benz quality - benz innovation advanced lens materials...
TRANSCRIPT
Advanced Lens Materials &Manufacturing Technology
Benz Quality - Benz Innovation
On the cover: A drop of pure saline on a machined and
hydrated Ultra O2 Plus lens supported by a plastic mandrel.
This picture shows the advancing contact angle of pure
saline on Ultra O2 Plus material of 22°C.
BENZ RESEARCH& DEVELOPMENT
ISO 13485: 2003File No. A7130
Introduction to Benz Research & Developmentby Dr. Patrick H. Benz, president
Benz Research and Development continues to make technology breakthroughs in both
high performance materials and manufacturing technology. Our company has been in
existence for 28 years and has always focused on developing advanced technology and
materials for the ophthalmic industry. Growing our business by developing superior
technology to make superior products represents my personal philosophy. Today Benz
Research & Development is active in
developing high performance contact lens
and intraocular lens materials as well as
automated manufacturing technologies that
drive market value and reduce costs. • To better
understand the position and expertise that our
company holds as a technology company, please review some of our accomplishments
shown on the following pages. • We believe you will find Benz Research and Development
represents Quality and Performance in both materials and manufacturing technology.
Today, we produce 31 high quality, high performance polymer products. Our Company
remains dedicated to developing advanced technologies that will bring powerful new
products and new opportunities for our customers.
1
This photo shows a
toric base curve with
fully machined edge
and diagnostic marks.
1994
Developed the first and still the only dimensionally stable soft contact lens material that remains 100% saturated on the eye. This familyof performance materials is called Benz-G materials. Today, almost10 years later, there is no othermaterial available to the specialty lens manufacturer that matchesthe on-eye performance ofBenz-G materials. Patented 1995.
Achieved ISO 9001 certification for monomer, and polymer blank manufacturing and development.
1995-96
Developed the first fully integrated automatic lens manufacturing process utilizing micron precision Optical Blocking.
Developed automatic machinery to provide customers, at no additional cost, with blanks containing a precision precut that reduces manufacturing time and expensive diamond tool wear.
1993
Developed and patented worldwide, an Optical Blocking and Inspection machine that delivers micron accurate radius measurement and concentric blocking. Patented 1994.
1997
Developed Benz IOL25 UV, a unique and mechanically superior hydrophilic IOL material. This material allows IOL manufacturers to precisely hit target even at35+ Diopters and create designsthat can be inserted through1.2 mm incisions. Patented 2002.
1998-99
Achieved EN 46002 for the manufacture of custom base curves, lenses and dry polished intraocular lenses using Integrated Lens Manufacturing with Optical Blocking.
Developed the first commercially available disposable lens that remains 100% saturated and dimensionally stable on the eye. This lens material is based on BENZ-G 5X and is called Extreme H2O. This product is manufactured and sold byHydrogel Vision Corporation.
2006-07Introduced Benz-G 4X 54% water G-material, a multi-modality capable high performance GMA hydrogel material designed for use as a molded lens as well as a custom lens.
Introduced Benz Natural Yellow™, a unique compound utilizing nature’s own UV-A blocker and violet light filter. Available in all IOL materials
Introduced Ultra O2 Plus, a third generation high water hybrid GMA soft lens material with a Dk of 50.
2001
Commercialized an automated lens manufacturing system utilizingmicron accurate Optical Blocking.This system is called Integrated Lens Manufacturing (ILM) and can manufacture IOLs and contact lenses with several times the efficiency and precision of normal methods.
2001
Initiated research to develop an automated wet packaging process and high volume moldingprocess for Extreme H2O lenses.The wet process went into production in the fall of 2002. The molding process began production April 2003. Our research and development effort initiated in 2001 has resulted in a complete cast molded lens manufacturing operation for Hydrogel Vision Corporationless than 2 years later herein Sarasota, Florida.
2003
Introduced ILM2, the second generation of Integrated Lens Manufacturing System for fabrication of custom contact lenses, including toric designs.This research and development effort has resulted in a further increase in speed and productivity of ILM.
2004Validated the entire ILM-2 automated contact lens manufacturing system to be compliant with ISO 13485: 2003 standard requirements from blanks to finished lens. This is a state of the art manufacturing system available “turn-key” to our customers.
2002
Developed new process technologycalled ES which results in more durable G-materials.
Developed the first commercial 70% water content soft lens material that remains 100% saturated and dimensionally stable On The Eye. This product, called Aqua 70, is made with ES technology.
2005
Introduced Benz-G 72-HW,a 72% water G-material to replace lidofilcon (NAPALM) Polymers for high water applications. This is the first easily manufactured material in the 70+% water content range that does not contain N-vinylpyrrolidone.
Introduced ILM-3, the second generation ILM for hydrophylic IOL manufacture.
Review ofBenz Research &DevelopmentAccomplishments
15 US Patents
7,067,602
6,627,674
6,599,959
6,566,417
6,555,598
6,627,674
6,517,750
6,267,784
6,265,465
6,245,830
6,242,508
6,096,799
6,011,081
5,891,932
5,532,289
5,080,482
8 US PatentApplications Pending29 Foreign Patents
PRT 99621
KOR 185411
CAN 2043417
JPN 12996777
EUR 0459280
NLD 0459280
CHE 0459280
DEU 0459280
DEU 69114360.9
GBR 0459280
HKG 1007421
GBR 2331754
EUR 1084427
EUR 1083844
DEU 69918108.9
FRA 1083844
GBR 1083844
ESP 1084427
DEU 1084427
FRA 1084427
IRL 1084427
GBR 1084427
4 ForeignPatents Pending1 PCT
1989
Developed the first precision,isotropically expanding polymaconand hefilcon contact lens polymers. These were the first commerciallyavailable materials that allowed soft contact lenses to be manufactured to order rather than manufactured for inventory. This development greatlyreduced the cost of producing custom lenses.
1991
Developed a high volume processto produce precision ground contact lens blanks, where all surfaces are ground, eliminating the need to trim blanks before manufacturing a contact lens. Benz blanks remainthe benchmark of the industryin their precision of diameter,squareness, parallel and thickness.This high volume manufacturing process is operated using Statistical Process Control.
1987
Developed a unique and comprehensive purificationprocess for 2-HEMA monomer that has been the source of raw material for most of the soft lensesproduced worldwide since 1987.
2 3
The On-Eye performance of the lens materials you chose can provide strong advantages for marketing your lens products and give you valuable differentiation in the marketplace. The choice of lens material is an important decision for your business growth.
One of the biggest opportunities available to the custom lensmanufacturer is in the area of high performance soft lens materials and the improvements they bring to on-eye lens performance that patients can see and feel. This opportunity is magnified today because consumer lens manufacturers are heavily promoting silicone hydrogel lenses for daily wear. Our second and third generation hydrogel materi-als offer the custom lens manufacturers a very positive and consistent patient response compared to silicone hydrogel lenses. Lens materials from Benz that exceed the criteria for high performance daily wear lenses are G-4X, G-5X and Ultra O2 Plus. Building a business strategy around these materials makes a lot of sense.
Another opportunity exists because most consumer lenses are still made of first generation hydrogels. This means that most molded lenses are not dimensionally stable. They also shrink, become tighter and lose their initial comfort as the wearing cycle progresses. This makes molded lenses look and feel generic and very similar to each other compared to high performance hydrogels. They all dry out, which means that they all show the following problems as the day progresses: dryness, shrinkage, tightness, reduced visual acuity, reduced oxygen transmissibility and reduced comfort. Marketing lenses made from Benz Second or Third generation materials G-4X, G-5X and Ultra O2 Plus solves these problems and makes for good business because they produce excellent results for the practitioner and noticeable improvements for the patient. High performance hydrogel lenses create a valuable separation between your products and low cost consumer lenses.
Selling Lenses made
of High Performance
Material as a
Business Strategy
Custom Lenses of these materials have the following selling benefits:
1. Lenses provide more than 20 Dk/t oxygen permeability, therefore are High Performance for Daily Wear and support healthy physiology.
2. Lenses remain completely saturated, ON-THE-EYE and maintain Dk during wear.
3. Lenses require no “Settling Time”.
4. Lenses remain 100% dimensionally stable ON-THE-EYE, resulting in excellent visual acuity and fit.
5. Lenses provide the lowest scleral abrasion of any contact lens
These unique selling advantages are supported by reliable data obtained in a controlled clinical environment ormanaged clinical trials by a trained practitioner. All data and best results are available to our customers.
4 5
Five Major MarketingAdvantages of Lenses made of G-4X, G-5XES andUltra O2 Plus Materials
p-HEMA, Polymacon
poly-Hydroxyethylmethacrylate (p-HEMA) is the oldest soft
lens material. This material is familiar to manufacturers world-
wide and relatively easy to fabricate into lenses of modest
performance. Polymacon has a saturated water content of 38%
(in the vial) and loses approximately 10% of its water content
on the eye.
2-HEMA lenses are made mostly in very low cost markets,
most other markets use higher performance lens materials.
p-HEMA/MA, Methafilcon, Ocufilcon, Etafilcon
Copolymers of HEMA and methacrylic acid are the most
commonly used materials for disposable soft lenses and are
typically found in a water content range of 55 - 60% (in the
vial or blister). During wear these lenses lose approximately
10% of their water content and gain substantial protein
accumulation because the positively charged tear protein,
lysozyme, precipitates onto the negatively charged lens.
Because of protein deposits, methafilcon-type materials are
not commonly used for custom lenses outside the U.S.
p-HEMA/NVP, Hefilcon A, B and C
Copolymers of HEMA and N-vinylpyrrolidone (NVP) are some
of the oldest materials in use for water contents below 55%.
These polymers typically contain 25-50% NVP by weight.
They are characterized by a soft “feel”, poor dimensional
stability and a water loss on the eye of 10 - 12%.
Silicone Hydrogels
Silicone hydrogel materials remain an unproven high performance
hope for the custom lens manufacturer. In order to get a true high
Dk (>100) a silicone hydrogel material will typically have a Glass
Transition Temperature (Tg) too low for normal machining and
must be cryogenically machined or molded. Lower Dk silicone
hydrogels may be machinable, but with great difficulty. Once the
lens is successfully made, the surface must be modified by
adding hydrophilic components that “bleed out” during wear or
by altering the surface through plasma discharge. Another
approach is to just call a material a “silicon hydrogel” by adding a
small amount of modified silicone monomer to a high water lens
material. This approach results in a material with a Dk of 50 – 60
and a wettability problem. This is not a real improvement in Dk over an
advanced high hydrogel (Dk 50). Both of these approaches have
resulted in compromises in patient comfort without providing
meaningful performance advantages for daily wear.
p-MMA/NVP, Lidofilcon A, B, C andmodified Lidofilcons such as Acofilcon A and B
These copolymers and terpolymers based on methyl
Methacrylate (MMA) and N-vinylpyrrolidone (NVP) are the
oldest high water materials used for contact lenses. Lidofilcon
materials are found in many versions, which are made by
adding other monomers to the base MMA/NVP formulation.
All lidofilcon and modified lidofilcon materials contain NVP
as their primary hydrophilic component. Lidofilcon based
materials range from 48% to 77% water content (in the vial)
and contain 30% to over 70% NVP by weight. All lidofilcon
based lenses are characterized by substantial dimensional
instability and water loss on-the-eye, resulting in significant
lens shrinkage. Water loss and lens shrinkage compromise
lens fit, lens movement, oxygen permeability and comfort.
Because these polymers bind water weakly, lenses lose 12
-18% of their water content during the first hours of wear.
All commercially available lathe-cut lenses above 60% are
lidofilcon based materials except Benz Ultra O2 Plus.
p-GMA/HEMA, Hioxifilcon A, B, D and the hybrid GMA polymer Ultra O2 Plus
Copolymers of Glycerol Methacrylate (GMA) and 2-HEMA were
the first truly new soft lens materials commercially available to
specialty soft lens manufacturers in the past 25 years. This
unique family of polymers is available in water contents of
49%, 54% and 59%. The GMA hybrid material Ultra O2 Plus is
a Third Generation high water soft lens material introduced in
2007. This completely new material has a water content of
75% on-the-eye all day long. Because these materials lose
little or no water on-the-eye, they remain 100% dimensionally
stable and retain their oxygen permeability during wear. Lenses
made of these materials out-perform other hydrogel lens
materials on-the-eye in dimensional stability, oxygen permeability,
end of day comfort, wettability, scleral staining and visual
acuity. All Benz GMA based materials lose less than 1% of their
water content during wear.
High Performance GMABased Materials
versusTraditional Soft Contact
Lens Materials
6 7
There are basically only two families of hydrogel
lens materials available to the custom lens
manufacturers in the water content range of 48 to
75% water: G-materials and various versions of
lidofilcon material, therefore a comprehensive
comparison of the two families of materials is
essential to understanding the strong selling
advantage of G-Materials. (Methafilcon is used as
a custom lens material only for the US).
100%
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Level of Saturation During Wear
AcuvueG-5XES
87%
99%
100
0
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On-Eye Dimensional Change (microns)
ES70G-5XES
60+% NVP0% NVP
Figure 1
Figure 2
BENZ-G Materials versusLidofilcon based Materials
Composition: Lidofilcon is a USAN (United States Adopted Names) name for a co-polymer of methyl-methacrylate (MMA) and N-vinylpyrrolidone (NVP). This lens material has typically been commercially available ina water content from 50 to 77%. Modified lidofilcon is defined here as a MMA/NVP copolymer with other monomer(s) added. N-vinylpyrrolidone is the primary hydrophilic monomer in all lidofilcon and modified lidofilcons and is responsible for the inherent ON-EYE characteristics of these lens materials. Modified lidofilcons are availablein a water content range of 48 to 72% water.
High performance G-materials are based primarily on Glycerol Methacrylate. Hioxifilcon is the USAN name for the co-polymer composition of Glycerol Methacrylate (GMA) and 2-Hydroxyethylmethacrylate (2-HEMA).The products, G-4X and G-5X are Hioxifilcon D and A respectively. Ultra O2 Plus is a new hybrid polymer with a very high level of GMA and no 2-HEMA. GlycerolMethacrylate is the primary hydrophilic monomer in all high performance G-materials and is responsible for the unique ON-EYE characteristics of these materials. Highperformance G-materials are available in water contents of 54%, 59% and 75%.
These two families of lens materials, lidofilcon and high performance G-materials also behave completely different ON-THE-EYE. Lidofilcon lenses are characterized by large dimensional changes and substantial water loss ON-THE-EYE. High performance G-material lenses show essentially no dimensional change or water loss on-the-eye even at the end of the wearing cycle. Figure 1 shows a comparison of ON-EYE dimensional change of the two types of lenses (lidofilcon A (ES 70) and hioxifilcon A (G-5XES).
The large ON-EYE dimensional change of lidofilcon lenses is caused by two factors, substantial water loss and a significant dimensional change with changes in temperature. ON-EYE hydration levels of high performance G-material lenses and lidofilcon lenses (ES 70) is shown in Figure 2. High performance G-materials are the only custom lens materials that can maintain complete saturation during wear. High performance G-materials have the same water content ON-THE-EYE as in the vial. This critically important ability is missing in other custom lens materials.
High Performance G-Materials versusPopular Disposable Lenses
The great majority of all consumer lenses sold world wide are still made of a first generation hydrogel material, a co-polymer of 2-Hydroxyethylmethacrylate (2-HEMA) and Methacrylic acid (MA). This material has various USAN names: Methafilcon, Etafilcon (Acuvue 2) and Ocufilcon (Biomedics 55). The differences between these ionic hydrogels are minimal, consisting of slightly different levels of MA and different cross-linking compounds. The water contents (in the vial or blister) of these materials range from 55% to 60%.
As disposable lenses these materials are typically used for a maximum of two weeks and are then discarded. During this time the lenses become heavily coated with the tear protein Lysozyme, a positively charged protein that precipitates (denatures) onto the negatively charged lens material. Enzyme cleaners must be used regularly to maintain a clean lens surface. Since these lenses also lose 10%+ of their water during wear, they become smaller and tighter fitting (Figure 3). This shrinkage combined with the protein deposits results in a significant loss of comfort and reduced wearing time for many patients. These lenses also cause very significant irritation of the sclera (Figure 4). Therefore, itis not surprising that most patients noticed a significant difference in comfort in a 4 X 2 week contra-lateral study. (Figure 5).
Any patient that has problems with end-of-day comfortor difficulty obtaining excellent vision regardless of the correction are real opportunities for your custom lens business when you offer lenses made of high performance G-materials.
These second and third generation hydrogels are highly competitive with disposable lenses because of the advantageous properties provided by the high level of GMA in these lenses. G-4X, G-5XES and Ultra O2 Plus lenses out-perform popular consumer hydrogel lenses in: ON-EYE water content, oxygen permeability, dimensional stability, visual acuity, and end-of-day comfort.
Conjunctival staining as shown in Figure 4 using Lisamine Green was much higher for the Acuvue 2 (etafilcon) lenses than for G-5XES (Hioxifilcon) lenses because of the tightness of fit and shrinkage on-the-eye of Acuvue lenses.A contra lateral study of Acuvue 2 (etafilcon) lenses versus G-5XES (hioxifilcon) lenses for patient preference showed a strong preference for high performance G-material lenses (Figure 5)
8 9
Patient Preference
Acuvue 2G-5XES
30%
70%
Conjunctival Staining
Acuvue 2G-5XES
1.2
0.2
Water Content On-The-Eye
Acuvue 2G-5XES
52%
60%
Figure 4
Figure 3
Figure 5
High Performance G-Materialsversus
Silicone Hydrogel MaterialsFor Daily Wear Lenses
Silicone Hydrogel lenses have been heavily promoted for their high Dk in recent years. The money being spent in both marketing and clinical research on behalf of these lens materials is truly impressive. The extensive marketing and the public awareness it is generating is having a strong “pull” effect in the market on both patients and practitioners towards silicone hydrogels which in turn results in custom lens companies wanting to offer custom lenses made from Silicone Hydrogel materials to their customers. Our position on Silicone Hydrogel materials for daily wear lenses is that the efficacy of silicone hydrogels for daily wear should be supported by sound clinical data, not marketing propaganda. The data definitely does not support the assertion that these lens materials are better for a daily wear modality than high performance hydrogel lenses.
Silicone Hydrogel lenses were originally developed for extended wear modality where their high Dk properties are definitely needed during the long closed eye periods of sleep. However, for daily wear it becomes much more difficult to make a strong case for Silicone Hydrogels when the actual measured oxygen transmissibility requirement for daily wear lenses is taken into account.
Currently, most Silicone Hydrogel lenses are being worn as daily wear lenses. This is due in part to practitioners opting to avoid the increased risk of infection of extended wear and the obvious fact that many patients prefer to sleep without lenses in their eyes. Daily wear remains strongly preferred by patients worldwide. It is also preferred by most practitioners because it is a less risky modality than extended wear. Because of the overall preference for daily wear modality in most countries and the fact that custom lenses are essentially all daily wear lenses already, a review of some important clinical facts concerning Dkrequirements for daily wear lenses is definitely needed.
Figure 6. Plot of Corneal Swelling versus Corneal Oxygen Flux at various lens Dk/t Values (Brennan et al, 2001; 20:104-85)Figure 7. Calculated Cumulative Percentage Corneal Oxygen Consumption (% Q) Dk/t for Daily Wear and Continuous Wear (Brennan et al, Optometry and Vision Science, 2005; 82:467-472)
6035 40 45 50 55 65 70 75 80Lens Water Content
G-5X
U-O2 Plus
G-4X
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DK Versus On-Eye Water Content of a Hydrogel Polymer
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Average Lens Thickness (mm)
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Figure 8
The original work of Holden and Mertz in 1984 determined that the minimum requirement for daily wear soft lenses should be a Dk/T of 24. This value was obtained using both published and calculated Oxygen Transmissibility data of various first generation hydrogel lenses. Unfortunately, the Dk values used were for saturated lenses and were not corrected for water loss on-the-eye which is known to be10 - 15% depending on the particular lens material.
Correcting for water loss during wear would bring Holden’s minimum Dk/T value closer to 20. This is precisely the value that Brennan found to be the minimum Dk/T required to prevent corneal swelling using RGP lenses as controls (Figure 6). RGP lenses are not dependent on water content for their Dk, therefore drying out during wear was not a variable. The clinical results of this physiologic effect of a lens’s Dk/T on corneal swelling clearly shows that corneal swelling disappears above a Dk/T of 20 for daily wear.
Another significant clinical study by Brennan determined the physiologic affect of a lens’s Dk/T on the percentage Corneal Oxygen Consumption (%Q) and clearly shows that Corneal Oxygen Consumption is at 100% of its maximum when a daily wear contact lens has a Dk/T of 20 or more. Therefore both of these clinical studies of corneal health, Corneal Swelling and Percentage Corneal Oxygen Consumption (% Q) clearly show that there is no significant clinically measurable Oxygen Transmissibility Benefit to the cornea for daily wear lenses beyond a Dk/T of 20.It seems reasonable based on this important clinical data that 20 Dk/T should be the Oxygen Transmissibility benchmark for High Performance daily wear lenses. Three high performance BENZ-G materials easily meet this Oxygen Transmissibility criteria, G-4X, G-5XES and Ultra O2 Plus (Figures 8 and 9).
When examining the water content versus Dk of a hydrogel lens material it is important to remember that the water content on-the-eye is what is important clinically, not the water content in the vial or blister. A material that does not dry out during wear is an important requirement of a high performance hydrogel because as a lens loses water it “slides down” the oxygen transmissibility curve, losing oxygen permeability as its polymer matrix collapses. High Performance BENZ-G materials maintain their saturation and their oxygen transmissibility on-the-eye.
Figure 8. Dk vs Water Content formulalog(Dk) = 0.01754 (WC) + 0.3897 Young & Benjamin, Eye and Contact Lens, Vol 29, No. 2,2003Figure 9, Dk/T versus average lens thickness
Figure 9
G4X hioxifilcon D
G5X hioxifilcon A
ULTRA O2™ Plus
Figure 6
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Figure 7
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12 13
What makes Benz-G Materials High Performance Soft Lens Materials?
BENZ-G materials are high performance soft lens materials because they are able to stay completely hydrated and dimensionally
stable on the eye as well as extremely wettable. Staying hydrated during wear means that a 54% water high performance
G-Material lens can provide an Oxygen Transmission of 20 Dk/T at 105 microns average lens thickness, and a 75% water
content G-material lens can provide 20Dk/T all the way to 300 microns average lens thickness. This means that virtually any
lens design can be a high performance daily wear lens. No other custom lens material can make that claim because they lose
water as soon as they are placed on the eye. Also, for a custom lens manufacturer, knowing that the precision lens you produced
has the same exact dimension on a patient’s eye has obvious benefits in lens design and fit as well as visual acuity. These high
performance lens properties are a function of the polymer’s water compatibility. Water compatibility is a general term used here
to describe a polymer’s affinity for water as opposed to its saturated water capacity or “water content”. In order to compare
hydrogel materials, a reliable method was needed to predict the ON-EYE behavior of lenses made from hydrogel materials.
During the early 1990’s we developed a method for predicting ON-EYE hydration of soft lens materials. This measurement is
called Relative Water Balance and is defined as the time for a standardized test lens to dry by 10% of its water weight divided by
the time for it to rehydrate, relative to a poly-HEMA control lens. The relative water balance of three high performance BENZ-G
materials compared to other commercial materials is shown in Figure 10. The benefit of the higher Relative Water Balance of
G-material is higher ON-EYE water content, higher dimensional stability, greater oxygen transmissibility and much better wettability.
Wettability is also an important lens material property that affects patient comfort and preference. Unlike the bulk polymer property,
Water Balance, wettability is a surface property and its measurement can be significantly affected by surface active contaminants.
In fact, the current silicone hydrogels on the market all use either an added surface active component or chemically altered surface
to make these polymers wettable. Therefore we have measured the advancing contact angle of pure saline on a very clean lens
hydrated and autoclaved in pure saline. We call this the Pure Saline Contact Angle. The relative difference in Pure Saline Contact
Angle of conventional poly-HEMA based polymers GMA /HEMA copolymers and a high GMA hybrid polymer is shown in Figure
11. As you can see, there is a substantial difference in wettability between these lens materials. The more wettable the material is,
the flatter the drop or the lower the contact angle. For the purpose of material comparison it is useful to examine the percent change
in the pure saline contact angle between each material rather than a particular angle. The contact angle is reduced by 24% in going
from a poly-HEMA based lens to a 54% GMA/HEMA copolymer 54% lens. This amount of change in contact angle may be what is
necessary for patients to consistently have a comfort preference between two materials. In a recent pilot study, 15 patients wearing
GMA /HEMA copolymer lenses (54% and 59%) were introduced to the same lens made from the GMA Hybrid polymer (75%).
The contact angle is further reduced by 27% in going from GMA/HEMA copolymer to the high GMA hybrid polymer, and the
patients preference for the new material was almost total, 14 out of 15 preferred the new material and asked to change their lenses
permanently. This suggests that a 24 – 27% improvement in wettability may be a very strong predictor patient preference if it is
large enough. Go-Materials with their high Relative Water Balance are all much more wettable than conventional materials.
Relative Water Balance Required To Maintain ON-EYE Saturation (Dashed Line)
Ultra O2 Plus
FUTURE
poly-HEMA
PRESENT
p-MMA/VPlidofilcon C
p-MMA/NVPlidofilcon B
p-MMA/NVPlidofilcon A
PAST
G-72HW
G-4X
G-3X
G-5xES
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tive
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poly-HEMA based GMA/HEMA, G-4X24% Lower Contact Angle
High GMA Hybrid Ultra O2 Plus27% Lower Contact Angle
Figure 11
Figure 12 Lens Material: Benz Ultra O2 Plus, 75% Water Lens Material: Competitor Silicon Hydrogel, 74% Water
-24% -27%
The inherent advantage of a very High Water Balance (17) hydrogel material overa silicone hydrogel of similar water content is clearly shown in Figure 12.
Comparison Of Relative Water Balance Ratio With Water Content
Contact Lens Manufacturing Technology
14 15
Benz Research and Development began an ambitious research project during the mid 1990s, to integrate optical blocking technology into a complete precision lens making technology. After over 12 years of development work, investing heavily inequipment, mechanical design and automation software, we have created many new manufacturing technologies that are highlybeneficial to our customers. This significant investment in equipment alone, demonstrates the level of commitment that Benz Research and Development has made to the development of new technology for the manufacturing of contact lenses and IOLs. No other supplier of lens materials is making this kind of commitment to develop the automated technology for your future lens manufacturing needs and providing complete systems fully validated to the ISO 13485: 2003 standard requirements.
The following pages describe in detail many of the products available today from BENZ that have resulted from this research. We continue to work hard to expand the boundaries of lens making technology. Developing superior technology to make superior products forthe contact lens and IOL industry – this is what Benz Research andDevelopment is all about.
16 17
PRECISION DIMENSION
BLANKS
Figure 14
Distribution Plot of Blank Diameter LOT # 03-37-213G3XLBUV
12.684 12.687 12.692 12.698 12.703 12.708 12.714
USL LSL
12
9
6
3
+3.0s-3.0s
Tag
112.690 112.696 12.700 112.706 112.711 12.716
mm
Fr e q u e nc y
Figure 13
Diameter, Thickness, Parallel and Squareness
Figure 15
Distribution Plot of Blank Squareness LOT # 03-36-210G3XHB
-0.0048-0.0032 3.6518e-005 0.0032 0.0064 0.0096 0.0128
USLLSL
16
12
8
4
+3.0s -3.0s
Tag
-0.0016 0.0016 0.0048 0.0080 0.0112 0.0144
mm
Fr e que nc y
The first and easiest step a manufacturer can take to improve his manufacturing efficiency is to use blanks with precise and square dimensions. Benz Research and Development has perfected the technology required to produce millions of precisely dimensioned contact lenses and IOL blanks with state of the art efficiency. Using a precision blank containing a precision precut further improves manufacturing efficiency and reduces tool wear. Precision blanks with a precision precut is a manufacturing technology benefit available to all Benz Research and Development customers, Figure 13. All of our blanks are precision ground to micron tolerances using advanced high speed equipment and Statistical Process Control to guarantee quality.
The distribution plot of blank diameter for a 40,000 piece lot of G-3X low blue UV is shown in Figure 14. This entire lot is contained within a 0.01 mm diameter range.
Precision blank diameter provides an important quality benefit by allowing the manufacturer to use a consistent minimum collet force during base curve machining and blocking. A wide range of collet force, caused by inconsistent diameter, resultsin radial error and asphericity in the hydrated lens. Therefore, non-precision blanks affect your quality.
The precision squareness of Benz Research and Development blanks is achieved by a sophisticated grinding technique using Statistical Process Control. The distribution plot of squareness for a 40,000-piece lot of G-3X high blue isshown in Figure 15.
To fully utilize the manufacturing technology represented by Benz Research and Development precision ground blanks, the manufacturer needs to use similar precision dimensions in the collet of the lathe(s) used for base curve machining as well as the blocker collets. We recommend the Benz Optical Blocker for ultra precise blocking, the Benz Spindle and mandrels for low collet to collet runout.
18 19
The reality of soft lens manufacturing is that hitting the ordered power, cylinder, base curve and diameter specification is of critical importance because there is no such thing as “re-working” a soft lens once it has been machined, hydrated and inspected. The expansion value of a soft lens material directly affects the final hydrated specifications. There is no way to alter the hydrated lens specifications. Therefore, a custom toric lens that does not hit power, cylinder, base curve and diameter is a total loss. Some manufacturers may save the lens, waiting for an eyeball that will match its specifications, but this is an inefficient way to run a manufacturing business. Other manufacturers make only certain base curves and diameters as a way of increasing manufacture efficiency. This is not a true custom lens business and it puts them in competition with disposable lens manufacturers, which means competing on price primarily.
Variability of expansion in hydrophilic materials is causedby variability in the polymerization process. The greater the variability in the polymerization process, the greaterthe variability in the expansion values of the material. Benz Research and Development materials are made from ultra high purity monomer using state-of-art polymer synthesis technique that results in a highly controlled polymerization and a high degree of expansion consistency as well as isotropic. No other hydrophilic materials match the precision expansion and batch-to-batch consistency of Benz materials.
Expansion values can also be affected by induced stress resulting from the machining of the lens. Excessive tool force during machining caused by larger tool diameter, depth of cut, or faster feed than recommended will affect the materials hydrated expansion value. To ensure the highest yield, we recommend that each manufacturer verify the radial and linear expansion values, given for each lot, using their own manufac-turing parameters. Although a minor shift in the actual value may occur due to your unique machining, the distribution should remain tight if recommended procedures are followed.
The cost of not hitting power, cylinder, axis, base curve and diameter in a custom toric lens can be significant. For example, if your total cost of manufacturing a custom toric lens through wet inspection is $10.00 and you produce 100 lenses a day, a 10% loss for not hitting a single parameter is a $100.00/day loss to your business or $25,000/year.
Many manufacturers struggle with this problem because toric lenses are a large part of their business and have multiple critical parameters. The manufacturer can eliminate completely all losses due to material variability by utilizing the precise expansion technology of Benz R & D blanks. Eliminating a significant source of manufacturing variability by simply choosing the right material is real polymertechnology at work.
Benz R & D uses the proven accuracy of Integrated Lens Manufacturing (ILM) to make identical precision test lenses from each lot of material. Each lot of blanks is statistically sampled and 33 identical test lenses are manufactured and carefully tested for radial and linear expansion. Typical standard deviations for radial and linear expansion of Benz materials are fractions of a percent.
To demonstrate how accurately an ordered prescription canbe using Benz precision expansion material, lenses of high expansion G-5XES material were manufactured using the precision ILM process. Tables 2 and 3 show the orderedpower and actual power as measured on a Zeiss-Humphrey lens analyzer.
ISOTROPIC & PRECISION
EXPANSION
Figure 16Table 1 Table 2
Table 3
A
B
C
Expansion A = Expansion B = Expansion C
Validation of Precision Expansion Lot# 0242127G5XHB Sample Power Measurement of Spherical Lenses
Lens Target Spherical Measured Spherical Power No. Barcode Power Material [Diopter] [Diopter]
1 JX70 G5X-ES -3 -3.02
2 JV43 G5X-ES -3 -3.01
3 JZ85 G5X-ES -3 -2.99
4 34Q7 G5X-ES -3 -2.97
5 72Q3 G5X-ES -3 -3.07
6 JV55 G5X-ES -3 -2.94
7 JV52 G5X-ES -3 -2.94
8 BK89 G5X-ES -3 -3.02
9 JZ07 G5X-ES -3 -2.96
Maximum Value: -3.07
Minimum Value: -2.94
Average: -2.99
Benz Research and Development blanks have both
isotropic and precision expansion characteristics.
“Isotropic expansion” means equal expansion in
all directions, e.g., radial and linear expansion is
the same, Figure 16.
Table 1 (below) shows the typical measured
expansion characteristics of two batches of G-3X
material with over 40,000 blanks each.
Product Lot Number Linear Expansion ± SD Radial Expansion ± SDG
3X HB 0339214G3XHB 1.300 ± 0.004 1.298 ± 0.004
G 3X LBUV 0310197G3XLBUV 1.296 ± 0.002 1.301 ± 0.002
Validation of Precision Expansion Lot: 04-01-154G5XLB Sample Power Meassurement of Toric Lenses
order target wet actual dry target wet actual dry dry center 3989 power power cylinder cylinder thickness
1 -5.00 -9.69 -3.00 -5.37 0.149
2 -5.00 -9.53 -3.00 -5.40 0.147
3 -5.00 -9.50 -3.00 -5.30 0.143
4 -5.00 -9.69 -3.00 -5.48 0.144
5 -5.00 -9.51 -3.00 -5.38 0.143
6 -5.00 -9.61 -3.00 -5.27 0.139
7 -5.00 -9.55 -3.00 -5.30 0.138
8 -5.00 -9.51 -3.00 -5.36 0.137
9 -5.00 -9.54 -3.00 -5.31 0.138
10 -5.00 -9.54 -3.00 -5.40 0.138
11 -5.00 -9.59 -3.00 -5.27 0.138
12 -5.00 -9.60 -3.00 -5.32 0.138
13 -5.00 -9.60 -3.00 -5.39 0.132
14 -5.00 -9.51 -3.00 -5.30 0.133
15 -5.00 -9.63 -3.00 -5.36 0.132
16 -5.00 -9.65 -3.00 -5.32 0.142
17 -5.00 -9.63 -3.00 -5.37 0.136
18 -5.00 -9.64 -3.00 -5.33 0.133
19 -5.00 -9.60 -3.00 -5.35 0.132
20 -5.00 -9.77 -3.00 -5.33 0.135
21 -5.00 -9.64 -3.00 -5.31 0.131
22 -5.00 -9.61 -3.00 -5.30 0.133
23 -5.00 -9.67 -3.00 -5.37 0.130
24 -5.00 -9.75 -3.00 -5.31 0.130
25 -5.00 -9.71 -3.00 -5.46 0.122
26 -5.00 -9.81 -3.00 -5.38 0.126
27 -5.00 -9.80 -3.00 -5.28 0.128
28 -5.00 -9.70 -3.00 -5.35 0.125
29 -5.00 -9.72 -3.00 -5.35 0.125
30 -5.00 -9.73 -3.00 -5.26 0.122
MEAN -9.63 -5.34 0.135
STDEV 0.09 0.05 0.007
actual WET MEAN -5.11 -3.06 0.172
actual WET STDEV 0.10 0.12 0.010
20 21
BENZ Ultra O2 Plus, G-5XES, and G-72HW
Environment Control: We recommend maintaining a Relative Humidity range of 35% at 21 ± 2°C
BENZ G- 3X, G-4X, BENZ 38, and Methafilcon Materials
Environment Control: We recommend maintaining a maximumRelative Humidity of 45% at 21 ± 2°C
M A C H I N I N G
R E C O M M E N D AT I O N S
Machining parameters and tool specifications
are very important for optimum surface finish
and reaching precise target every time.
Benz R&D validates the expansion values,
target hitting ability and surface quality of
every lot of Benz materials when machined
strictly according to recommendations.
Diamond Tooling
Tooling Radius
Rough 0.400 mm
Fine 0.300 mm
Edge/Bevel 0.300 mm
Oscillating 0.300 mm
Machining Recommendations for Benz G-4X, G-3X
Base Curve Speed (RPM) Feed (in/min) Depth (mm)
Diameter 10,000 3.0 0.3
Rough 10,000 3.5 0.3
Edge/Bevel 11,000 0.8 0.1
Fine 9,500 0.8 0.09
Front Curve Speed (RPM) Feed (in/min) Depth (mm)
Rough 10,000 3.0 0.35
Fine 9,500 0.65 0.06
Machining Recommendations for Benz 38 & Methafilcon
Base Curve Speed (RPM) Feed (in/min) Depth (mm)
Diameter 10,000 3.0 0.3
Rough 10,000 3.5 0.4
Edge/Bevel 11,000 0.9 0.15
Fine 9,500 0.8 0.9
Front Curve Speed (RPM) Feed (in/min) Depth (mm)
Rough 10,000 3.5 0.35
Fine 9,500 0.8 0.07
Table 4
Diamond Tooling
Tooling Radius
Rough 0.400 mm
Fine 0.300 mm
Edge/Bevel 0.300 mm
Oscillating 0.300 mm
Machining Recommendations
Base Curve Speed (RPM) Feed (in/min) Depth (mm)
Diameter 10,000 2.0 0.30
Rough 10,000 3.5 0.35
Edge/Bevel 11,000 0.4 0.08
Fine 9,500 0.7 0.09
Front Curve Speed (RPM) Feed (in/min) Depth (mm)
Rough 10,000 3.0 0.35
Fine 9,500 0.6 0.06
Table 5
22 23
Precision and productivity have always been key ingredients for the success of lens manufacturing, both contact lenses and IOLs. Today a modern CNC lathe can produce highly complex geometries with ultra smooth surfaces. These lathes provide excellent precision for one step, but once the part is removed from the collet, the precision is lost. Therefore, lathe precision has not necessarily resulted in ultra precision contact lenses because the precision of front side machining is lost during each of three discrete mechanical steps: blocking (2) and second side machining (1). Significant precision is lost during these steps as the part moves from collet-to-collet. Before the total lens manufacturing process can become very precise, collet-to-collet precision repeatability must be improved. We have solved the problem of collet-to-collet repeatability by using technology specifically developed to address the two components of collet-to-collet precision run-out and position.
Collet run-out occurs because the collet’s center of rotation does not match the lathe spindle’s center of rotation. This mismatch of rotational symmetry typically produces a collet run-out of 20 to 40 microns. During the first lathe step the base curve is machined on the spindle’s spin center and with the spindle’s run-out, which is typically in the range of a micron. If the part is removed from the lathe collet and placed back into the same collet, the part’s run-out will be the run-out of the collet relative to the spindle, 20 to 40 microns. This loss in precision is compounded through blocking and front curve machining, (3 more collets). In the Benz spindle the mismatch of the collet to its spindle is eliminated by precision lapping the collet cone into the spindle shaft until reaching the desired collet/spindle run-out.
The second component of collet-to-collet precision is repeat-ability of position. We have solved this by designing a precision dead-length collet and a precision steel mandrel, see Figure 19.
Using this precision dead-length system and precision dimension blanks, it is no longer necessary to measure the position of the surface before beginning first side machining. This saves time on every lathe machining cycle. Figure 17 shows a picture of the Benz mandrel with a precision blank attached and the same mandrel and the centering ring used for wax mounting the blank into the mandrel.
Front surface mandrels are shown in Figure 18. There are 8 color coded plastic mandrels available in order to provide optimum blocking of most contact lenses, including high expansion soft lens materials. The Benz spindle with precision lapped dead-length collet and precision mandrels for soft lens and IOL manufacturing plus blank mounting centering rings are all available as technology products from Benz R & D.
A C H I E V I N G
C O L L E T T O C O L L E T
P R E C I S I O N
Reading # Total Indicated Run-out
1 0.0036
2 0.0038
3 0.0039
4 0.0036
5 0.0036
6 0.0041
7 0.0034
8 0.0025
9 0.0036
10 0.0029
Average 0.0035
STDEV 0.0005
Figure 19
Figure 17 Figure 18
Table 6
0.930 [23.62mm]
0.555 [14.10mm]
Ø0.4995±0.0001 [Ø12.687mm±0.0025mm]
24 25
Recommendations for Soft Contact Lenses:Hydration of lenses made from hydrophilic materials serves two functions. First, hydration transforms the “dry” plastic into a soft hydrogel. Second, it cleanses the lens by removing residuals from the lens. During this process you must follow sterile controls and keep bioburden levels low to ensure no biological growth on lenses while hydrating.
Benz G-3X, G-4X, G-5XES, Ultra O2 Plus:Lenses made with G-materials will hydrate much faster than lenses made from other materials of comparable water content. Place lenses into the Borate Buffer pH 7.2 isotonic saline and allow the lens to sit in solution while stirring for a minimum of:■ Benz G-3X 3 hours■ Benz G-4X 2 hours■ Benz G-5X 1.5 hours■ Benz Ultra O2 Plus 1 hourHydrate for the minimum time specified at constant temperature (T = 20 + 2oC). A minimum 10 ml per lens should be used for hydration.
Benz G-72HW and Methafilcon:A two-step process best achieves lens hydration for this type of ionic material.Step 1: hydrate lenses for a minimum of 14 hours at a constant temperature of 20 + 2oC, while stirring for a minimum of 3 hours.Step 2: transfer the lenses into a pH 7.2 isotonic saline and allow lenses to remain in solution while stirring for a minimum of 3 hours.
After hydration, lenses should be rinsed, autoclaved, and stored in the pH 7.2-buffered saline solution for packaging and sterilization.
HYDRATION OF
BENZ CONTACT LENS
MATERIALS
Two Solutions for G 72-HW and Methafilicon
Carbonate Buffer Borate Buffer pH 8.2; 250 mOs pH 7.2; 295 mOs
NaCl 7.0 grams NaCl 8.01 grams
NaHCO3 1.25 grams H3BO3 2.47 grams
Na2B4O7 0.14 grams
The weights for the buffered saline formulas are based on a 1 Liter Volume
solution. The borate solution shows excellent performance through the
sterilization process (autoclaving) and leaves the lenses free of residue.
Table 7
Table 8
Isotonic Saline
Borate Buffer pH 7.2; 295 mOs
NaCl 8.01 grams
H3BO3 2.47 grams
Na2B4O7 • 10H2O 0.14 grams
26 27
Figure 20
Figure 21
1.280±0.002 [32.51mm±0.05]
Ø0.4995±0.0001 [Ø12.687mm±0.0025mm]
0.870 [22.10mm]
Rad.(C)
0.550 [13.97mm]
(A)
Direct HydrationThis technique allows for hydration of a lens directly from a mandrel eliminating the use of solvents for deblocking and additional handling of finished lenses in the dry state.Preparation for lens hydration starts at the blocking step. During the blocking process, the finished base curve is blocked on to a precision plastic mandrel, using a water-insoluble wax. After front curve lathing and polishing, the plastic mandrel is inserted into the saline solution and as the lens hydrates, it will expand and detach itself from the wax, eventually falling into the saline solution as shown in the sequence above. The lenses are clean and contain neither wax nor solvent residues. Precision plastic mandrels are available from Benz R & D, Figure 20.
The hydration tray is composed of a tray-top with holes cut to allow placement of the plastic mandrel with the finished lens placed face down (to allow immersion in the saline). The tray top is designed to allow the lens mandrels to be inserted while on a table without the bottom tray. The tray-bottom contains polished wells capable of holding about 20 ml of theappropriate buffered saline. The top/bottom fit is designed to have the dry lens fully immersed in the saline and to cleanly release from the mandrel as it expands. Once the lenses are hydrated, the top is removed and inspection, cleaning and packaging can take place. Hydration trays of various sizes are available from Benz R & D, Figure 21.
Figure 22 Table 9
Optical Blocking was invented and patented worldwide by Benz Research and Development in 1994. Since building our first machine twelve years ago, we have greatly expanded the functions and overall ability of the Optical Blocker for manufacturing contact lenses and IOLs. The Benz Optical Blocker today represents the only commercially available blocking interface between base curve machining and front curve machining that achieves accuracy and precisioncomparable to the lathes currently used in the contact lensand IOL industries. The Benz Optical Blocker is designed and built to deliver unequaled accuracy and precision through years of trouble free use. Our original blocker is still in every day use at Benz R & D.
The Benz Optical Blocker provides many manufacturing advantages and can be used as a stand-alone machine operated manually, by robot, or fully integrated into an automated system, Integrated Lens Manufacturing.
Optical Blocking eliminates the common manufacturing problems associated with blocking:■ Prism error■ Edge thickness ■ Center thickness variations
Increased yield with improved quality are the obvious benefits of Optical Blocking. Additional benefits to your manufacturing competitiveness that may not be obvious are:■ Automatically sets toric axis and offset blocks to the ordered cylinder axis to ± 0.5° ■ Automatically provides micron accurate radius measurements of spherical radius as well as major, minor axis of toric lenses and a permanent record of all measurements■ Automatically rejects base curves that do not meet tolerances you set■ Calibrates your lathes for radius and sphere to tolerances that you set and provides a real time process control record of lathe calibration.
The money you currently spend everyday manually perform-ing these steps is saved using Optical Blocking in your manufacturing process. An Optical Blocker that is used in a toric lens manufacturing process is closely associated to the oscillating tool lathe used to produce the base curve toric surface, so that the finished base curve can include a finished edge, front bevel and diagnostic marks (on the front bevel), all of which can be performed during the base curve cycle on the lathe, Figure 16. The base curve can now be blocked on the offset to the ordered cylinder axis. The front curve can then be machined with a common 2,3, or 4-axis machine. No additional oscillating tool step is needed for a custom toric lens.
The money saved in time and equipment alone using this manufacturing approach more than pays for the cost of an Optical Blocker. Market figures show that 70 to 80% of custom toric lenses are prismatically stabilized lenses
Specific Features Of The Optical Blocker1. Measures radius of curvature with ± 2 microns accuracy2. Measures both major and minor cylinder radii with ± 2
microns accuracy3. Positions apex of concave and convex lenses with ± 1
microns accuracy4. Concentric blocking - average max - min variations in edge
thickness of 5 microns, see Table 95. Cylinder alignment on FCM to better than 0.5° accuracy6. Constant center thickness of contact lenses ± 5 microns7. Measures 10° offset radius of curvature for lathe sphericity
adjustments8. Calibrates lathes for radius and sphere9. Provides “dead-length” apex blocking - constant distance
between front curve mandrel base and apex of mounted base curve lens
10. High accuracy decentration for prismatic stabilization for off-set blocking of torics
11. Full suite of DIP and motion control routines for manual lens analysis
12. Includes full automatic, semi-automatic and manual modes of operation
OPTICAL BLOCKING
Calibration Values (X And Y Axis) for a Typical Set-Up Sequence on the Optical Blocker
Note the standard deviation of total position (max-min) repeatability.
Part # Cntr (mm) Y1 (mm) X2 (mm) Y2 (mm) X1 (mm) Max-Min
1 0.158 0.135 0.135 0.131 0.131 0.004
2 0.153 0.145 0.147 0.146 0.142 0.005
3 0.155 0.145 0.146 0.141 0.141 0.005
4 0.155 0.143 0.147 0.142 0.140 0.007
5 0.152 0.142 0.145 0.141 0.141 0.004
AVEG 0.155 0.142 0.144 0.140 0.139 0.005
STDEV 0.002 0.004 0.005 0.006 0.005 0.001 28 29
Figure 23 Figure 24
Integrated Lens Manufacturing (ILM-3) is a lens manufacturing process developed and refined over the past 12 years. Benz Research and Development has spent millions of dollars developing the component systems and automation technology used in ILM. In ILM each lens manufactured has a discrete identity. This identity is defined by order number and the bar code numbers associated with each portion of the manufacturing process:■ base curve manufacturing and blocking■ front curve manufacturing and hydration■ inspection, packaging, labeling and shipping
These three separate bar codes are associated with each lens from the first machining step through labeled vial. All data associated with each lens, including the order, the practitioner, the patient and all manufacturing data from each step is saved in the Oracle 10 database of ILM-3.
The Benz Automation Program is a large C program that coordinates the communication and storage of all data associated with each order including machining parameters created by the front end design program for use in each manufacturing step plus all robotic moves. Figure 23 illustrates the flow of information and instructions including all robot moves and bar code reads coordinated by the automation program.
ILM is designed for robotic handling of parts. Manual part handling can be substituted for robots, but with a substantial loss in productivity. A 2-cell ILM-3 operated at full capacity and using ILM’s validated statistical parameter verification will require approximately 1/5 of the manpower of a traditional manufacturing process. Also, all lathe calibrations for radius and sphere are automatically performed using ILM. This further reduces total manpower because all lathe calibration is done manually in a traditional manufacturing process.
ILM utilizes the following manufacturing technology in a fully integrated system:■ The Benz precision collet/spindle assembly with
Benz mandrels■ The Benz Optical Blocker■ The Benz ILM automation program utilizing an
Oracle-10 database■ Custom ILM part handling robot effectors■ Re-calculation of the front curve radius for every part based
on the actual measured base curve radius■ Real-time re-calibration of all lathes for radius and sphere ■ ILM in-feed and out-feed tracks and transfer tracks with bar
code readers and sensors■ Design front end program for spherical and toric lens
designs that is accessible for further customization by eachmanufacturer
■ Windows-based operator interface for all manufacturingoperations including Order/Entry, Maintenance, Quality Control, Inspection, Packaging and Labeling. Shippinginterface to accounting software for automatic billing options.
ILM Systems Operation:The ILM system has been designed for both function and flexibility. The system can be used in two modes: semi-auto and fully auto, or any combination at the same time. The system allows the process manager to select each machine mode, thereby optimizing operation time and allowing for other functions like maintenance and diamond change, that take a single machine off line while the remaining equipment remains in automation.
Operational Modes:■ AUTO: In auto, the A/PC determines when a lathe or
blocker can be loaded based on whether the robot assigned to that lathe or blocker is ready, whether the part tracks for that lathe or blocker have parts, and whether the out-feed tracks for the lathe or blocker are full. Parts are pre-fetched according to assigned sequences of manufacturing steps within a cell. When either a lathe or a blocker is on its last step of a process, it sends a signal to the A/PC, which in turn signals a robot to initiate the appropriate pre-fetch sequence. A track’s full or empty status is determined by the state of the track’s sensor, which is read by the A/PC software. Barcode readers are attached to each in-feed track for reading the mandrel barcode for the next part in the track. When the track’s sensor indicates a part is in the track and the robot that services the track is activated, the robot will pick up the part from the in-feed track, remove the finished part from the machine, place the next part into the machine and then take the finished part to the blocker or finished lens track. ILM uses both 2 and 3 hand effectors.
■ SEMI-AUTO: in semi-auto, the ILM software controls all machines, the lens design parameters and the manufacturing sequences are coordinated through the Automation Control PC (A/PC), which runs the automation program and contains the database that holds the information that is the basis for all actions within the system. Lathes, mills and blockers operate without robot interaction. The operators use the barcode readers attached to each machine to scan the steel mandrels before placing them in the machine. The A/PC sends the appropriate information to each machine.
INTEGRATED
LENS MANUFACTURING
(ILM-3)
Prismatically Stabilized Toric Lens Manufactured by ILMPrismatically Stabilized Toric Lens Manufactured by ILM
30 31
1. Order Entry &Customer ID
3. Blank Mounting
4. 1st Side OpticsLathing & Milling
(Robotic)
5. Optical Blocking(Robotic)
8. Hydration & or Inspection
7. 2nd Side OpticsLathing(Robotic)
9. Packaging &Labeling
2. Lens Design
6. Deblocking& Cleaning
(Robotic)
AutomationSoftware
& Database
■ MIXED MODE: In mixed mode, the system manager selects which machines will run under which mode, allowing the operator to run in combined/selected modes for purposes of testing, calibrations, maintenance, etc. The operator can take machines in and out of auto mode and run in either semi-auto or manual within the same cell.
The Order Entry (O/E) program allows communication with the system database. O/E is used to enter all production orders and to provide high-level production control, like deleting production orders and sorting the production queues and prioritizing orders for daily production. High priority orders can be introduced into the system at any time, and the A/PC will re-arrange the queue using the priority in-feed and out-feed tracks.
Auto-Lathe CalibrationOne of the unique features of the ILM-2 is auto-lathecalibration. This feature allows for automatic adjustments to be made to all the lathes in the system for radius and sphere. During start-up, two calibration parts are machined on each lathe, one to calibrate and a second to verify both the radius and the sphere adjustments. During the production day, calibration parts can be automatically run on the lathes in the system at an interval chosen by the operator. Lathes can be maintained to tighter operational tolerances using the precision of the Optical Blocker inspection and the auto-calibration feature. All basecurve lathes are 100% monitored because all basecurves are optically inspected before being blocked.An example of a DAC ALM calibration record and all of its basecurve radius measurements is shown in Figure 25.
Productivity of ILM-3The productivity of ILM-3 has been extensively studied at BRD. We have tested a 2-lathe, 1-blocker, 1-robot cell for more than three years, see Figure 26. In the ILM-3 approach, prismatically, stabilized custom toric lenses are manufactured by first machining the basecurve, toric cylinder, complete edge, front bevel and diagnostic marks (placed on the front bevel) all on a DAC ALM OTT lathe during the basecurve operation. After the basecurve step, the part is taken directly to the optical blocker, where the part is optically inspected for major and minor radius and blocked off set from the center to create the prism stabilization. The toric cylinder angle is also set via the blocker rotary table at this time. After blocking the robot takes the part to the automated deblocking and cleaning station.
The robot then picks up the blocked part with cleaned mandrel and places it into the front surface lathe. Finished lenses are placed in the finished lens output track or the priority finished lens output track. The base curve manufacturing cycle time for toric lenses made from Benz-G materials averages 3.5 minutes. This determines the production rate of a single cell ILM-2 system at approximately 17 toric lenses per hour (Figure 27).
INTEGRATED
LENS MANUFACTURING
(ILM-3)
Priority Queuing with priority in-feed and
out-feed is a very useful feature of the
ILM-3 operation, because it allows “priority
orders” to pass through the ILM system in
minutes, to be hydrated, inspected, packaged
and sterilized and possibly shipped the same day.
Figure 26
Figure 27
Figure 25
Single Cell ILM-3
By adding 1 ALM OTT lathe, transfer track and robot to the above single cell ILM-3 system, creating a second 1 lathe cell for front surface, twice as many basecurve operations can be performed in the same time or approximately 34 toric lenses per hour. The number of operators remains the same, only the productivity doubles, see Figure 27.
60.0 µm
40.0 µm
20.0 µm
0.0 µm
-20.0 µm
-40.0 µm
-60.0 µm
RO E
rror
(mic
rons
)
13:00 13:30 14:00 14:30 15:00 15:30
Production Results for Lathe002 Production Error Mean = 1.8 µm Std. Dev + 1.2 µm
Production Calibration Measurement
32 33
Two Cell ILM-3
DAC ALM
DAC ALM
DAC ALM DAC ALM
Robot
DAC ALM
Transfer Track
Input & Output Tracks
Input & Output Tracks
Input & Output Tracks
Deblock & CleaningStation
Deblock & CleaningStation
Opticial Blocking
ILM-3 Performance, toric parameter accuracy:To determine the true accuracy of ILM-3 toric lens manufacturing we have made many tests utilizing 30 identical lens prescrip-tions and measured each lens both dry and wet on the Zeiss-Humphrey Lens Analyzer. We also calculated what the wet power should be from the measured dry power and compared this to the actual measured wet power. The results of two of these tests are shown in Table 10.
As the data clearly show, the accuracy and precision of ILM-3 in toric lens manufacturing is extremely high, especially when you consider that half of the measured standard deviation of sphere and cylinder measurements is due to lens analyzer measurement error. The error of axis measurement is too great to measure the Optical Blocker axis error but is definitely less than +0.6°.
Validation of ILM-3 to ISO 13485:2003For validation tests, we have used actual prescriptions from a group of participating practitioners and the orders were processed as received with no batching or arrangement of parameters for manufacturing ease.By manufacturing a wide range of parameters, as received, we validated the average yield and reliability of ILM-3 to such a statistical assurance level that parameter inspection is elimi-nated, only statistical verification of parameters is required. The validated range of parameters are:
Spherical Lenses ±25D
Prismatically Stabilized Toric Lenses Sphere ±25D Cylinder 8D in .1D increments Axis 0-180º in 1º increments
The distribution of parameters of the lenses made from actual prescriptions is shown in Figures 28, 29 and 30.
To operate ILM-3 as a no inspection process, a series of verification lenses (2-4) are run at three different times during the day: 1) immediately after system calibration at start-up 2) at mid-point of the production day and 3) at the end of the production day. These lenses are parameter verified, which in turn verify the entire day’s production. The ILM-3 has passed FDA inspection for statistical parameter verification.
INTEGRATED
LENS MANUFACTURING
(ILM-3)
Test No. 1, 30 Lenses, G5XLBWet Sphere Power: -3.00 Wet Cylinder Power: -1.50 Cylinder Axis: 50°
Sphere Cylinder Axis CT Major R Minor R (D) (D) (°) (mm) (mm) (mm)
Dry Mean -5.33 -2.85 49.8° 0.161 5.702 5.541
Std. Dev. 0.09 0.07 0.6 0.004 0.003 0.004
Calc. Wet -2.96 -1.58 NA
Actual Wet -2.97 -1.56 50.1
Test No. 2, 30 Lenses, G5XLBWet Sphere Power: -6.00 Wet Cylinder Power: -3.00 Cylinder Axis: 90°
Sphere Cylinder Axis CT Major R Minor R (D) (D) (°) (mm) (mm) (mm)
Dry Mean NA* -5.23 980.2 0.113 5.701 5.374
Std. Dev. NA* 0.08 0.8 0.002 0.005 0.005
Calc. Wet NA* -2.91 NA
Actual Wet NA* -3.01
*These values were not available due to a problem with the Lens Analyzer
Figure 29Figure 28 Figure 30
Table 12
Actual Yield of Prescription Lenses for Validation Test
QUANTITY MADE QUANTITY YIELD PERCENT YIELD
637 602 94.5
Validation Test Validation Test
0.00
-0
,20
-0.5
0 -0
.80
-1.0
0 -1
.20
-1.5
0 -1
.80
-2.0
0 -2
.20
-2.5
0 -2
.80
-3.0
0 -3
.20
-3.5
0 -3
.80
-4.0
0 -4
.20
-4.5
0 -4
.80
-5.0
0 -5
.20
-5.5
0 -5
.80
-6.0
0 -6
.20
-6.5
0 -6
.80
-7.0
0 -7
.20
-7.5
0 -7
.80
-8.0
0
100
90
80
70
60
50
40
30
20
10
0
Cylinder Powers (D)
Num
ber o
f Len
ses
Cylinder
Lens Distribution by Cylinder Powers Lens Distribution by Spheric Power (Dpt)
12.0
0 11
.50
11.0
0 10
.50
10.0
0 9.
50
9.00
8.
50
8.00
7.
50
7.00
6.
50
6.00
5.
50
5.00
4.
50
4.00
3.
50
3.00
2.
50
2.00
1.
50
1.00
0.
50
-0.5
0 -1
.00
-1.5
0 -2
.00
-2.5
0 -3
.00
-3.5
0 -4
.00
-4.5
0 -5
.00
-5.5
0 -6
.00
-6.5
0 -7
.00
-7.5
0 -8
.00
-8.5
0 -9
.00
-9.5
0 -1
0.00
-1
0.50
-1
1.00
-1
1.50
-1
2.00
60
50
40
30
20
10
0
Num
ber o
f Len
ses
Spheric Power (D)
Product Distribution by Cylinder Axis
Cylinder Axis (degrees)
Num
ber
of L
ense
s
0 90 180
50
45
40
35
30
25
20
15
10
5
0
34 35
There were no losses due to parameter errors
Profitability of ILM-3Installing an ILM process is not inexpensive. However, the return on investment is very substantial, particularly if your company has a significant business in custom soft toric lenses. Using the worksheet shown in Table 11, you can determine the appropriate gross profit potential from a 12 hour day, operation for the ILM two cell configuration shown in Figure 31. This configuration has a productivity of 338 lenses per day at 94+% guaranteed yield in the vial using G-4X or G-5XES material. The maximum per day gross profit can be calculated by multiplying the Yield, Average Sale Price of lenses made and Total Blanks (360) and subtracting the Direct Costs (Table 11).
Per day profitability Formula for Single Cell ILM-3(total yield x ASP) – Direct Cost =PROFIT (338 x $25) - $1,349.00 = $7,101.At 80% capacity the profit per day is(271 x $25) – 1188 = $5,587.
ILM-3 software allows for unlimited expansion of the number of production cells. The 2-cell system shown in Figure 31 has the capacity of 338 custom toric lenses per 12 hours of operation (including 1 hour for starting and calibration). The ILM-3 system for 700 lenses per day is a 3-cell system (not shown), consisting of 2-cells as in Figure 25 and 1-cell with 2-DAC ALM lathes. The labor to run these larger systems remains the same as the single cell.
The ILM-2 Quality SystemThe Benz Integrated Lens Manufacturing Process (ILM-3) was developed with quality products in mind and is part of the overall Quality Management System of Benz Research & Development. ILM-3 is compliant with the stringent quality system requirements of ISO 13485, which embraces the principals of good manufacturing practices and quality system regulations. These quality standards and regulations satisfy the specific quality management requirements for the development and manufacture of medical devices.
As a result, ILM-3 is a fully documented, controlled and validated process that delivers a product of consistently high quality. ILM-3 is a turn-key process for the manufacture of prismatically stabilized toric lenses and spheric lenses. ILM-3 is fully validated for automated manufacture of toric lenses to +12.0D of sphere and up to 8.0D of cylinder with the toric axis in 1o increments 0 to 180o. Spherical lenses are validated +25D. ILM-3 is validated for statistical sampling parameter verification.
INTEGRATED
LENS MANUFACTURING
(ILM-3)
38 39
Table 11
Direct Cost Of ILM-2 Custom Toric Lenses Using The 2-cellConfiguration Operating At Capacity On A 12 Hour Day Basis
Item Description Per Day *Cost at Cost ($) 80% of Capacity
Cost of blanks as (G-4X) 360 @ $1.18 425 340
Operators 2@15 Hr. +20% 288 288
Average Total Cost 6 relaps + 1 tool wk 92 74
Diamond Tool Cost
Average Other Materials Wax, Saline, Vials, 130 104
Stoppers, Labels
Visual Wet Inspection 1 @ $15 Hr. +20% 144 144
and Vial Preparation 100% visual inspection
Including Autoclave statistical parameter
and Label verification
Sub Total 1,079 950
Daily Overhead Direct Cost x .25 270 238
Total Direct Cost 338 lenses (*271 lenses) 1,349 1,188
Total Direct Cost Per Lens 3.99 4.38
Figure 31
Lenses Sold Per Day
Ave
rage
Sal
e P
rice
$150
$140
$130
$120
$110
$100
$90
$80
$70
$60
$50
$40
$30
$20
$10
$0
50% Gross Margin
66% Gross Margin
75% Gross Margin
80% Gross Margin
50 70 90 110 130 150 170 190 210 230 250 270 290
Gross Margin Based on Direct Cost Only at 80% of Capacity
This table includes total cost, blank to inspect, packaged lens ready to ship
In today’s highly competitive environment of consumer contact lenses,it is more important than ever to clearly differentiate the benefits of your company’s products and services from those of the disposable lens companies. This is essential for growth as well as holding onto your lens price in today’s market. Benz Research and Development offers materials and technologies that can dramatically impact your ability to favorably differentiate products and services for bothsmall and larger market businesses.
For a custom lens business selling 100 to 200 lenses per day, your business must focus on high value added lenses such as custom toric, multifocal and any special lens for medical practices. You can increase your position in this value oriented market by making these lenses from G-4X, a material that is easy to machine, inherently more comfortable to the patient, dimensionally stable to give superior visual acuity and meet the 20Dk/T criteria (at 105 microns). Offer the higher performance G-Materials G-5XES and Ultra O2 Plus only if you can meet the environmental constraints of these materials and sell them into high value (high selling price) markets along with an excellent warranty. You can increase your quality and toric lens manufacturing efficiency by adding a Benz Optical Blocker which is about the cost of a DAC ALM OTT. You can also add auto loaders to your basecurve (toric) lathes and run part of your toric manufacturing at night, unattended to reduce labor cost per lens.
For the custom lens manufacturer that is selling 200+ lenses per day there are additional advantages provided by Benz materials and technology. All high performance G-materials can be offered as quarterly replacement totally custom lenses by investing in ILM-3. The G-4X material can be offered inconventional (1 year) or quarterly modality and the G-5XES and Ultra O2 Plus can be offered in eitherquarterly or 6-pack per year modalities because your total direct lens cost is approximately $5/toric lens.Make all your G-material spheres and torics on ILM-3 and the same operator monitoring production on ILM-3 can manufacture multifocals and others such as bi-torics using an DAC ALM OTT with an auto loader. This is very efficient manufacturing of very consumer friendly lens materials and modalities. All Spheres and torics can be shipped within two days using this manufacturing approach – we guarantee it! A strong reputation for fastdependable service will further enhance your product’s value.
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