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Feature Story
Refraction
3 Contacts With Clout
In the last two years, a funny thing happened: As LASIK
gained popularity . . . so did contact lens wear. Indeed,
instead of cutting into the contact lens market, LASIK may
have actually fueled consumer demand.
The statistics tell the story. According to Market Scope,
which publishes an industry newsletter called "Refractive
Market Perspectives," 480,000 laser vision correction procedures
(one per eye) were performed in 1998. The 1999 projected
figures were 980,000, up 104 percent. And for 2000, the
projection was 1.5 million procedures, up 48 percent from
the previous year.
During the period from 1998 to 2000, noted Peter C. Donshik,
MD, editor of The CLAO Journal (Contact Lens Association
of Ophthalmologists), the number of contact lens wearers
increased from 25 million to 32 million. He associates this
rise in wearers with an overall renewed enthusiasm by spectacle
users for vision alternatives–an enthusiasm spawned
by the growing availability of LASIK.
In addition, contact lenses have their advantages over LASIK.
"One thing that LASIK can't do is correct presbyopia," noted
Donald J. Doughman, MD, professor of ophthalmology at the
University of Minnesota. "The industry has identified these
patients and continues to create better and better disposable
bifocal contact lenses. The same holds true for disposable
toric lenses, which today are meeting the needs of people
with astigmatism who are not candidates for refractive surgery."
Perhaps the greatest innovation in contact lenses is the
development of high Dk soft lenses, made from a new silicone-hydrogel
material that allows for extended wear without the complications
that in the past have proved extremely troublesome.
All three contact lens alternatives–high Dk, disposable
bifocal and disposable toric lenses–have their advantages
and challenges. Ophthalmologists can provide great benefit
to their patients by being familiar with the available options.
High Dk Lenses
Perhaps the most exciting newcomer in the market is the
silicone-hydrogel high Dk lens, which represents a major
breakthrough in increasing oxygen permeability–an especially
important feature for patients who want extended wear lenses.
Dr. Donshik, who is a corneal specialist with the University
of Connecticut Health Center in Farmington, said, "Past
studies have shown that a major factor responsible for complications
in extended wear was the low level of oxygen available to
the cornea, especially during sleep. This not only resulted
in corneal hypoxia but also caused bacterial adherence to
the cornea, which was felt to be an important factor in
developing microbial keratitis.
"With the new silicone-hydrogel high Dk lenses, it looks
like we have solved the oxygen problem. But we still need
to see whether these new lenses when worn on an extended-wear
basis will have problems with the ocular surface," Dr. Donshik
said. "The amount of oxygen reaching the cornea in someone
wearing these lenses is significantly high–in fact,
the amount of oxygen reaching the cornea with or without
wearing the lens is about the same."
The FDA approved Bausch & Lomb's PureVision high Dk lenses
for seven-day extended use in 1999. So far, these are the
only ones on the market; Ciba Vision's Focus Night & Day
are in clinical trials. Typically, patients wear these types
of lenses for six days and take them out on the seventh.
"The optimal patient is someone who has no ocular abnormalities
that would preclude contact lens wear and wants to wear
the lenses on an extended basis," Dr. Donshik added. "The
myopic range is up to –6 D. It is also good for people
who have problems with hydrogel lenses of low to moderate
Dk and require a contact lens with a higher oxygen transmissibility."
Zoraida Fiol-Silva, MD, director of the contact lens department
at Wills Eye Hospital in Philadelphia, welcomes the new
high Dk lenses and believes they may be safer. However,
she expressed concern that the lenses will not necessarily
herald the end of such dangerous complications as ulcerative
keratitis. "While oxygen transmissibility is a very important
factor," she said, "we need to look at other issues, such
as patient compliance. Compliance is increasingly important
because, despite new lens materials and solutions, we still
have not been able to eliminate complications or significantly
decrease the incidence of serious complications.
"Although data are not yet available on the new lenses and
their impact on the incidence of ulcerative keratitis, I
don't believe this complication will be eliminated just
with the new lenses," Dr. Fiol-Silva said. "I believe the
current lens care systems need significant improvement,
and patient compliance will continue to play an important
role. Aggressive public education is necessary.
"Improving professional care to our patients is also important,"
she said. "Alternative methods of lens acquisition, void
of proper patient education and professional care are quite
disconcerting to me. Both the contact lens industry and
the professionals must continue to work together toward
the development of improved lens materials, care products
and proper patient education to improve contact lenses and
continue to keep them a safer alternative to refractive
surgery."
A Look at Contact Lens Stats
Disposable Bifocal Contacts
Enthusiasm. According to James E. Key, MD, a private practitioner
in Houston and clinical professor of ophthalmology at Baylor
College of Medicine, enthusiasm on the part of both the
ophthalmologist and the patient is crucial to successfully
wearing disposable bifocal contacts. There is no doubt that
the market for this product is large; James D. Atwood, MD,
of California's Napa Valley who retired from practice in
1998 but acts as a consultant to physicians, noted that
four million baby boomers born between 1946 and 1964 turn
presbyopic each year. However, the new disposable bifocal
contacts introduced in 1999 are not perfect for all presbyopes
and require some experience on the part of the fitter. Dr.
Key's article published in the CLAO Journal in 1999 showed
that in the first 100 patients who were fitted with Johnson
& Johnson Acuvue Bifocal disposable lenses, the lens was
"satisfactory 50 percent to 60 percent of the time." The
other 40 percent did not achieve the vision that they needed
with the contact lens. He added that satisfaction substantially
depended on the patient's attitude concerning the product
and that subsequent success rates with good patient selection
are now 70 to 80 percent.
Bifocal lenses can be divided into two main groups–rigid
gas permeable (RGP) and soft. There are two main designs
of bifocal lenses: simultaneous vision and alternating vision.
While both soft and rigid lenses are available in the simultaneous
vision design, only RGP lenses are available in the alternating
vision design.
The alternating types are the only kind of contact lenses
that behave as bifocal glasses do, Dr. Key explained. The
lens "translates," or lets patients look through two distinct
visual zones. Patients can adjust their gaze accordingly–straight
ahead for distance vision or lowered for reading.
Dr. Key said the ideal candidates for RGPs are those who
wear rigid lenses to begin with. This vastly simplifies
the transition to RGP bifocals. He warned that fitting an
RGP lens takes more time and is more complicated than fitting
a soft lens. "Many more factors affect a good fit including
lid tension and the quality of the tears. Yet once the fit
is accomplished, patients are generally very happy."
Dr. Atwood added that the consumer demand for soft bifocal
lenses has been fueled by the fact that more than 80 percent
of contact lens wearers in the United States wear soft lenses.
Many are reluctant to give up the comfort they are accustomed
to for an RGP lens. Dr. Key explained that soft bifocal
lenses are really a misnomer. They are actually multifocal
lenses that use simultaneous vision, meaning they provide
near and distance focus at the same time. Patients adjust
their visual attention to the sharpest image, depending
on whether they need distance or near correction at the
time. The lenses are available in aspheric, concentric,
diffractive and multizone designs.
Dr. Atwood noted that the disposable Acuvue bifocal is a
concentric ring, distance-center, simultaneous vision lens.
It uses a patented "Pupil Intelligent" design made up of
five invisible zones alternating near and far correction.
Peter R. Kastl, MD, PhD, a contact lens specialist with
Tulane University in New Orleans, noted that the drawback
of this design is that it goes against the mammalian neurological
system, which is based on alternating vision.
"A soft lens can't move on your eye like the RGP lens can,"
said Dr. Kastl, "so instead the eye is forced to focus on
everything at one time. According to the manufacturer, one's
brain will be able to differentiate near vision from distance
vision automatically. However, simultaneous vision is not
natural vision, and certain people can't tolerate this approach."
In fact, Dr. Kastl is one of those people. He wears RGP
bifocal contact lenses because they allow him to look near
and far–in an alternating fashion. On the other hand,
Dr. Key wears soft multizone, multifocal lenses.
Dr. Atwood noted that the ultimate success of the disposable
bifocal contacts lens is dependent on the patients' willingness
to compromise on the quality of vision they remember as
30-year-olds. He also suggested that practitioners should
not assume that patients require 20/20 vision to be happy.
"If most patients can see to drive and what they want to
read, they are happy," he said. "If you can't get them to
see 20/20, give them better correction with the dominant
eye for distance and with the nondominant eye for near."
"The real point," noted Dr. Key, "is that there are many
options out there for presbyopic lenses that are easy to
fit. All that is required is that the contact lens technician
in the office, under the direction of the ophthalmologist,
has the time to deal with the patient. We actually set aside
one hour for the initial disposable bifocal lens fitting,
and from a practice management standpoint, you have to charge
for that hour of time, which we do."
Enthusiasm–and patience–are key in this brave
new world of disposable bifocal contact lenses.
Toric Disposables
Although toric lenses have been on the market for many years,
the advent of the two-week disposables is a fairly recent
phenomenon. "The challenge was designing and manufacturing
lenses that could be good quality, reproducible lenses at
an affordable cost to patients," noted Dr. Fiol-Silva. "Early
on, the industry had to consider the priority of toric disposables
compared with other products such as disposable bifocal
lenses. The bifocals won, of course, because the potential
market for bifocal lenses is 77 million people."
However, manufacturers did pull through. The first truly
disposable toric lenses became available about a year and
a half ago. Until this point, only frequent replacement
toric lenses were available.
Dr. Fiol-Silva noted that, as with other disposable lens
users, the optimal patients for toric disposable lenses
seek convenience, may have poor quality and quantity of
tears or may produce a lot of protein and oils in their
tears. As for whether the patient needs toric lenses, Dr.
Fiol-Silva and her colleagues do not base this decision
by absolute amounts but rather the ratio of astigmatism
versus the full prescription. "The rule of thumb is that
when the astigmatism is less than 20 percent of the overall
correction, oftentimes you can ignore it and have a happy
patient," Dr. Fiol-Silva maintained. "However, if the ratio
is 20 percent or more, the patient will typically do better
in toric lenses."
Currently, the disposable toric lenses are only available
in limited parameters. On the positive side, the two-week
disposables are better than frequent replacement lenses
because they are healthier for the eye and require less
care. "Any patient who requires a toric correction in a
soft lens would be the proper candidate for wearing the
new disposable toric lenses, provided that the proper parameters
are available," Dr. Fiol-Silva said.
A Look to the Future
Dr. Doughman predicts that the future of the contact lens
industry could very well rest on the success of high Dk
lenses. While only approved for seven-day extended use in
the United States, the lens is being worn for 30 days in
Europe, Brazil and Australia and has the potential to rival
LASIK in terms of convenience without the risks posed by
surgery.
"If the 30-day option becomes available in the United States,"
Dr. Doughman said, "it could have a serious impact on the
numbers of people opting for LASIK. It is a removable and
reversible alternative."
He also believes that contact lenses continue to be a vital
practice builder for ophthalmologists, bringing in patients
who do not want LASIK or who are not eligible for the procedure.
"With contact lenses, patients return to your practice on
a routine basis," said Dr. Doughman. "In fact, you can fit
your patients with bifocal lenses even after LASIK."
Whatever is ultimately the impact of the new lenses, it
appears that because of–or despite–the growing
popularity of LASIK the number of contact lens alternatives
will continue to expand.
Advantages and Disadvantages
of New Lenses
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