Progressive addition lenses (PALs) provide a gradual transition from distance to near vision without visible lines. PAL designs aim to maximize clear vision zones for distance, intermediate, and near viewing. Key design considerations include lens hardness, symmetry, prescription parameters, and lens surface asphericity. Modern PALs utilize advanced optical modeling and eye tracking technology to minimize distortions and provide natural vision across a wide range of viewing distances. While PALs offer continuous vision without lines, their transition zones may require more eye and head movement compared to single vision lenses.
3. RANGE OF CLEAR
VISION
Single vision
Bifocal
Progressive
0.33 0.50 1.00 2.00 5.00
NEAR INTERMEDIATE DISTANCE
NEAR INTERMEDIATE DISTANCE
NEAR INTERMEDIATE DISTANCE
4. PURPOSE
Understand experience with current
correction
Highlight limitations of current correction
Explain feature/benefits
Refer to “change in vision” when refitting
into different design
Listen to the wearer’s needs
Restate the wearer’s needs (avoid technical
jargon)
Make the recommendation
5. What are progressive
addition lens ?
1
Progressive Addition LensesProgressive Addition Lenses
What are progressive
addition lenses?
A lens designed for
presbyopes with
power gradually
increasing from the
distance zone,
through a
progression to the
near zone.
7. The usable
field of view is
comprised of
head and eye
movements as
shown here for
the horizontal
plane.
Usable Field of View
Eye
rotation
Head
movement
PALs design
and personal
movement
characteristics
8. Binocular Vision
Binocular vision:
As the patient’s gaze is
lowered for near objects, the
eyes converge to maintain a
single binocular image. The
progressive lenses should
ensure that this is maintained
for different object distances
from the eyes, as illustrated
by the lines.
9. Peripheral (Extra-Foveal) Vision
Peripheral vision:
The PAL design should
ensure that * objects in
the periphery of the
visual field are easily
fused. * * The
distribution of prismin
each lens should also
be balanced for
binocularviewing.
* * * Corresponding
areas in the two lenses
should provide a
similarlevel of vision.
10. Why Use PALs?
Uninterrupted vision from
distance to near
No visible line
No jump in vision from
distance to near
Better vision as intermediate
is clear
Looks like single vision
Lighter/thinner than SV
Looks better
More natural vision
More visual comfort
Confidence in mobility
Feature Benefit
11. Intermediate Vision
Intermediate vision:
(a) Poor head position as a consequence of the eyes
searching for the best focus in the bifocal’s limited
range of intermediate clear vision. (b) Using the
intermediate portion of a PAL enables more natural
head position.
(a)
Bifocal
(b)
PAL
12. Why Use Progressive Lenses?
Bifocal lens Progressive lens
The bifocal lens (left) can disrupt the patient’s view with visual disturbances
(arrows) when the eye crosses the boundary of the near seg. The progressive lens
(right) has no such problem and enables a smooth transition between different
reading distances.
15. How a progressive addition
lens works?
Invariably follow the traditional lens optics
Power in the midline follows the same
distance prescription as addition increases
below until desired add is reached
For the most of the lenses, this addition
power is reached at a point 10-16mm
below and 2.0-2.5mm nasal from distance
optic centre
WidthWidth =
Lens design
+ Add
AstigmaticAstigmatic
errorerror =
Width of
near area +
add
16. Progressive Lens Design -
Optics
Distance
Zone
Near
Zone
Umbilical
line
Intermediate
Zone
Lens Radius Changes AlongLens Radius Changes Along
Umbilical LineUmbilical Line
17. Principal parameter :
Size of distance & near area
Type and intensity of aberration
Depth & usable width of corridor
18. Design in PAL’S :
Hard design
Soft design
Symmetrical design
Asymmetrical design
Mono design
Multi design
Prescription based design
20. Hard design
Regular distance single
vision
Spherical distance zone
Wide distance & near zone
Narrow & short intermediate
corridor
Rapid increase in unwanted
astigmatism
21. Advantages
Large distance & near area free from
astigmatism
More accessible with downward rotation of
eye
Wider near zone even at high Rx
Disadvantages :
High intensity aberration at periphery
Distortion for longer and more difficult
period of adaptation
Swim effect
22. Soft design :
Aspheric upper halves
Narrower distance & near
zone
Wide & large intermediate
corridor
Gradual increase in
unwanted astigmatism
23. Width of Far
Vision (+4mm):
0.5 [D]- 16.2 mm
1.0 [D]- Unlimited
Max Cylinder [D]-
Nasal: 1.5[D]
Max Cylinder [D]-
Temporal: 1.5 [D]
Width of Corridor
(-6mm):
1.0[D]- 9 mm
Length of corridor:
14.2 mm
Minimum fitting:
19 mm
Width of near
Vision (-18 mm):
1.0[D]- 21.63 mm
Soft Design
24. Advantages
Decreases intensity aberration at
periphery
Easier, more rapid adaptation
Less distortion of peripheral viewing
Reduce swim effect
Disadvantages :
smaller field at sharp vision
Need dropping of eye farther near to
read
25. Indication for selection
Hard design :
Previous successful hard lens
wearers
People who do a lot of reading
Soft design :
Young presbyopes
Active outdoor profession
Professional driver
26. Symmetrical design :
Add is straight down
from distance optical
center
No right & left lenses
Required rotation to
achieve desired inset
for near (9 degree)
27. Advantages :
We can give the inset according to
patient
Disadvantages :
As the wearers looks to the side
they will experience different power
& differential prism
28. Asymmetrical design :
Lenses have pre-
set inset for near
Different lenses
for right & left
29. Progressive Lens Design
3. Symmetrical Vs Asymmetrical
Symmetrical
PAL - same
lens design
is rotated to
fit the other
eye
Asymmetrica
l PAL - each
eye has a
different lens
30. Advantages :
This will not produces experience
of different power when patient
looks to a side
Disadvantages :
Fixed inset may not match with
patient’s required inset
31. Mono design :
Describe range of power for a
given design
It classify hard & soft
It describe the characteristics of
progressive zone
Maintain design principles
throughout the range of addition
32. Multi design :
According to add power lens
design changes
It start from soft design for low add
power & as the add power
increase it will turn to hard design
lens
1.50 Add Design1.50 Add Design
2.00 Add Design2.00 Add Design 2.50 Add2.50 Add
DesignDesign
33. Prescription base
design :
Result of years of Vision Research
Dedicated design for every Base and Add
Design by Base : different designs for
Hyperopes, Emmetropes and Myopes (FOV
& Magn.)
Design by Add: effective near zone sizes
change as the add increases
Near inset position varies relative to level of
Presbyopia / reading distance
Corridor length also varies relative to both
Base and Add
34. Incorporating Single
vision aspheric design in
to the PALs
Aspheric advantage
Flat, thin, lighter
Earlier front surface aspheric
design
Back surface Aspheric design
Bi-aspheric design
35. USE OF CONTOUR PLOT
TO EVALUATE
PROGRESSIVE LENSES
Distortion of grid patterns viewed
through the lenses
Visual acuity attainable at different
portions
The amount of vertical imbalance
at paired peripheral points
Areas of equal cylinder power plotted with a connecting line-
Isocylinder line
Equal spherical equivalent powers-
36.
37. Lens Design Selection
Consider how the wearer uses their lenses
for most wearers a good modern progressive lens
design is the best solution
but not all designs provide wide fields of view at
distance, intermediate and near
consider the design that will suit the wearer
general purpose : balanced fields of view
mainly for reading : wide near visual fields
mainly for computer : wide intermediate visual fields
39. Disadvantage of PALs
Straight line appears curved
More adaptation
Decreased width at intermediate
and near
Limited lateral movement
Increase in eye and head
movement
Eye must be dropped a longer
distance
40. Rodenstock Perfect read
R
For half eye reading glass users
who need trifocal
Ordinary PALs to much peripheral
aberration occurs
Use of full lens useful area
Near power is the reference power
Near IPD is the measured
estimation
Power of the lens starts out with
intermediate prescription
41. Varilux readable
Full working field enjoy as single
vision lens for intermediate and
near
Much clearer intermediate which
can’t be attained by single vision
lens
INTERMEDIATE
+0.75
+0.75
12mm
4mm
28 mm
45. Some of the common
Progressive lens from
essilor
Espace: affordable price and field
of vision for all distances
Adaptor; soft design, good
distance, optimized intermediate
and wide near vision area
Varilux comfort: sharp and natural
comfortable vision, good distance,
optimized intermediate and
adequate near vision area
46. Varilux comfort 1.6: Thinner and lighter
than normal progressive
Varilux panamic: wide field of vision for
all distances
Varilux panamic 1.6:
Nicon Presio: wider intermediate and
near zones, for small size frames
Comfort transition: progressive
+photochromic
Nikon web.lens: enhanced near vision
for computer savvy presbyopes
47. Sola Progressive
Solamax: highest reading area,
Spectralite; thinnest of all
Percepta: wider clear vison for all
XL gold: intermediate for sports and arm
length activity
Graduate: first time wearer, wide
distance and near
XL
48. Computer lens
Upper portion for
mid-range
distances
Lower portion has
reading Rx
Power varies
smoothly from
top to bottom
12 mm
power
transition
zone
Mid-range
Near
Access uses a unique aspheric surface:
49. ACCESSTM
Breaks the Mid-Range BarrierBreaks the Mid-Range Barrier
Access provides
Extended range
Wider breadth of field
Mid-range vision is as wide as close-up vision
Continuous vision throughout the lens
Ease of use
50. mc compared to Adult
Progressive Lenses
Addition Power Plot
mc Myopia Control
Standard Adult
Progressive
Short Corridor
Adult Progressive
53. The technology that enables us to design progressive lenses
through an exact simulation of the natural human eye view.
Eye Point Technology
54. The optical power is created by 3
parameters: thickness, index and curvatures
The surface of the lens is scanned by a 3D measuring
system, mapping the curvatures of the lens.
Eye Point Technology
55. The surface data & a highly advanced mathematical algorithm are the basis to Shamir's
Eye-Point Technology™, which takes into account numerous parameters:
1. Lens index refraction
2. Lens prescription
3. Lens center thickness
4. Distance from the eye to the back vertex of the lens
5. Distance from the lens to the object
6. Object's angular position in the eye's field of vision
7. Pantoscopic tilt of the frame
8. Pupil distance
9. Thickness reduction prism, and more.
By taking all of these parameters into consideration, Shamir's Eye-Point Technology™
enabled the creation of the perfect progressive lens.
Eye Point Technology