progressive addition lenses , needs of PAL, permanent and temporary marking of PAL, parts of PAL, design of PAL, Progressive corridor and their importance ,theory behind the PAL,Sand box analogy,OPTICAL DESCRIPTION OF PROGRESSIVELENSES,patterns of PAL,Advantage and Limitation of PAL,fitting of PAL and Frame selection for PAL,measurements for fitting,verification of PALs, traubleshooting in PALs,Brands and special design of PALs

1. Aging has a wonderful beauty and
we should have a respect for that.
Progressive lens
- Anurag shukla
Fellow optom
Dr. Shroff charity eye hospital,Delhi

2. i n t r o d u c t i o n
• Benjamin franklin invented bifocal in 1784.
• Invented in 1959 by Bernard maitenaz, an engineer at Essilor..
• A progressive addition lens has more than one focal point or
dioptric powers, without need to switch the lenses.

3. W h a t i s PA L
• A lens designed for presbyopes with power
gradually increasing from the distance zone,
through a progressive zone to the near zone.
• Curvature of surface increases from its minimum
value in distance zone to maximum value in near
zone.

4. W H Y PA L s ?
• Unlike bifocal or trifocal lenses, progressive lenses ensure
that the presbyopic spectacle wearer finds the right
dioptric power for every distance, guaranteeing smooth and
uninterrupted vision and without any visible line of
demarcation.
• The power increases is achieved by constantly decreasing
the radii of curvature in the vertical and horizontal portion

5. Conti….
• There is no visible reading segment
• No any dividing line between distance and near portion
• No image jump
• Eye rotation is required to see from distance to near vision
area and head movement is required to see across the
lateral areas of astigmatism

6. marking
• Distance reference circle: A stabilized region in the upper
portion of lens provides the specified distance prescription.
• Fitting cross:
• Located exactly at the centre of the pupil.
• Used to measure MPD and fitting height.
• Prism reference circle:
• Used to check amount of prism.

7. marking
• Near reference circle:
• Its used to check the near vision power.
• Lateral circle:
• Two small lateral used to relocate the temporary marking.
• Exactly position is 34mm apart one each on the nasal and
temporal sides.
• Lens logo and material code:
• Lens type is identified with the help of lens logo and it is
located nasally.
• Lens material code is used to identified the lens material
types.
Permanent marking

8. marking
• Addition power
• Located below the temporal locater.
• Umbilical line
• It is a vertex line long which spherical add
power increases towards the bottom of the
lens
• Surrounding the vertex line are increasing the
amount of unwanted astigmatism
Umbilical line

9. marking
• Progressive corridor:
A corridor of increasing power connects these two
zones and provides intermediate or mid range
vision. The length of corridor is the distance from
the center of the fitting cross to the position
where 85% of the near add is achieved.
• The average rate of change in Add power along the
progressive corridor is equal to the total add power
divided by the corridor length of lens.
Add power
Length of corridor

10. Minkwitz’s Theorem
• The rate of change in unwanted cylinder power (Δ Cyl) at a small distance
away from the centerline of progressive corridor is nearly equal to twice the
rate of change in Add power (Δ Add) over an equal distance along the
centerline of the corridor.

11. Sand box analogy
• A round sandbox with the surface of a sand smoothed to a spherical
shape to resemble the front of regular ,single vision lens.
• Suppose we want to change the surface curvature of one area of
sand, to give a new “power” so that it will resemble the near portion
of PALs.
• It can be done by starting at the centre and gradually increasing
the curvature of the surface in the certain area corresponding to
the progressive portion of a lens.

12. Sand box analogy
• In other words, we start shaving the surface
of the sand, removing sand from that area.
• But in sandbox rule, the sand are not allowed
to throw out of the sandbox.
• So sand have to piled on either side of the
progressive zone and then smoothed out.
• This changes curve of the surface and causes
unwanted cylinder.

13. OPTICAL DESCRIPTION OF PROGRESSIVE
LENSES
1. • Power profile
2. • Contour plot
3. • Grid plot
4. • Three dimensional plot

14. Power profile
• The curve represents the power progression
of the lens along its meridional line from
distance to near vision.

15. Contour Plot
• Two dimensional map of the lens
representing either the distribution of power
or of astigmatism
• The map shows lines of equal dioptric values
• Between two consecutive lines, the power or
astigmatism varies by a constant values.

16. Grid Plot
• The grid highlights the distribution of
prismatic
• effects of the lens by showing how they alter
a regular rectangular grid

17. THREE DIMENSIONAL PLOT
• A 3-D representation which plots vertically
the value of a given optical characteristic
at each point of lens in relation to a
reference plane
• May be used to show the distribution of
power,astigmatism, prismatic effects,
gradients of power variations.
• More demonstrative of lens characteristics
than contour plot.

18. Design of PALs
• Aspheric front surface provides power progression.
• Progression determines
• --the length of the intermediate zone
• --the position near addition lens
• --the gradient of peripheral lens abberrations.
• Peripheral surface to provide the comfortable down -gaze vision.
• Advance designs are transitions from “harder” to “soft”.

19. Hard Design of PALs
“Hard” Design
• Wider areas of stable optics in
both distance and near.
• Narrower intermediate
• Longer adaptation
• Some apparent curving of straight
lines.
• Shorter distance down to near
viewing.
•

20. Soft Design of PALs
• Longer distance down to the near
viewing area
• Wider intermediate shorter
adaptation
• Less apparent curving of straight
lines
• Less peripheral distortion than
hard design
Soft Design

21. Pattern of PALs
#Symmetrical patterns
. Available but are less common.
. Right and left lenses are
identical.
. 10 degree rotation requires for
nasal decentration.
. An induced vertical prismatic
effect causes poor adaptation.
.

22. Pattern of PALs
# Asymetrical pattern
. Separate designs for the right and left lenses.
. Incorporate a nasal offset of the near addition.
. Vertical prismatic effect is minimised.
. Better adaptation and visual comforts

23. Mono design
• Describe range of power for a given design.
• It classify hard and soft.
• It describe the characteristics of progressive zone.
• Maintain design principles throughout the range of addition

24. Multi design
• According to add power lens design changes
• It starts from soft design for low add power and as the add power
increases it will turn to hard designs lens.

25. Unwanted cylinder
• Unwanted cylinder is the greatest problem inherent in progressive
additional lenses.
• Although the progressive zone gives clear vision when properly fitted.
• This cylinders varies in amount and orientation depending on design
and add power.
• There are certain design characteristics that change the amount of
unwanted cylinder in the periphery of the lens.
• To help understand how this works, we use an oversimplified example
of a sandbox.

26. • Continuous vision from distance and near
• Comfortable vision for all intermediate
distance.
• No image jump
• Continous support for accommodation.
Advantage1
Optical aberration
Some adaptation time
Cost factor
More chair time.
Limitation2
Advantage and Limitation of PAL

27. PATIENT SELECTION FOR PAL
Who are good candidate ?
• Those who require add power for certain
task but prefer edge not visible
• Presbyope complaining image jump
• Emerging presbyopes
• Person needing trifocal
Who are poor candidate ?
• Having motion sickness
• Satisfied with bifocal
• High add requirement(3.00D)
• Significant vertical muscle imbalance
• Anisometropia (>3Ds

28. Part 02 Add the subtitle
Fitting of PAL

29. Fitting progressive lens
When fitting progressive lenses, use the following procedure
1 select the frame
2 pre-adjust the frame
3 measure the fitting heights
4 measure the distance monocular PD
5 verify lay out card

30. Frame selection
• The frame must have sufficient vertical depth, if there is not
enough vertical depth , then either different frame must be
chosen, or a special short corridor lens that is designed for
frame with a narrow vertical dimensions should be used.
• The frame must have sufficient lens area in the nasal
portions where the near progression optics is found.
• The frame must have short vertex distance.
• The frame must be able to be adjusted for pantascopic
angle. .

31. Pre- adjustment of the frame
• Ensure a minimal vertex distance.
• Ensure at least 8 degree or more of pantoscopic tilt.
• Adjust frames with demo lenses in place.
Effect of vertex distance
• Shorter vertex distance increases the field of view through the
viewing zones of the lens.

32. Pre adjustment of the frame
Effect of pantoscopic tilt
• Pantoscopic tilt brings the near zone closer to the eye and
increases the field of view through the near zone of the lens.
Measure the fitting height
• The fitting cross on progressive additional lens must coincide
with the pupil centre of the wearers in their natural posture.

33. `
The following procedure is used to measure the fittings heights
• Fitting height should be measure with Fit and fully adjusted frame.
• Place your self opposite and at the same height as the wearers.
• Ask the wearers looks straight ahead
• Ask the wearers to looks at your left eye.
• Hold a pen torch just below your left eye.
• Close your RE to avoid parallax error.
• Observe the position of the light reflection in the wearers RE
relative to vertical PD line already marked on the lens.
• Place a small horizontal marks on PD line corresponding to the
pupil centre

34. Conti….
• Ask the wearers to look at your RE and complete the
procedure for the other eye.
• Move the frame up and down slightly , let it settle, and
report for both eyes,

35. Fitting Cross Heights for Children
• progressives might be used for children is in the case of
accommodative esotropia.
• A fitting cross height 4 mm higher than the pupil center.

36. Distance PD measurment
• Monocular PD is most important.
• Measure from the centre of nose to centre of the pupil.
• Another method include:
Pupillometer
Pd ruler
Direct pupillary reflex marking method

37. Centration chart: for verification

38. Verify cut out card
• Use the correct cut-out card for the lens design
• Place the dotted demo lens on the fitting point of the
lay out card and ensure that the frame will cut-out at
the desired measurement
• Mark the pt.’s fitting height and distance PD on the
sample lens creating a cross
• Place the lens cross over the layout chart cross to
verify that the lens will fit within the lens diameter
circle
• If the lens does not fit choose another, more suitable
frame that will accommodate the lens

39. CONFIRM MEASURMENT AND PRESCRIPTION
• Using the centration chart ,centered the frame
over the inverted V
• Confirm the monocular PD and fitting height
• Confirm the distance prescription with the
lensometer
• Confirm prism at prism reference point [PRP]

40. RECREATE FITTING CROSS [IF NEED]
• Mark the lens micro-circles with a felt tip pen.
• Lay the glasses over the cut out chart and align the micro
circle to the microcircle on the cut out chart.
• Mark the fitting cross with the felt tip pen.

41. Confirm fit on patient
• With the lenses marked or using decals,verify that the
fitting cross is at center pupil
• Adjust the frame to raise or lower the fit if necessary
• .

42. Part 03
T R O U B L E S H O O T I N G
I N P R O G R E S S I V E

43. TROUBLESHOOTING IN PROGRESSIVE
FACTORS IN ADAPTATION
• Motivation
• Expectation
• Education and encouragement
• Occupation and hobbies

44. Source of error
• Fitting of frame
• Heights
• Monocular PDs
• Wrong power and axis

45. Understanding the design of progressive lens

46. A perfect fit…

47. COMPLAIN AND REMEDIES
• Problem:
• Blurring of distance vision
• Difficulty in outdoor activities.
Possible causes
• Fitting to high
• Wrong priscription
Remedies
• Open the nose pads
• Remake the lenses

48. Problems:
Near vision blur
Possible causes;
• Fitting to low
• Inadequate pantoscopic tilt
• Incorrect RX
REMEDIES;
• Bring in nose pad
• Frame adjustment
• Remake lenses
COMPLAIN AND REMEDIES

49. TROUBLESHOOTING IN PROGRESSIVE
• Problem:
• Blurring of distance vision in one eye.
• Difficulty to walking the stairs
(poor depth perception)
Possible causes
• temples are not correctly aligned
• Wrong priscription
Remedies
• Adjust the temples correctly
• Remake the lenses

50. LOOK AT THE BLACK LINE BEHIND THE LENS
PRISMATIC EFFECT

51. COMPLAIN AND REMEDIES
PROBLEM
• Different widths of clear zone.
POSSIBLE CAUSES
• Different vertex distance
• Inadequate pantoscopic tilt
REMEDIES;
• Adjust the frame.
• Pantoscopic tilt.

52. COMPLAIN AND REMEDIES
PROBLEM
• Blurred vision for D&N ,
Swimmy sensation,small field
of view .
POSSIBLE CAUSES
• Incorrect PD and heights
• Adaptation
REMEDIES;
• Remake new glass.

53. COMPLAIN AND REMEDIES
Problem
• Reading area too small
Possible causes
• Incorrect PD
• Fitting height too low
Remedies
• Frame adjustment
• Refit lens

54. COMPLAIN AND REMEDIES
Problems
Having too look to the side to read
Possible causes
Incorrect PD
Swapped lenses
Remedies
Refit to correct the PDs
Swap the lens if frame symmetrical

55. COMPLAIN AND REMEDIES
• problems :
• Having to tilt head too far back to read
Possible causes
• add too weak
• Change in design
Remedies
• Bring in nose pad
• Increase the add
• Refit lenses

56. Part 04
B ra n d s a n d s p e c ia l
d e s ig n o f PA L s

57.  Many Brand's progressive lenses available in the market
1. Hoya
2. Ziess
3. Essilor
4. Kodak
5. Nikon

58. Design features
• New free-form aspherization process
• Clear, natural vision in all directions
and at all distances
• Dramatically reduces swimming
sensations
• No special fitting parameters needed
Name Corridor
length
MFH
Clarity 15 mm 18 mm
Clarity cd 11 mm 14 mm
Harmony 14 mm 18 mm
General purpose PAL

59. Drive safe : new technology
 Develop with Luminance Design®
Technology by ZEISS.
 Reduced glare at night. : DuraVision®
DriveSafe Coating by ZEISS.
 Accurate vision of road, dashboard and
mirrors.
Name Corridor
length
MFH
Precision pure 13, 15, 17, 19
and 21mm.
17 - 26 mm
Gradal HS 14 mm 18 mm
Zeiss
Individual
10 - 16 mm 13 - 35 mm
ZEISS
DriveSafe 14 ,15 mm 17- 19mm

60. Design elements :
Sphere to asphere
Multidesign
Asymmetric
Name Corridor
length
MFH
Adapter 14 mm 18 mm
Varilux comfort 12mm 18 mm
Varilux
panamic
12mm 18 mm
Varilux physio 12mm 17mm

61. GENERAL PURPOSE PALs
Relaxsee neo :Accosupport
 32.4% of adults and 9.1% of children
report experiencing eye strain. ( The
Vision Council reports on digital eye
strain,2019.)
 Recommend for relief eye strain and
for support to accommodation.
Name Corrido
r length
MFH
Add
power
Range
Presio
Power
17 mm 21 mm +0.50D to
+4.00D i
Presio
Balance
15 , 17
mm
18, 21 mm +0.50D to
+4.00D i
Move
digital
13, 15 mm 16, 18
mm
+0.50D to
+4.00D i
Relaxsee
Neo
17 mm 21 mm +0.37 D to
+0.95 D

62. GENERAL PURPOSE PALs
Kodak unique :
 Available in 36 material.
 KODAK Unique Lenses are not
available with Rx prism.
Name Corridor
length
MFH
Add power
Range
KODAK
Unique
13 ,14 ,15 ,16
,17 ,18 mm
Starting at 13 +0.75 to +
3.50 D
KODAK
Precise
13.5 mm 17 mm +0.50 to
+3.00 D
KODAK
Concise
14 mm 17 mm +0.75 to +
3.50 D

63. Special PALs
 Short corridor progressive lenses
 Near variable progressive lenses
 Occupational progressives that
include distance powers

64. Short Corridor progressive lens
 Allows a PAL to be worn in a frame with a small vertical
dimension.
 Faster transition from the distance and near portion of lens.
 Wearer is quickly into the near portion when looking
downward.
 Minimum fitting height should be suitable for the frame

65. Benefits
• Cosmetically appears good
Disadvantages
• Slightly more expensive than
standard progressive lenses
• difficulty adapting
• distortion
Short Corridor progressive lens

66. Short Corridor progressive lens
NAME MANUFACTURE
R
CORRIDOR
LENGTH
MINIMUM FITTING
HEIGHT
Hoyalux summit cd Hoya 11 mm 14 mm
Harmony cd Hoya 10.5 14
Varilux Ellipse Essilor 9.5 mm 14 mm
Gradal Brevity Carl Zeiss Optical 12 mm 16 mm
Kodak precise short Kodak 10 mm 13 mm

67. Near variable progressive lenses
 Started out as a replacement for single vision reading
glasses

68. Near variable progressive lenses
Name Manufacturer Add power
range
iD LifeStyle 3 Indoor Hoya + 0.75 to +3.50 D
Zeiss business Zeiss Upto +3.50 D
Essilor interview Essilor Upto +3.00 D
Home and Office Neo Nikon +0.50D to +4.00D.

69. Benefits
• great for people needing
Intermediate and near view
• Provide wider Intermediate
zone
• help alleviate visual fatigue
(CVS)
Disadvantages
• Slightly more expensive than
standard progressive lenses
• Difficulty to carry
Near variable progressive lenses

70. OCCUPATIONAL PROGRESSIVES WITH DISTANCE
POWER
 Used for small office environments and
computer viewing.
 Include a small distance portion located at
the top of lens.
 Intermediate area of the lens positioned in
front of eye.
 Intermediate and near zones considerably
wider than standard progressives but not
as wide as near variable focus lenses

71. OCCUPATIONAL PROGRESSIVES WITH DISTANCE
POWER
EX:
1.AO Technica
2.Hoya Tact

72. THANK
YOU