Choosing The Ideal Progressive Lens Corridor Length
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- čas přidán 28. 06. 2024
- In Choosing The Ideal Progressive Lens Corridor Length, we'll cover how corridor length is related to minimum fitting height (MFH) and why choosing the proper length is more important than you might think in getting the best results and reducing non-adapts.
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This video was produced by Laramy-K Optical
Laramy-K Optical is a digital uncut and coating lab unlike any other. The only exclusively uncut lab in the country; we provide our customers with independent, high-end alternatives to corporate brands. Through craftsmanship, technology, and independent, innovative vendors like Younger, IOT, A&R, and Quantum Innovations we offer our customers the Integrity portfolio of freeform lenses and coatings. Made in the USA, the Integrity brand is not a generic house-brand, but is the absolute best available, designed to give the wearer that “wow!” experience.
In addition to the digital line, we still offer conventional surfacing, including glass. Maintaining traditional equipment gives our customers vastly more flexibility in their dispensing, particularly when it comes to more difficult prescriptions.
Learn More: www.laramyk.com
I’ve been an optician for 20 years. I’m Advanced certified and published over 50 articles on the subject. I’m constantly looking for new information. I’ve always been frustrated by much of the training and educational materials available for ECPs. Much of it tends to be overly simplistic or it just parrots already available information with no real explanation as to how it can be applied in actual practice. But these videos and other related educational materials Laramy-K provides are fantastic!!
They’re original, useful and actually contribute to helping ECPs develop a practical knowledge base and skill set!
I’ve been recommending them as a supplement to our companies training program (which is abysmal). I’ve always found it eerie, in a good way, that I can find a video detailing a topic that I was just discussing with a coworker! It’s something they can watch to add clarification to what I was trying to explain.
Keep up the phenomenal work! You are definitely filling in those knowledge gaps out there that most ECPs education is missing!
So sorry I just caught this two months late. Thanks for the kind words and encouragement. If you have ay ideas for a video topic just let me know! I'm always looking. We can co-create if you like. John
Wow! What you described 11 minutes into the video about 1.25->2.50 and not being able see without horrible distortion is exactly what happened to me. I'm returning the glasses and researching the topic more in your videos. Thanks for a great resource !!!
I can't begin to express my thanks for this channel. I have learnt so much from watching your videos and really appreciate you taking the time to share such knowledge.
I was in your frame adjustment course at Expo yesterday! You are awesome. Thanks for explaining things simply enough to completely understand!
You are welcome and thanks for coming to the workshop. John
As an optometrist with years of experience. Watch this video. I recommend it to all my friends. It took decades to learn was Laremy shows you in a few minutes.
I've been watching your videos for a while now and I think you are fantastic. Thank you so much.
You are welcome.
Must say, I absolutely love this channel. I'm learning so much about this field, and I've been in the game since 2012 - mind you, I'm just a simple lab tech from southern Alberta Canada, but I want to learn as much as I possibly can about this field, and your channel is a massive help; so I thank you for that!
Thanks! John a simple optician from South Carolina, US. The Laramy-K OpticianWorks motto is Keep On Learning!
Gord Birch III we are professional chinese lenses manufacturer. Our lab equipped with Top producing machines from Germany satis loh, Schneider, France SCL.
We already got many clients from all over the world. Ups,fedx to the world only costs 2-4days.
Expecting cooperation.
www.select-optical.com
I like u a lot. Your teaching method is clear. I am an Optometrist in Nigeria, and learning a great deal.
Excellent! Without being an Optician but because of my medical profession, I can understand, the explanation was an eyeopener for me! No Optician in the last 20 urs that I am using progressive has dealt with me in a way that he was factoring all that told here while designing glasses for me!
Thanks, I will now be a demanding and also understanding cutomer!
Hello Mr John, I'm an optometrist in Nigerian and I just started seeing your video and they have been very educative and helpful. Thank you for doing this.
God bless you.
Not an OPT just an eyeglass user. I really learned a lot from this guy's videos! Very informative and easy to comprehend. Thanks LKO!
And that guy says, "You are welcome." John
I recently started teaching a training course Optometric Tech Assistant and your video's are so helpful in remembering why I do what I do (Optician for 25+ yrs) I'm sharing some of your info with my students. Thank you, thank you, thank you.
You are welcome, welcome, welcome... John
Still doing a wonderful job, thanks for the wealth of information.
Thanks John, its wonderful content and fun learning with you
Where were you when I was an optician 12 years ago! =)
wow. this is best corridor length explantion on the web. Thank you!
This is extremely useful knowledge for consumers as well. Many thanks
I also absolutely love this channel. I am an optican from Vietnam. Big Thanks for your helpful sharing ! Wish you have a good health , dear Sir !🥰🥰🥰
AMAZING VIDEO. I’m not an optician. I’m a glasses wearer and was prescribed progressives. First pair did not have my distance in my line of sight. I was told it takes a while to get used to it. I gave them 3 weeks + headaches but still didn’t work. Went back to ask them to draw a line where the distance was. It was too high. I’ve reverted to distance only and during COVID ‘work from home’ discovered my 5 year-old distance glasses (-.5 difference) are perfect for my laptop distance. I love my optometrist and optician so I don’t want to go elsewhere (unless I can go to you) but am going to watch ALL your videos and take notes so I can ask the right questions when they’re measuring me and helping me choose frames because I need good progressives. It has been such a frustrating experience. 🎃head 🤣😂🤣
Sounds like you are actually quite good at troubleshooting for your own needs! Glad the videos are helping you build your skill set even further. John
AWESOME JOB DOC. THANKS, GOD BLESS.
Thank you! Very informative
Great information! currently a student optician so this helps me alot!
vhi i .
superb information Sir ......Love and respect from INDIA
Merhaba. Optisyenim. Türkiye'de yaşıyorum ve her videonuzu takip ediyorum. Ne mutlu ki otomatik çeviri diye bir şey var. İlk defa yorum yapıyorum. Video için teşekkürler! Çok yararlı ve açıklayıcı.
Hoşgeldiniz. Onları yararlı bulduğuna çok sevindim. John
@@LaramyKOptical Hoşbulduk :) Gerçekten çok yararlı. Abartmıyorum. Bunları ücretsiz bir şekilde insanlarla paylaşmak mükemmel bir şey. Tekrardan teşekkür ederim. Ben de Türkiye'de sizinki gibi bir video serisi paylaşmak istiyorum. Bunu Türkiye'de yapan yok. Ne yazık ki Türkiye bu konuda geride. Optisyenlik kanunumuz bile 2004 yılında çıkartıldı.
Thanks I'm going for my state license.. this helps alot
Just took my state practical last month. These videos helped me too! John
Excellent information
Thanks for this
I watched this twice in a row!
Thank you for your time, it helped me a lot to maintain the minimum height and improve my adaptations, greetings from Argentina, we are eyeglass artisans and we manufacture custom glasses, thanks for your videos
You're very welcome!
Always enjoy your videos! I can always learn something :)
Hi there!
I work with Nikon lab and the only two corridors are 12 or 14.
How should I "pick" the right one.
Should I "play" with a seg drop to make it work?
Shareena Wilkins Gord Birch III we are professional chinese lenses manufacturer. Our lab equipped with Top producing machines from Germany satis loh, Schneider, France SCL.
We already got many clients from all over the world. Ups,fedx to the world only costs 2-4days.
Expecting cooperation.
www.select-optical.com
Very informative video and I will use what I've learned to help my eyeglass center help me select the correct progressives for my glasses so that I'll be 100% happy with a comfortable MFH. My first pair were perfect, but my second pair were a complete miss. I don't wear them. Expensive desk ornament. Now, I'll take them back, along with my updated prescription to see if they can now change the lens with a comfortable MFH.
Thanks so much for your channel and informative videos! Liked! Subbed! Bookmarked! Will return for more!
I just found your channel and am so glad I did! I got my first set of progressives in my mid 40s. I'm now 69. I hated progressives for office/computer work from the get-go, so I added single-vision computer glasses for my work day and home computer use, along with bifocals for reading books and for digital reading on tablets.
Because you explained how distortion increases as "add" power increases in your previous two videos on basic progressives and office progressives, I now understand the reason for my increasing disappointment with progressives as I have aged. But now, after watching this video on lens corridor length, I have a much better feel for what to consider when selecting frames for the new progressives I'm about to purchase to maximize my chances of getting lenses I can live with. I may also consider office progressives in lieu of a single vision computer lens to see if that will enable me to go from three pairs of glasses (regular progressives, single-vision computer, and bifocals) to just two pair (regular progressives and office progressives.)
Whether or not changing to two pairs of progressives works for me, the things I've learned from just the three videos I've watched so far will help me be a much better informed consumer as I start shopping for new glasses.
Thank you!
Me - I'd stick to what works. SV for different distances and lined bifocals are excellent choices and you'll even end up with a few $100 left over to buy something nice. John
@@LaramyKOptical Thank you John for the quick feedback.
Thank you so much!
Thank you very much
Good stuff !
Thanks for this informative video. What is the difference between progressives for plus and minus patients? I believe the design is different for each, is that right? Thanks.
Thank you sir
Hello Mr. Laramy ( I know your name is not Laramy ) I liked your explanation about the right fitting segment high...thank you...
Laramy K with all respect but this channel is so educative and you are really an inspiration for me on this field . I'm studying right now for Optometry and i have been watching your videos because they have helped me a lot on diffrent cases to be understood and clarified . As i said you are an inspiration for me and i have just started a CZcams Channel regarding Eye Care field . I'm on my way to make progress in my New Channel and also to learn more from you . 👍🏻
He is really awesome regarding explanation .
Progressive lenses are really a key case on optic . Especially these days that it have so many diffrent kind of lenses and technologies .
Keep on going on your new youtube channel , and Laramy is really a good inspiration ...
👏👏👏👏👏
Thanks! I know the videos are very popular with optometry students. Funny though that they rarely, if ever admit it, but their instructors do! More to come. John
Thank you for posting. Trying to educate myself after some failures due to opticians and myself. I learned a lot on this video. So, you're telling me a Seiko Superior is something to stay away from?????? I now totally understand the fitting height and the lesson on the frame design. I'm wearing a pair right now, small frame and I understand why this frame work so well. It's an original Armani..... they were not stupid......I should've bought 10 of these frames.
Sorry, I don't know anything about the Seiko Superior designs. If it is fit correctly and the optician chooses the right fitting height (18) and the frame allows for that it should be fine. John
Thank you for the wonderful content. All of your videos have been really helpful. I have a few questions.
1. Is "short" or "perfect" corridor better for previous bifocal user wanting to convert to progressive?
2. "Regular" corridor lenses have lesser distortion and thus wider intermediate zone, so why are "perfect" corridor lenses better? Can you please provide some insights?
3. Which corridor is best for heavy desktop or laptop user?
Awesome videos! I have a question, is the MFH number in millimetres, or centimetres or just an arbitrary one? thanks. I am going in later today to pick up 2 new sets of high priced progressive glass's Oakley tin cups and a pair of Ray ban sunglass's and want to find out about the mfh when I do. Thanks in advance.
All eyeglass related measurements are in millimeters.
amazing explanation. thanks Guru
I think there’s deference between fitting highlights and segment highlight ( corridors )for example the fitting hight 32 and he need progressive for read mobile ( most now using for reading mobile) between 14 to 16 . so the fitting hight depends on frame and segment hights depend on using .
Not really sure what you are saying but --- I think that would fall under lens design. This was answering a question about daily wear progressive lens corridors. It was not about an office design. John
awesome!! this is so helpful and so apt. Thanks for giving realistic "optical situation" examples, its funny but yeah it happens!
Nice video Sir! I am optometrist from India,love to see your videos.
Sir does Blank Size(Small or large) of Progressive Lens Affect corridor length.
No. The blank will always be large enough to allow for cut out and keep the full corridor length. That does NOT mean that you can't cut away near power if you choose the wrong frame and MFH.
Thanks! John, great video as always, great job. I am a bit confuse, when you say 18 you mean the MFH right, and in the 13:05 when you say you went to IOT, frame MFH is 18 will be a 14mm of corridor or progression lens is the best combination, but when you got a MFH of 20mm or 22mm for example , do you recommend we stay on 14mm of corridor?
I think, yes. The MFH of 18 and a lens built around 18 will provide the best "spread" of power through the corridor. Any less and you are cramming 10 pounds of poop into a 5 pound bag. Any more and you can fit the lens designed for 18 at any height from 18 - 50.
Hey all. John here. Let me say it one more time. This recommendation comes from someone who actually designs progressive lenses. It does not come from a lens rep, or an ad, or from some talking head at a conference. I literally asked someone who designs progressive lenses what corridor length works best for optics and adaptation. His answer was 18. Who should you listen to?
It's very nice
Great lesson. Love it. Question: I warned my glasses for 2 days. Well adapted but look in the mirror without my glasses and saw my left eye crooked to outside. I suspected the position of in glasses is wrong. I respect your kowleage. What would be the reason for my eye brocked. Thanks in advance and thanks for your teaching.
If you feel that you have adapted well to the glasses I wouldn't worry much. If you have worn glasses in the past and these feel the same I wouldn't worry about it. Eye movement and eye position are nothing that opticians deal with. That would be a doctor of optometry or ophthalmology.
This stuff is good to know even if you are not an optician- and just want to know about the glasses you are wearing! I love having this knowledge when getting my glasses.
Viewing the videos without a valid opticians license is in violation of federal law and subject to fines up to $5000 and a maximum sentence of 3 years imprisonment. Oh, no, wait, that is something else - I forget what. Anyway THANKS FOR WATCHING ;-) John
@@LaramyKOptical lol, you had me there for a second!!
Then I am thinking, well...just take the plunge and become an optician (should have done THAT 40 years ago!!) That's what you have done to me - made me WANT to go back to school!!!
But the the $5000 fine is soooooo much cheaper than school. What's a girl to do? 🤣🙃😉
Great video. I understood *some* of it. I am just a customer who wears progressives, and I routinely have trouble getting progressives that I can read in, which brought me here. The last place I got them (2 years ago) had to try 3 times to get it right, and they had to call the lab to figure it out. They were told by the lab to "narrow the corridor", and that seemed to work. For me, the issue seems to be that with the current trend of huge frames, the reading portion is so low in the lens that in order to see through it, I have to literally lift the glasses up with one hand so the reading portion is higher. After two years I'm getting glasses from a new place, and they are now remaking them. I wonder what they need to do to get this right? Is this a case where they should be using a lower number than 18 (I have no idea what number they are using BTW)
If you have to lift the glasses up to use the reading area (and that works) then the lens is simply fit too low. If you have "decent" distance vision and when you lift them you can find a sweet spot for reading then the lens is just plain fit wrong. After that you might benefit from a SLIGHTLY shorter corridor lens like a 17 or 16. Avoid those "huge" frames and shoot for the middle not too big not too small. If your add is still quite weak (say a 1.25) a 0.25 bump up might be some help but that is getting into dangerous territory. With all that --- sounds like a lot of remakes so it may be a combination of fit issues and maybe a progressive just isn't a great lens for you. You may actually want to find a place that uses one of the electronic measuring devices (and they seem experienced with using it) and go with a higher end lens design. It doesn't have to be the top-tier all the bells and whistles but a decent free-form with default POW. John
do you have a video that goes into detail about the miminum fitting ht and how much corridor length will result from this? e.g minimum ht 18 results in 14 corridor length?
James, I kind of think that is exactly what that video (Choosing The Ideal Progressive Corridor Length) is all about? I'm not sure I know what you are asking. John
How about a video on specialty progressive lenses... like the difference between a distance vs. driving. What makes sport lens special? Thanks.
I think driving is only optimize for distance.... Less near zone, more far zone
Ok, yes I can add that to the list. There is enough there to do a lesson. More to it than just favoring a certain distance. John
Dear larmy K,
It is an amazing channel for opticians. Keep up the good work.
I have few questiona for john
1) If a patient need progressive for driving, cant we redice the progression length from 14 to any no less in order to give more distance portion?
2) for an office user, cant we increase the fitting height of progressive lens with the increase of addition to 0.50. for example if a person has +1.75 add, can we increase the addition to +2.25 (with the increase of fitting height+ selecting a bit bigger frame).
Regards
No & No Shortening the corridor does not in any way provide for greater distance area. In fact by shortening the corridor you are more likely to create less usable area across the entire lens. If you want a driving progressive choose a design that favors distance. By bumping up a fit height you are just forcing the eye into the top of the narrow corridor and providing less working area not more. If you need an office lens then you need and want an office lens. Watch the other videos we have on progressives. Keep in mind that as you move the lens the corridor moves with it!
Hi John. Love your videos, as always. 2 questions:
1) Are freeform progressives better than the old conventional designs?
2) What’s the difference between a cheap (entry level) and an expensive (top of the range) progressive lens ?
Each of our major labs offers us a dozen different brands in progressives. It gets so confusing to choose a go to lens design. Cost Pricing and size of patients wallet dictates my eventual choice.
Iqbal,
1) A properly designed and properly manufactured free-form lens will always be far superior to a conventional design. Easier to wear, wider vision areas, sharper optics, happier customers.
2) Sorry - but that is like asking what is the difference between a cheap car and an expensive one. Quality, add-ons, status, looks, engineering, pedigree, power, technology --- all sorts of things, some real, some more or less preference.
Sadly, there is no magic go-to lens and certainly not a magic low cost go-to free form lens that you can sell all day and make every customer happy. I'd suggest you look away from those major labs and check out Laramy-K we do everything we can to keep it simple and transparent and we certainly don't have a dozen different anythings. www.laramyk.com John
I'd like you to talk about pantoscopic angle and how to adjust the frame please .
We do cover that on the OpticianWorks website. We are just starting to shoot some dispensing videos but it may be a year before we get to adjustments for the individual wearer. John
Laramy-K Optical thanks
I just purchased my first set of progressive lenses and have been wearing them for about 4 days. I have been near sighted since I was about 14. I am now 48 and have had trouble with small print for a few years now. I decided it was time for progressive lenses. The lenses I have are terrible for peripheral distant vision. When driving and trying to glance in the side mirror it is very blurry, especially to the left which makes sense since my left eye is worse than my right. I have watched your all your videos on progressive lenses trying to get a better understanding on how they work. I am thinking of having my optometrist remake my lenses, but was wondering how to get the most benefit from them.
4 days is not quite long enough to get used to progressives. What you are describing is more adaptation than a problem with the lens. I'd give it about 2 weeks, yeah I know a long time, before giving up or trying something new. The acid test: when looking out straight ahead with your head level and neck relaxed are things clear in the distance? Yes? Lens is probably OK. When looking down while holding an ordinary book with ordinary print can you read? Yes? Lens is probably OK. Distortion to the sides = normal. John
I'm just a customer, not a an eye care specialist, but I found this video very informative. I just took back a new pair of glasses because when I look down to read, only one eye is in focus. I have to turn my head to get the other eye in focus which puts the original eye back out of focus. Thanks to your video, I understand how my eyes move between and through the distant, progressive, and near focal sections.
I suspect they installed the lenses in the frame incorrectly. When comparing a line between each micro circle of each lens, the lines are not parallel with one another. I understand one eye may be higher than the other so the two lines may not be level, but I expect them to be parallel if they were continued to the other lens. Both lenses tilt in towards the nose. This seems to explain why I have to turn my head to find the near focal point for my other eye.
Trying to explain this to the optician was excruciating and she never understood my problem. I explained that my eyes do not spread out (opposite of converge) when I look down so I cannot look through the reading portion of both lenses simultaneously, but she simply sat there with a baffled look on her face.
She sent them back to the lab for a redo but I suspect they will come back the same way as the redo order doesn't explain the problem. I'm wondering if the lab tech didn't take into account the shape of the frame, somewhat like horned-rimmed glasses, and they are placing the lenses parallel with the frame top and not considering the relationship to the other lens.
Do you have any suggestions on how I can describe this problem to them in terms they would understand?
When you say micro-circle I'm assuming you figured out that the progressives have a set of "invisible" laser etchings. Yes, absolutely 100% positively yes those marks should be level or straight across each eyewire opening in the frame or run at a perfect 0-180. If they are tilted (rotated) at all the glasses were made wrong, period. Now - a progressive can be fit with different heights for the R/L eye. So if the marks are perfectly level but one set is a little higher/lower than the other that is not necessarily a bad thing. But - that would be indicated on the work order, super easy to check. Height = 18/19 or 16/19 or something like that - but - you would probably be able to see that your one eye is a little lower than the other? Let me know. John
@@LaramyKOptical just like I suspected. Thanks so much.
I was lucky to go to a good optometrist for my First pair of progressive. He recommended the frame and explained to me why they had to be of a certain size and shape.
Wish you had said optician but nice to hear you had good advice. ;-) John
@@LaramyKOptical oh yes optician LoL actually what's the difference?
@@SailingUJUD Optometrist is the doctor who does the medical exam, optician is the person that handles the frames and lenses. I'm an optician and the videos are for opticians and consumers.
@LaramyKOptical thank you for the videos. Am here to educate myself about progressive lenses so that I know what to get for my spare pair. Kodak, Hoya and Zeis are the choices available here in Malaysia, the lens I use now is Kodak and the optician I saw is far away from where I live now.
For the lifestyle of a sailor, always outdoors ... What do you recommend I ask the optician about?
Am thinking Kodak
Corridor length 18
Must have UV
Must have that tint for sunlight
Needs to last me next 5 years or more if possible
Sorry I don't know technical terms ... Still very new at this.
@@SailingUJUD If you are wearing Kodak and like them it is usually best to stick with what works. This is one time where a photochromic lens might be an excellent idea - outside changing light conditions. All lenses except old CR-39 offer UV protection. (Both Hoya and Zeiss also make some excellent lenses)
Hi, I just question regarding minimum fitting height, does the measurement start from the fitting cross just right at the bottom of the distance to half of the ADD or to the full circle of ADD?
I kind of have problem understand this cause most of the PAL fitting chart showed that minimum fitting height is measured from the fitting cross to the half of the circle of ADD.
MFH is not an exact concept. Lens makers will fudge any numbers they can to make a lens more appealing to marketing. You know enough to make the call on your own - or the answer is in your question. Think about actually wearing a progressive. Think about why you need that add or reading area. Would you like to have that complete circle to work with or half that circle to work with? IMO I'd always try to go with providing that full reading area or at least 2/3 over 1/2 of it. John
Hi John, great video. What about some companies, for example, Zeiss? They have a minimum fitting height and also recommended fitting height. So their corridor length of 14mm has an MFH of 18mm, but a recommended fitting height of 20mm. Are you essentially saying the "recommended" fitting height in this video? On their layout charts, the MFH will be in approx middle of the Add circle.
Everything I can possibly convey is already in the video. I think you are confusing both some of the terms and concepts too. John
@@LaramyKOptical Thanks, all good, rewatched it a few more times with fewer distractions to take it all in properly. 👍
Any chance there will be a Part 2 for variable corridors?
Variable corridors???? Tell me more. I'm not sure the variability in corridor shape, length etc. warrants an entire lesson? Or are you talking about the comment below on overall variable lens design for different tasks? John
I’m interested too! I’ve seen fixed and variable. Would love to know more! Great seeing your course at Expo yesterday
I picked my frames out and when they made my lenses they used same same style and size but not the same frames i tried on the clinic. My frames are large enough for the progressive i did understand this. I just can see c9mfortable in my lens. But its the first day too.
Look4Good this video only touches on fitting height and corridor length. It’s only one of many factors an eye care professional needs to consider when it comes to fitting progressive lenses.
It’s difficult to determine what factors are contributing to the poor visual performance of your glasses without knowing your prescription history, seeing how your frames are adjusted or what style of progressive lenses you are currently wearing.
Ideally the opticians where you purchased your glasses should be able to examine these variables and work with you while explaining what it is they are checking. An optician may have thoroughly examined factors like fit and prescription. But unless they practice good communication skills a patient has no clue as to whether their issues are being addressed or simply ignored. This is also complicated by the fact that the level of education for opticians varies considerably from state to state!
If you feel your visual complaints are not being addressed don’t hesitate to ask another practice for help and advice! Some might be less than enthusiastic to assist someone who isn’t a paying customer. Others won’t hesitate to assist ANYONE, to the best of their ability, who is experiencing visual discomfort.
Eyewear is an investment and your quality of life can be seriously impacted by good or bad visual comfort. Call around and look for a place with a knowledgeable staff who practice good communication skills and treat you as a patient not just a paying customer! All that effort will be worth it and save you considerable frustration down the road!
(If you should decide to look around for help from another practice be sure to have available your current prescription, any previous prescriptions, your current glasses and the previous pair that worked better. The more information you can provide the better an optician will be at figuring out what is causing your current discomfort)
Question; I've recently purchased progressive glasses. then as i look at the full moon i have "ghosting" (if that is such a thing ) meaning: i see 3/8 of the moon on top , and 1/4 of the diameter on the bottom .
That being said i notice this effect when i look at lettering that is white font on black background.
Am i hypersensitive to the progressive correction being correct? or is it a valid misprescription of said progressive ?
Just a guess but it sounds like you are looking through the lens corridor. The fitting height of the lens might be set too high. If you drop your head and look up through the top portion of the lens does it get better? If yes - probably set too high.
@@LaramyKOptical no. I've tried all views. I have noticed that when I squint it gets better.
Any recommendations?
I’ve just taken delivery of new pair of progressive spectacles (I’ve worn progressives for many many years). Immediately aware of differences in lens performance (compared to old lenses) from first try on but optician asked me to “run them in” for 2 weeks and come back for adjustments if I don’t get used to them. My distance prescription was unchanged. 5 days in and I’m still having to put my chin on my chest to get the proper focus I find acceptable when walking outside or sitting watching TV. Performance is improved if I tilt the frame forward at an angle but can’t wear them like this. Should progressives work “out of the box” and what kind of adjustments (frame bending I presume) is my optician likely to perform?
If you have worn progressives for many years then you should have no adaptation period at all. Sounds like a fitting issue perhaps combined with a design issue. I'd have them double check the fit and the lens and see if the new design is anything like the last ones you had. If you need to move the lens around to find a clear area that is a fitting issue. Fitting meaning the lens was not cut to sit in the frame in the correct position to work for you. Yes, that could possibly come down to trying some frame bending that can work. Frames sitting close to your face, a little tilt in at the bottom of the frame towards your cheek, a little face-form or very slight wrap that mimics your head/face. If you have to drop your head to find distance the lens fitting height is too high. SWAG you may well have some good intermediate (computer) when looking straight ahead?
@@LaramyKOptical Thank you very much for replying so quickly. It was exceptionally kind of you to reply in such detail. I’m seeing my optician on Saturday and I am now well informed in advance. I will let you know the outcome. Thank you again.
@@LaramyKOptical Ended up with a new prescription (less power) and the lens centres raised slightly. Very pleased with the outcome. Thank you again for your thoughts and for your channel here on CZcams - very helpful and informative.
So I am probably answering my own question here, but for those lower distance plus wearers who claim they can see better at the very top of the lens (near the frame) rather than above the fitting cross, the longer corridor would solve this issue? I have Patients with Dist Rx's of plano up to plus 1.25 in adds of +2.25-2.50 who complain of blurriness near the fitting cross. I've compensated by dropping seg hts down as much as 5-6mm and often it works. But not always. We regularly use 15mm corridors and for most it's been fine. Would using a 17 solve this particular issue? Thanks. Love these videos, they are quite helpful
I've never heard anyone say that they find vision sharper well above the distance circle. It always returns to the same things --- a progressive lens is designed to be fit with the fitting cross at pupil center, a corridor of 18 +/-2 works best, you should never fit high/low and power changes create vision changes in all areas of the lens. On one hand you say "...most it's been fine." On the other hand you are saying that som plus folks are having troubles. Find the video, One Simple Trick To Choose The Freeform Lens, since maybe it has more to do with lens design than fit?
John, how does one know if a frame to just too small for a progressive lenses? The frame in question is an antique American Optical (1920's. 30's) thin gold oval frame that I've always wanted to wear. As mentioned earlier, I had progressives made the other day for this frame and now all words on the computer, and on my phone, seem fuzzy around the edges.. I don't have this issue with my older pair of progressive glasses, which are slightly larger. Do I simply need time to adjust, or is the frame simply too small? I appreciate your opinion.
Rough estimate - stand in front of a mirror and stare level headed at yourself. Use a marker and dot the center of your pupil. Now measure down in mm to the lowest point in the frame. You have 18 you should be OK. If you have 19, 20, 21, 34 all is good. If you have 17, 16 eh maybe. Less than 16 it ain't gonna work. Frame shape also plays into all this. So does PD. I do cover that stuff in several of the other videos about progressives. Depending on use maybe a weak lined bifocal which could go in anything might be better. Heck it would even match the vintage look!
Trying to understand: so did you mean that what we call a "corridor" is really a MFH, so 18 is what we order when we order what is ideal?
I have been wear progressive lenses for a long time. Usually have to get them made over. Stresses me out. Should I use the 18 rule? Thank you.
Great video as always.
I've also watched your video on why PALs have unwanted astigmatism, but I have a question:
Say you have a frame, where the patient's pupil sits at a height of 29 mm.
You fit them with a progressive lens with an 18 mm corridor length... What resides in that lens at 19-29 mm??
A lovely, spacious reading zone with 100 % add power? Unwanted astigmatism, like on the sides? Unicorns? 🙈 What will the patient see in that part of the lens?
Sorry Christian I never saw this comment until today. Short answer: once you get past the bottom of the near circle you are in the land of optical garbage again. Wouldn't matter on heights past the bottom of the near circle it's going to be a mess.
Hi sir,
What If the customer has got use to pervious glasses with short corridor lenses and do the new glasses should be the same short corridor lenses ? But the customer has the 20 fitting height.
Please advice.
The answer is in the video!
Really enjoyed this video. I have a question though. I can see great up to 12 inches away without my glasses. I find myself taking them off when reading. I am myopic and my add is 2.25. Since the height of these lens are within your suggestions, why don't progressives work for someone like me?
Cathy, I'd need to know a little more about your distance powers* but --- for day-to-day stuff there is no reason a correctly fit progressive wouldn't work. With that said many myopic people do have a strong tendency to take off their glasses to see things up close. I think it is the difference between looking straight at something without them and having to look through that little area at the bottom of the lens with them? *If your distance is -2.25 (or near that) in both eyes when you take your glasses off you have a natural add of +2.25 so to speak. Then by moving you or the book a little you can fine tune and read what you want. You might want to look at the other two videos on progressives and office progressives we did just a few weeks back. John
@@LaramyKOptical You are right, my distance is near to -2.25 and I just tried what you mentioned. I have to tilt my head up and/or place the reading material down to get the best vision up close with my glasses. I usually forget to position my eyes and book at the best position to see clearly and when I do its not comfortable. Much more comfortable for my neck to have the glasses off and look straight ahead. Darn, guess there is no fix for that.. :-) Thanks again for your videos!
@@mmiller195 Nope! But --- if you are not a perfect -2.25/+2.25 in both eyes then having a single vision reading pair of glasses would make all the difference in the world. Also if you have a middle number and an axis on your "prescription" then a pair of readers made for you would help. John
@M Miller sounds like you might not be in a progressive best for your rx or your measurements and/or frame could use some adjustment. I find most of my patients who have discomfort finding their “sweet spots” are not properly lined up in the lens. I don’t love progressives over 13 mm mid range for that reason- not the minimum fitting height, but the actual amount of space between the distance and reading zones.
I have a Mr. Pumpkinhead go from a frame with a 25 seg to a 32 seg. He can’t adapt to the 32 seg, he says the distance is blurry unless he tips his head to the very top of the frame. The clearest distance vision is 5mm higher than his seg of 32, should I drop the seg 5mm to account for this?
Something isn't adding up here. Even for a pumpkin head in a HUGE frame 32 seems VERY high. If he has to tilt his head DOWN 5mm to see clearly then, yes, the fitting is (at least) 5mm too high. I'm assuming this is a progressive not a lined bifocal. I'd start from scratch on measurements and as mentioned in the video frame size doesn't dictate corridor choice. If you can put him the same exact style/brand/make of lens he was in before and was happy with then do that using the same corridor but fit for the larger frame. Reading between the lines I can't help but think you are missing some pieces of the puzzle. www.OpticianWorks.com
So with digital lenses and heights of 24mm and more because patients wants big frames. The frame fits nice and centered and the lab says they can adjust the corridors......can you explain that plz
I'm guessing they mean that they are using free-form and are plugging in the numbers and letting the software design the lens to the defaults. Again - a frame could have a B of 80 and you would still want about 18. Can your eye sweep in the 90th more that 20mm?
Wish I would have watched this before I ordered my first pair of prescription glasses (went with progressives). The super narrow focus column is SO annoying its making me reconsider getting two separate pairs of glasses. Jeez, what 2 crappy choices.. either move your head left/right like a robot (progressive) or change glasses 50 times a day (single lens). Does a bifocal lens have a wider focus area?
YES, YES & YES a good old fashioned lined bifocal has a MUCH wider range, are much cheaper and actually have better optics. It is what I wear myself! You know Ben Franklin and all that --- progressives have been around 25 years.
What if we have a patient with different pupil heights ?
You would choose a lens that allows for the MFH for the eye with the lowest position. My own rule of thumb was I did different fitting heights when I could tell just by looking at someone that one eye was higher than the other. Regardless it wouldn't change corridor or PL or MFH. You would still shoot for the perfect range. John
Interesting videos! I'm a simple glasses user only :). Question: TL;DR got my first progressive lens glasses a few days ago and I'm experiencing blurry image on "the right side"of near (mostly) area of the lenses and haven't been able to get the image sharp no matter how glasses are placed on my head. Could this be me not adapted to lenses or an issue with the lenses? Long explanation: I haven't used these glasses long enough yet but I've tested them extensively for two days. I haven't experienced any major image/view rendering quality issues overall as a user so far, (expensive Hoyalux id Myself lenses), no feeling of needing to adjust to them in any way. But this blurriness thing got me a bit worried so far: When looking down to see the screen of a mobile phone or tablet (especially text content), if I look straight ahead towards phone display and look through the bottom part of the lens, the right side of vertical mobile phone display is slightly blurry. Same for medium size tablet in portrait mode. Also, when looking at a 16:9 horizontal computer display, using a different part of eyeglass lens, not the bottom part, I get the same effect. Blur is not much, but enough to bother someone working with images daily. When I turn my head slightly towards right, texts on right side of mobile phone get sharper. But there seems to be more sharp horizontal area towards left, no matter what. I've tried to slightly wiggle the glasses sideways, twist them around vertical axis, and I've tried to move them closer or further away from my face, but this doesn't seem to help with the blurriness. Also, based on a side view selfie, I noticed that angle of lenses (pantoscopic tilt I guess?) is more vertical than in my old glasses, even though the frame design and lens shape are pretty much 1:1. Also, the reading area is very small vertically, I pretty much have to look down through the edge of lens to see sharp text (34mm lens height). Any Ideas? I do have astigmatism on both of my eyes, and minus glasses.
Whew - kind of reads like you are doing a really good job of trouble shooting all on your own. And you are correct that you have about 10 variables to consider. Since nothing you do seems to be a "fix" my hunch would be lens design. If you could sort what you had before and then figured out what that design favored (distance/intermediate/near) and then compare it to the current design that might be your answer. If the old favored near (offered a wider reading area) and the new is a balance or perhaps one that favors distance at the cost of near that might do the trick. You will find several other videos on progressives on the CZcams channel - where I strongly advocate for SV intermediates for any long term tasks like computer use. John
@@LaramyKOptical Thanks for the reply - I guess I'll have to visit my optician tomorrow. These were my first "proper" progressive lenses. Previous ones were "Nulux Active Eyas 1.60 SHV A / B" lenses from Hoya (based on my previous prescription, and the new ones too are from Hoya) - I've been given two answers by different opticians now - my old lenses were single vision lenses or some sort of young adult progressive lenses - I'm not sure, can't verify. Anyway - I tested the new lenses today again - at 50cm distance, I get maybe 4cm width of sharp focus with smartphone screen in vertical orientation (6.6 inches screen), I'll have to rotate my head few degrees to right to be able to see sharp text on the right side of the screen... maybe I'm too observant about sharpness. BTW - for computer work (unfortunately I nearly live in front of screen) I bought new single vision lenses - I'm not 100% sure but I think I got the idea for this from your videos / or a comment by you to some viewer :)
@@322ss czcams.com/video/B3I57YY0vnk/video.html
@@322ss czcams.com/video/1bGwFJW7_SU/video.html
Even if the frame is big customers do not adapt with 18 mm corridor, they use to seek the close vision in the bottom and move their head up for reading, the best corridor is 14 mm the wearer can read without moving his head only his eyes.
By experience the corridor 14 is the one that we expect less customers claims.
I recommend an 18. 18 worked well for me for 20+ years. 18 is recommended by a lens designer. But as I always say, "If 14 works for you then by all means keep doing it." John
Laramy-K Optical -i have also 21 years experience and i'm among a family who has over than 40 years in optics, i've seen differents steps evolution of the progressive lens manufacturing since the narrow filed of the 80's until the digital surfacing and nanotechnology right now. So in the 80's and 90's there was no short corridor , only 18mm and 20mm, the short corridor appeared from years 2000 and the goal was not only for trendy small frames (for that time) but also to give the wearers the reading possibility without moving head up . 12 mm is not recommended, the 14-15 mm works well , if you have an add +3.00 for close vision then you can use the 16mm in order to not squeeze the transition. There are rare cases that we find patients with +3.00 (for exp over than 75 years old) add +3.00 don't give a depth of field for a young wearers .Good luck!
Hi sir my question is when frame B size is above 40 that time what we can do
18, 18, 18 or 18. Watch the video again! Your eyes don't have a rotation of 40mm so all that lens is just wasted space. John
@@LaramyKOptical thank you sir
I was just told by my eye doctor that short corridor is best for the size frame that I have. I had regular progressives, but everything on the computer was fuzzy with the new prescription. The thinking was that the short corridor will give me greater reading room. Can you please comment on this issue? Thank you. P.S. Have short corridor lenses been improved here in 2022 since this video was made in 2019?
I thought I make that wicked clear in the video? Or maybe it was one of the others? Anyway - short corridors kind of work when you are young. They don't work as you get older. Not that they ever really worked in the first place... The magic 18 with a lens designed for a MFH of 18. John
@@LaramyKOptical - Then you know more than my Eye Doctor. That's not said to be flippant. So many different opinions on this issue, which really sucks because these lenses aren't cheap. You never answered my question concerning if short corridor progressives have improved at all since you made this video over three years ago. I do appreciate you getting back to me.
@@sinatralala No. There is no magic pixie dust. Any change in progressive design at this time is all infinitesimal. Take a mm ruler and draw two lines 1cm apart. Now in 0.25 steps write the values from 0.25 to 1.50. Now do it again and this time write the values from 0.25 to 2.50 and see how that goes for you. As the very crude saying goes, "It's like packing 10 pounds of s*** in a 5 pound bag." And yes many opticians do know a lot more about lenses and lens design than doctors do. John
I watched this video several times and I did not catch where you actually explicitly defined the term MFH. I couldn't find such via an internet search either.
I get that the term Corridor does not have a standardized definition and yet the two are 'closely related' - and that by 'closely related' I gather that you mean the Corridor is more or less contained within the MFH - so giving a definition of MFH would be very helpful. In fact a definition of terms is, in general, always important, no?
So I assuming that the definition of MFH is implied here to be the length from the top of the Distance Circle to the bottom of the Near Circle on the progressive lens. Is this not so?!
So do you think a 42mm diameter circular lens will be fine for a 50y person?
Really impossible to say without seeing it on you but 42 is a pretty large frame so should be OK.
What about free form digital lenses that say 13-25mm?
I stand by my 18 100% regardless of design. Keeping in mind that you can have a fitting height OVER 18 anytime and you just use a lens with a 18 MFH - I know it is confusing. So FH over 18 is OK good even. Less than 16 and you are in the danger zone. Again - this stuff came from a fellow who designs progressive lenses, not a marketing department, not an optician, not a lens brochure. That isn't some made up story - I did ask him that exact question: If you are fitting your mother, father, husband, wife what do you want to see? I know who you are so I'll add this: If you have a strong optician with low remakes and they use 16, 15 heck 14 and it isn't a problem, well then don't fight it. If you have a stable of newbies with high remakes then you want the magic 18 and the security of them knowing what that actually means. Back to why 18 is a good thing - if you are hiking would you rather climb 1000 meters over 10K or 5K? Would you rather build from 1.25 or 2.50 over 12 mm?
How far below is the ideal sight height from where the pupils sit and where the vision to address presbyopia begin? in millimeters
A progressive lens is designed so its fitting cross is pupil center. There is no drop, or raising/lowering possible.
czcams.com/video/-PIDGBn8RY4/video.htmlsi=Odc7BwTJQ0Ua6Ckg
Thank you Jon. You are such an invaluable resource
I would not say to never use short corridor lenses. Some lens designs build the intermediate power quicker than other designs, short corridor lenses can be exactly what's required depending on this.
How can a consumer find out what lens lab their doctor uses or how can I find a doctor that uses Laramy K lab?
Drop me an email through the OpticianWorks website with your location and I'll see if we have a customer nearby. Otherwise you would have to be specific and ask them straight up. If you are using a vision care plan then you and they have little or no choice but they should still be able to tell you - they certainly know what lab the order is being sent to.
Damn, I have a 70 mm PD-I’m beyond pumpkin head! 😂
Where can I get pal ID catalog ?
Last I knew it was through The Vision Council and had been moved online. Your lab might be able to track one down. I have lost track since I don't need one anymore.
I have been watching your videos for awhile and learning a lot (customer not an optician) so requested the full computer printout of my new order for frames and lenses just sent to the lab which included the following: Pantoscopic Tilt, Wrap Angle, Vertex Distance, and NWD.
Blank size is 99, Decen. is dd In, Measure 'A' is 54, Measure 'B' is 40 and Eff. Dia is 59. Frame size is 54x16.
Seg. Height is 21.5 above rim.
So based on your video, is Seg. Hgt. the same as MFH or am I missing something, and is 21.5 good or bad?
Also, can I tell this is a Free Form order based on these specs?
21.5 = Good and that would be a free-from lens order. I'm assuming measurements taken with an electronic device of some kind?
Thanks, John. Unfortunately, no electronic device was used so the extra PoW measurements must all be the Default values for that frame.
I am trying to locate this lens in the PAL ID catalog but don't see it. The order shows it's an XYZLabs (real lab obfuscated) Essential 14, so I assume that means the lens MFH is 14?
A Seg. Height of 21.5 is okay in that lens as my Add just increased from a 1.5 to 2.5, and the previous frames were quite small, probably around a MFH of 14?
Awaiting your earliest reply.
@@SuperG11123 I actually prefer the defaults! The store should be able to tell you the brand they are selling. It. might be a store or in house thing but it must have a name. IN MY OPINION If it really is a 14 corridor you are going to be miserable. 1.5 spread out over 14mm is one thing squeezing 2.50 into 14 mm not good. You are confusing height and corridor length.
Thanks, John. Still waiting for lenses to arrive so called Optical Location A, and they said the 14 lens referred to MFH.
Called Location B to verify, and they initially said the same until I told them they were going into a frame with Seg. Height of 21.5 and ADD of 2.5. Immediately they changed their story and said 14 now referred to Corridor Length, and that this lens was made in CLs of 14, 17, 19 and 21!??
They are free form, made by Hoya, ground in their large independent lab and considered Premium but not top-of-the-line.
So is the Essential 14 referring to MFH or CL?
Also, assuming they are spec'd using MFH, and if they don't have 18 is 17 or 19 better?
Sir, I m optician. I see somecase of customer of India theire eye is move down for near vision is lazy .and they could not read easily. So how to decide their eye movability??
I'm sorry but that isn't something opticians in the US handle. But sometimes prism is used in the lens to realign the vision or to train the eye to realign or both. Prism and direction is covered on the OpticianWorks website. But "lazy" eyes can have many causes. Wish I had more to offer you.
What about fitting short progressives, lowering the height and giving a lower addition? Fitted thousands. Not even ONE non adapt.
As I say as often as, "Don't say I didn't warn you." I say, "If it consistently works for you and your customers are all happy, keep doing it."
@@LaramyKOptical keep up the great work. Your channel is amazing!
Does this apply to kids too?
?????????? I guess in the rare case that you put a kid into a progressive (1 in a million) you might consider a shorter corridor. Generally segmented bifocals are used for vision therapy stuff.
Thanks.
Shouldn’t you take in consideration the prescription also? I understood that for myopia a shorter corridor is better as opposed to hyperopia witch favors a longer corridor. Sorry for my English, I am not a native speaker.
That is more about individual lens design. Or the shape of the power mapping within the lens. Yes some progressives favor minus and others plus. That may include changes to the corridor length or progression length I really don't know. That would all be within the design or inside while MFH is outside of it. One the designers control one we opticians control. But as always if it consistently works for you and your customers are happy keep doing it! John
@@LaramyKOptical a shorter corridor is more appropriate for a myopic prescription because we encounter more BD prism as the eye turns downwards, and so it doesn't need to turn as much to be looking at the same eccentricity. Also, the downside of a shorter corridor (narrowness of corridor as surface astigmatism increases more rapidly away from mid-line as per Minkwitz's theorem) is less problematic for moderate/high myopes where the divergence of the lens means that the angular FOV for any absolute corridor width on the lens is wider than for emmetropes and hypermetropes.
Dear Sir, will Short corridor length suitble for Asean People ?
I'd stick with 18 but if shorter corridors work for you then keep doing it. I believe progressive design does vary in Asia.
Is there a PAL solution for that older person who has lost accommodation ability but needs near, intermediate, and distant correction, and has two complaints, 1) that they have too much head movement for intermediate vision tasks and 2) that the distant and near zones are too far apart requiring physically adjusting the glasses to read.
Short answer is, no. If you really need full distance, intermediate and near. Next choice would be a lined trifocal. Best choice would be multiple pairs. With a lined bifocal that provides you with the int/near distance you use most often. You do that by playing with the add power. Yeah, this getting old thing ain't no fun.
@@LaramyKOptical If you think of a flat-top bifocal as a progressive with a zero length corridor why would having a progressive with the far and near zones physically closer together with a non-zero length transition/progression zone and more aggressive transition would not work since the person described likely needs the more aggressive transition more add power for intermediate vision, anyway
@@MikeL85850 I have no idea what you are asking/saying. You asked is there a PAL solution, I answered "no" and provided a few alternative solutions.
Kindly can you help to identify my lens type, How can I mark or identify the width of the corridor from mid to all the way down to the reading area to draw the same window as they show on the catalogue like to vack to back brackets here ) (
Or to put it another way, .. I doubt that I have been charged for wide corridor lens but actually they are ordinary narrow corridor,.. that is what mostly defined in catalogue or videos as wide reading field of view ... Just to be clear here I am not talking about length of corridor..
I did device a way, I wish I could share pics here .. by magnifying the fine net through the progressive lens and it will show the magnification according to the progression of the addition number, after drawing the outline on this progression I am able to get virtually the same curves ) ( but is it the right way to do it and challange the optician or the lens supplier?
I doubt you will like my answer but - you can't. The only tool that can do that is the dual-lens-mapper. The problem is that every corridor width will be a little different depending on power. +/- 0.25 in any direction will effect corridor width. The "drawings" are just that - a generic one-size-fits-all illustration. You may have figured out a way to "see" yours (doubtful) but that wouldn't really be something for comparison to any catalog drawings which are often mostly about marketing. I wish I had a nicer answer for you. [the lab may have sent the lens map image with the lenses to the store - probably not] If you can't adapt - don't like them return them and try another make/model from another location.
@@LaramyKOptical
Thank you so much
I understand and agree, it just that I wanted to go beyond to challenge the supplier :) .. my numb is spherical+1.5 with add +2, .. I had before ordinary progressive at cheaper price and I know how it behaves in terms of what field of view I get when I am reading which is almost 5 inch at the reading distance of 12 to 16inch, now I ordered digital free form wide corridor but the result is the same..
I was kind of forced to develop understanding of progressive lens and fittings as no one was able to make my glasses, PD error, height error, skew or other very basic errors, finally I did my own glasses .. :-)🙂
So here I am and feel that I unnecessarily spend money on getting wide corridor lens when there is no change ..
can I send you an email?
@@designaids Are you taking into account the Golden Rule? If your power went up (that is quite a bit of plus) regardless of the design the overall distortion across the entire lens goes up with it. You can find my email on the OpticianWorks website. John
@@LaramyKOptical Thanks John, I just sent an email to you with the subject line "Mapping of Progressive lens"
You only casually mention the relation between "fitting center" and the corridor (for good reason!) Is there some standard, where the "fitting center" is, such as at the 10% add point? The reason I ask is that the "magic number" that opticians ask for is "segment height". It took me awhile to figure out that with the "head level", looking straight out horizontally, this is the distance between the line-of-sight to the bottom of the lens "box". Like a crude IPD measurement, my optician dots the lens with a Sharpie and measures this distance.
The relation between "fitting center" and the 2 reference dots is yet another variation (most centers are 2mm above the line connecting the reference dots, but some are on the line).
IOT needs to educate the opticians on what measurements go into a "freeform digital" lens, at least for theirs! I feel that most opticians (including good ones) put in nominals (or the lab does because they were not specified) because opticians have no real way to measure them. Just as the automated edger has largely replaced the manual edger, there need to be in existence tools to make these measurements. This is something the "optical shop of 2019" could provide as "value added" to survive in today's "online" era.
Like the diopter, prism diopter, IPD measurements, angle standard, and patient right-before-left, fitting height and corridor length (and their relation) needs to be standardized. (I assume there is some worldwide "consortium" that covers optical standards. They need to step up to the plate and issue standards for this!)
So how - as a consumer/client - does one ascertain that they get a lens with a MFH of 18 if the professional she is working with doesn’t seem aware of all this?
You would have to ask. At some point during the fitting process they will either dot your lens or use an electronic measuring device. Then they should either measure and record the height or save it your profile in the EMD. Either way there is nothing stopping you from asking. Keeping in mind (as mentioned in the video) it is possible for a very competent optician you trust to choose a shorter corridor. If you have someone you don't trust and does not appear to know what they are doing and they say 12 then run away. If they tell you they cam "move it" then run away. Kind of comes down to finding an optician you trust and that could be anywhere, certainly not necessarily some fancy doctors office.
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Does the height of the frame matter? I'm trying to get an online order right and the first one has failed. 😢 These dimensions you are talking about don't exist in online ordering.
For a progressive lens to work you need at LEAST 18mm from the center of your pupil down to the "bottom" of the frame. The vertical opening in a frame is the "B" and you need enough B to have everything fit and work like it should. So - you can't use a frame with B of 20 etc.
So, 18 is the magic number plus 14 transition zone equals 32,but how do you account for the upper distance measurement? My problem exists in the distance portion. Years ago I went through this and the whole thing was shifted down which made the distance correct, but then the mid to close was compressed. My takeaway is that the frame size "b" has a minimum. Is this correct, and if so, what "b" minimum should I be looking for?
Lastly, as a customer, how do I convey this to the optometrist?
@@rondonato7443 Any decent optician should be able to address all of those concerns and get you a lens that would work great. Sorry - I have nothing against online shopping except for progressives and high powers. You are asking for advice that can't be provided without seeing a particular frame as it fits on you. If you really want a progressive two work then go and see an optician.
4:15 everything in normal let's continue.