How Progressive Do You
Want To Be?
These steps may be the
blueprint you need for greater PAL success.
By Irwin Shwom, O.D.,
R.D.O Everett, Mass.
Progressive addition lenses (PALs)
have made our lives easier and richer. But how's your success
rate? Success with PALs isn't an easy task without a consistent
plan of action when fitting these lenses. I know that many of you
leave fitting PALs to your technicians, but neither you nor your
technician should miss out on these ideas to achieve more success
Finding a scapegoat
After years of experience in both
the opticianry and optometric ends of our field, I've discovered
that many us find it easier to blame our patients for not
adapting to PALs rather than to search for better solutions so
they can adapt to these lenses.
For PALs to become the workhorses
of our practice that they should be, we need only make sure we
consistently follow a few steps when fitting patients with PALs.
Here are the seven steps that I
- "scope out" the
right patient candidates
- explain PALs to them
- examine and prescribe
- select frames that make the
- "dot" them
- fabricate them
- adjust them.
Once we've done all of these, then,
and only then, can we assign to our patients the relatively
simple task of getting used to PALs.
Scope out the right
I've found that most successful
PAL users need to present to us with some concern regarding their
inability to visually function smoothly and completely with their
emerging presbyopia. Initiate a full discussion with your patient
about the alternatives of two pairs of glasses and lined bifocals,
listing all the advantages and disadvantages, prior to
recommending PALs. After having this discussion with patients, I've
found that for most of them, PALs provide a more than reasonable
Patient candidates for PAL use
fall into a couple different categories. For instance, patients
who are considered:
pointers" will sight targets in their
peripheral fields and always move their head toward the
target. By far the most successful patients we have are
- "eye turners"
keep their heads still and search peripheral targets with
their eyes only. You can fit them with PALs, but they
have a larger rate of failure. Reforming them into "head
turners" just creates frustration for both the
patient and you.
You can fit monocular patients
successfully with progressives at a cost. Even when we do
everything correctly, those monocular patients who're in need of
wide fields of view, especially at near, are limited by many of
today's PAL designs. In our office, we fully advise successful
monocular progressive users of the field limitations and
demonstrate these limitations to them where possible.
Strabismic patients who function
monocularly fit into the above description. Despite some
limitations, they can be successfully fitted with PALs.
Intermittent and large phoric patients have shown relatively
large failure rates. A basic tenet of successful PAL fitting has
been, "Both eyes and the nose need to be pointing to the
same target at the same time," and they don't always meet
Head tilting patients are all
right as long as they're constant and repeatable. Patients with
mild to moderate degrees of head tilting from vertical can be
successfully fitted with PALs as long as this is a normal and
natural position for them to remain in.
Discourage patients who drive at
night and lift their chin upward to decrease the glare of
oncoming headlights from using progressives.
Negative selling isn't something I
like to do, but it's important to explain up front things
that PALs don't do well.
Backing up a car isn't easy for
PAL users. If you were to look way back over your right shoulder
now, you'd notice how your chin moves up. Think about what occurs
when we raise our chins with a PAL. Good for reading, bad for
Lying down while watching
television isn't easy, either. When we lie on our backs, our
chins again rise. This helps with reading, but unless a
television is mounted at or near the ceiling, we're now looking
out of the reading/intermediate portion of the progressive.
For long-term, detail tasks, PALs
aren't necessarily the best option. Although we've made great
strides to a truly wide field of view for near tasks, especially
in higher add powers, we know that we've yet to reach optical
nirvana. The relatively limited width continues to create visual
comfort issues for even my happiest patients.
I've still found nothing more
comfortable for a uni-distance focal length task than to have a
pair of single vision near-only glasses to read with for extended
periods of time. In situations like this, I can continue to feel
comfortable prescribing progressives. But in this situation, you
have a great opportunity to offer a pair of prescription readers
as appropriate adjunctive therapy.
Rock climbing, hiking, cycling and
some racquet sports are also difficult for PAL users. Odd head
tilt requirements along with the need for quick eye movements
consistently remain on target for single clear vision. Given
these conditions, I'd fit a PAL only to an experienced wearer,
but never to a rookie.
Unfortunately, the lens design
always has an area that is out of focus for the patient. We all
know that the optical engineers in our field have done a great
job of designing today's new progressives, but they know and
share with us their frustration in not being able to make the
Unwanted, but inherent,
astigmatism exists in every PAL design. Most of the unwanted
power is located in the lens in both the nasal and temporal
portions of the intermediate and near segments of the lens. As
opposed to waiting for patients to tell me about the "blur"
they see at intermediate and/or near, I demonstrate that to them
I use a standard Amsler grid chart
and have the patient move the glasses closer and farther from the
chart to demonstrate the "by design out of focus zones"
in the PAL. Doing this has dramatically cut down on my patients'
objections to peripheral blur at near symptoms.
Examine and prescribe
A great refraction has no
substitute, regardless of the technologies that we use to get
there. Knowledge and comfort with your refracting and prescribing
techniques are a must. This is no time to try "new"
techniques on the refracting side of the table.
Prescribe your full-powered
prescription for both distance and near, making sure not to
add "extra power" at either distance or near for
compensation. The compensation has already been done for you in
most new lens designs.
In prescriptions with greater than
5.00D of power, know the distance at which you're refracting and
the vertex distance at which you'll fit your patients. Here's the
opportunity to prescribe "small" changes in the final
prescription to get your desired visual outcome. We do it with
contacts, so we can also successfully do it with PALs.
I've found that the unequal image
size found in anisome- tropic patients creates about the same
amount of post fitting frustration as conventional lined bifocals.
Patients who report classic
difficulties while reading with lined bifocals will report the
same effects with PALs. However, I've found that prescribing a
slab-off compensatory prism, a widely underused but successful
option, fixes this problem.
Also, I've had great success
fitting patients who meet all standard fitting criteria, but who
also have a relatively large amount of astigmatism. With today's
super-calculated, computed and manufactured PALs, astigmatism
doesn't pose a big problem for a successful fitting.
Select the best lens
How do we know which PAL to fit?
To be honest, this is where you have to try them yourself and
decide. My lens representatives do an excellent job of providing
us with information on the comparable strengths and features of
their company's lens designs. However, I've found that I need to
try them on myself first to "see" what they're trying
to tell me, then decide where I can best use the lens.
- Decide what your patients
need for an intermediate/near "ramp power" (rate
of lens power change). If we're fitting PALs with segment
heights of 16 mm or so, you need to remember that the
patient only has a relatively short ramp to get from his
full distance prescription to his full near prescription.
If the patient expresses that he'd like to see and do
everything quickly, then this PAL design might not be a
success. The rate of lens change might be too quick.
In opposition, a PAL that has a minimum fitting height of
21 mm or more has relatively slower acting optics (longer
ramp) from maximum distance to maximum near powers.
- Select frames that make your
lenses work. In our office, I choose frames that make my
lenses work well. I've found in my dispensary that once I
permanently adopted that philosophy everything --
including successful PAL fittings -- flourished. It's
only when I let our patients tell me what they want that
I sometimes still get into trouble.
- One of the biggest challenges
is making sure that the frames I most often sell have an
adequate "B" dimension to make my PALs work.
Not only do I pay attention to the near minimum fitting
heights of my recommended PALs, but I also need to ensure
that the patient's eyes are far enough away from the top
rim of the frame to make the distance aspect of the PAL
I've recently run into a risk of PAL failures due to post-fitting
symptoms of difficulty with distance visual acuity. The
failures were because of PALs I fitted when I didn't pay
attention to choosing frames with an appropriate "B"
dimension compatible with a good visual outcome at both
distance and near.
Make it work
Use adjustable nose pads. Unless
you have a super adjustable, pliable, fixed bridge resin frame,
always fit PALs with frames that have adjustable nose pads. You
need the feature of adjustability while dispensing to make those
last-minute tweaks on the completed spectacles. You also need to
use adjustable face form and pantoscopic tilt capabilities.
Choose frames that either
incorporate this feature or that you can manipulate at either the
fabrication or the dispensing time. These types of frames have
the ability to be rounded to the face and create between 10 to 15
degrees of pantoscopic frame tilt. You should be discouraged from
using any frame that you can't reasonably bend or won't maintain
Once you've found the frames that
work best, supply them in multiple bridge sizes in your
dispensary. As I walk into my own dispensary, I see many frame
shapes that look nice, but similar, from a distance. I'll carry
the same effective shape frame in multiple sizes but each one has
the nose pads mounted in a different place on the frame.
For instance, if I'm looking for
an oval-shaped frame, and the one I've initially selected causes
the frame to sit too high on the patient's face, I just look for
the same type of frame that has the nose pads mounted a little
higher on the frame. This feature causes the frame to drop a bit,
creating a better fitting advantage.
Don't purchase a frame that you'd
use for fitting PALs if you can't make adjustments smooth-ly,
fully and without breakage. Some frame designs and materials make
adjusting more challenging than necessary.
You've heard it for years: "Place
the optical center of the patient's lenses directly in front of
his line of sight for the required tasks." Fitting PALs is
no different. The concept of dotting the optical center is a
necessary technique we all must master.
Remember that the patient's right
eye sights his left eye and the patient's left eye sights his
right eye. Don't cross sight because that causes parallax,
resulting in a false optical center and possible PAL rejection.
Make sure you're at the same
height as your patient when dotting so that you see eye to eye.
Either get up to his height or have him come down to yours.
Have the patient place the
adjusted frame on before and after dotting in the position that
he's most likely to wear them. Before I asked patients to do this,
I consistently had a high rate of PAL failures.
Think about it: I want frames to
fit certain ways, so I place them where I think they should be on
the patient's face. Patients listen to me in my office, but once
they've left, the real world takes over, and they adjust the
frames to their comfort level.
Of course, this doesn't always
mesh with how I've adjusted the spectacles. At the time of
dotting, I'm as insistent as I can be that my patient place the
frame on his nose and face in a location that they "most
likely" will end up using them. In most situations, I can be
kept in the positive column of PAL success by making small, easy-to-do
compensations on frame fit.
Dot the patient's pupil location
in a consistent manner. I've found that searching, locating and
dotting the nasal aspects of the patient's pupil has helped a lot
in making me accurate with proper centration of the finished
With today's patternless edgers
and computerized lens layout technology, this is the easy part.
Let the machines do it. Uncut finished PAL lenses come with
marking dots that are easy to locate and use.
After you've used the standard
layout and blocking techniques, edge, finish and insert the
completed lens like any other simple single vision job. Nothing
special is required to edge and finish these in your own in-office
Inspect the finished job optical
center using the lens manufacturer's layout charts and against
the dotted sample lenses. Should your dots not line up with the
prescribed fitting centration, stop and either re-align the
lenses in the frame or throw them away and start again. This isn't
a situation where close is good enough.
After you've completed and
inspected the finished eyeglasses, ensure that the finished
product is "bench fitted" with 10 to 15 degrees of
- We know that all
PALs by design are aspheric. However, there's
been a wonderful proliferation of single vision and
multifocal aspheric lens designs. In the past 10 years,
keys to successful fitting have been to fit and adjust
frames so that they rest as close to the apex of the
cornea as is reasonable.
When fitting PALs, I loosely think of these lenses as
contact lenses. I'd never fit a contact lens at any
appreciable distance from the tear film, so I try not to
do the same with PALs. The closer to the eye I fit the
progressive, the better it works.
- It makes no sense
to fit curved lenses to curved eyes with flat fitting
frame fronts. We need to fit curved lenses
to curved eyes with curved frame fronts. I've found that
many frames today have less face form to better fit the
flatter aspheric single vision lenses. Well, this might
work well for these lens combinations, but this is a
recipe for potential failure when fitting PALs.
- Maneuver nose
pads to control the visual outcome. Using
the proper pliers and techniques can help you create the
final vertex fitting distance that will make the PAL work
easily and effectively.
Times are good
We've never had a better or easier
time to prescribe, fit and troubleshoot PALs. Today, most
progressives work well "out of the box." Certainly,
some work better than others, and we've all developed our
favorites. With the unveiling of the next generation of lenses
fitting progressives just gets easier.
Dr. Shwom's brother, Leonard C.
Shwom, O.D., R.D.O., contributed to this article.
Dr Shwom is in private
practice in Everett, Mass. He's an associate professor at the New
England College of Optometry in Boston. If you have your own
"Tricks of the Trade" on progressive addition lenses,
please send them to: Irwin M. Shwom, O.D., R.D.O., 421 Broadway,
Everett, Mass. 02149-3435. Phone: (617) 387-1904. E-mail: email@example.com.
New Directions for PALs
An ophthalmic lens expert
forecasts the next big step for PALs.
By Joseph L. Bruneni, Torrance, Calif.
Have you been wondering about
the latest changes in progressive addition lens (PAL) designs?
Well, here's a brief rundown of what's been happening in this
advanced lens category. The past 18 to 24 months have seen major
changes in PAL designs.
The first such change was
prompted by the fashion trend toward smaller, vertically narrow
frames. Trying to dispense a conventional progressive design in
one of the popular new small retro frames became a blueprint for
disaster because the narrow vertical height of the frame or
mounting cut off much of the reading portion of the lens.
Recognizing a new market, American Optical produced their Compact
lens with a progressive channel shorter than anything available
at that time.
Since then, other short
channel PALs have become available, such as the Hoya Hoyalux GP,
Pentax AF Mini, Rodenstock Progressiv series, Kodak Concise and
Sola Solamax, to name just a few.
The next major change came
with the "position of wear" concept in which the
manufacturer or laboratory alters the O.D.'s prescription to
compensate for the way the lens is positioned when worn by the
patient. The prescription changes are subtle, but they do seem to
provide enhanced acuity for the patient.
Another example of an advanced
progressive concept is the long-awaited cast-to-prescription
progressive from Johnson & Johnson. The new lens from Johnson
& Johnson places half of the progressive addition curves on
the front surface and half on the back surface of the lens.
According to Johnson & Johnson, the result of this hybrid
approach is a considerably wider field of view for intermediate
SOLA recently introduced a
totally new progressive design called Solamax, featuring a short
channel with an intermediate zone considerably wider than
conventional progressives. SOLA President Brett Olson recently
told a laboratory audience that the non-adapt rate for this
design is running .006%. He stated, "SOLA believes the
future in progressive design will be specific progressives for
specific tasks. The concept of fitting every patient with a
general purpose progressive design will be outmoded by
progressives that are designed for specific patient lifestyles."
He added, "Future
products from SOLA will focus on performance, technologies and
fashion. We plan to continue expanding our family of progressives
with lenses designed for the patient's custom needs."
Rest assured that Sola won't
be the only company seeking to produce newer, more advanced
progressive designs. At a recent OLA convention, a new type of
generator was unveiled that could potentially permit laboratories
to produce lenses that would have progressive curves placed on
the back surface of the lens. The same machine can also produce
atoric back surfaces, something labs are unable to surface with
As a result of these
advancements in progressive designs, coupled with the
extraordinary improvements in laboratory processing equipment,
the concept of producing progressive lenses specifically designed
for each patient's lifestyle is close to reality. This continuing
advancement of progressive lens design may create a somewhat
confusing range of choices for eyecare professionals, but the
long-term beneficiaries are the patients who wear these
Optometric Management, Issue: February 2001