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Wednesday, 29 June 2016


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How did you get to know your PD MIke?

Oh, my. I hope my offthemalogist (I can't spell it either, but I can pronounce it pretty good) doesn't get wind of this Fuch's Dystrophy business. I already have cataracts, glaucoma and macular degeneration. Anything else and I am going to need a bigger camera.

I've always thought it a bit misleading to say you look 'through the lens' when using a (D)SLR, since you're actually looking at an image projected by the lens onto a screen.

Inquiring minds want to know; how _did_ you wrangle the PD information from you ophthalmologist?

[Don't actually recall now. It was years ago. I don't like not having information. [s] --Mike]

Yeah, I don't know why it's a trade secret to get that PD measurement, but I ran into the same thing as well. I had a pal that had all her measurements, and she was getting glasses for literally nothing (OK, like 20 bucks a pair) from China, and they were so cheap, even the ones that weren't perfect she just threw out (which was about 10%).

I need that measurement, because I also have "fathead syndrome"! When I go to a glasses store for a sale, there are only two frames that fit my head, two-ugly-frames!

There was a time when I would go to an ophthalmologist, because as a photographer, I really wanted to make sure my eyes were being looked after. Those were expensive sessions (well, a couple of hundred dollars at the time, which was a lot), but they'd check for all diseases, and give you your prescription in it's entirety, because they weren't making money selling you glasses. I can't afford it now, but that's the way to go...

I remember a 60 Minutes or some other news show, where they checked cheap mall glasses stores, against high-end opticians and ophthalmologists, and they found zero difference in the delivered product quality, but did warn that the mall places probably weren't going to discover any esoteric eye problems you had.

Living in Hong Kong makes me wonder how people get away with charging what they do for glasses elsewhere. Much, much cheaper here.

Worth doing a bit of research into the Luxottica Group. They control around 70% of the worlds eyeglass market. Think Lens Crafters, Sunglass Hut and many many more. Monopoly anyone?


My sympathies on your Fuch's, and a shout-out to all TOP readers of all ages to wear and use sunglasses. I've got Drusins, which are a precursor to macular degeneration. This may have something to do with my doing theatrical light design for many years. The interrelationship between photo graphy and painting a stage with light? Well, that's an essay I haven't written yet.

So, look, I know that it's a PITA to wear sunglasses outside and have to take them off to look through a viewfinder (esp. a LCD mirrorles finder...) and take the shot. But do it.

Mendocino (for a week or so)

The Walmart optometrist I saw last month was perfectly happy to measure my pupillary distance and provide the figure as part of my prescription, knowing that I intended to order from Zenni in addition to getting updated lenses for my existing frames. He went so far as to remind me that different PD figures apply to distant vision and close-up work like computer use and reading because the eyes converge when the target is closer. He provided both. And yes, I've been getting my glasses at Walmart despite seeing an ophthalmologist twice a year for glaucoma and cataract monitoring. He's an excellent surgeon but not so much when it comes to optometry. The guy at Walmart is an ace. The glasses purchased there cost one-eighth of the same thing from the retail optician associated with the ophthalmologist's group practice. Zenni Optical -- about one-tenth.

Don't be hard on your offamologist (sorted the spelling for you), she has to wait for the specs to arrive to her from China and then change the packaging before sending them on to you.

I managed to see my pupillary distance when I last bought glasses, and made a note of it. I'm less sympathetic of the opticians, at least in England, that tell you that they can not replace the lenses in your perfectly good old frames, nor can they supply lost or worn out screws. I can't see that glasses use more than a few different thread forms and it would not be hard to keep a selection.

I've used this http://www.opticalmailorder.co.uk/system/index.html company before, and they are quite willing to reuse good condition old frames.

I've had good eyesight for most of my life, though I've needed glasses for short sightedness since I was 19. A nasty eye infection, a side effect of septicaemia, caused my retina to detach.

It was persuaded to reattach by the injection of a gas bubble, but didn't quite go back right. There was extreme distortion so that an ordinary house door was almost shaped like an hourglass. The injection of the gas bubble usually causes a cataract, so after a few months I had cataract surgery.

With the new lens in place, nearly all of the distortion is gone. There's little enough that I don't notice it, day to day. They also matched the prescription of the right eye which is my viewfinder eye. They also managed to reduce my astigmatism.

Now here, at last, is the photography bit. I've be able to view stereo pairs without the aid of a device for years; I go cross eyed, and when I can see three images in a row, I just focus on the middle one.

Now, if you look at two identical pictures and do this cross eyed trick, there's an illusion that you are viewing a stereo pair. It's very handy for spot the difference competitions, where the differences shimmer. The effect is reduced for me since my eye troubles.

I got into the habit of doing this with pictures here on TOP, where when you click on a picture it will open in another window. If it's the same size as the picture in the column, I just drag it next to the original and do the cross eyed trick.

I tried it with a picture that was a little bigger than the one in the main column and found that the stereo effect was increased. Anything more than 8 or 10% larger is too big a difference and my brain can't cope with it, but below that, it works well. I've never seen this mentioned anywhere else, so has anyone else found this?

Just guessing that the glasses you ordered through your optician may have come from China as well ...

I think that one of the reasons that brick and mortar retailers are getting slammed is because they have not yet figured out that they have to raise their game. With all the business best practice information avalable (for free) now, there is virtually no excuse for a business not understanding customer needs, and providing products and services that provide maximal value and quality.

I have a friend that used to work for an optician and can get my PD any time I need it. It's usually measured with a ruler fer cryin' out loud. My local Walmart employs an ophthalmologist. Their cheapest frame is under ten bucks, I ordered three pairs with the same frame, regular for driving. bi-focal for everyday, and a pair I call my computer readers corrected for about 4 feet, no eyestrain when on the PC. If the frame is discontinued I can just swap out the lenses with another frame. I broke a frame recently and Walmart swapped my lenses into another set of "my" frames for $10.00 out of warranty.

Sorry to hear about your eye problems. We can just hope that the rate of deterioration is very slow.

I have been short sighted since I was 12 and now need progressive glasses and a second pair for work at the computer. As a hobby photographer this has always been an irritating problem. I tried the Super Focus glasses recommended by Ctein, but it's still a bit of a hassle. On my last visit to my op-person, I asked if contacts could work for me, and explained my problems with the camera. So she set me up with a pair where the right eye (my dominant) that I use to look through he finder is set for distance, and the left eye is set for closer so that I can adjust the controls. She said that my brain would compensate for this after a few days. I was a bit dubious, but I took a month trial. However, I found that I absolutely loved using the contacts right away for everything. So I got the years supply.

This isn't much help to you Mike, but other aging manual focus types like me in your audience may be interested. I wish I had done this long ago.

Hi Mike, I thought you might write about vision and its relation to photography. I have been thinking about it for quite some time and gotten around to the point where I very frequently try to photograph the way I see or don't see things in terms of blur, focus, etc. I often wonder why we demand that our photos look as though we have 20/20 rectangular vision. I think it would be a subject worth exploring.

Agreed, it does seem a little silly that a pair of spectacles cost more than a decent multi element camera lens - so thanks for the PD tip.

If we're talking crud in the eyes, try a slow, 20 year development of floaters.
It does give one a physical appreciation of veiling glare - I always try to ensure light sources are behind me even when not carrying a camera; prescription sunglasses are a necessity rather than a luxury... and I've gotten really good at using the camera to push my spectacles up, rather than taking them off, when looking through the EVF (optical viewfinders are definitely a disadvantage - hooray for mirrorless).

You can measure you own PD with a ruler and a camera (hey, this is a camera blog!).

1. Set your camera on a tripod or get someone else to take the photo. These days a selfie with a cellphone works better than a camera.

2. Stand by a window for light and hold the ruler at the bridge of your nose just above your eyes. Square on to the camera.

3. Look at something distant for far PD (the most useful one). Or look at something at reading distance for your close PD.

4. Take the shot.

5. Bring the image into a photo editor. Clip out the ruler and overlay it on the eyes. Assuming you have symmetric pupils there's no need to estimate the center of the pupil. Measure the distance from left edge of the right iris to left edge of the left iris and the.

You can even measure the 1/2 PD from bridge of nose of each eye. Some people fitting progressives do this to center both lenses properly on (the usual) slightly asymmetric face.

This will be more accurate than a optician doing it "by eye" and about as accurate as the modern automatic PD machines though I suspect they can also deal with vertical offsets of the eyes (more common that you might think).

I've had good success with inexpensive prescription single vision and bifocals. For prescription readers it's a no brainer. The win for the local provider though are progressive/varifocal lenses which need rather better measurement of PD, precision in manufacturing and a good fitting. If you understand how progressive lenses work you can do this yourself but a local expert is very useful.

I've used Indian, Pakistani and Chinese made spectacles but the first one I got back from Pakistan came in a sisal envelope that was crudely sewed shut with a handwritten address on it. The USPS asked me to come down to the post office to pick it up. They were rather curious/suspicious about what it was (early 2000s, post-9/11) and rather amused when I opened it and showed them the spectacles. Neither they nor I had seen a package like that before but I guess the locals were just reusing materials to hand. to make a tough envelope.

Interesting... I had no idea that PD was "guarded" information. I've been going to Costco for eye exams for a number of years now- they've always included that on my prescription, and I've used that info to get prescription sunglasses from elsewhere. Costco doesn't seem to care whether or not you buy glasses/contacts from them, either- they're more than happy to simply do the exam for you and nothing else, if that's what you want.

I stopped going to a "small" optometrist many years ago- their lens/frame prices were completely outrageous compared to what was available elsewhere. I can get 4 or 5 new pairs of glasses, with the fancy anti-reflective coatings and non-scratch coatings and all that jazz, at Costco prices for roughly the same as what my old optometrist used to charge for a single pair. Hearing things like this don't make me regret the change one bit!

I've been wearing weak reading glasses for about four years now, and when my girlfriend told me about Zenni, I immediately wanted to order a spare pair (since I have a tendency to leave them at work when I go home and vice versa). I solved the pupillary distance problem in an approximate but very reasonable way: I grabbed a set of measuring calipers, handed them to my GF (who is a scientist and no slouch at making careful measurements), and asked her to measure. Might not have been the most accurate measurement, but the results were more than sufficient for my weak correction.

The "brain compensation" is the reason that you can get laser surgery to have one eye for distance and the other for close up (reading) and it works. I thought it would give you a headache but a friend who had it done tells me it works fine.

As for how do you know your pupil distance, take a small (metric) ruler and hold it so that it is just below your pupils when you look in the mirror. Put the 0 end under one pupil and read the measurement under the other pupil. Alternatively use a strip of thin cardboard and make a mark under each pupil as you look in the mirror and measure the space.

There are mail-order makers of eyeglasses that do the work in the U.S. Do the usual web research.

As a member of a health plan, I asked for my PD. The plan also operates an eyeglass store, but the doctor included the PD with no fuss on a prescription that I used to order online.

Mike, you live near a very small town.

If any small business owner there reads this blog and learns that you are undercutting local merchants (and barely a year after moving there), it is remotely possible that you might get a cold reception in some shops. Especially the opticians, when you go to pick up your glasses!

Folks upstate are kind and forgiving, but hey, Nathaniel Hawthorne's 'Scarlett Letter' was set in a small Northeastern community, too :)

On the other hand, an eight-fold price differential is hard to subsidize for the sake of neighborliness.

[Did I not mention that I spent $465 at the local optician, despite the fact that I didn't have to? How do you figure I have anything to apologize for in terms of supporting local merchants?

Besides, think of what I did when I came here. I imported a good job to the area, one that pays into the local economy, and yet I didn't take a job away from a local person. They should love someone like me. --Mike]

We have a chain here called SpecSavers who have undercut all the traditional optical shops in the past 15 years. Funny, it always takes two weeks for your glasses to be ready. I strongly suspect that they just send your prescription off to the Chinese factory, then add a big margin to the price when they arrive here.

The same applies to dentistry. I knew a dental technician who used to make caps and crowns, etc. But he said his business had died because the dentists were simply sending the moulds off to Chinese factories, having them made at very cheap prices, but still charging the full Australian price to us.

What to do? I don't know.

Of course you need to apologise - $465 is $465 short of $930.

Very good advice there on PD. I normally "steal" it off the person making my glasses by looking at their order sheet and noting down the values.

I tend to do also as you do -- order two glasses at the same time. If one is notably better than the other, you have a clear reference to complain about. The last time I did this, the person who put in the order put in DIFFERENT PD values for the two glasses.

No wonder I had a headache!

Lesson learnt: You should always check your PD value on the order sheet, even if they don't want to share it with you.


Target Optical is a Target branded Luxottica store. Luxottica rents space from Target.

The Optometrist associated with the Target Optical/Luxottica store is a separate business (usually a single Optometrist) that/who rents space from Target, owns his own equipment and pays for his own phone.

In my experience, after the eye exam the Optometrist hands the client (me) the prescription and I am free to buy glasses anywhere I want.

A couple of random observations on this topic.
My primary care doctor tells me that an interesting aspect of an eye exam is that the eye has the only major blood vessel which can be directly observed in a non-invasive manner.
I get my eyes checked about every year and my eye doc snaps a digital image of my eyes blood vessels and compares them year to year. I don't know what this tells him but it seems to make him happy and I'm kind of codependent so it makes me happy too.
Second, both my 96 year old mother in law and Mrs Plews suffer from age related macular degeneration. Both take Preservision (AREDS) Vitamins daily and this has slowed the progression of their disease to a near standstill. They take this under the care of their respective eye doctors.
My general opinion of over the counter vitamins is that they are a good way to make expensive designer urine but AREDS and D are useful. The D is not for vision but rather calcium uptake and in my case it has helped brighten my mood slightly which is nice.
And finally TOP spends a lot of time discussing all that iPhones can do. Last month I shot this story on an interesting and on topic use for the little devils.


Happy weekend all.

I've been buying Warby Parkers. They have a tool on their website to measure your PD using a webcam. Glasses around $100 and they do a lot of social work with the money they make.

One of the drawbacks with Warby Parker is that their glasses are all 'keyhole' bridge style, i.e. there are no little adjustable supports on the bridge of your nose.
I bought a pair and within a day, the keyhole bridge had worn bloody grooves on either side of my nose.
There isn't any adjustment possible and so I had to return them.

Zenni will provide you with a ruler to measure your own PD which you can do with a mirror or have a friend do the reading. I have ordered glasses from them several times and have been very satisfied. Makes you wonder how they can provide them for $35-75 while the same (nearly) in the US runs $200-300.

[They have a chart on their site showing the supply chain and the number of middlemen involved in each case. Click on "The Hidden Costs You Pay For Glasses" under "Infographics" at the bottom of the website home page. --Mike]

PD disclosure varies by state. In many states the PD must be disclosed by an offamologists on request if it's been measured. But docs aren't generally required to measure it (though if you ask they should be able to) and opticians aren't docs, so may not be required to disclose it. That said, being pushy is a virtue, and I had an optician hand it over because there was obviously going to be a calm but audible lecture about ethics in front of the other customers if he didn't. Now if I could only figure out where I put it...

I was in an apprenticeship opticians course in the late '60s until I learned I was too uncomfortable with people to deal with them properly. There was (then) a close and distance PD measurement. And a segment height for bifocals too. Lab work grinding lenses and so on I liked, but no money in it. So I did something else.

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