Tinting – from gut feeling to process control

Tinting – from gut feeling to process control

A software-based approach to improve process control in a tinting lab

Automation and digitalization are omnipresent. Their benefits on the shop floor in terms of costs, quality and throughput are well acknowledged. Now there exists a promising approach to introduce a new level of control and predictability to the process of tinting plastic ophthalmic lenses. A software may soon supply the missing quantitative link between the in-process parameters and the outcome, i.e. the color of the tinted glass. By Peter Weber


For this approach, Dr. Klaus Dahmen has merged his years of experience in ophthalmic’s R&D with his background in surface physics to set up a new model of diffusion processes in ophthalmic lenses. In close cooperation with tec5, manufacturer of the well-established TFM spectrometer, he now presents a software, that directly communicates with the TFM. It yields a new intuitive representation of the pigments’ effect in the lens and the results of the tinting process.

Finally, it links spectra (= colors) to process parameters (= recipes) and vice versa. That opens completely new opportunities to make the output of the tinting labs more predictable. In parallel this will stimulate equipment suppliers to keep up with the emerging opportunities of automation and provide a new generation of tinting hardware. Recent developments on the shop floor are governed by automation and digitalization. While the second half of the last century saw the rise of information technology, nowadays we are still far from tapping its full potential. Algorithms, machine learning and artificial intelligence provide great opportunities to better control our production processes and subsequently improve quality, increase throughput and reduce costs. However, progress can only be achieved step by step. Implementation within existing processes needs the courage to invest in new ideas.


Beacon of automation – surfacing

Prime example in ophthalmic industries for a consistent implementation of new concepts is the lens surfacing process. Within the last ten years automation and in-process data acquisition were implemented on many shop floors. Other parts of the ophthalmic process chain lag behind. Implementation of the coaters into a fully automated process chain is an unsolved task. And, most remarkable, the whole tinting procedure of prescription lenses is still a fully manual procedure with only a minimum of automation, data acquisition and systematic process control.


Mostly manual – tinting

One must pay maximum tribute to the operators in the tinting labs. With years of experience, combined with a perfect gut feeling and a lot of patience they manage to create impressive outputs during tinting season year by year. But the other side of the coin: each tinting season is an ordeal, a test to the nerves of operators, process engineers and management. With only a minimum of process control, setbacks in terms of output are more the rule than the exception. Keeping up with delivery schedules puts an enormous amount of stress onto the operators. And whenever setbacks cannot be absorbed, unsatisfied customers are the result. Uncontrolled rework loops create an equally uncontrolled rise of effort and costs. And eventually the planning of manpower in a tinting lab comes close to squaring the circle. Training new operators may take months, and only operators with years of experience and frequent practice can manage the job to its full extent. This severely conflicts with the highly volatile demand for sunglasses over the year, which requires quick and flexible allocation of personnel. With a small portfolio of just a few standard colors, a tinting lab may be well manageable in the “classic” way. But if you wish to exploit the opportunities of the sunglasses’ market to its full extend, you need to quickly adapt to fashion and offer a wide range of colors to be in vogue.


Make tinting predictable

The potential for improvement in terms of stable, reliable, and predictable tinting processes was well known to Dr. Klaus Dahmen, when in mid-2020 he established his own business in the Rhine-Main area (Germany). Based on his years of R&D experience with a global player in ophthalmic industries, he committed himself to the vision of a software, that would establish a sound basis for well-controlled processes in any tinting lab. To accomplish that the gap between process result (i.e. the tinted glass) and process parameters (e.g. pigment concentration, temperature, time) had to be closed. After half a year of theoretical work and programming, and reality-checks with hard-ware expert Jürgen Krall (IPS), in January 2021 the software was ready to be calibrated on practical tests.

Visualization of the effect of tinted glasses on sunlight. Source: K. Dahmen

The approach is based on the characterization of glasses by their transmission spectrum. It embraces the TFM, the ophthalmic standard spectrometer of metrology specialist tec5. Since September Dahmen and tec5 are closely cooperating in aligning interfaces. Shortly the software will be available with direct access to the TFM and respective data.


Merging process and metrology

At tec5 Dahmen’s activities were received very positive. Steffen Piecha, head of Sales, was involved in the TFM’s development (with Rodenstock) from the very beginning. As tec5 is specialized on process analysis by means of optical methods, in his eyes Dahmen provides the crucial missing link to process control, while up to now the TFM was mainly used to ensure compliance with legal regulations or to do sample quality control.

Nikolaus Petzold, Managing Director of tec5, points out that the TFM is a very alive product, getting regular overhauls of the hardware and continuous updates of the software. And thus, the additional customer value of the TFM by means of the new software fits perfectly well into the product strategy. The benefit of the cooperation is mutual, as the TFM is one of the few spectrometers, which measure valid spectra independent of the lens’ refractive power.


About colors and wavelengths

Light is an electromagnetic wave and can be characterized by its wavelength. Our eye is, technically spoken, a sensor for light. And the color we see depends on the wavelength of the light. The detection limits of this bio-sensor, called eye, define the visible range of light, reaching from roughly 380 nm to 780 nm wavelength.

In theory each wavelength is related to a certain color. For example, light of a wavelength of 520 nm would be seen as green by the eye. In nature no single-wavelength light exists, all light is a mixture of wavelengths.
Most prominent example is the sunlight. It consists of all colors of the rainbow, each contributing with a different amount. Our eyes recognize this mixture as white light. If you measure the amount (intensity), by which each color (i.e. each wavelength) contributes, you determine the spectrum, in this case, of sunlight. If you manage to remove a particular range of colors out of the sunlight’s spectrum, the remaining light appears colored. This is what you actually do with sunglasses.


Tinting – a highly complex process

The software calculates color contributions for given tinting times and pigment concentrations to predict the outcome of the process. Source: K. Dahmen

The tinting process is generally based on tree pigments: red, yellow, and blue. The concept is to disperse a certain amount of each pigment in water, put the glasses into the water, and let the pigments diffuse into the surface of the glass. Higher concentration of pigment in the water means higher amount in the glass afterwards. Within the glass certain pigments then absorb certain parts of the sunlight, the amount of each pigment in the glass finally determining its overall color.

As simple as the basic concept may sound, as complex the implementation may become. The pigments are large molecules thus one needs to accelerate the diffusion process into the glass by increasing the temperature of the bath. One may also add chemicals to the water to enhance the diffusion process. Already now you see quite a bunch of process parameters, that finally influence the result, i.e. the color of the lens.
Next, different speeds of diffusion within the lens for different pigments need to be considered. And the fact that diffusion is bidirectional comes into play, meaning that depending on the conditions, pigments may also diffuse back out of the lens into the water. To add further complexity, each different refractiveindex of a lens has its own diffusion parameters. Even different suppliers or different batches may make a difference. For the final impression of the lenses’ color, the depth distribution of the pigments is not of much importance. Only the overall quantity counts for that. But to predict process parameters and the outcome of a certain process chain in terms of color, the depth distribution actually is very important, particularly when talking about rework steps or mixing of light colors on the lens in different baths.

With years of experience operators in a tinting lab get to know their tinting parameters by heart. But nevertheless, for the before-mentioned reasons an industrial process needs a certain level of systematic backup. Dahmen is convinced that his new software approach will not make the experienced operator obsolete but will support him. It will increase and stabilize the output in terms of quality and quantity. Positive side effect: this will improve the working conditions in the tinting lab by reducing stress and taking off unreasonable responsibilities from the shoulders of operators.

The software

As Dahmen illustrates, the basic scope of the new software is to link process parameters to the spectra of tinted lenses and vice versa. As tinting is based on a dynamic diffusion process, his simulations do not only predict the amount of the three different pigments in the lens. One step further, he integrated a model of the time-dependent diffusion process within the lens to heed the distribution in depth. The whole simulation finally consists of three sub-models: one sub-model describes the state of the bath and the respective diffusion process into the lens surface. The second sub-model describes the diffusion process of the pigments within the lens. And finally, the third sub-model describes the resulting absorption spectrum in dependence of the before-mentioned pigments’ distribution in the lens. One basic paradigm shift in Dahmen’s approach is to leave the established path of the 3-dimensional CIE- L*, a*, b* representation, as found in the DIN ISO Norm. As he states, for certain topics the color space is an important model, but it is by far too abstract, to deduce parameters for the shop floor. Instead, he chose a completely new way of describing the “coloring power” of the pigments in a glass in terms of a relative number in percent for each of the three colors. Baseline for these relative values is a set of reference-tinted lenses, where each of the three pigments is applied separately under given standard conditions. These relative values then completely characterize a lens in terms of color with respect to the used set of pigments. Core feature of the software is to calculate these three relative values (for red, yellow, and blue) from a given spectrum or vice versa. Then, with the tree relative values for a spectrum being known, the software can deduce the necessary process parameters, to reproduce exactly this spectrum.



Intuitive visualization of measurement results for the operators: relative contribution of each pigment and its respective specifications for each of the two lenses. Deviations between the two lenses are depicted as well. Source: K. Dahmen

According to Dahmen the software will support and considerably accelerate development of new processes by automatically suggesting recipes for given colors (i.e. spectra). Additionally, the software will be able to reconstruct the necessary tinting process for existing lenses, e.g. for old reference samples. Furthermore, the software can be used for quality control: continuous sample measurements can be evaluated, and statistical envelopes can be generated in the spectrum graphs to represent a wavelength-dependent spread of the process. This leads to production cards which will indicate upcoming instabilities of the process. The software can even quantify the respective amounts of pigments within a measured sample and track them in the same way. In case of color deviations, the software will make suggestions on how to adjust the process to bring it back into specification (i.e. adjustment of pigment concentration, temperature, tinting time). Another prominent application could be the scenario of switching to another supplier of pigments. Based on sample measurements with the new set of pigments the software could calculate new recipes for the future set of pigments from the old recipes.

Or another application of the software: it is well known that the suppliers of pigments suffer from certain batch-to-batch variations. It may be possible to qualify a new batch by tinting standard samples and evaluating the results in comparison to earlier batches. It may even be possible to automatically create suggestions, how to compensate these variations in the process. The systematics of the software may also give the means to align different production sites and make sure that the same sunglasses from different sites actually look the same.
Last but not least, the software will provide support for teaching new operators and will assist experienced operators by comparison of target to actual parameters of the tinted lenses in an intuitive graphical representation.


Status and outlook

Just recently, as Dahmen reports, compatibility testing and validation with the TFM spectrometer was finished successfully in cooperation with tec5. The user can now take control of the TFM, carry out measurements directly out of the software and get full access to recent measurement results and data. This means, that as of now the software with the above-mentioned features is available and utilizable for any owner of a TFM spectrometer. At the bottom line this is a very promising approach to introduce a new level of process control in the tinting labs. Key innovation is the establishment of a link between measured outcomes of tinting, i.e. spectra of the lenses, and the initial process parameters, which actually determine this outcome. The software has high potential to reduce efforts in the development of new recipes, to reduce rework, and, on the whole, to stabilize the processes in terms of cost, quality and output. As Dahmen points out, it will not provide 100% automation of the tinting processes but give support to developers and operators by supplying them with measurable, quantified data, that were never available up to now. Of course, this new approach also opens new opportunities for the manufacturing equipment. Making process results measurable and feeding them back into control parameters will demand for a next generation of hardware with enhanced in-process data acquisition as well as improved means to control the process. ◆


Peter Weber

The author is professor at the University of Applied Sciences in Frankfurt and acts as journalist in the field of science and technology. In the past he managed production and engineering departments in semiconductor and ophthalmic industry. www.connects-by-knowledge.de


Interview Partners

1. Dr. Klaus Dahmen, entrepreneur: expert for tinting processes, surface physics and software implementation.
2. Nikolaus Petzold, Managing Director, tec5 AG: years of experience as head of sales in the sensor business with strong scientific background in optical metrology.
3. Steffen Piecha, Head of Sales, tec5 AG: 20 years of experience with tec5.

Sustainable manufacturing for lens generating

Filtration and waste management started as a means to save companies money by reusing resources through their process. As the world has turned to sustainability and improving our ecological footprint, filtration and waste management technology has evolved, offering equipment that not only helps the environment, but helps the business too. In the optical and lens generating industry, we see this happening at an increasingly rapid rate. By Jamal J. El-Hindi

Optical lens generating requires hefty amounts of water and coolant to maintain clean and precise machining. Like many industries, it only made sense to invest in ways to reuse water and coolant, reducing operation costs.

The Environmental Protection Agency of the United States defines sustainable manufacturing as “the creation of manufactured products through economically-sound processes that minimize negative environmental impacts while conserving energy and natural resources”. Filtration in industry has always been an element of sustainable manufacturing. Although environmental conservation has not always been a priority in manufacturing, filtration has been a means to conserve natural resources and save money.


Filtration — how to deal with waste?

Fig. 1: Bigger labs generate more waste.

Optical is by far not the only industry reusing coolants, oils, water, etc. Filtration among other industries has been a profound part of their process for a long time. So much, that large industries turn to specialized filtration companies to provide entire filtration systems.
In the optical industry, especially in the United States, we have only recently seen a rise in smaller labs expanding in size. This transformation brings all sorts of new obstacles to overcome, making it more practical to implement these same filtration practices from other industries.

Most smaller labs got along just fine without any special equipment for filtration or waste. As a lab gets bigger, however, it generates more waste, or plastic “swarf”. Swarf generated from lens grinding takes up a lot of volume, and as labs grow, we see costs such as garbage disposal, hazardous waste removal, coolant, storage, and water increase.Just the increased volume of swarf alone can cost labs a lot of money, not to mention how much coolant is being thrown away with that swarf. There is often more alloy and spent polish that needs to be disposed of as well. Alloy, being a hazardous material, has to be taken away by specialized hazardous waste companies that treat the waste-water. In some areas polish is also regulated, and must be treated as hazardous material.

These are not only concerning for the bottom line, but they also concern our environment. The waste from making lenses takes up a lot of landfill space. Plastics, such as polycarbonate and other thermoplastics used in lens manufacturing do not decompose for hundreds of years. They are also saturated in coolant if not properly dried, which leaches into the ground. Alloy water and polish compounds cause concern for the environment as well. These have hazardous metals that have contaminated entire sewage systems.
Optical is certainly not the first industry to encounter these hazards. The same issues have been present in several other industries for many years. Filtration specialists have been creating solutions for these issues, and only in recent history do we see some of that technology spreading to the optical industry.

One of the first obstacles to overcome is filtration itself. Filter technology has not only allowed companies to reuse their coolants, but has also provided clarity well enough to keep their equipment running longer. In the optical industry, cleaner coolant means changing the diamond tip tooling less often. The filter must also allow the waste swarf to discharge with as little coolant remaining in it as possible. In most industries you will see the filter with a long, steep discharge ramp. This is to allow sludge or swarf to drain for as long as possible before being discharged. In industries like copper production, we go as far as adding heaters and special reclaiming methods to dry and reuse as much of the waste as possible.


Labs start investing in briquetting technology

Fig. 2: Some labs start investing in briquetting technology.

Copper mills will often reclaim their waste and run it back into their production. Many industries have seen the need to either reclaim or condense their waste. Briquetters or compactors have played a large role in condensing and reclaiming.
The optical industry has recently begun implementing this technology. What started as a means to reduce the volume of swarf waste, quickly became a means to retrieve more coolant. We are starting to see labs investing in briquetting technology as a goal to reduce their ecological footprint and help the environment. This has proven to save manufacturers thousands in coolant costs per month, making it a perfect choice for sustainable manufacturing.
The problem with briquetters, however, is that most are not designed for optical swarf. The first few in the industry were saw dust briquetters, which proved just how difficult lens swarf is to deal with.
After several years of development, there are now some options for compacting swarf and retrieving more coolant than ever. With swarf volumes being reduced to a 20:1 ratio, and squeezing nearly all coolant out of the swarf, this may be one of the most environmentally friendly advances in the industry.

Waste-water treatment

Fig. 3: DAc aqua distill water/waste recycler.

Many industries have had to implement systems for treating their waste-water because of how much they produce. As optical labs grow, so does their hazardous waste production. Some labs simply outsource their waste-water treatment by having companies pick up their hazardous materials. Some labs pour those hazardous materials down the drain. As environmental regulations increase and government focuses their lens on optical manufacturing, optical labs face some tough decisions.


Waste-water filtration systems

Filtration companies have been producing waste-water filtration systems for many years. Most of these systems were designed for much larger industries that typically have more space and more waste-water. All technology adapted to the optical industry must be functional and small enough to fit in an already crowded optical lab. In rising to this challenge, there are now new technologies available.

Fig. 4: Waste water treatment

Waste-water evaporators and waste-water treatment systems seem to be the leading products available to labs currently [Fig. 3, 4]. Evaporators, although they take time and a lot of electricity, are great for isolating hazardous materials and removing them from the water, making hazardous waste a lot easier and less expensive to deal with. Another waste-water treatment system uses a method that large waste-water treatment plants have been using for decades.

They use an environmentally safe clay-based chemistry to latch on to the hazardous materials in the water, separating them entirely. The hazardous material can then be extracted by several different filtration methods [Fig. 5].


Fig. 6: Waste water filtering.

One of the prominent methods is using a centrifuge, which separates and condenses the waste material. This allows each lab to safely discharge the waste-water knowing it is free of hazardous materials. This technology is now conveniently provided as a turn-key system for labs to treat their own hazardous process water, with the benefit of a smaller footprint.


The industry is growing and so are the challenges

As the optical industry continues to grow, there will be more issues to face, especially those regarding our environment. This can be especially difficult when policy, practice, and procedures vary across lens manufacturers.
It is difficult to compete when regulations in every country are different, and enforcement varies. It is critical then, that sustainable manufacturing technology continues to improve so that it not only helps protect our environment, but can be justified in cost savings. As this industry grows, it is on filtration and waste management that the industry will depend on for sustainable manufacturing. Filtration, compacting, recycling and waste-water treatment technology will be necessary so they can follow regulations without consequence.

Fig. 6: 100% recycled content.

As we look to the future of sustainable manufacturing, many are looking beyond simply reducing swarf waste and retrieving coolant. The industry has been asking what we can do with this waste and how to prevent it from ending up in a landfill. Many have been trying to answer these questions, and in the United States there is one group that has an answer. A development that is dramatically impacting sustainability in the lens industry is a new technology that enables recovery and recycling of lens swarf into permanently sustainable products.From its Dallas headquarters, DEVCO Services is currently developing a North American network for recovery of densified swarf. The company’s CEO, Alex Rankin, commented “We are focused on delivering value for the entire lens industry through recovery and conversion of swarf into a raw material used in production of quality products with positive environmental impact.” Their success in developing and selling a product from compacted lens swarf has given hope to the entire industry. As optical labs allow other industries to play a part, we will see more options for a cost-effective means of helping our environment and practicing sustainable manufacturing. ◆


Jamal is a sales and field engineer for Filtertech with a Masters of Business Administration. As the third generation of this family-ownedand-operated company, he started at an early age building filtration equipment. After finishing his college career, Jamal began working as a field operator, fixing and maintaining filtration equipment across the world. With extensive knowledge of the mechanics and technology behind filtration, he began applying his experience in the field to engineering and design. Today, Jamal works directly with companies across the world, finding filtration solutions to meet the unique needs of multiple industries.


Pushing the frontier of automation

Pushing the frontier of automation

Picture by kalhh on Pixabay

Robots and digitalization for stable processes

Robotics is no rocket science anymore. Affordable and reliable modules reveal new views on automation. Experienced equipment-suppliers profit from the opportunities. Based on existing process know-how robotics merges with Industry 4.0 and empowers highly efficient and stable production equipment of the next generation. Labor cost reduction is by far not the only benefit. Automation basically stabilizes processes. Combining it with digital tools and smart metrology, real-time quality data can be generated and processed in an unprecedented way. Feedback of this output into the process will raise the level of process stability and quality significantly. Stable processes and high quality-level are the bedrock of competitive production in high wage countries. In other words: robotics and digitalization are the tools to secure the future of high-quality production sites.
By Peter Weber

The complex process chain in ophthalmic lens production is subjected to innumerable influencing parameters along each single process step. Single deviations of these parameters may sum up to severely reduce the quality of the final product, the eyeglass. Thus, in theory, one gains control of the process by measuring and monitoring each parameter in a control chart and instantly reacting on significant deviations by adjustments.


Automation meets digitalization

Let us consider a very simple example. The control parameter “temperature” is measured by a sensor within a curing oven. This parameter is fed back into the temperature control electronics, which in turn changes the magnitude of the parameter “heating current”. By this the measured temperature is adjusted towards the target temperature. In this case, the process control is straight forward.
Now the next step is, to monitor the more-or-less fluctuating temperature and connect the actual oven temperature to each lens (or batch) in a database. This is the key to connect deviations in quality with fluctuations along the process chain.
The data monitoring is, for this example of a simple temperature-reading, just a technical question of connecting the sensor output to a digital database. Still, if your process depends on many such parameters, the systematic monitoring becomes a challenge.
On the other end of the complexity scale, consider the inspection step of the glasses after surfacing: In that case the measured data do not only consist of a “few” overall parameters. For each glass an enormous amount of data is created, each calling for elaborate algorithmic evaluation. On top of that each glass needs individual handling to be positioned precisely in the sophisticated metrology setup. In this environment, the combination of robotics and digitalization unfolds its full benefit.


Strong process knowledge is a must

We all know that the exact measurement of all parameters along a process chain can never be obtained. And subsequently, the exact control of all influencing factors is not possible. The great challenge in mastering processes is the determination of those parameters which influence process stability the most. Thus, no matter what sophisticated metrology or data-analysing tools you use, the groundwork is sound process engineering with a deep understanding of the interdependencies within and between process steps. This is one core message of Jürgen Krall (IMACO Products and Solutions), based on years of experience in automation: One can only harvest the benefits in the field of robotics and digitalisation with a strong understanding of the processes.


Robots enable real-time process control

Proper understanding of existing processes yields well-defined interfaces for the new approaches of robotics and digitalization. We all know how tedious it can be to control a process based on three-times-a-day handwritten temperature and conductivity tables.
For real-time process control it is inevitable to have all the relevant data available in digital format. Basically, the lab becomes an Internet of things (IoT). Every piece of equipment, every gauge, every sensor needs to be connected to a central database. And, as mentioned before, in many cases this data acquisition on large scale cannot be integrated into the existing process just “en passant”. Many key-measurements require extensive handling. This is the reason why new prospects of robotics and automation open completely new ways for the equipment suppliers.
In the last years, many equipment manufacturers extended their R&D activities into the fields of software and data management. Dr. Christian Laurent, head of development at A&R, reports that just recently his company rolled out a newly developed DataHub in the field. The core of the system is a central database which directly communicates with the lab’s metrology about product quality and constantly feeds these data into intelligent analytical algorithms. By means of automation and digitalization an enormous amount of data can be evaluated statistically in real time, yielding patterns and interdependencies, which in turn can be fed back to control the production process. Fluctuations in the process can be compensated before there is any violation of customer’s specifications.


Glimpse into the handling unit before brush cleaning. Source:J. Krall, IMACO Products and Solutions

Robots master complex handling steps

In the context of merging automation with metrology it is worthwhile, to take a look at the interface between the surfacing process and coating. Krall describes an amazing ensemble of robotics and image recognition. In the past an operator manually moved glasses from job trays onto the conveyor belt of the brush-cleaner. In that movement, by a brief glance, the operator checked the glasses for damages or unacceptable residues after pre-cleaning. In parallel the operator moved the job ticket from one tray to another.
The challenge is the complexity of the seemingly simple human work step. In that case, according to Krall, the solution is a linear system for the ticket transfer, a SCARA (=selective compliance assembly arm) robotic system for the glass handling, and a simple CCD camera system for the inspection. Krall points out that there are a lot of human motion sequences which, in terms of speed, no robot could reach.
The key point in fact is that a robot does a motion sequence always in the same way, independently of factors like personal fitness or the operator’s training. When considering process stability, this is of cause the decisive advantage. And this is particularly eminent for a visual inspection step. Evaluation algorithms for the CCD-data define quantitative and measurable criteria for allowed and not allowed residues or damages. A visual inspection by operators always leaves space for subjectiveness.
Thus, the combination of robotics and software-based camera inspection boosts the quality of the available process data. It is less probable, that unsuited glasses are processed onwards, and the quantitative data can be used for quality tracking and continuous improvement.


Central process-data management: The A&R DataHub collects and shares statistical product and process metrics. Source: C. Laurent, A&R

Robots help create mass data

Another vivid example for automation being the enabler for metrology is given by Laurent. He describes the possibilities of a control chain for the free-form surfacing process. A survey of each glasses’ power-map in automated inspection right after deblocking yields an error map for each single glass. This is a coloured map of local deviations with respect to the target surface. Based on such error maps, design deviation datasets are computed. Primarily this allows to individually tolerate each glass.
But the essential feature in connection with the DataHub is the statistical evaluation of all error maps of all glasses. As the expected (i.e. tolerated) deviation for each position on the glass is not a constant over the whole surface and also differs from glass to glass, it is quite sophisticated to calculate. But by analyzing each individual free-form against the actually measured error-map, smart algorithms can, by application of certain criteria, draw conclusions on the stability of the front-up free-form surfacing process.
By these analytical means it becomes possible, in real time, to trace systematic deviations back to certain process steps, certain machines, and certain root causes, and to instantly adjust the related process parameters in the surfacing process.
To gain even more process control and to improve lens quality, Laurent suggests, to measure the front surface of each semi-finished glass before it enters the free-form surfacing. According to his experience these surfaces tend to deviate significantly from the specifications. On the one hand the free-form parameters for each glass could be instantly and individually adjusted to yield better free-form results. On the other hand, knowledge of the exact initial state of the surface before free-form processing greatly increases the efficiency of the previously described process control mechanisms. Essential Factor for the creation of this enormous amount of data is a smart automation of the complex measurement workflow.


Real-Time Process Control Loop stabilizes lens quality and productivity: Violation of specifications (hor. red line) is anticipated, and corrective actions (after vert. red line) readjust the process proactively. Source: C. Laurent, A&R


Robots support Statistical Process Control (SPC)

Philippe Vaudeleau, CEO of FISA, manufacturer of cleaning and hard lacquer equipment, regards automation as part of his company’s DNA. By now FISA equipment only comes with fully automated processes. Apart from the reduction of labor costs, for Vaudeleau stabilization of processes is the greatest benefit for his customers from automation. Automation is closely linked to digitalization and process data acquisition.

Fully automated in-line cleaner with a combination of two robots and a linear handling system. Sorce: P. Vaudeleau, FISA




The fully automated FISA equipment is designed with a range of sensors to feed all the relevant process data into a central database in real-time. This opens up completely new opportunities for statistical process control (SPC). Process data are directly accessible for evaluation, yielding control charts for everybody in real time, allowing statistical evaluation, and to establish the direct link to the quality data of each respective glass.
Vaudeleau enthusiastically reports about the extra possibilities, which arose at customer’s sites, where RFID-tagged job trays were already implemented. But also for the classic paper production card, the link between each individual glass and the respective process data can be easily done via the classic barcode scanning.


From robots to cobots

As one of the biggest challenges for a company like FISA in the context of robotics and automation, Vaudeleau sees the need to stay ahead of technology. R&D has a strong position in the group, reporting directly to the CEO, with roughly 10% of the company’s turnover going back into the central development site at Milano.
FISA developers rely on a combined strategy of linear handling systems and 6-axis robots (or, more specifically: Cobots). The flexibility and adaptability of the robot is necessary to grab glasses from the tray, lying there in a more-or-less undefined position. The high-precision linear system on the other hand is the proper choice for a critical process like extracting the glasses out of the lacquer. Concerning robots, FISA recently made the step towards cobots.
Collaborative robots are equipped with advanced sensors and safety features that allow humans to work right next to it, while a classic robot represents a severe hazard to human personnel and needs to be kept separately. The rise of cobots, as Vaudeleau estimates, will have significant impact on the degree of automation in ophthalmic industries. For small loads like eyeglasses, cobots are sufficiently affordable and fast enough by now to play a major role.

A&R, FISA and IMACO incorporate decades of experience in the specialized market of eyeglass production. They represent the archetype of equipment suppliers in this segment. Based on their process knowledge, they all heavily rely on three paradigms: First, keep hardware simple to ensure feasibility on the shop-floor. Second, put the complexity into the software and the data acquisition. And third, embrace the new possibilities of robotics, automation, and digitalization to stay ahead in terms of quality and costs. Common expectation is that with cheap, easy-to-maintain, easy-to-program cobots, the remaining gaps of automation along the process chain of eyeglass production will soon be closed.


Interview Partners

[1] Dr. Christian Laurent, R&D Director Automation & Robotics: Manufacturer of equipment for accurate measurements, process control and automation in ophthalmic industry. www.ar.be
[2] Jürgen Krall, IMACO Products + Solutions GmbH: 20 years of experience as general manager in the field of industrial equipment and expert for automation. www.imaco-ps.de/
[3] Philippe Vaudeleau, CEO, FISA Group: Supplier of cleaning and hard-lacquer coating equipment for ophthalmic industry and other fields of manufacturing. www.fisa.com



Peter Weber is professor at the University of Applied Sciences in Frankfurt and acts as journalist in the field of science and technology. In the past he managed production and engineering departments in semiconductor and ophthalmic industry. www.connects-by-knowledge.de

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.




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).

How eyewear goes green – within the realm of the possible

How eyewear goes green – within the realm of the possible

Today every company is talking about becoming sustainable. That is the future. But it is also a demand that many consumers – especially from Europe – and many governments are now making. However, entrepreneurs consider some “green” demands to be unrealistic.
But how does a viable way of making the global frame and lens production more sustainable look like? MAFO has spoken to an expert who knows the eyewear industry like the back of her hand and who leads the way forward into a green future. By Hanna Diewald



How can the optical industry work sustainably and economically at the same time? What is the best place to start as an entrepreneur? Where do you get sustainable raw materials for glasses and how do you differentiate “greenwashing” from really meaningful campaigns? Lene Bille Hoegh knows the answers to all of these questions. She and her husband ran an international eyewear company for years before she decided to found the sustainable consulting agency GreenOpticalPlanet, out of personal conviction. Today their team consists of industry veterans who specialize in advising optical companies on how they can become more sustainable. Bille talked to MAFO about the opportunities and pitfalls of sustainable production and her appeal to the industry to find a sustainable recycling system for demo lenses.


What is your philosophy at GreenOpticalPlanet (GOP)?

Our focus is on the client´s sustainability objectives. We are here to help fill the gaps. Most companies already have their own networks but maybe they need help with more suitable, sustainable raw materials or certificates, or maybe they need the overall view of the United Nations sustainability goals relating to their own strategy. We assist where needed, whilst not staying on board longer than necessary. Our aim is to help the clients move forward and then let them move on to their own green path.

From left to right: Lene Bille Hoegh, Clark Sui Wonders and Michael Jardine.

Our personal GOP philosophy is to try to do quite impossible things within the realm of the possible. There is no 100% sustainable eyewear solution yet, however, by piecing the options together as they are introduced in the market, even helping them emerge, we believe that eventually you will reach some fully sustainable and at the same time truly scalable options.

The planet increasingly needs all of us to change the way we manufacture, transport and consume goods, and this needs to happen sooner rather than later. At the same time the eyewear industry leaders have not really hurried to find green solutions; other industries have lead this way before the eyewear industry.
We think the reason for this is less about unwillingness to change, and more about not knowing where to begin. Therefore we really need people, who actually know the eyewear industry, to band together regarding the sustainability aspect. The future needs sustainable fashion – and the consumers in Europe are asking for it loudly.


How “green” is the eyewear industry already?

Image by Comfreak auf Pixabay

I think everybody in the eyewear industry has started to think about sustainability, but not everybody has implemented it yet. We are still in the beginning of the process as an industry. There are many aspects to a fully sustainable product range. Our experience is that after companies have taken the first few steps, most come to a halt. Many start with greener packaging or sustainable measures at their retail locations. The next step for these companies would be to look at raw materials, manufacturing and freight. Or they have already implemented one type of biobased or recycled raw materials, but have not looked at their storage or retail aspects.
Often it is not unwillingness that keeps a company from taking the next green step – they are simply not confident about which crossroads to take. Should they go with recycled, recyclable, biobased or biodegradable? Each of these choices has their own host of challenges as well as the design and manufacturing processes and locations that need to be taken into account.

The European governments have already taken lots of regulatory steps and the European consumers request more sustainable products, and this forces us all to look for more sustainable solutions. If you look at the North American markets, there are still only lesser parts of the consumer segment and only partial government regulations that cater for change, while other parts of that market are trying to keep the status quo.


If you are trading into the Asian markets, then there are very specific minority groups that are requesting more environmentally sustainable products. In Asia it is actually the governments that have really started to look towards sustainability demands and regulations, as they are looking from a manufacturing point of view, first of all. For example, China issued the “Made in China 2025” report, in which they ask the manufacturers to start producing greener in China. One issue here is that parts of the manufacturing base will just move outside of China, and thus avoide change for another handful of years.
The current global drivers for green change are consumer demands and governmental regulations, and we are seeing both demands emerging more and more strongly. At GOP we urge the third driver, which is the industry leadership, to drive this change and create the sustainability demand from within as well.


What is the biggest challenge for most companies on the way to a sustainable production?

There are challenges and blockers. In our experience the greatest challenge is to have a clear long term plan that will still serve your company´s objectives in 1-2-3-5 years. Another big challenge is the protection against “greenwashing”. This includes the choices of certification, the insight into carbon offset, and the assurance that the chain of custody is not compromised. In our experience the real blockers for many are the restrictions with sustainable raw materials, design processes and manufacturing processes. Considerable compromises have to be made regarding ability, quality and cost compared to the conventional materials and manufacturing processes.

This also requires careful consideration, so that the company chooses the material that supports their type of product best. In our experience choosing the raw material is the key, and so is choosing the best suited manufacturer for that material. The manufacturers are not all alike when it comes to getting the most out of an alternative raw material. That said, there are better and better sustainable raw materials introduced to the market all the time. In particular the chemically recycled materials are promising, as they hold no quality and process restrictions compared to conventional materials, their challenge is the cost structure instead.


Could you please explain the term greenwashing?

The idea of greenwashing is that something looks good and green, but when you look deeper into it, it is not. That means, for example, that somebody simply claims that something is green and when you check the chain of custody you discover – it is just a lie. That is the worst kind of greenwashing.
Another example of greenwashing is when companies try to do good things but they are actually not sustainable, even though they were meant to be, for example ocean-plastic frames. There are wonderful campaigns for eyewear that is made of reclaimed fishnets and ropes, but the production process is often very carbon dioxide and water consuming, and most of the end material does not have the quality you need for eyewear, which creates double waste. In general you end up spending a lot of resources trying to extract and recycle the plastic and then you have to discharge maybe 50% – 70% of the recycled material, because it is not good enough. Basically you end up with a product that is a beautiful idea, but it just doesn’t work.
If you want to go that route it is just smarter to join forces with one of the organizations that work in cleaning up the oceans and simply pay them an amount for each frame sold. That will have a truly efficient impact on the environment.


Which raw material do you recommend the most?

The pros and cons depend on where you are placed in the value chain. At GOP, we currently tend to promote recycled raw materials more than anything else. Because for most companies in the eyewear value chain that is still the most manageable option. For a manufacturer or an optical company, the natural first choice is to transition to raw materials that are already recycled, and to produce recycled-content product and offer this to their consumer. This is what we consider a quick win. This way you have already taken your first step towards sustainability, without having to revolutionize your whole business.
The raw materials we recommend have a relatively low carbon footprint, and we also check whether they are ethical. That is important because you can also get recycled products that actually have a higher carbon footprint than a conventional product. That is not really green!

For an international retail chain or for a trade organization, for example when we talk about demo-lenses and central labs, looking at producing products from conventional raw materials and concentrating your effort on creating recyclable loops post-consumer is a very necessary – but also a much longer – strategy, because it has to be done on a bigger scale, in order to be financially and carbon offset sustainable. It requires taking back infrastructures and localized recycling systems, so it is a much slower win, but also one with a much larger impact when it is finally implemented.


What do you think about biodegradable and biobased products?

This concept of biodegradable has many interpretations. Most biodegradable claims still require a particular environment in order to actually degrade. Instead, a solution would be to work with recycled materials or indeed with materials that are biobased, from simple wood to the more complex processed natural materials. But you still need to consider carefully. There are several levels of sustainability just within the term biobased. For example, you can think you are choosing sustainably when you use castor oil based raw materials, but only some of the castor oil plantations are sustainable, others have taken their acreage from rainforest, in which case it is not really sustainable.


Which are the most important aspects that should change in the optical industry in order to make eyewear more sustainable?

1. There is a truly desperate need to develop both sustainable demo lenses and spectacle lenses, with a clearness, hardness and price that can keep up with traditional products.
2. There is a need for a motivation from the heart to invest in research and develop much better alternative raw materials.
3. There is a need to develop a design ethos that constantly challenges use of material, ratio of waste and also of weight and space for transport. 4. There is a need to understand the differences between recycled and recyclable, and setting up workable loops for both. Recycled is pre-consumer, so we are talking about raw materials and manufacturing scrap programs, whereas recyclable products are on the retailer and the consumer side. For retailers there is a big task ahead in not creating the same level of unsold returns and also in learning alongside their consumers how to consolidate take-back systems that work. 5. In the end everybody has to understand that we probably won’t get eyewear for one and a half dollars anymore.


What should and shouldn´t companies do in general?

No company should work with partners who don’t comply to local and international compliance rules. This goes for clean water, filtration, energy, work ethics, quality or wages. You need to know if the people or companies you work with follow the local standards or not, and if they are committed to even going beyond local standards.
Besides that, when you talk about the manufacturing part of our industry, then the most important thing is that it is certified, because in a good certification program most or all of these things are taken into account, and companies should look to enroll and create constantly better trade standards.
If you are a volume product business and you produce and distribute fast fashion products for a very price-sensitive market, your first step probably would not be to look on the life cycle or responsible consummation. But you can still look to the United Nation´s sustainability goals number six, seven and eight. These goals are about protecting the environment. You can work with how much water you should use, how much carbon reduction you can achieve, and how you can choose different, greener raw materials.

If you are a premium product business, you can do a lot for sustainability in one go. The consumer will see those glasses/brands as an investment, and they normally keep the product for a longer time. Your initial price point is higher, and you can either absorb more cost for sustainable work, or you can even promote sustainable consumption and raise the price for the consumer.


Is it also more sustainable to produce and distribute eyewear locally instead of, for instance, producing in China and selling frames in the USA?


If you produced everything you bought next door, then you would be “hyper green”, but that is not the way things work. It is not financially sustainable. The environment is not the only aspect of sustainability, economic viability and social equity are also important.
There is no problem in making a premium product nearby because you can price up and you can sell it, but if you want to produce higher volume products, then either the consumer has to be willing to pay more or you have to do it in places that work and that also feed families. So, sometimes your best option is to do it in Asia.



What can lens manufacturers do?

For me this is one of the areas where more research and development is required. If you are one of the bigger organization within lenses, than you can definitely invest into research. There are a bunch of big companies that are really investing and trying to find solutions.
And if you have a small business, then you can still put a greener option for your customers into your portfolio. But be very transparent about any issues, for instance when the lenses scratch easier or they are less clear or cost a little bit more. Because those are some of the issues, concerning the options that are in the market right now.
The most important thing is to be ready and willing to try. Just understand that sustainability is the way it is going, and you don’t have to wait before getting on board.

The lesser issue for me is prescription lenses, because they have a longer life. The first and bigger issue is demo lenses, because labs and opticians take them out and throw them away. Demo lenses mainly end as waste in landfills, or have downcycle programs that are too complicated and costly. It is important to find an infrastructure for the central labs. To find a way to send the demo lenses back into the value chain and recycle them, either chemically or manually. Be it into new demo lenses or another product.
Creating take back programs and recycle programs requires optical companies, trade organizations, organizations like our own GOP and maybe even raw-product manufacturers, to all band together with the big retailers, and create infrastructures with pick up points for the central labs. This level of sustainability is not a commitment you onboard alone. It really requires that everybody works together.

Thank you for the interview. ◆



In early 2019 Michael Jardine, Lene Bille Hoegh and Clark Sui Wonders started the consultant service GreenOpticalPlanet. It is their belief that the best possible legacy will be to work to assist all companies in evolving to be environmentally friendly and to support the people involved to become responsible citizens of the Earth. Co-founder Michael Jardine started in the eyewear industry in 1980 as a founding partner of the Canadian TannerEye leather eyewear factory. He moved into developing and exporting high quality eyewear in Japan in the late 80´s and operated as a manufacturer´s agent in the early 90’s in Hong Kong. In 2000, he founded Mondottica, his own eyewear company, developing and distributing licensed fashion brands throughout the world. In recent years, since Michael and Bille, his life and business partner, prepared to exit Mondottica, it has been their wish to give something back to the industry that has been their home for many years. They teamed up with their business partner from the industry, Clark Sui Wonders, and founded GreenOpticalPlanet.