Eyecare professionals in the U.S. dispense 17 million pairs of
bifocals each year to presbyopic patients. Although bifocals work
well for very close reading, they provide no correction at all for
intermediate distances, so bifocal wearers are missing an important part of today’s demanding visual environments. Trifocals
could restore the intermediate, but they create other problems.
Progressive lenses provide intermediate correction but for several reasons are not always the lens of choice. Until now, bifocal
wearers have had to accept the missing intermediate.
atLast! Enhanced Multifocals are a new kind of lens combining
advanced lens design
and material technologies to provide four
ranges of clear, spacious vision. These
new lenses deliver distance vision correction
plus continuous vision
from 14 inches to five
feet. atLast! restores
the intermediate vision
that bifocal wearers
have been missing.
THE FORGOTTEN FLAT TOP WEARER
Flat tops have a big
presence in the U.S. lens
market. That is because
many patients don’t care
about the cosmetic
advantages of progressives, have tried them unsuccessfully or have been wearing bifocals so
long they and their opticians are reluctant to make a change.
Just how many people wear bifocals? Not everyone gets new
glasses every year, so when those 17 million bifocals are multiplied by a purchase cycle of more than two years we can estimate
there are over 35 million flat top wearers. And according to
VisionWatch, a study conducted by Jobson Medical Information
and Vision Council, in the 12 months ending March 2008 the
volume of bifocals was up from prior years’ levels, representing
an increasing business opportunity for optical retailers.
Most bifocal wearers are somewhat older than progressive wearers, yet the distribution is not as skewed as you might expect. In
fact, the figures show that many Baby Boomers are wearing bifocals. This may surprise many eyecare professionals, who have long
known progressives as the Baby Boomers’ lens. The chart (Chart 1)
shows the relative age distribution for each type of multifocal.
We also know that today’s presbyopes face more demands for
intermediate vision than before. Many face the challenges of the
technology revolution at work and even when retired they still
need intermediate correction for things they do every day.
Whether looking up information on the web, checking email or
simply trying to see items on shelves at a store, the modern presbyope is active and immersed in a complex visual environment.
Because two thirds of bifocal wearers are older than 55, an age
when accommodation is almost entirely lost, the average add
power is now close to +2.50D. That means the majority of wearers have adds greater than +1.75D, a power where intermediate
clarity is significantly reduced. For most people the depth of
focus through the seg is only about 14 to 18 inches. Through the
distance part of the lens patients can’t see closer than about
seven to 10 feet. This means there is a big gap of blurry vision
from the fingertips out to five feet or farther. Another problem is the sharp discontinuity
between powers, what
we call the “power
jump.” This causes
image shift and also is
perceived as a sharp
and jarring change in
focus. Finally, the typical FT28 bifocal in
higher adds has a very
thick segment ledge
that is not just a cosmetic problem. It is
very visible to the wearer, especially because
of reflections.
Of course, progressives could solve these
problems. But many
bifocal wearers have tried progressives and were unable to adapt
or they preferred the larger reading area of bifocals. Whatever
the reasons for rejecting progressives, we can be sure that millions of bifocal wearers would benefit from a new kind of lens
that provides an extended range of intermediate vision and
reduces or eliminates power jump while retaining some of the
familiar characteristics of bifocals. As we will see, new technology has made it possible to provide this kind of a lens.
INTRODUCING COMPOSITE LENS TECHNOLOGY
Composites are combinations of materials that are brought
together in a way to achieve properties superior to either material alone. For example, composites allow the creation of new
kinds of optical designs.
One example of this is Composite67, a composite lens material recently introduced by PixelOptics. In Composite67 lenses,
a front component of Trivex and a rear component of 1.67
index material are fused by molecular bonds. Both materials
are familiar to eyecare professionals. Each material can be used
to make a stable, high-quality lens. In combination, they can
achieve much more.
Because there is a difference in refractive index between the
two materials, it is possible to create optical power where the
two materials bond. It is this structure that enables new kinds
of lens designs to be developed. In addition, Composite67 lenses are as thin as other 1.67 index lenses because the Trivex
component has parallel surfaces that contribute no distance
power. Yet the weight of Composite67 lenses will
be somewhat less than 1.67 lenses of equal center
thickness because the Trivex component has a
lower specific gravity.
A Composite67 lens is also very durable. Unlike
older laminated lenses that could fail when the component parts separated during processing, the PixelOptics composite technology results in intermolecular bonds that make the lens perform as a single
unit. Composite67 lenses can be surfaced, edged,
grooved, drilled, made anti-reflective or tinted just
like other 1.67 lenses.
ATLAST! ENHANCED MULTIFOCAL LENSES
In this particular application of composite technology
a new category of lenses was created, called Enhanced
Multifocals. The atLast! lens design increases the
range of near and intermediate vision more than 10
times that of a bifocal. This is accomplished by adding
a power gradient to the embedded power segment. It provides a
wearer with four zones of stable vision: near, intermediate, far
intermediate and distance. Here’s how it works:
In atLast! the rear component has a 28mm round segment with
a single, fixed power. The Trivex front component includes a
power gradient that contributes the rest of the add power. (Fig 1 Index A & B respectively). The embedded segment is nearly
invisible and the front and back surfaces of the lens are smooth.
atLast! lenses provide four zones of vision (Fig 2). Above the
segment is a distinct zone for distance vision, much like the area
above a bifocal segment. The other three zones are continuous.
As the eye looks below the embedded segment border it encounters the power of the seg itself, which is less than a third of the
prescribed add. This provides far-intermediate clarity at distances beyond arm’s
reach, out to about
five feet. The power
gradient starts about
4mm below the top
of the segment to
provide intermediate
vision and continues
to increase to a point
just above the segment center, where it
reaches full add
power for near vision
correction. The
results are large, clear areas of vision with a small power jump
at a soft line discontinuity.
Let’s take a look at a specific example. In a +2.00 add atLast!
lens the front component has a power gradient from plano to
+1.50. The embedded segment contributes +0.50D of the total
add power (Fig 3). The resultant power inside the segment border now ranges from +0.50 to +2.00D of add power (Fig 4).
Above the segment border there is no add power, only the distance prescription.
At the soft line discontinuity, power jump is significantly
reduced. Compared with a +2.00 add bifocal, the atLast! lens
has a power jump of +0.50D at the edge of the segment, a reduction of 1.50D. The reduction of power jump results in easy adaptation and minimum visual disruption.
Not a Progressive or Blended Bifocal Progressives have no
lines, but atLast! has a soft line discontinuity. Blended bifocals
have a fixed add power and a wide band of distortion surrounding the segment. atLast! lenses have an embedded segment with
a power gradient without distortion.
CLEAR FAR-INTERMEDIATE VISION
 Unlike other lined multifocal lenses, atLast! provides clear far-intermediate vision. To demonstrate increased fields of intermediate and far intermediate, a test table was constructed with acuity targets at several distances and viewing angles. For each range
and angle the visual acuity was recorded. Fig 5 shows the difference in “visual footprint” for +2.50 add wearers. Green squares
represent the clearest areas of view, while black represents a failure to see any of the targets. Clearly the results are superior for
wearers using atLast!
ECP BENEFITS
In a tight economy, patients may be looking for greater value in eyewear. This may be especially true of the
millions of bifocal wearers, who sometimes have a
reputation for being price sensitive. One way to deal
with this is to lower prices, as many optical retailers
are doing. An alternative way is to provide better
information about product performance. The advantages of this new Enhanced Multifocal lens for bifocal
wearers include clear vision from 14 inches to five feet
away, a segment that is virtually invisible for excellent
cosmetics and the thinness and lightness that results
from its Composite67 material. The introduction of
atLast! provides an opportunity to talk to all of your
practice’s bifocal wearers. Now is an excellent time to
enhance your professional reputation by informing
your patients about new technology that can provide
immediate benefits.
Of course there also is a premium positioning opportunity
with atLast! that will contribute incremental margin to any
practice. Bifocals have not been a highly profitable category
for a long time, but an advance in technology like this will
convince many patients to move up to premium price points.
It also makes sense to offer AR coatings with atLast! because
of its high index.
Although the most obvious target is the lined multifocal market, consider taking advantage of some additional practice
growth opportunities. Perhaps as a second pair for the progressive wearer who may want a second pair of glasses with a stable,
wide near zone for desk work or as a less expensive second pair
option. Think occupational lens when the tasks require more
intermediate. atLast! also makes a great option for patients
who might have rejected a progressive in the past. In fact, we
have found that many former bifocal wearers reject progressives for what might seem surprising—they have no line. It’s
true, some of these folks find a level of comfort in knowing
where the reading area is.
FITTING AND DISPENSING
Rx Range: The current prescription range is +3.50 to -6.00D
spheres, cylinders to -4.00D to a combined power of -6.00D in
add powers of +1.75 to +3.00. Additional base curves and add
powers will be introduced soon so check with your lab for changes
in availability.
Fitting atLast!: Simply specify the distance PD and the segment
height. Position atLast! higher than a bifocal because it provides
intermediate powers. For most people a seg height of 2 to 3mm
above the lower lid works best, (Fig 6) but you may specify higher
or lower according to your judgment of lifestyle, work, previous
eyewear and posture. Ensure a minimum fitting height of 14mm.
Verification: Verify lens power just like bifocals. Measure distance power at the optical center or the prism preference point.
Verify add by reading the semi-visible engravings. The add
power can also be measured on a lensmeter at the center of the
embedded power segment.
To verify distance PD, dot optical centers and measure the
distance between them. Another method is to measure the distance between the left engravings of the right and left lenses.
(Please note: near PDs are fixed at 4mm less than distance PDs
and segments cannot be decentered by the surfacing lab to
achieve separate distance and near PDs.)
To verify segment height, measure from segment top to the
lowest point on the lens edge.
CONCLUSION
In summary, atLast! is designed to replace lined multifocals. Unlike
traditional flat tops, atLast! provides patients with an expansive
intermediate vision. There is 70 percent less power jump at the top
of the segment. A new “fourth zone” of far-intermediate is now
available for the flat top bifocal and trifocal wearer. atLast! provides
distance correction plus continuous vision from 14 inches to about
five feet. And atLast! is more appealing cosmetically since the segment is virtually invisible.
Most importantly, you can provide a great lens upgrade option
to what has become an all but forgotten patient group. Now look
up because some of those 35 million bifocal wearers are probably
in your reception area right now. |