varilux (progressives in the digital age speaker notes)

Progressive Design in the Digital Age

-Pete Hanlin, ABOM

This presentation has been submitted to the American Board of Opticianry for one hour of continuing education credit. These notes and slides are being provided to educators and speakers for use in Essilor sponsored presentations. Use of these descriptions, images, and slides in other presentations is permitted (and encouraged), but any alterations to the content of this presentation should be approved by Essilor of America. Please contact Pete Hanlin at [email protected] if there are any questions regarding the information or use of this presentation.

Overview

Importance of the Design

Potential of the DS Process

Design Formats & Capabilities

Introducing

Introducing


Design is everything!

...poor design leads to poor

performance...

(Somehow, designer forgot to leave his name on the base...)

There was nothing wrong with the PROCESS used to build the Tower of Pisa. However, the DESIGN did not take into account the foundation necessary to keep the structure stable. The lesson being even the best processes do not deliver performance in the absence of a good design!


New processing technologies do enhance great designs...

...but they cannot make an

average design exceptional!

That said, a good design (content) CAN benefit from new technologies. Avatar is the most profitable film of all time, and part of its magic is created by the extremely high definition provided by modern advances in audio/visual technology. However, those same advances will not "improve" the quality of a mediocre film (such as Waterworld). Other than improving the sharpness of Kevin Costner's gills, viewing Waterworld is still going to be a 3 hour beating!


There are several fundamentals a PAL design must provide- to name a few:

–Natural Reading Posture (rate of progression)

–Properly Placed Near Zone (correct inset)

–Binocularity (balanced peripheral vision)

–Central Focus (sharp vision in all zones)

–Natural Reading Posture (rate of progression)

–Properly Placed Near Zone (correct inset)

–Binocularity (balanced peripheral vision)

–Central Focus (sharp vision in all zones)

The foundation of a great PAL design is built of the following blocks: Natural Reading Posture- the wearer must be able to hold his head in a natural posture while reading through the lens Proper Near Zone Placement- when the wearer is reading, the near zone must be properly placed in front of the eyes (and this position is different for each wearer) Binocularity- the eyes must be able to work together, which requires binocular balance in the periphery- when binocularity is challenged, depth perception is lost Sharp Central Focus- the central zones of the lens must provide sharp vision- this is the #1 expectation of progressive wearers.

Natural Reading Posture

Natural reading posture characteristics:

Head tilts down 40°

Eyes vertically scan 15°

PALs should require at most 25°downward gaze

No Eyewear Non-Optimal PAL Optimal PAL

The "natural reading posture" of a person who does not wear correction uses a downward gaze achieved almost solely through head movement. The subject looks down at an angle of about 45 degrees, and uses eye movement primarily for scanning the length of the document. Once the head makes its initial movement, it rarely varies from that position by more than 5-10 degrees. Most progressives require the wearer to reduce the amount of downward head gaze- relying instead on eye movements. This creates an unnatural posture in which the eyes are looking downward 30 degrees or more. Additionally, the head must be moved when moving from the top to the bottom of a printed page. Although most wearers will eventually "get used" to this position, it will never feel completely natural. All Varilux progressives allow the wearer to move the head downward by 35 degrees or more. The result is less than 25 degrees of downward eye gaze. This is important for reasons described in the next slide.

Natural Reading Posture

The ideal progression length is around

12mm to 85% of the ADD power

>12mm requires eye to look downward >25°

<12mm increases peripheral astigmatism

Patent FR 2 699 294 "...a very low sphere gradient for a

so short power progression and a maximum gradient

value located in the intermediate vision zone"

The graph on the left shows the amount of effort which must be exerted to hold the eye in position. As you can see, when the eye is in a position within a range from straight ahead to a downward gaze of just under 30 degrees, there is no effort required. Since 2 degrees of eye movement causes the visual axis to travel approximately 1mm across the lens, this means the eye can look about 14mm down the lens without effort. This is important, because it is unnatural to hold the eyes in any position requiring effort (try looking down at the floor without moving your head- if you keep looking down you will feel your head being "pulled" to the floor). All Varilux lenses provide 85% of the ADD power in about 12mm or less. In most reading positions, 85% of the ADD power is required to see the top of a normal page. This means the Varilux wearer can read a page without exerting any effort. This is what is meant by "natural reading posture." During the development of Varilux Comfort, Essilor R&D discovered an algorithm which provided the lowest level of peripheral astigmatism for any given progression length. This algorithm was patented and has been used in all subsequent Varilux designs.

Properly Placed Near Zone

The near zone must be optimally placed

Convergence inset is determined by:

Prismatic effects of the Rx

Convergence required at focal length of ADD

0.75 1.00 1.25 1.50 1.75 2.00 2.25 2.50 2.75 3.00 3.25 3.50

BASE ONE 1.81 1.92 1.98 2.09 2.29 2.29 2.29 2.29 3.05 3.05 3.05 3.05

BASE TWO 1.94 2.03 2.09 2.09 2.29 2.29 2.29 2.29 3.05 3.05 3.05 3.05

BASE THREE 2.09 2.09 2.09 2.09 2.29 2.29 2.29 2.29 3.05 3.05 3.05 3.05

BASE FOUR 2.69 2.71 2.72 2.74 2.80 2.95 3.11 3.21 3.51 3.72 3.90 4.10

BASE FIVE 2.92 2.94 2.97 2.99 3.00 3.04 3.29 3.39 3.70 3.90 4.17 4.30

Patent FR 2 683 643 "...a near zone which gets higher and

more nasally decentered with the increase of the addition"

Even the "widest" progressive designs have a spherical reading zone that is much narrower than a FT28 bifocal. To ensure the wearer receives a suitable width of clear near vision, the reading area must be centered in front of the eye when the wearer is viewing at near. Essilor progressives accomplish this by employing a variable inset. The primary factors used to determine the correct inset are the focal length of the ADD (which determines the optimal reading distance and therefore the amount of convergence). The amount of prism generated by the distance Rx and ADD power is also taken into account (since prism influences convergence as well). Subsequently, all Varilux designs feature an inset that ranges from under 2mm per eye to over 4mm. The concept of a varied inset was patented during the development of Varilux Panamic.

Binocularity

The optics of a PAL must be similar in every

viewing position

The eyes must work together to maintain stereopsis (depth perception)

A progressive must also not interfere with binocular vision. When the eyes are presented with disparate images, one eye is "suppressed." The result is the loss of stereopsis, or depth perception.

Dissimilar Similar

Binocularity

Even low levels of astigmatism will disrupt

vision if it is imbalancedThe visual system can handle peripheral aberration- as long as it binocularly equivalent

Patent EP 0 994 375 "...a very low difference in sphere for two corresponding

points of the right and left lenses, and this for all points of the space"

Varilux designs support binocular vision by providing "balance." This is important because when the eyes view through the peripheries of the lenses they are looking through opposite sides of the design. If the optics of each lens are not similar, binocularity is challenged. The images show the level of difference between each point in the lens. Each image represents the level of similarity throughout the lens. A pair of plano SV lenses would be primarily white across the entire graph. The lenses on the left represent an unbalanced design, the lenses on the right represent Varilux Panamic (this design concept was patented during development of Varilux Panamic).

Central Focus

The central zones of the lens must provide

sharp focus

Astigmatism is usually located in the periphery

Higher order aberrations (HOAs) reduce

sharpness in the central zones of a PAL

A lot of attention is given to the control of peripheral astigmatism, but there are also aberrations in the central area of a progressive lens which must be controlled. These are higher order aberrations (the most notable being coma), and although they do not disturb acuity, they do decrease sharpness (expressed as contrast sensitivity). These aberrations are perhaps most noticeable to emmetropic presbyopes and low ametropes. These patients sometimes refuse to wear progressives during distance vision- because the higher order aberrations reduce sharpness. They literally "see better" at distance without their eyewear!

Central Focus

Control of the wavefront results in the

sharpest possible central vision

W.A.V.E. Technology™ provides clinically proven improvements in vision

Patent FR 05 07378 "In a wide angular zone (150 to 160) with a vertex 4 below the fitting cross, the high order aberrations, including coma, are

reduced, allowing a clear far vision zone. At the same time, the near vision

zone is easily accessible at 25 of gaze excentricity downward"

Varilux Physio Comp A Comp B

Varilux Physio and Varilux Physio Enhanced control higher order aberrations in the central zone of the lens. The images depict the wavefront produced over a 6mm area (the center dot is at the FRP and the other dots are 2mm in each direction). This technology is called W.A.V.E. Technology (the customized form being called W.A.V.E. Technology 2), and has been clinically proven to provide measurably sharper vision compared to non-wavefront controlled PAL designs. The results of these clinicals have been reviewed and approved for presentation by several professional associations including the AAO. The application of wavefront correction to progressive design was patented during development of Varilux Physio.


ALL of the fundamentals of design can be delivered by ANY processing format:

Traditional Surfacing

Digital Surfacing

All of these foundational design aspects can be delivered using any processing format- including traditional surfacing. In a age when digital surfacing is being promoted, it is important to remember that the foundations of a great PAL are found in these design concepts- not in the way the lens is processed.

Potential of Digital Surfacing

Limitations ofTraditional Surfacing

•Tooling required for each shape

(designer is limited by # of tools)

•Tooling limits accuracy of lens

•Only one surface can be used for

the progressive design

Solutions of

Digital Surfacing

•Tool can create unlimited shapes

(designer is not limited by tools)

•Tool is exceptionally accurate*

•Both surfaces can be used for the

progressive design

So if the foundation of a PAL's performance is the design, what does DS contribute to performance? There are three primary limitations associated with traditional surfacing which will be detailed in the following slides. First, traditional surfacing is limited by the use of physical tools- which limit the number of surfaces which can be created by the designer. These tools also limit the accuracy of the distance portion of the lens due to "rounding." Finally, traditional surfacing cannot place a design on the rear surface of the lens, so only one surface can be used for design. NOTE: Remember to go in a "Z" pattern on this slide- cover the limitation and then the solution, then the limitation followed by a solution. The asterisks beside "accurate" on the digital side is just to get them thinking (we'll be talking about the necessity for process control later).

How Digital Surfacing Works

A DS generator is similar to a lathe

Lens starts as a block of material...

...a single point cutter

removes material from the spinning blank to create a 3D surface...

...finished surface can

be virtually any shape-with the potential for great precision.

In digital surfacing, the cutter is precisely controlled by motors which follow a path contained in the form of a computerized (digital) file.

There’s nothing "magical" about digital surfacing. It is just a way to make a product, just like a woodworker uses a lathe to shape a bowl from a piece of wood. The control in the case of the lathe is limited by the woodworkers skill. In digital surfacing, the lathe is controlled by equipment which relies on a computerized path. The important point being the digital surfacing process does not- in and of itself- add anything to the design of the lens.

Increased Tool Capability

Traditional Surfacing is limited by physical tools

Molds for complex front surfaces

Laps/Tools for simple back surfaces

Digital Surfacing uses "digitized" tools (digital files)

A virtually unlimited number of shapes can be produced

Designer is free to create an ∞ number of surfaces

DistancePower

ProgressiveDesign

Distance Power and/orProgressive Design

Traditional surfacing uses physical tools (molds and laps/tools). Therefore, the number of designs is physically limited (it is impractical to create millions of different tools to create different surfaces, so the designer is limited to 144 molds and a 1,000 or so laps). In DS, there is only one physical tool- surface designs are stored in computer files (and its relatively easy to store millions of design files). So, the designer is free to create more designs in a DS format.

Increased Tool Capability

The impact of DS capability is limited by:

the quality of the initial design

the ability to create meaningful customization

Otherwise, digital surfacing is just another way to make a lens

=

There is a perception in the market that a lens that is created specifically for an individual is always better. But the freedom that comes with digital surfacing, is not, by itself, a good thing. That freedom is only meaningful if you are using it to customize a quality lens design in the first place, and whether you have the technical ability to create customization that is meaningful – not just customization for its own sake. For example, the ability to customize the progression length by 0.1mm increments is not helpful if the progression length is over 12mm!

Increased Precision

The DS process is capable of greater

precision than traditional surfacing

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TRADITIONAL SURFACING Digital Surfacing

Traditional tooling creates "rounding errors" which cause up

to 0.06D of distance power error

Digital tooling can be accurate to within 0.01D of target powers

+/-0.06D

+/-0.12D

In traditional surfacing, the molded nature of the lens ensures that design will be almost perfectly accurate every time. However, since traditional surfacing uses physical tools that are inventoried in 0.10 increments, "rounding" will result in up to 0.06D deviations in distance power. Since digital surfacing is accurate to within 0.01D, the control of power is tighter. But even with the tightest digital surfacing process, there is slightly greater potential for design variation.

Increased Precision

DS processes must be tightly controlled

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UNCONTROLLEDTRADITIONAL SURFACING

UNCONTROLLEDDIGITAL SURFACING

Process variations usually affect only the distance power of

traditionally surfaced lenses.

When DS is used to create a PAL design, process variations

will affect the design

When the surfacing process is not tightly controlled, the variations increase. This is especially problematic for digital surfacing, where even a slight lack of calibration between the surfacing file and the surfacing equipment can result in significant variation in the accuracy of the design.

Increased Precision

DSPC

Essilor has > 20 years invested in DS R&D

Essilor Digital Surfacing Process Control (DSPC) is a

complete quality assurance system

every laboratory required to test/calibrate processes daily

A "DS PAL" = design + process

If the process is bad, the design will not be accurate

All major manufacturers have a defined process

No other manufacturer has invested more in R&D of digital surfacing processes. DSPC ensures that the surfacing equipment at every DS lab producing Varilux lenses is calibrated every day and the processes used to create the lens are capable of the highest levels of control and consistency.

DEPARTMENT MANAGERDEPARTMENT MANAGERE. COMTEE. COMTE

Ass istant

M.HAGER

SURFACING MANAGERB.GELB

B.TAYLOR

B.BEESON

M.MODH

K.SCHROWANGEN

J.MONAGHAN

M.JACOB

H. NG UYEN

DALLAS

J.SHERIDAN

SURFACING MANAGER

INDUSTRIALIZATION

WORKSHOP

L.GRELICHE

TECHNOINDUSTR IALIZATION

G.MARTIN

PRODUC TS

INDUSTRIALIZATION

B.GODEAU

P.RENAUD

Y.DUPIN

Y.FELTEN

JF. BELLY

G .BOLT EAU

B.CALLIER

M.LIBBRECHT

J. DE BARROS

D.BOULET

PH.CORNE

S.PICHOUX

M.DURANT

P.DEMION

S.SPOHR F.LAFON

TECHNICAL LE ADER

BLOCKING

M.LE GALL

TECHNICAL LEADERMACHINI NG/POLISHI NG

X. BULTEZ

CRETEIL OUDRY

BANGKOK

SURF ACING MANAGERW.MAYUREE (T OY)

P.WASANCHAI

(T A)

C.PETCHARAT

(Poy)

K.SANRAYU

(JO Y)

C.ING ON

(ING)

T.NIDA(KERNG)

K.PHANUWAT

(JO)

K.CHETTHAPHON

(EARTH)

A. SAUZE

Apprentice

Digital Surfacing Process Control

I. KATESANEE

(KATE)T. T OVEY

B. LYONS

CALCULAT ION

T. BAUDART

J-L. ARBESSIER

D. DRUGEON

J. CO NCIALDI

N. BELHACHMI

Apprenti

F. G AUCHI-MART INO

Intérimaire

V. MARTIN

Conges 18 mois

N. FARIA

M. METTEL

B. ROMAIN

S. WEERAPON(MAN)

M.KALUZA

Its easy to say Essilor invests millions of dollars in digital R&D... Here is one proof. Essilor hires over 50 researchers who are focused solely on process research and the development of process controls. Each of these people from around the world are dedicated to ensuring that lenses produced in Essilor labs (and our partners) are "on target." (Note: Essilor has more researchers dedicated solely to process control than most ophthalmic manufacturers have in their entire R&D department.)

Increased Design Flexibility

Traditional surfacing is limited to one design

Design (D) placed on the front surface

Distance power (d) surfaced on the back

Traditional PAL

D d

Playing music through a single speaker system limits the ability to design sound effects...

Using only one surface for progressive design

also limits the effects the designer can create...

D = Design d = distance power


Traditional surfacing is limited to one design (placed on the front surface), because the process is not capable of producing a progressive surface on the back surface of the lens. This limits the designer in the same way having only a single speaker limits how music can be played. You can play beautiful music through a single speaker- but there is not much freedom to change the sound (basically all you can do is adjust the volume).


FBS PALs are also limited to one design

Design (D) placed on the back surface

Distance power (d) surfaced on the back

FBS (DRx™)

D d

The location of the speaker is changed...

...and the flexibility of DS does allow the designer

to customize to a limited degree



The FBS is also a "single surface" format. However, as already mentioned, the DS process does allow the designer to create a greater number of designs, because it is not limited by an inventory of physical tools. So, the designer can make changes to elements of the design- even though there is still only one speaker. In our music analogy, it would be like adding an equalizer- now we can not only play the music, but we can "tweak" the sound by increasing the base, the treble, or the midrange.


Digital surfacing can support two designs

Designs (D) are placed on both surfaces

Distance power (d) is digitally surfaced on back

D

d

D

Two speakers makes it possible to create stereo and other sound effects...

Using two surfaces makes it possible for the

designer to create new optical effects...DualOptix™



From a designer's standpoint, the really exciting aspect of DS is the ability to place a design on two surfaces! With two surfaces, the designer can create an unlimited number of effects. Beyond just "tweaking" the levels of sound, the designer can create effects not possible with a single speaker. Likewise, with two speakers you can create effects like stereo.


Two designs allow the designer to address

both defocus and distortion simultaneously

Patient's Blurred Vision

Management of Distortion

Management of Focus

Controlled Correction

Two surfaces can be used to control focus & distortion simultaneously...

A single surface can control focus or distortion (usually a compromise of the two)

Specifically, the main benefit of allowing the designer to use both surfaces is the ability to simultaneously control focus and distortion. In single surface PALs, the designer must (and does) find a compromise between provision of focus and reduction of distortion. When using a single surface, the more distortion is controlled the less focus can be controlled (and vice versa). With two surfaces, it is possible to control both focus and distortion simultaneously!


An example of two-surface design:

6B

9B

6B

6B

6B

7B

-1.00 -1.00 -1.00

+2.00 +2.00 +2.00

Rx -1.00 sph / +3.00 ADD

D d D

d

D

d

D

Single surface progressions cannot provide the optimal curvature for both

the distance and the near powers (and asphericity alone cannot overcome all "base curve effects"). Disassociating the power change from the curvature change reduces distortion to levels not otherwise possible.

TRADITIONALTRADITIONAL FBS (DRx™)FBS (DRx™) DualOptix™DualOptix™

Here's ONE example of how two surfaces improve progressive optics. In a traditional PAL, the front surface is used to create the ADD power. This creates distortion- because you cannot optimize the front curvature for both the distance and the near powers (because changing power by 3 diopters does not require a 3 diopter change in base curve). Moving to the back surface does not improve the situation (because the same base curve is definitely not optimal for two powers 3 diopters apart). Only by disassociating the power change from the curvature change can distortion be reduced below the levels found in single surface PALs. By the way, asphericity CANNOT "do away with the base curve effect." Asphericity can reduce marginal astigmatism and power error- it cannot eliminate distortion. Hoya is the only other manufacturer using both surfaces of the lens (Hoyalux iD), and the benefit is similar (control of skew distortion).

Review

Digital surfacing provides three advantages

Removes tooling limitations

but customization must be meaningful

Potential for greater precision

but the process must be controlled

Allows designer to use both sides of the lens

allows simultaneous control of focus and distortion

New PAL Formats

D d

Traditional PAL

d

D

DRx™ (FBS) PAL

Dd

D

DualOptix™ PAL

•A single surface PAL

•Design on front•Distance power on back•Compromise between control of focus / distortion

•A single surface PAL•Design on back•Distance power on back

•Greater accuracy•Compromise between control of focus / distortion

•A two-surface PAL•Designs on front & back

•Distance power on back•Greater accuracy•Control of both focus / distortion



There are three PAL formats currently available on the market. Traditional PALs & FBS PALs use a single surface which strikes a balance between providing good focus and reduction of distortion. DualOptics PALs are two-surface designs which can control both focus and distortion (the result being clear central vision and exceptionally well-controlled peripheral vision).

Advantages of DS Formats

Benefits of both FBS and DualOptix™

More precise compared to Traditional PALs

Additional Benefit of DualOptix™

Control of both focus and distortion

DualOptix™

D

dD

Essilor uses the DualOptix format for customization- since it offers the greatest

ability to control focus and distortion.

FBS

D

d

Both FBS (DRx) and DualOptics gives us greater precision. DualOptics also gives us unlimited ability to customize.

Types of DualOptix™ Customization

Personalization to Head/Eye Ratio (Varilux Ipseo IV)

W.A.V.E. Technology 2 (Varilux Physio Enhanced)

Maximized Zone Width (Varilux Comfort Enhanced/All Varilux)

DUAL ADD TECHNOLOGY (DEFINITY)

FrameOptimization Technology (Accolade Freedom)

Additional benefits common to ALL DualOptix PALs

Atoricity (to reduce peripheral aberration)

Customized Near Zone Inset (to promote reading)

Customized to Fitting Height

Length of Progression

Distribution of Zones (wider distance angle) D

dD

Remember, the DualOptics format by itself does not improve the design- digital surfacing is just a tool! However, Essilor designers have used the DualOptics format to accomplish many types of customization and design improvement.

DS Design Capabilities

DEFINITY- reduces astigmatism/distortion

Widest Intermediate

Least Swim

Varilux Physio Enhanced- customized wavefront

Sharpest Vision Possible

New Varilux Comfort Enhanced- peripheral width

Wide/Smooth Vision

Accolade Freedom- instant adaptation

95% adaption in first 5 minutes

Benefits of DualOptix PALs

Varilux Ipseo IV is the only PAL featuring a DualOptix design which adapts to the wearer's

individual visual strategy

the design is individualized to 7 parameters

wavefront correction pupil map

sphere slope management

position of wear

visual zone width

distance Rx atoricity

progression length

zone distribution


Varilux Physio Enhanced is the only PAL providing customized wavefront correction

W.A.V.E. Technology 2 personalizes the design to 4 parameters

wavefront correction pupil map


progression length

zone distribution

wavefront correctioncustomized

wavefront correction

pupil sizepupil size


DEFINITY is the only PAL to split addition to achieve levels of astigmatism not possible in a

single surface PALDUAL ADD TECHNOLOGY customizes the design to 2 parameters


progression length

Conclusions

The foundations of PAL design can be

delivered in ANY format

Two new DS formats are available:

DRx™

greater precision than traditional PALs

DualOptix™

greater precision than traditional PALs

unlimited ability to customize

varilux (progressives in the digital age speaker notes)

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