Prismatic corrections – a communication challenge between the industry and opticians

Prismatic corrections – a communication challenge between the industry and opticians

Picture by Michael Dziedzic on Unsplash

In my career of over 30 years as a lecturer in ophthalmic optics, I have been through all the stages from student to teacher to developer to expert authority – trusted with confidential knowledge about the industry. I would like to thank everyone for the trust they have shown in me, because this was the only way I was able to explain complex optical issues to opticians in a clear and understandable way. Here aberrometry with its wavefront measurement is a case in point.

By Fritz Paßmann

Knowledge means recognizing connections and developing links to topics that are already understood. The conversion of prismatic prescriptions into spectacle lenses that a wearer is comfortable with is something I care deeply about. Both from the point of view of the end customer, i.e. the improvement of his vision and possible alleviation of asthenopic complaints, as well as from the point of view of the optician, who needs support in exercising his skills and offering his – sometimes emotional – recommendations. This calls for broad backing by the industry. This article is aimed at bringing about a willingness to offer opticians more information, education and transparency.

This is a huge challenge: converting values ​​determined in the refraction room into spectacle lenses that are comfortable for the end user. It requires close cooperation between all the parties involved. The optician is the link between the lens manufacturer and the customer.

Let’s start at the beginning

When looking through a spectacle lens, a prismatic effect is created outside the optical center. Normally this does not pose a problem for the spectacle wearer, as the prismatic effects of different versions and base settings mutually diminish each other resulting in an “almost zero” overall prism; except where there is anisometropia, in particular in the principal meridian of the spectacle lens in the respective direction of view.

To calculate this, the optician uses the “Prentice law”: P = c * S`. Charles F. Prentice is considered as the father of optometry in the USA and in 1921 he recognized the connection between the distance of the path of the light beam in the spectacle lens from the optical center to the vertex power for calculating a prismatic effect.

If someone wants to achieve a prismatic effect by decentering the lens, they must not use the Prentice law as the formula does not take account of the rotational direction of the eye when looking through the lens. For more accuracy, the ‘Weinhold formula’ or ‘extended Prentice law’ (Fig. 1) which includes the BVD (back vertex distance) must be used.

‘extended Prentice law’

Technically the distance between the eye center of rotation and the lens vertex b` should be taken into account, as the eye rotates around its optical ocular center Z` in the opposite direction to the base setting of the prism. But how can you measure the distance to a virtual point? This raises three fundamental questions for the lens manufacturer:

  1. Is the BVD or b´ always included when ordering prismatic lenses? In which case a specifically developed order form including all the necessary data is recommended.
  2. What distance does the industry use to calculate b’? The ‘standard eye’ according to Gullstrand specifies 13.5
  3. Is there any conversion made between ‘Prentice’ and ‘Weinhold’?

This leads to a further issue: the difference between the measurement position and the position of use of the spectacle lens which needs to be communicated precisely, both for the clarity and understanding of the optician and for the technical details to be printed on the lens bag. Admittedly the differences in calculation will mostly have an effect ‘after the decimal point’, i.e. in the decimal range.

However in problem cases several factors often occur together, or the customer is particularly sensitive, in which case precise communication can minimize misunderstandings.

Prismatic effect through decentration and its limits

The application of the Prentice law is already taught during training and thus opticians are able to autonomously decenter the lenses and determine the reference point in order to achieve the desired prismatic effect. I was already proud to be able to do this in the early days during my apprenticeship. At a time when considerable subsidies were still paid by the health insurance for spectacle lenses (editor´s note: that was the case in Germany until 2004), ordering a spherical or toric single vision lens (multifocal lenses naturally did not apply) and achieving a prismatic effect with the help of a larger uncut lens diameter was a great art and did not involve changing the prescription or even cheating the health insurance.

The desired effect was achieved and afterwards it was not possible to see by the lens how this had been done. However, this approach does have its limits, which should be clearly communicated by the industry:

  1. The vertex power and uncut lens diameter are mutually dependent. That means that, where S` is rather low, the blank will not have the required diameter. My recommendation for maximum dioptric power is the number “4”. This means that above a vertex power of0 D and prismatic effect of 4 cm/m, the prism should be created industrially, i.e. by tilting the blank when blocking. This procedure is not known to all opticians, but it explains the limitations of what is feasible when the blank only has a limited edge thickness.
  2. For toric lenses the effect in the meridian must be taken into account. This means that where the principal meridian and the base setting of the prism to be generated are not parallel to each other but intersect obliquely, this approach tends to lead to approximate results.
  3. If the lens manufacturer is not aware of the prismatic effect to be achieved, the increased aberrations that inevitably occur will not be corrected or even minimized. At this point the occurrence of ‘astigmatism of oblique bundles’ in wedge-shaped lenses should just be mentioned. An optimized prismatic correction for the comfortable vision of the spectacle-lens wearer requires the aberrations to be corrected at the reference point.

Mandatory: BVD and PD

During training to become a refractionist (not a refraction assistant), a distinction is made in the correction of a latent squint (heterophoria & associated heterophoria – explaining the difference would require a chapter of its own) between the pupil-center centration (PMZ) and the formula-case [1] when using a trial frame [2]. When centering on the pupil center using the Viktorin method, the PD setting is retained during the entire measurement process.

On the one hand, this is a straightforward procedure, on the other hand, it contains inherent inaccuracies and may even reach its limits. As already mentioned, after inserting a prism the customer no longer looks through the optical center of the existing sphero-cylindrical correction. Two prismatic effects occur: that of the measuring prism and the unwanted prismatic power of the spherical and toric lenses, leading to a weakening or strengthening of the overall prismatic effect.


The refractionist does not know the overall prism value and has to rely on the expertise of the lens manufacturer to produce the exact prismatic effect. However, to do this, as already mentioned, the PD and BVD need to be known. A prismatic prescription cannot be followed precisely without specifying the PD and BVD.

Furthermore, the visual acuity/vision of the customer may be impaired during refraction due to the resulting aberrations, which may lead to the refractionist giving up on further prismatic correction, although the status of binocular vision of the customer could still be improved. In addition, the binocular field of vision becomes smaller.

When using the equation case for lens centering, the far distance centration (not the customer´s PD) is adjusted. Two similar rules of thumb are used which are by no means only marginally different: for every 3cm/m or every 4cm/m, the set distance in the trial frame is corrected in the opposite direction to the base setting of the inserted prism. This minimizes the prismatic effect of the main lens but by no means removes it completely.

Furthermore, new questions arise as to the practical procedure used: if the formula is only used from 3 cm/m or 4 cm/m, what procedure is to be followed below these values? In the case of higher vertex powers, a noticeable prismatic side effect quickly becomes apparent, even if the trial lenses used are of low prism. What is the right setting for 5 cm/m on the trial frame? The required accuracy of 1.67 mm or 1.25 mm cannot be achieved.

In practice, this results in a combination of the two variants: partly further adjustment, partly accepting the prismatic side effects of the main lens. I recommend making the size of the ‘readjustment’ dependent on b`. The larger the VD, the more likely is it necessary to make readjustments. This results in the next demand on the measurement protocol/order form for spectacle lenses with prismatic effect: the indication of the PD at the beginning and at the end of measurement as well as the BVD. As previously stated, progressive lenses must always be ordered with the prismatic effect.

Potential sources of communication errors between the optician and the lens manufacturer

The question sometimes arises for the optician: “If the customer’s PD is readjusted already during refraction, (I am deliberately using this imprecise wording here because it is so often used; which does not make it any more correct. The correct terminology would be to readjust the centration point distance in the trial frame) then do I no longer have to take it into account when readjusting?” The answer is: “It depends.”

The crux of the matter is that it depends on the optician’s workflow. A refraction is usually carried out after taking down the case history and assessing the requirements. The PD setting of the trial frame is rarely recorded. The optician takes the centering data from his centering system using the – hopefully correctly adjusted – trial frame.

However, at this point the prismatic correction is not in front of the eyes, so they take the ortho position. This data is then sent to the lens manufacturer. In this case, the centration correction must be carried out over the entire prismatic effect, not just over the ordered prism, regardless of whether readjustment has already occurred in the refraction room.
If the optician specifies the readjusted PD when ordering the lens, only the small difference to the newly calculated total prism needs to be changed. In my opinion, it is desirable to indicate this correction on the lens bags as the new “distance centration distance”.

Some lens manufacturers have recognized this potential source of error in communication and have for some time now been taking a new approach, at least for progressive lenses: relocating the stamp by moving the engraving. The lens manufacturer calculates the new position of the reference point exactly, i.e. to an accuracy of 1/10 mm, thereby offsetting the centration marking of the stamp which makes sense. The optician has one less thing to worry about and continues to work as usual. However this is not a general solution to the problem.

New questions arise: “Can this approach be used for all types of lenses in the portfolio?” Is the centration correction clearly shown in the price list? At what point in time was the change made?” This question may be of key significance when handling complaints. Since specialist opticians usually work with a number of lens suppliers: “Which lens manufacturers offer this, and which do not?”

Prism distribution

Personally, I prefer asymmetrical prism distribution. I find it satisfying when aesthetically pleasing lenses can be achieved by adjusting the thickness. It is down to the refractionist to decide whether a symmetrical or asymmetrical distribution of the prismatic effect is more appropriate. Only he knows the visual acuity and the tolerance of any prism combinations as well as the influence of the customer’s “dominant eye”.

Only the lens manufacturer can calculate the absolute effective thickness ratios for ground lenses with a sphero-cylindrical and/or progressive surface. From these two points of view, an interaction is recommended through which all possibilities can be envisaged.

Taking account of the refraction conditions in the trial frame

The lens manufacturer should have a further skill and needs to communicate this to the optician: namely modification of the overall prism in the finished lens. In the refraction trial frame, lenses are placed in different holders, whereby the prismatic trial lens with its base setting is usually inserted into the front lens holder for practical reasons. The lens is thicker and would otherwise scratch the subsequent lenses or would not even fit into the lens holder. However, in the end only one lens is manufactured and ground to fit into the customer’s spectacle frame, with the resulting effect corresponding to the sum of all the individual lenses.

This poses additional questions: Are the various distances between the trial lenses taken into account when calculating the spectacle lens? Is the forward prism wedge of the trial lens converted into the same effect on the spectacle lens in which the prism wedge protrudes backwards? How is the prismatic trial lens labeled? According to DIN, the basic deflection of the prism is defined in such a way that the principal beam hits the front surface at a right angle and deflection only takes place at the rear surface. Has the trial lens already been adjusted in this regard and, with the wedge protruding forward, does it have the same effect as is required in the position of use of the corrective lens for the main direction of view, despite the principal beam being refracted twice?

Measurement position versus position of use

In addition, there is the well-known problem of distinguishing between the measuring position and the position of use. The requirement for the measurement protocol/order form for spectacle lenses with prismatic effects should therefore include information on the respective slots used. In this context, the position of the edge of the ground-in spectacle lens is also important. Usually, only the optician has exact knowledge of the spectacle frame in question. Only the details of the lens shape are passed on to the lens manufacturer.

However, if the details of the entire frame – with its material, type of manufacture and the possibility of hiding the thickness of the lens rim – are passed on, new possibilities of producing aesthetically pleasing spectacle lenses by shifting the facet are opened up.

In addition, the position of the spectacles on the face is important. Are there any anatomical features such as strong eyebrows or deep-set eyes or protruding cheekbones to be considered? If you want the standard facet to deviate from parallel to the front surface, i.e. to be incorporated in the middle or even in the rear third of the edge thickness, this option must also be made clear on the order form.

Interplay between lens thickness, transparency and color fringe

I would also like to see more information about different lens materials and their Abbe number. This knowledge should then be used to advantage by the optician during the consultation. Thinner and more expensive does not always mean lighter and better!

Using easily understandable graphic charts, the interplay of lens thickness, transparency and color fringe of spectacle lenses can be used as a sales-support material to find the ideal combination, thus leading to the greatest benefit for the customer.

Taking account of the reference point

In the next point, too, I would like to plead for a commitment to sustained communication by the industry to the optician: “How can I (the optician) check lenses for prismatic effect?” This is only possible at the reference point. For this reason, single vision lenses should always be delivered with the reference point marked on them.

In the case of progressive lenses, the corrective prism effect cannot be measured solely at the prism reference point. At this point, the prescription prism and the calculated thickness reduction prism of the lens manufacturer have to be considered together. Often the optician is not aware of this combined effect. In addition with a height prism, the difference between the prismatic effects must be calculated separately from right to left.

One question after another

With regard to the previous point, the optician needs the expertise of physicists and physiologists from the industry. What does the spectacle wearer need to know about prismatic corrections? What tips and recommendations can the optician pass on to his customer? The comment “You’ll just have to get used to it!” is simply not good enough and certainly not professional.

How do increased distortions and dispersions affect vision? What can help to reduce these aberrations? How can it be that a customer reports seeing colored objects in different layers due to color stereopsis? Can anything be done about this? Can micropsia (objects appearing to be smaller) and macropsia (objects appearing to be larger than they are) be identified and avoided during eye testing for spectacle lenses?

Questions upon questions that can only be satisfactorily answered through a cooperative partnership where both sides bring in their expertise.

In conclusion, I hope that this article will create a better understanding of the vital need to collect all this data. A certain amount of transparency is desirable for calculating ideal lenses in order to demonstrate both the quality of the lenses and to stand out from the competition. This applies equally to lens manufacturers and opticians.

[1] Formula case means that the pupil distance in the trial frame is corrected by 1 mm against the base for every 4 cm/m. An example: Initial situation; PD 32 mm, 4cm/m base-in, then the trial glasses are readjusted to 33 mm.
[2] A Trial Frame is an adjustable spectacle-like device containing cells used to hold multiple trial lenses during subjective refraction.




Vision Expo updates safety guidelines for exhibitors

Vision Expo updates safety guidelines for exhibitors

Photo by Leohoho on Unsplash

The Vision Council and Reed Exhibitions, organizers of Vision Expo, have updated VisionSAFE, the comprehensive set of health and safety guidelines, policies and resources designed to support a safe experience at Vision Expo East 2021, with specific guidelines for exhibitors. An exhibitor FAQs document is now available to view on the website, which provides detailed information on booth specifications, cleaning and health and safety recommendations and requirements for exhibitors.

To view the guidelines for exhibitors, click here. To view other VisionSAFE guidelines and resources, click here.

The exhibitor FAQs includes information on:

  • Updated booth specifications to accommodate health and safety measures
  • Occupancy limits reflecting the number of people allowed in booths at the same time
  • Distancing and cleaning protocols for customer engagements and transactions
  • Changes to expect on the show floor
  • Details on the “no handshake” policy
  • Information about the Health and Safety Acknowledgement

VisionSAFE will continue to be updated and expanded upon regularly to ensure it reflects best practices and complies with CDC, local and state public health guidance.

The guideline complements the health and safety measures in place at the Orange County Convention Center (OCCC).  The OCCC has strict health and safety precautions in place, including mandatory mask-wearing and social distancing. Additionally, the OCCC is part of a first of its kind collaboration between Orlando Health and Visit Orlando, which provides convention groups with personalized medical planning and support. The OCCC was one of the first convention centers in the USA to receive the Global Biorisk Advisory Council’s GBAC STAR accreditation, which is designed to help facilities establish a system of cleaning, disinfection, and infectious disease prevention. The Orlando International Airport holds the same accreditation.

Vision Expo East 2021 will take place at the Orange County Convention Center in Orlando, Florida from June 2–5, 2021. The Show’s educational program, together with OptiCon@Vision Expo, will open Wednesday, June 2 and exhibits will open Thursday, June 3.


The Vision Council releases results of eyecare provider insights survey

The Vision Council releases results of eyecare provider insights survey

Picture by Martin Lutze on Pixabay

The Vision Council has released the results of the February 2021 Eyecare Provider Insights Survey. The Vision Council fielded the survey to the organization’s panel of more than 1,700 eyecare providers during the last week of February. The survey, which launched in March 2020 and is being conducted on an ongoing basis to track the state of the optical market, asked respondents to provide insight about how business conditions—including number of eye exams and eye exam scheduling and follow-through, capture rate, revenue, and staffing—compare to a typical month, pre-pandemic. The survey also asked respondents for their insights on their economic outlook for 2021 and included a special section on issues specifically relating to COVID-19, including vaccinations, safety precautions, and business assistance.
To download the February 2021 Eyecare Provider Insights Report, visit The Vision Council’s Research Download Center,  here.
“The February results closely follow what we saw in January, with over half of optometry practices and optical retailers reporting reductions in business compared to a typical month. While low patient volume has continued, the capture rate remains high. Practice owners report that they have sought and received support to supplement their lost business revenue, with 72% applying for some sort of assistance,” said Alysse Henkel, Director of Research Data and Analytics.
“The Paycheck Protection Program (PPP) was a common source of support, with nearly all owners reporting receiving PPP funds after they applied. Overall, government and private assistance programs have provided much-needed funds equal to about 10% of practices’ typical annual revenue. The most promising news in this report is about vaccinations: eyecare providers reported a very high vaccination rate (70%). However, most respondents said there was some hesitancy to receive the COVID vaccine among at least a few of their co-workers.”

Key takeaways from the report include:
• Eyecare providers are getting vaccinated at a much higher rate than the general public: 70% of providers reported being fully or partially vaccinated by the last week of February.
• Patient volume (exam counts) remains below normal: 58% of providers report the number of exams as below normal, consistent with the recent trends of the last three months.
• Capture rate continues to be strong: 58% of providers report their capture rate is normal or better than a typical February.
• Practice owners have taken advantage of government assistance programs: 96% of owners who sought assistance reported applying for federal Paycheck Protection Program (PPP) funds.
• Overall, practices are still suffering the effects of the pandemic: 59% of providers report revenue is down compared to a typical January and 23% of owners report a reduction in staff from last month, but respondents show signs of hope for the future with 47% of owners believe business conditions will get better in 3–6 months.

EssilorLuxottica publishes financial statements for 2020

EssilorLuxottica publishes financial statements for 2020

Picture by ds_30 on Pixabay

The Board of Directors of EssilorLuxottica met on March 11, 2021 to approve the consolidated financial statements for the year ended December 31, 2020. These financial statements were audited by the Statutory Auditors whose certification report is in the process of being issued.

“To really understand what EssilorLuxottica is made of, just look at how we fought through the past year, the way we flipped adversity on its head and turned it into fuel for 2021. […] EssilorLuxottica is now in a unique position to lead the eyecare and eyewear industry into its next chapter, using our unparalleled assets and new categories like myopia management and complete pairs to capture long-term potential” said Francesco Milleri and Paul du Saillant, respectively CEO and Deputy CEO of EssilorLuxottica. “I would like to thank the current management for the important results it has achieved in a very difficult year. In the light of these results, I intend to propose to the new Board to confirm Francesco Milleri as CEO and Paul du Saillant as Deputy CEO”, added Leonardo Del Vecchio, Chairman of EssilorLuxottica.

EssilorLuxottica reported revenue of Euro 14,429 million, down 17.0% at current exchange rates and down 14.6% at constant exchange rates, compared to 2019. These declines were the result of COVID-19 related lockdowns across markets in the first part of the year. The Company’s reported and adjusted gross profit came in at 58.7% and 58.9% of sales respectively while reported and adjusted operating profit were 3.1% and 9.5% of sales respectively. Reported and adjusted net profit attributable to the owners of the parent were Euro 85 million and Euro 788 million respectively (reported result also reflects Euro 528 million of negative non-cash PPA impact related to the combination of Essilor and Luxottica).

And the winner is …

And the winner is …

Picture by Peter Fischer auf Pixabay

How market data in optics comes to life: When Mark and Ingeborg Mackenzie began to conduct studies on the global optical industry in 2003, Ferrari won the Formula 1 with Michael Schumacher. At that time, the industry experts described Asia as the “Ferrari” of ophthalmic optics – and thus the undisputed number one on the world market.
In 2021, Ferrari is no longer a synonym for Formula 1 world champions, and the optical world market has also changed. But which three candidates are on the optical winners’ podium today? And which country has the greatest future potential? By Hanna Diewald

In this interview Mark Mackenzie explains how to create reliable market data, how and why COVID-19 has affected the global market in extremely different ways and how several countries have developed over the past 16 years. Some of Marks predictions from the year 2004 were absolutely right, whereas other forecasts turned out to be wrong. That does not surprise, as none of the most experienced experts could have predicted some of the global political events, which disrupted the world in the last years and therefore also affected the eyewear industry.


Mark Mackenzie

You have been researching the global optical market for 20 years. How did that happen?

I went into the optical industry in 1994. In 1999 I joined Carl Zeiss and I realized how difficult it was to find good research on the optical market. You could get research for one country that was good, but in another country, it was done in another way. I felt if one could conduct research across the optical industry with people who understand optics and using the same methods in every country, that this would be a service which could be of interest to other companies in this sector as well. So, we started Strategy with Vision in 2001. In the last four years alone we have done 78 studies.


What are the objectives of the “world lens and frame demand study 2020”?

The objective was to estimate the total number of optical outlets operating in 2019 in the countries researched. To assess the number of ophthalmic lenses sold worldwide and to make an estimation of the number of ophthalmic frames sold by country. We wanted to assess the ophthalmic lens and frame market in value at net manufacturers/wholesalers selling prices to optical retailers in local currency. And finally, we wanted to make a growth forecast for ophthalmic lenses and ophthalmic frames in volume and net value by country for the period 2019 -2022.


How many countries were researched?

For the study – I talk about today – we collected data from 63 countries. We did the work in 2020, the year measured was 2019. These 63 countries are presenting 94% of the gross domestic product and they make up 78% of the total population in the world.



You compared your first study from 2003 with the current outcomes. What are the most interesting trends?

We said in 2003 that Asia was the undisputed Ferrari of the ophthalmic world because at that time Ferrari was the car winning the Formula 1. We stated also that Western Europe lies in third position in the world league table but not even the increase in the European Union to 25 members would allow them to catch up with North America. On the positive side the new European Union with a total population of 455.5 million inhabitants at that time, of which 187.5 million were over the age of 45, would provide a potential for much higher demand in the future. And we advised lens companies to look more carefully at the markets of the Near East.

Then we looked at the data today – 16 years later. We got the forecast of Asia growing fast correct. It is the market which has grown the most from 2003 to 2019. It grew by 3% per year from 326 to 536 million lenses. Western Europe has actually overtaken North America, although the population isn´ t growing very fast in Western Europe – but they have been very clever. They sold second pairs successfully across several countries and could therefore overtake North America. But we got the European Union totally wrong because we did not forecast Brexit and so the European Union has actually shrunk since 2004 from 455 to 447 million people. However, the number of people over the age of 45 is growing to 210 million and the markets of the Near East and Middle East have grown by 3.6% per year. That didn´t surprise us because we had told people that they should look at it. In those days, Syria and Yemen were countries that were showing economic growth. Now Syria is in civil war, but countries like Turkey and Iran have shown an enormous amount of growth.


Which further outcomes are important?

The ophthalmic lens market in volume grew from 2003 to 2019 on average by 2.6% per year. That has been a rate of growth which has been very constant. It is not surprising because this industry relies on population growth and the GDP because you need money to buy those glasses. These factors all together lead to long-term growth. The population grew by 1% per year, the GDP by 2% a year. But I said has proved very regular because this clock mechanism, which was perfectly working until 2019, has now stopped working regularly across the world, due to coronavirus. What may surprise people: single vision has remained at the same unit share in the last sixteen years, from 76% in 2003 to 75% in 2019.

We always talk about progressive growth but one of the big reasons for the increase in progressives was the decline in bifocals. What is perhaps surprising is that progressives now make up 60% of total lens value but ten countries in the world make up 70% of the total world value of progressive lenses. This shows how dependent we – I mean the whole optical industry – are on just these ten countries in the world: USA, France, Germany, Japan, Brazil, UK, Canada, Italy, Spain, and India.


Can you guess the reasons?

They tend to be countries with quite an old population, they are all countries with high income per capita, and they are partly countries which have social medical health plans which include eyewear.


                                                                                                                        Which products have the biggest potential in the future?

I think progressives will continue to grow. Even if we are affected economically by COVID-19, richer and wealthier people will probably still have money to afford progressives. Whereas poorer people maybe can just afford a single vision lens and may be more affected by COVID-19. I think we will see continued growth in high-index lenses, we will see continued growth in multiple layer AR coatings and we will probably see growth in blue light cutting. Furthermore, we are seeing one strange thing happening in 2020 which is the demand for workplace lenses. These lenses were always very difficult to sell in certain markets in Western Europe, but suddenly workplace lenses are selling quite well. We think this could be due to the fact that people are spending day after day in their houses in front of the computer and are maybe realizing that a workplace lens is a much better lens if you are doing a lot of work, either on the computer or at home in a distance of one meter to four meters.


How exactly do you gather your data?

The method you use is very important. Because if you don´t understand what you are measuring and how you are measuring, then the numbers very often raise further questions.
We are measuring lenses sold to optical outlets – ophthalmic lenses do not include the sales of ready readers and pre-mounted spectacles – and we use the lens data gathered to make an estimate of the number of ophthalmic frames sold by country. This is because normally an optician will order a collection of frames for several months in stock in the shops. If consumers come in and chose a frame, then they decide what lenses should go into it. Therefore, the order of a lens is very much in time with the sale of the frame to the consumer. We always do the research in local currency because otherwise you tend to pick up the variations in value between either the euro or the US-Dollar, but what if you buy your glasses in Turkish lira? Then we split frames into three price categories: Under 100,- euro, under 199,- euro and 200,- euro or more.


Are there particular challenges in collecting the data in individual countries?

The ophthalmic lens data have been researched in five separate studies and I believe that the numbers in most places are very close to reality. We are using the term “close to reality” because when you are studying countries like Indonesia, Iran or India you are never going to find the last lens sold. You can just try to get as close as possible. The biggest challenge we had is not with lenses but with frames. For instance, we worked with a consultant who knew the branded frame market in North Africa very well and when his numbers came back we realized that there was a mistake in those numbers because it turned out that Algeria was the most valuable market for frames in the whole world and we knew that this wasn´t the case. We tried to understand why and the following happened.

People who sell a branded frame tend to look at a segment of a hundred euro or two hundred euro, because that tends to be the prices at which branded frames are sold to the consumer. But they don´t go down to the market and to the cheap shops. But especially those cheap shops sell to 80% or 85% of all people living in Algeria. Because the reality is that the annual income is just over 3,000 dollars. If you divide that by 254 days you can work out how much someone earns per day and there is no way that that person ever buys a branded frame. Because a branded frame would mean 30 or maybe 60 days of work and they still have to put the lenses in it.
So what will they do? They go to their local shops! But very often someone focusing on the branded segments doesn´ t go into the local shops, because it does not interest him or her. So I tried to explain to the consultant: 85% of all frames sold in this country are sold through the local shops and not trough the smart shops in the main street which sell to the very rich Algerians. That was a big problem we had, trying to make people think of the whole market and not just a little segment of the market. In the end the guy actually said “Mark, that was very good advice because the market is so big and I never realized that the prices were so low!”


How has COVID-19 affected your work?

We star ted on the f irst of April 2020 with having all our orders cancelled. After we got over the initial shock we realized that COVID-19 was bigger than we had thought. It was going to stay for quite a long time. So we thought maybe it is good to have a good set of numbers for 2019, which was the last pre-COVID year. Because companies need to do budgeting, they need to do forecasts, they need to make plans and you cannot really plan on the basis of 2020. Then we had to get in touch with people, but some didn´t answer their phones, because they had business phones but they were not working at that time. So we needed to find new ways to contact the people through social media, at home and so on. But then it worked very well, because a lot of people were at home and they had time to talk to us and were very interested.


How did you measure the influence of COVID-19?

For the bottom-up method we asked consultants in each country in May and June to use a color for the year 2022. And we said: “If you think the market is going to have growth give us green, if you think it is going to go down give us orange or red” and so on. The system was simple. At the end of August we went back to them and we asked them to check their color again. It was interesting that especially in some countries in Europe we got changes in the color because people had seen how the markets had recovered. Furthermore, we used a top-down method. We looked at the data and we said, let´s see what we know about the coronavirus on a country by country basis. A country like Malaysia is less affected by the virus than a country like Austria and we asked, what´s the economic impact of COVID-19?


What are the main differences?

The United Arab Emirates have not had that many cases of COVID-19 but they have a lot of expatriates. Their families have gone home because it is very expensive to have medical treatment in the United Arab Emirates or they haven’t had their contracts renewed and the permit visa is linked to the work contract. If you don´t have a work contract you need to go home. If you look at New Zealand, exactly the opposite happened. There are about fifty to a hundred thousand New Zealanders working in top jobs in the world who have either moved back or are planning to move back to New Zealand during the period of 2020 or 2021. The reality is: if you have lost your job as a banker in New York, then you may decide to go home or maybe your wife says to you “look we earn 300.000 dollars here in New York, the quality of life especially for our children is not that great with COVID-19, but in New Zealand they have done a fantastic job with controlling the coronavirus and even if we only earn a hundred or fifty thousand dollars, the quality of life may be much better at home. So there have been countries that have had a positive effect from corona.


What are you currently working on?

In December, SWV started working on new projections by country for 2022. The reason for doing this is that significant changes have taken place since September 2020: vaccines have now been developed and are being used. Mutations of the coronavirus, which are more contagious, have been found in South Africa, Brazil, and the UK. Many countries in Europe have now entered a strict lockdown. A new president of the USA has been elected, who may inject significant sums of money into the US economy. The economy of China grew by 2.3% in 2020[1]. For these reasons, we are preparing new projections for 2022, which can be compared with the initial projection of September 2020. These projections have been prepared following direct contact with all 63 countries in the study. These 63 countries made up 94% of the world in 2019.


Is there anything else you would like to tell us?

There is one thing we didn’t cover and which is something a lot of people in the optical industry never think about. We always tend to think about progressives or individualized progressives, about all the lovely frames we produce and all the wonderful methods we have. Magazine covers and articles in trade journals like yours are full of theses high-end products. But at the end of the day we are probably just talking to 70% of the world. Because there are a lot of of people in the world who do not earn much money and who can never afford those spectacles – that is something that really concerns me.

Thank you for the interview and these uncomfortable but true words. ◆
[1] Source: Statista (preliminary data published by the National Bureau of Statistics of China).