Over the last month or so, I've really fallen down a rabbit hole on the state of the art in prescription eyeglasses. It's amazing how deep a hole it is. I can't tell how much is marketing and how much represents real improvements in the state of the art, but gee willikers things have changed since I started going to America's Best and ordering my extra eyes for $8 a pop online.

(At some point in there I became a presbyop too, which is why I've finally had to leave the world of super-cheap, single-vision lenses. That said, I still wear single "intermediate" vision lenses now when I'm programming, as I've talked about, before.)

I'm going to dump something like a real weblog here, showing lots of URLs I've visited during my fall down the hole with a little commentary. But it's not going to be a nice, processed dump of info. It's going to be a raw-ish log. You know, unlike the rest of the stuff I post here. :eye-roll:

But let's frame (dang. no pun intended) this dump with a video between an "optician educator" from OpticianWorks (an online training program funded, it appears, by a optical lab called Laramy-K) and a marketer from IOT, a lens manufacturer.

Though they're talking about single vision lenses, it's a great intro to how the state of the art has changed from quarter-diopter blanks to "personalized" free form lenses.

Good freakin heavens, that's complicated. Keep in mind that's all about single-vision lenses, the simplest lenses there are. Even with single vision lenses, with this newfangled freeform stuff they're trying to shape the front and back of your lens in the context of your selected frame (and your pupil distance and height and...) to make sure every angle, not just the one centered precisely on your pupil, has the widest cone of perfect vision.

Here's some stuff grabbed from their marketing video that demonstrates the concept reasonably well, normal curve (old style) lens on left, where light enters in different places and correspondingly hits different parts of your eye, and freeform custom on right (note the red line on the inside that's not a normal/smooth curve; click the image for a larger version):

Though I am somewhat suspicious of how well they deliver -- I think they must be saying that this formula for a lens will, when off-center, always produce a lens experience that's minus diopters from the "perfect" sight point, allowing your eye to fix the difference, rather than having the change from perfect fall into positive diopter differences that your eye can't (apparently?) fix -- I'd buy that there's got to be some benefit from a perfectly customized lens.

So now, in 2020 (so much better a number than 2021 for talking sight, if absolutely nothing else), instead of taking a perfectly normal curve of a lens and finding which matches your eye best, they take a lens that's close to your prescription and essentially CNC mill it to make it best fit your eye and glasses frame, whatever that takes.

Pro tip: Afaict, that's all this free form, digital stuff is: CNC milling that creates non-normal/simple curved lenses.

When you start talking about "digital free-form" progressives, a type of lens that even before CNC style milling was already a long ways away from a normally curved lens, you can see how much space there is for "innovation" -- well, and snake oil sales.

The really flooring part of it for me is, well, I mean, progressive lenses are for one very specific subset of the population: People who wear glasses and are over 40. If you don't wear glasses and you're over 40, you just grab readers from Walmart.

Then the market gets further striated: People who wear glasses and are over 40 who work at a computer, because normal progressives are essentially the same as bifocals: they provide distance vision (driving, talking to others) and close vision (reading), not intermediate (hello, computer monitor). The intermediate vision spot in a standard progressive is about keyhole sized. It's possible to see your monitor, but it's not sustainable for daily work. And so there's a whole sub-industry catering to "occupational progressives" for the office that we'll talk about, below.

It's a large market, I'm sure, but the attention it's getting still seems disproportional. You can bet, I think, an interest in using progressive lenses (much less progressive office lenses) tracks reasonably well to a customer with money. That is, if you're old and worried about your eyesight enough to buy a highly specialized pair of glasses, not to mention that you might also be vain enough to want to avoid bifocals or switching glasses to see your monitor at all costs (bifocals and a pair of single-vision computer glasses really do work great, btw), you must correlate pretty strongly with having a lot of expendable income.

And, of course, IOT, at least, is taking that progressive customization and putting it on a single-vision lens. So their market is potentially much larger -- anybody that wears glasses and is willing to drop major coin for those last few baby steps towards perfect vision.

Anyhow, let the dump proper begin:

More on free form lens machining:

• Here is Zeiss marketing the same sort of process as the IOT video
• Here's IOT's marketing video about the lens style the original video discussed.
• Though see this, again from the Laramy-K guy, in spite of the fact that he seemed reasonably on board with the IOT salesperson:

  • Do know that all current, brand-name, lenses and many new free-form house brands are pretty darn good – to – excellent. If you are being told that a certain lens is somehow above and beyond all others and is worth considerably more money than other lenses, you are being fed worthless sales propaganda. There is no magic pixie dust!

  • That said, note that he also writes both of the below in his consumer's guide to buying glasses:

  • Beware of glasses with switches, wires, knobs, batteries and any “new-technology” that has not been on the market for a few years and had the bugs worked out.

  • ... and then, later...

  • Do try to buy a lens produced in the last year or two. Progressive lenses are still getting improvements, so many new designs are actually easier to wear than those made just a few years ago.

  • ¯\_(ツ)_/¯
    • (Okay, he's obviously saying buy reasonably new lenses with slightly older technologies that have had the bugs worked out, but how the heck do I know what's what without knowing the ins and outs of lens manufacturers' lines?)

Here's a good explanation of free-form and digital lenses. The quick distinction:

All free-form lenses are digital, but not all digital glasses lenses are free form.

Then they explain that digital simply means not a regular curve and free-form means "complex back surface curves" that can be "made to 0.01 diopters of accuracy". That site (RLab) also does custom bifocals, which it's starting to seem like most independent labs do.

And here's a second source on free-form vs. digital:

A standard progressive lens starts as a semi-finished premolded lens with the progressive design already molded on the front surface (hard, soft, short corridor, etc). The manufacturing lab will then generate the Rx on the back surface of the lens without altering the foundation of the progressive design already molded on the lens.

A digitally surfaced progressive, in contrast, uses ware which takes into account pantoscopic tilt, vertex distance, Rx, frame fitting position, and sometimes even eye movement patterns, to create a “customized” progressive design for each particular patient. In theory, this will provide greater peripheral vision and definition. This is why “Freeform” is often used interchangeably with “digital”, to imply that the lens is not confined to the same premold parameters as standard lenses are.

And from that second source, an interesting distinction on your prescription:

Consequently, freeform prescription optimization attempts to provide that same clarity, but when worn in real-life. This optimized Rx is called the “compensated Rx”, which is the prescription you will see when analyzing it in the lensometer, not necessarily the same as that which was prescribed.
...
Most freeform lens manufactures will send you a “Compensated Rx” verification ticket along with the lenses.

Your prescription in diopters is nearly a modernist anachronism.

My guess: I think "digital" must mean "cut by a computer", similar to how CNC literally means "computer numerical control". It's the same meaning here. And free-form means the inside of the lens isn't a normal curve, afaict. It would be hard to cut that precisely on the inside of your lens without a CNC milling device, so all free-form is also digital.

Also interesting from the same source (keep in mind this was written in 2014):

[I]n 10 years the designs available will make today’s options look like the Edsel.

Brands

Which brings us to trying to learn more about brands. Everyone seemingly has their own version of the special progressive snowflake-lenses-just-for-you sauce.

The best overview I've found to date (though with substandard actual reviews) of them all is easily this one from Progressive-Glasses.com. Though it's called "Who Makes the Best Progressive Lenses? The Big Comparison", the best part, far and away, is the list of different brands and lens types he includes, each linking to a more in-depth description of the offerings.

From progressive-glasses.com:

Which Progressive Lenses Did I Compare?

In this test I compared the following progressive lenses side by side:

• Essilor Varilux X
• Hoya Hoyalux ID Myself
• Leica Varioid Volterra Continuum
• Novacel Eden Alpha
• Rodenstock Impression Freesign 3
• Shamir Autograph Intelligence
• Zeiss Individual 2
• Seiko Brilliance

...

Every of the progressive lens designs mentioned above has a feature set that is bound to the manufacturer. I do have those details like the different coatings also listed in the summaries about the manufacturer’s progressive lens line up which you can find here. [Note: these are different pages than the ones linked earlier -mfn]

• Essilor
• Hoya
• Leica
• Novacel
• Rodenstock
• Seiko
• Shamir
• Zeiss

And which does he say is the best? Well, he doesn't.

So in short getting the best progressive lenses are far more dependent on the optician. If he works thoroughly knows his craft and likes to work with people you will get the best progressive lenses possible.

Forget about the manufacturers. As you saw in the comparison PDF above the actual width in regards to the clear field of view is definitely comparable. I can not say there is this one progressive lens design out there that is lightyears ahead of its competition.

…

That is it. This is my take on the best progressive lenses and comparing them was fun. 

That's it. That's pretty much his conclusion. Not, "given that they're pretty much the same, I say get the cheapest," or, "These three offer the best coatings, so if you value scratch-proof lenses" or whatever. Nothing. Just, "Yep, they're lenses. Hope you trust your optician!"

Speaking of, wow, the prices!

Here's a Varilux listing at over $600 but then here's the same lens, afaict, for $350. Over here, they're $300. It's worse than buying a used car. I can't even tell for sure if those are single lens or left-and-right lens prices.

Lens types

Here are a few useful progressive and bifocal movies.

• Progressives
  • One thing you hear over and over from this guy about progressives is the "optical swamp" and "land of optical garbage"
    • These are the dead spaces on the left and right of bottom halves of typical progressives.
  • How the optimum corridor from distance to near vision is selected
  • Office progressives
  • Why progressives have distortion
• All lens types review, single, bifocal ("D" shaped and executive), progressive, even trifocal
  • Placing the bifocal in a frame
  • Distance top, blank ("plano") on bottom aka "making an executive bifocal by hand"

Bifocal lingo from the OpticianWorks prep for ABO study guide:

ST 25, 28, 35, 45 ST stands for Straight Top, and the number indicates the width across the add segment. They will also be called Flat Tops or be marked FT. ST 28s are the current industry standard for bi-focals.

My bifocals from Zenni are 25mm.

Here's a decent description of the difference between hard and soft progressives -- hard gives clearer vision for a wider corridor in the middle but changes to the "optical swamp" (see below) very quickly. Soft gives less stark a switch to craptastic vision, but there's a narrower clear corridor.

And here's a video from another source that shows how bifocals are made. There are lots of videos on this, but this one, from Optometry with Tarik, has the best diagrams I've found to date -- though his description and commentary is possibly less dependable.

Note: I'm pretty sure when he says executives are made as one-pieces he's wrong. Executive bifocals are literally two lenses stuck together.

• Bifocal Lenses Introduction & Types

Related...

• Some of the same images as a slideshow
• Another slideshow

Varilux pamphlet

Occupational lenses

This page has a good run-down (with images!) on the standard "occupational lens" uses. It seems like "occupational" mostly is there to make the distinction, "This is for work only, not for driving."

• Double-closeup (like a D bifocal but with close insets above and below)
• E-D trifocal:
  • Wider intermediate with embedded close lens, large half-distance view on top.
  • I think I've seen that movie directors like this
    • script close,
    • camera intermediate,
    • actors distant.
• A high-segment height bi- or -trifocal
  • Your "close" lens, which normally comes up to just under your natural straight-ahead vision, covers your pupil
  • Sounds potentially great for computers?
• A golf bifocal
  • Apparently embeds a little bifocal in the corner of one lens,
  • It's on the same side as your dominant hand.
  • So it's out of the way for your swing, and there just to help you fill in your score card

But the most popular is the computer progressive. Normal progressives stink for intermediate vision, and there are many sources that will happily tell you progressives aren't for sustained office use, like this page at Zeiss.

Zenni has a good review of the difference between standard progressives and two versions of office progressives.

One point to note: Zenni's progressive image shows close and intermediate zones. Essilor's shows a tiny distance zone too. I'm not sure if that's an actual functional difference or not. (I did order some Zenni intermediate distance workspace progressives to find out.)

This page from Vision Ease, another lens manufacturer, has three different office lens choices striated by peak distances, 6, 12, and 20 feet. Note how width shrinks as distance increases.

Here's Nikon's version.

And here's a retailer with a description of Essilor's specialized progressives, including an "anti-fatigue" progressives that gives just a little ADD at the bottom. I think the IOT video I start this post with talks about that as a "baby-progressive" or "pre-progressive".

I ran into this post on optiboard that runs through a few computer lens brands.

Progressive-glasses.com talks about computer progressives here. He also has a nice worksheet asking what you need to see in your office and how far away each is. This should kinda determine if you can use "close progressives" or "intermediate progressives".

Optical Labs in the US

I've found a few US based custom labs, though it appears you've got to go through a regular glasses shop to buy them, which introduces the middle-man problem. I hate that. I wish you could get some prices directly like you give or take can with Zenni and know what the glasses are really going for. I mean, I'd pay a good shop to size me and fit the frames when they come if I could know what that service cost outside of the frames and lenses.

That complaint out of the way, each lab really does try to sell this as a custom-created lens. They're pitching different frames depending on your head size and eye placement and at least ostensibly are making progressives that maximize that combination of eye, frame, and size.

One, Laramy-K, has this "education" guy who has an entire site and course for people who want to become opticians and pass the American Board of Opticianry (ABO) certification test. Luckily he makes tons of stuff available on YouTube for free, so if you're curious for some free lens larnin', it's a good source -- especially this doc for ABO test prep, though the word find was... unexpected.

RLab in Rochester, NY.

Designs for Vision on Long Island: Mostly dental telescopes for looking at teeth, I think, but also, for instance, highly customizable executive bifocals, mostly for "high ADD" needs on the bottom, but it sounds like they can do most anything... and with perhaps a little more practiced a hand than the outsider artwork by our buddy at OpticianWorks.

Here's what Designs for Vision claims:

Any prescription not exceeding a combined power of +20.00 diopters in any meridian in the bifocal segment can be fabricated (for near powers greater than +20.00 diopter sphere, use the Aspheric Bifocal Microscope).

Any segment height and decentration can be ordered, and the doctor has the capability of prescribing prism segments, or even a different cylinder axis in the top and bifocal segment of the lens.

That's essentially full bifocal customization.

Labels: Other Stuff, presbyopia