I've had them for months now and I still notice them. While walking, while looking around. While driving.

Is it much better? Yes.

Stop noticing? Heck no.

I'm still giving it some time but I really don't like the sudden weird feeling I still get from time to time. And I can't even figure out why it's fine much of the time and then suddenly I get that weird feeling again.

And just having to double chin it to see the ground in front of you is so annoying.

Progressives maximize legal compliance for automobile driving, with bonus impact on optical industry profits.

Multiple lenses for different focal lengths are now affordable and practical and offer higher optical quality and more comfort.

I've been wearing progressives for around 30 years. The only time I haven't had a good experience was once when my optometrist at the time retired and I foolishly tried a few of the chain optical stores. It's hard to say whether it was the doctor doing the exam or the person measuring me for glasses, but I ended up returning several pairs of glasses until I found another independent optometrist with enough experience and trained staff members to make a proper set of glasses. Since then, I've had to switch doctors several more times when they sell their practice but have gotten better about picking new ones.

I use computer glasses when staring at a screen for any length of time and I end up taking my glasses off to read e-books, one of the few benefits of being as nearsighted as I am. For everything else, the progressives work well for me. The first few pairs took close to a week for me to get used to wearing. Since then, I occasionally notice minor distortion with a new prescription but that usually goes away in a day or two.

> I got my first bifocals last year. I got the "no line" variety and, so far, I hate them.

They are called progressives (or multi-focal – depending on whom you speak with).

Progressives come in a few «ranges»: near-range, mid-range and all-purpose. There are also «premium» options available, although I am not entirely sure how much different they actually are.

I have found that having two separate pairs of progressives (near-range for reading, laptop use and all-purpose for everything else) works the best. All of them can also be had as the transition variety and with different tint colours, thus obviating the need for a separate pair of shades.

In fact, when I first tried the near-range progressives some 5 years ago, it was an eye-opener in the almost literal sense of the word – the laptop screen flattened and became bigger despite obviously not changing its physical size. It was something that I had struggled with for a long time before the progressives entered mainstream. At high prescription numbers, the lenses for myopia start distorting the true shape of objects which creates mild to substantial visual discomfort, and near-range progressives fix that.

Another source of discomfort might be the suboptimal «Add» number on the script for progressives. This can be fixed by going to an optometrist clinic rather that a street optometrist (or find a reputable and good one first). If the «Add» is too small, the progressives will make little difference compared to conventional lenses, and, if it is too big, they will make it difficult to see in the distance.

Based on own subjective experience, I can't recommend the progressives enough, although a little bit of fine-tuning might be required (none in my case).

Like you but it began at 51 y/o. No glasses 'till 52 y/o.

We had good runs mate!

Same: presbyopia and I hate low-light now: it's just as you wrote: better acuity in bright settings. Either during day time or with proper lighting.

Still can read signs from the car (say while on the highway) before anyone else so there's that.

Can't really share any experience as I don't have a good understanding of glasses/focals.

> Like you but it began at 51 y/o. No glasses 'till 52 y/o.

40s but it's been a slow grow. I got by on magnifiers until 50 or so.

I'm still on my original script. My indy eyeglasses guy got taken out by a hurricane and he was the last one. I can't bring myself to visit s vision mill.

I had good luck with the eye-q device, but I am unsure if it is still made or supported. If you dont have a complex scrip, it works fine. My lenses got scratched so I just ran out of luck, dont think there's much to be done with glasses for me anytime soon.

It gives you a prescription after running it 3-6 times for each eye. It is tiring but much cheaper end-to-end than going to an OD or whatever. And just get glasses online! Dont get extorted at the "vision mills"!

I'm in my mid 40s and I'm now switching between three different pairs of glasses for different distances. Bifocals and progressive lenses wouldn't help given the things I need to focus on are usually directly in front of me. Changes have been happening rapidly.

I had a congenital cataract removed, and the intraocular implant can’t adjust focus like a normal lens. So I have a similar problem. Progressives suck. Bifocals also suck. Finding an optometrist who was willing to listen, experiment, and adjust three different prescriptions (distance, computer, reading), and then carrying around three pair of glasses also sucks, but it sucks the least. Accepting that this is just a thing that is part of me and that I can’t fully optimize away has made it suck less!

And I have a central floater, too! Also sucks. Sorry you’re in the same boat! Helpful optometrist tells me that vitrectomy is the only real solution and the juice isn’t worth the squeeze. Another thing to accept and move on from.

I’ve had the same issues. Bifocals are definitely better, though I now have progressives for general around town or driving purposes because I was talked into them by the saleswoman. “Oh, they’re so much better now than they used to be”. Maybe, but they’re still not great. For reading, computer and other generally fixed focal length purposes I have different, single prescription glasses.

Right in there now. On the plus side, I'm near sighted, so I don't need two sets of glasses, I can just take my glasses off.

Usually only happens when I'm tired. Bifocals are probably in my future though.

If I want to do circuit repairs, I have to do it in the morning though. Detail work is too hard on my eyes otherwise.

after COVID i experienced macular degeneration—first in the left eye, later in the right. unfortunately, I was in a rural area of India at the time, and there was no good ophthalmologist available. So the macular degeneration was diagnosed as cataracts; which were also there, but in a nascent stage and not yet the cause of vision problems. So I got a cataract procedure done on the left eye, and it basically changed nothing.

Later I moved to Sri Lanka, where there are good eye hospitals in the local area. There I got a proper diagnosis and was discouraged from a second cataract procedure. I am controlling the macular degeneration by high doses of ocular vitamins. As far as glasses, I also found progressive lenses pretty useless, so I have two pairs: one for distance and one for computer work.

FDA approved red light therapy. About USD $100 for device.

> I got my first bifocals last year. I got the "no line" variety and, so far, I hate them.

Same. I tried bifocals and they annoyed me to no end. Now it's muscle memory to move my glasses between my pocket and my face. I don't even notice I'm doing it.

The camera analogy is a really good one

look into occupational glasses