GPPWWOLCFAVD Guess what does this acronym stands for IMCMPALUSPTRMA GPPWWOLCFAVD A freeform lens is an I ndividually M easured C omputed and M anufactured P rogressive ID: 554158
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Slide1Slide2
“IMCMPALUSPTRMA
GPPWWOLCFAVD”
Guess what does this acronym stands for?Slide3
“IMCMPALUSPTRMA
GPPWWOLCFAVD”
A “free-form” lens is an “
I
ndividually
M
easured,
C
omputed and
M
anufactured
P
rogressive
A
ddition
L
ens
U
sing
S
oftware
P
rograms
T
o
R
un
M
ultiple-
A
xis
G
enerators and
P
olishers to
P
rovide the
W
earer
W
ith an
O
ptimized
L
ens
C
orrection
F
or
A
V
isual
D
efect!”Slide4
WHAT IS IT?
That acronym may prove a little long so …
Lens designers are coining—and Trademarking or Registering—terms, and phrases to describe—and differentiate—the free-form process.Slide5
Terms Synonymous to Freeform
Digitally Computed PAL.
Individual PAL.
Direct-to-surface technology.
Digital Surfacing™.
Direct-to-surface PAL.
Vision First Design™.
High Definition (HD) Technology.
Personalized Progressive Lenses.
These are but a few of the names and terms all being used to describe the same, new category of lenses generically called free-form.Slide6
WHAT IS IT?
It is a manufacturing process, not a lens.
This technology allows lens designers greater freedom for lens designs as they are not confined to using the traditional semi-finished lens blanks.
The new lens designs can be customized and optimized to the fitting requirements and prescription of each patient.Slide7
TRADITIONAL LENS TECHNOLOGY
VS
FREE-FORM TECHNOLOGYSlide8
TRADITIONAL LENS MANUFACTURINGSlide9
Conventional PAL GeneratorSlide10
Conventional PALSlide11Slide12Slide13
Soft vs Hard DesignsSlide14
LIMITATIONS OF PROGRESSIVE LENS DESIGNS
Restricted visual field
progressive curves are often positioned a considerable distance from the eye as they are fabricated on the front side of a conventional progressive addition lens,
this restricts the wearer’s field of visionSlide15
LIMITATIONS OF PROGRESSIVE LENS DESIGNS
Off- center astigmatism and power errors
The near portion/ reading area in a progressive addition lens is affected the most regarding astigmatism and power errors because that portion of the lens is positioned so far away from the optical center of the lens Slide16
LIMITATIONS OF PROGRESSIVE LENS DESIGNS
Compromised optics
Conventional PALs are produced in varying base curves with each base curve averaged for a wide range of prescriptions. This represents a compromise from the best possible opticsSlide17
IS THERE A SOLUTION?Slide18
FREE-FORM: A Triad TechnologySlide19
Lens DesignSlide20
SoftwareSlide21
Freeform Generator
Freeform PolisherSlide22
FREE-FORM LENS MANUFACTURINGSlide23
LENS DESIGNSSlide24
LENS DESIGNS
Conventional front surface with specialized backside surfacing
Internal technology
–
front side spherical with progressive back surface
3.
Dual-add technology
-
Add power on both the front and back lens surface
- proponents of this lens designs “Add power balanced between the front and back surfaces” is said to reduce unwanted astigmatism.
4.
Progressive front surface with aspheric/
atoric
back surfaceSlide25
Freeform Lens DesignSlide26
THREE BASIC DESIGN CATEGORIES
1. Optically Optimized
The free-form design is used to overcome common optical aberrations and mechanical limitations of traditional surfacing.Slide27
LENS DESIGN
Any ophthalmic lens with refractive power placed in front of the eye will cause aberrations away from the optical center.
Spherical Aberration,
Chromatic Aberration,
Coma,
Marginal Astigmatism,
Distortion,
Curvature of Field.
Progressive addition lenses compound the problem inasmuch as they use asymmetric curves to correct for distance, intermediate and near vision creating more physical distortions in the lens. Slide28
OVERCOMING LENS ABERRATION
Spectacle lenses suffer from various ‘
lens aberrations’ that affect the quality of peripheral
vision afforded by the lens.
Optical performance can be improved by reducing these aberrations, or ‘
optimizing’ the lens.Slide29
Optical use of Aspheric Surface
The primary use of aspheric lens design is to reduce or eliminate the lens/ optical aberrations produced by looking through an ophthalmic lens obliquely.
Lenses can be made flatter, thinner, and lighterSlide30
THREE BASIC DESIGN CATEGORIES
2. “Framitized”
The PAL designs are modified to specific fitting, frame or adjustment characteristics.Slide31
FRAMATIZED
The PAL designs are modified to specific fitting, frame or adjustment characteristics.
Intermediate corridors can be lengthened or shortened depending upon the frame “B” measurement.
Powers can be calculated based upon measured vertex distances.Slide32
THREE BASIC DESIGN CATEGORIES
3. Personalized
The PAL designs are created specifically to the prescription and individual viewing habits.Slide33
PERSONALIZED
Individuals look at the world differently
Head movers
Eye movers
Reading distance
Specific physical measurements
Measuring these tendencies allows the program to offer even a better design
Vertex distance
Frame wrap
Pantoscopic angleSlide34
Vertex DistanceSlide35
Effect of
Pantoscopic
TiltSlide36
Effect of Face Form WrapSlide37
BENEFITS OF FREE-FORM
Field of view is wider
Less unwanted astigmatism
Lenses are flatter and thinner
Less adaptation period
More comfortable
Unusual Rxs are accommodatedSlide38
Prescribing & DispensingSlide39
Do I need to refract the patient differently for free-form PAL lenses?
No difference – use standard refracting equipment & instrumentation
Ask questions about the patient’s
lifestyle
viewing needs
viewing distances
not wanting to drop their eyes too far into the lens when doing near work,
and other questions you would normally ask before performing a refractionSlide40
Good Technique
One of the biggest contributors to progressive lens failures is inaccurate measurements, especially segment heights and monocular PDs.
Measure monocular PDs.
Pre-adjust the frame
Vertical & horizontal positioning
Pantoscopic tilt
Face form (wrap)
Vertex distance
Sit properly aligned in front of the patient to avoid parallaxSlide41
What information do I need to provide to the lens laboratory?
For most – no more than usual
Fitting height & mono PD
Frame data, lens material, etc.
Others – more info
Ex. vertex distance, pantoscopic tilt and face formSlide42
Measuring – con’t
Once you begin – don’t move your head!
just your hands from eye to eye.
Moving your head creates errors
If you break alignment, start over.
Take fitting height readings at least twice to ensure accuracy. Slide43
Do I need any special equipment to measure the patient for free-form PAL lenses?
In most cases – no
Just mono PD and fitting height
For vertex distance
Ruler measurement of VD?
For pantoscopic tilt & face form
Use a protractor Slide44
I’ve heard that free-form PAL lenses may be too complicated for ECPs to dispense. Is this true?
No.
Some lenses use standard measurements – no more difficult
Some need more measurements
A little training is the key to success
Emphasize accuracy of measurements
Why is less important than how
.Slide45
Fitting Heights:
Expert: 16mm
Infinity: 18mm
Natural: 20mm
Dynamic: 22mm
is a back surface free-form progressive lens developed using Optotech's proprietary Ray-Tracing Optimization Technology. This guarantees virtually distortion free natural vision at all distances.Slide46
Fitting Heights:
Expert: 16mm
Infinity: 18mm
Natural: 20mm
Dynamic: 22mmSlide47Slide48