Abstracts 2010

This is the eleventh conference dedicated to the professionals of the ophthalmic business which is organized by the publisher of MAFO – Ophthalmic Labs & Industry. Taking place in Milan MAFO – The Conference opens its doors on the day before Mido.
Three sections – lab technology, progressive surfaces and lens material & treatment – contain 13 lectures with a high value of pure technical or physical information without any kind of advertising. As keynote speaker we will present Prof. Dr. Holger Dietze, Physiological Optics and Optometry at Beuth University of Applied Sciences, Berlin.

KEYNOTE SPEAKER
Physiological limits to the precision of subjective, objective and aberrometry-based refraction
Prof. Dr. Holger H. Dietze, Germany
Modern aberrometry-based technology promises a higher precision for correcting refractive errors with customised sphero-cylindrical spectacle lenses, and hence improved vision. However, physiological adaptations and dynamic changes of the eye restrict the assumed improvement of visual function and the measurement precision. The talk addresses some prominent and some subtle aspects of optical and neural image formation in the eye. It describes some mechanisms for the neural compensation of an imperfect retinal image and the role of micro-fluctuations of accommodation and higher order aberrations.
Recent research results illustrate the influence of higher order aberrations on vision, the tolerance against ocular defocus and the accuracy and precision of subjective, objective and aberrometry-based refraction under clinical conditions. The precision of some methods of refraction will be discussed with respect to current ISO-tolerances for manufacturing monofocal spectacle lenses.

LAB TECHNOLOGY
Transform your finishing department into a profit center
Andy Huthöfer, USA
As a business owner, your goal is to be as profitable as possible while providing your clients with the best product. The lecturer´s presentation discusses five areas, as well as detailed steps, that can be taken to increase your lab’s efficiency and yields. Huthöfer draws on his experience as an optician and more than 15 years in the optical business to provide you with a clear, common sense approach to transforming your finishing area into a profit center. Topics covered include automation/continuous workflow, using state-of-the-art tracers, complex edging for fashionable sport frames, remote edging, and automating power validation and finish blocking. He outlines how installing a ‘systems approach’ in your finishing department – that is putting all of these components together – will drive your breakage down and your revenue and profits up.

300 years of technological standstill are enough – Welcome to the future of eyecare
Wilhelm Anger, Austria
Over the past 300 years, eyewear has been dramatically transformed from a heavy, unshapely vision aid to a lightweight fashion accessory. Technologically, though, very little progress was made during this period. Rimless eyewear is still drilled, just as it always has been. This technique creates problems such as lens breakage and stresses in the lens, which even the most modern processing technologies have still not eliminated.
The innovative Lensbond system is the first assembly technology that dispenses completely with drilling and opens up new possibilities based on nano bonding. In this lecture advantages of the new technology will be discussed.

Remote lens thickness calculation via WebService technology
Dr.-Ing. Bernd Freyermuth, Germany
This lecture deals with the different aspects of using a powerful state-of-the-art internet communication technology for remote lens calculation. Several important features are described and discussed in details. The usage of the standard protocol SOAP enables a standardized and powerful communication between the client and the webservice provided by a dedicated lens calculation server.
The main target of the approach is a complete decoupling of the analytic lens surfaces’ data generation (by using a respective mathematical model), and the lens surfaces’ data analysis for visualization (the lens model interpretation). This leads to the possibility to decouple the client program from the server program.
Since the webservice technology is an internet standard, any client can easily access the calculation engine from remote to receive the surfaces’ numerical data of any calculated lens, that had been requested by a plausible input data stream previously. He should be able to evaluate this numerical data, belonging to front and back surface, and the reference information of their distance and orientation to each other. By this interpretation of the data a powerful animation of the lens can be implemented, taking also into account any frame shape data.
Finally potential applications of the described technology will be presented by several examples that already run in different labs successfully.

PROGRESSIVE SURFACES
Full field measurement of eye glass lenses in the production line
Dr. Markus C. Seraphim, Germany
‘Phase measuring deflectometry’ is a recently developed tool to measure the local slope of specular surfaces with extremely high accuracy. From these data, the local surface refractive power of progressive lenses can be measured with an accuracy better than 0.01 D. The surface shape can be determined within an accuracy of 3 µm. Full field data with about 105 measuring points are available after a few seconds. Surface defects of only a few nanometers can be detected. Several big eye glass manufacturers are using the device for quality assurance.
The lecturer will explain the measuring principle, as well as opportunities and drawbacks of the new tool. In this context new options to overcome problems occurring by backside reflections will be discussed. They will report experiences of users from the laboratory and the factory.

Ten years Rodenstock individual lens technology – more than FreeForm
Dr. Werner Müller, Germany
With the launch of the first true individual progressive addition lens ‘Impression’ ten years ago, Rodenstock has set an outstanding milestone in modern lens technology. Since then, the concept of individual spectacle lenses has proved to be a success story based on unprecedented optical performance and flexibility in lens designing. Today, over 10 million of Impression lenses have been sold and the Impression family of individual lenses now comprises more than 10 different lens types. In the light of the historic development path, the most important technical fundamentals are explained and the performance benefits of individual lenses are quantified.
At present the ophthalmic expert, unfortunately, is faced with confusing debates and marketing claims using the terms individualisation, FreeForm, wavefront optimisation, personalisation etc. as synonyms for high-end PAL with superior optical imaging properties. However, today true individual lenses with best optical performance are still the exception, because simply using a FreeForm CNC manufacturing technology to produce a back surface PAL is by no means equivalent to the expertise of calculating, optimising and producing a truly individual lens. These differences in lens concepts as well as the most important building blocks of individual lenses will be discussed.

New scientific approach to use wavefront and subjective refraction data for optimizing low order prescription
Jesús M. Cabeza, Germany
Subjective refraction is a well established clinical procedure intended to determine the ophthalmic prescription for correcting the refractive errors of the eye. In this procedure, different corrective lenses are presented to the eye while looking at an optotype chart, until the patient assesses subjectively his/her vision as optimum.
Wavefront sensing, a newer objective refraction technology, made its appearance in the medical ophthalmic industry ten years ago. The added value of wavefront sensing can be summarized as follows:
- More precise assessment of changes in refraction with time
- Measurement of local changes of refraction all over the pupil, giving information about the quality of daylight and night vision
- Determination of phase information of the eye, enabling a detailed analysis of the optical properties of the eye with consideration of physiological phenomena such as the Stiles-Crawford effect.
In this talk the lecturer present a method to optimize the prescription of ophthalmic lenses, where subjective refraction is refined with the information provided by the wavefront measurement of the eye. The resulting ophthalmic lenses lead to an improvement of night vision for many patients.

Evaluation of progressive addition lenses
Bert-Elmar Pawlow, Germany
One of the complaints from some progressive (PAL) wearers is the unpleasant feeling of image deformation while changing the visual direction of the eye. From an optical point of view, this phenomenon is commonly described as an optical aberration called ‘distortion’. However, the classical theory of distortion is based on axial symmetry, which is not given for a PAL. Therefore, the Hoya researcher Dr Hua Qi has developed a new approach to describe such image deformations.
In the first part of lecture, the ‘pros and cons’ of selected simulation techniques (e.g. eye-model camera or computer simulation) shall be discussed in general. Then, a parameter index calculation for point- and dynamic image deformation shall be suggested, based on a differential calculation for very small light ray-bundles and this may deliver an illustration of these mentioned image deformations. The effect of such strange phenomena like that ‘swim and sway’ effect (while wearing PAL) may be illustrated in a generalized kind of way.

LENS MATERIAL & TREATMENT
Waste water treatment technology
Dr. Philippe Pousaz
Various processes in surfacing the lens are source of water pollution: filming-blocking-edging-grinding-smoothing-polishing-deblocking-cleaning of either resin or mineral lenses. Contaminating materials consist of small solid particles which are easy to separate by traditional filtration systems, high alkaline or acidic aqueous solutions and dissolved heavy metals which require efficient reaction with chemical species for sludge formation before filtration. Membrane filtration processes are mainly used to control the fluids generated by colouring the lenses.
The purpose of the lecture is to present concrete applications of waste water treatment technologies used in the ophthalmic industry for both following purposes: elimination of waste fluids to the drain in conformity with the official environmental regulation and ‘on site’ recycling of production fluids for water economy and better surface quality.

Advancements in sun lens performance technology
Dr. Federico Menta, Italy
Intercast-PPG is the leader in the innovation of sunlenses over the last 35 years with more than 40% of the sales coming from products less than two years old. In the lecture a perspective on Intercast-PPG innovation strategy and technology drivers is given. Recognizing photochromism and polarization applied to sun filters as key innovations over the past several years, a technical review of these two performance lens features is also provided. The review will mention the history of photochromic and polarized lenses to provide the right perspective on the recent and next evolutions of these products along with the most common production methods and the science behind them. The main features and benefits to the consumer but also the limitations of the prior or current technologies will be outlined focusing on how the most recent or next developments will generate further improvements of the performances delivered to the user.

Lens materials for sunlenses
Dr. Willem (Wim) Bos, The Netherlands
The quality of the lenses used in sunglasses is much more important than one would suspect. Non-correcting sunglasses may sometimes be perceived as inferior to corrective glasses, but that image is far from just.
Sunglasses are used to reduce the amount of sunlight reaching the eyes and to protect against UV. The light that ultimately passes through the lens, in whichever fashionable colour, must create a sharp, undistorted & clear image on the retina of the beholder. Features like low haze and low dispersion are very important to achieve this, especially because the high intensity sunlight is attenuating any defects or inadequacies of the sunlens material fitted.
At the same time, the lenses should be able to take some punishment. For instance, bending and compressing are usually part of normal handling and should be possible without lens breakage. This is ultimately true for rimless sunglasses.
The combination of all such requirements must be imbedded in the lens material. It should provide perfect vision, but be safe & strong at the same time.

COX – a new non-destructive laser engraving method for organic lenses
Gerold Simke, Germany
FreeForm Lenses require ‘semi-visible’ laser engraving so that the lenses can be edged into the frames accordingly. In the past mainly Excimer and CO2 Lasers covered those tasks.
The obvious advantage of CO2 systems is their low price but due to the 10,600 nm wavelength an infrared heat radiation affects the lenses outside the actual engraving. In contrast, Excimer-based systems ablate the engraving points and lead to a very clean and high-quality engraving. But it is relatively extensive in investment and maintenance. The alternative is the COX laser system. Under the engraving the lens material is neither ablated nor melted.
The new, patented COX system engraves all plastics from CR39 through ‘High Index’ to polycarbonate in a high quality and without heat-affected zone around the actual engraving. Intensity and engraving contrast can be set in a much broader range than for traditional methods.
When comparing investment and operational costs for all three engravings systems, the results seem to be clearly in favour of the CO2 engraving systems. This, however, changes significantly where only 1% of the CO2-engraved lenses are categorized as rejects.
Thus, COX qualifies as the best new engraving method for all kinds of plastics with low investment and consumption costs and a high engravings quality.

‘Slippery when dry’ – surface modification by easy to clean coatings
Teodoro Tarantino, Germany
Surface modification by easy to clean coatings become more and more important in a world of high end glasses. It protects glasses from grease, watermarks, dirt and mechanical stress and provides an added value and additional benefit for your product and your customer. The combination of Cotec´s coating systems and ultra hydrophobic material DURALONUltraTec will leave you with a long lasting coating. The hydrophobic and oleophobic performance will remain the entire lifetime of the lens. The properties are proved by abrasion and contact angle tests. The lecturer accompanies you through trial and development periods, shows measuring methods and offers technical and scientific supervision.