With Silicone Hydrogels
contact lenses make for a patient and a practice success story.
KIRK L. SMICK, O.D.
hydrogel lenses, which have been on the market for about five years, are proving
to be an all-around success story. Today, many eye care professionals make lenses
with this hyper-oxygen transmissible material their preferred choice for patients
of all sorts for good reason. Silicone hydrogel lens materials offer distinct
health advantages to the patient, while presenting eyecare practices with an opportunity
to benefit financially. It's a win-win situation.
Counting down the benefits
Silicone hydrogel lenses are distinct in their ability to transmit
more oxygen to the cornea than conventional HEMA-based lenses. This affords numerous
health benefits to the patient. There are six types of silicone hydrogel lens materials
currently on the market, with Dk values that vary from 60 to 140, as well as Dk/t
values that range from 86 to 175 for a -3.00D lens.
As a group, silicone hydrogel lenses deliver 97% or more of available
oxygen to the cornea (according to individual manufacturer's reports to the FDA).
No one lens material really holds a significant edge in oxygen availability, so
practitioners must evaluate the lenses based on criteria about wettability, modulus,
UV protection, long-term comfort and other attributes.
Ask the right questions
As practitioners, the ability to offer patients the many benefits
of silicone hydrogel lenses requires that we ask the right questions ... the right
In the screening stage, even before the patient sees a doctor,
a staff member asks, "How many hours a day do you wear your contact lenses?" They
then ask, "How does that compare with a year ago?" and, "Are your lenses still comfortable
late in the day?" These three questions tell us a great deal about the patient's
needs and whether silicone hydrogels might offer improvements. These questions also
prompt patients to think about their contact lens-wearing experience. This opens
them up to sharing their concerns.
When that patient reaches one of our doctors for the exam, their
chart will bear a short note: "Eyes get dry late in day ...," so we can address
Trends in lens wear
We prescribe silicone hydrogel lenses to about 85% of all new
contact lens fits. This is up from approximately 15% just a year ago. We firmly
believe that patients in silicone hydrogel lenses will do better in the long run.
In our large practice, we see more than 200 patients each day.
With this kind of volume we spot trends as they emerge and track them for the benefit
of patients and the growth of our practice.
First and foremost, we've seen a dramatic reduction in the incidence
of red eyes among silicone hydrogel patients. Many of our patients who still are
in conventional lenses recognize that these past-generation lenses make their eyes
appear red and irritated. "People ask me what I've been drinking," patients tell
The reduction in redness is also a great comfort to practitioners.
Many doctors believe that limbal redness is a precursor to neovascularization. That
may well be the case, as some recent articles indicate, though we don't know that
definitively at this time.
Another trend we see with silicone hydrogel lenses is a decrease
in myopic creep. With conventional HEMA lenses, patients often require a small amount
of over-correction in their distance every time they come in for an annual exam.
It might be only 0.25D, but over years it adds up. We see this with patients even
in their 20s, a time when myopic creep generally stabilizes. With silicone hydrogel
lenses, we hardly ever see it.
The discomfort factor
According to a recent study (sponsored by Vistakon) involving
40 doctors across the United States, discomfort due to dryness affects 67% of the
more than 36 million contact lens wearers in the United States. Many patients complain
that their eyes feel tired and dry during certain activities and in select environments
(e.g., long hours of computer use, frequent ground or air travel, or everyday exposure
to heated or air-conditioned surroundings).
In the same study, researchers examined clinical data taken from
1,092 wearers of soft contact lenses. Nearly half (48%) met at least one of six
criteria for frequent or constant discomfort or dryness. The most commonly reported
problems were: uncomfortable wear at the end of the day (31%), frequent or constant
dryness (28%) and discomfort (17%). In my practice, patients who have switched to
silicone hydrogel lenses report being able to wear their lenses longer into the
How to compare lenses
When prescribing silicone hydrogel lenses, be aware of a number
of patient benefits that may take some getting used to. The lenses typically have
a higher modulus than traditional hydrogel lenses. Therefore, counsel patients on
initial comfort issues relative to other types of lenses they may wear. We always
inform the patient not to make any initial judgments of lens comfort relative to
his or her current lens design until about 72 hours have passed.
The following points are useful in comparing the various silicone
Consider Your Options
We now have at our disposal
a variety of silicone hydrogel lenses from several manufacturers, some with designs
to address astigmatism, which greatly extends the application of this lens material.
And we will see future generations of silicone hydrogel materials with additional
patient health benefits in the future.
following are on the market today:
Daily wear; Extended wear up to seven days
with Hydraclear (Vistakon)
& Day (CIBA Vision)
Extended wear up
to 30 nights
Daily or extended
wear up to six nights
Extended wear up to
►Flexible wearing schedules. Silicone hydrogel lenses are approved for varied wearing
schedules and can meet different patient needs and preferences. In our practice,
we believe that two-week daily wear is optimal, and that's what we prescribe most
often. Many practitioners agree with this "shorter is better" philosophy, though
attitudes may change as enhanced, next-generation materials emerge. However, some
patients want seven-day or 30-day continuous wear, and we can fill that need with
silicone hydrogel lenses that are approved for a longer wear schedule.
►Silicone hydrogel lenses deliver greater comfort over long periods. In fact, most
patients are able to wear their lenses for more hours each day than with traditional
soft contact lenses. Very few patients now tell me, "I can't wait to get home and
get these lenses out." That was commonly heard with previous lens materials.
Furthermore, silicone hydrogel lenses will likely become even
more comfortable in the future. The goal of manufacturers has always been to make
contact lenses feel as natural as the cornea itself. The dynamic contact angle (DCA)
of a lens is a measure of its wettability, and manufacturers are adjusting lens
materials to increase this. Lens designs with a higher DCA seem to be more comfortable
on the patient's eyes.
Also, manufacturers use different surface treatments or internal
wetting agents that can affect lens comfort. These are proprietary, but clinicians
are aware that differences exist. This allows us to monitor patient symptoms relative
to each lens.
►UV blocking. Finally, the inclusion of a good UV blocker in silicone hydrogel lenses
is also an important patient benefit that we should discuss with them. The only
silicone hydrogel contact lenses now on the market with a Class I UV blocker are
those in the Vistakon Ultra Comfort Series: AcuVue Oasys, AcuVue Advance, and AcuVue
Advance for Astigmatism. These contact lenses block more than 90% of UVA rays and
99% of UVB rays, more than other contact lenses currently on the market. (Other
contact lenses have the ability to block or absorb UV, but not to this extent.)
A word about presentation
Moving patients into silicone hydrogel lenses requires different
strategies for existing patients than for new patients. With new patients, it's
easier. They seek our guidance. We simply present and prescribe silicone hydrogel
lenses as the latest technology, and we highlight a few patient benefits, such as
comfort and long-term health. Patients who are new to contact lenses don't know
what kind of lenses they want. However, they likely have heard about different products
and benefits, and we want to be sure to let them know we offer the newest options.
For existing contact lens patients, we explain the benefits relative
to the lens materials they now wear and present them with the healthiest technology
available today. A discussion of pricing comes after they try a demonstration pair
of lenses. We believe that ancillary staff, not the doctor, should initiate and
engage in discussions of cost.
We find that giving veteran contact lens patients a demonstration
pair of silicone hydrogel lenses is an effective way to spark their interest (people
are prone to stick with what they know). After a week's wear, about seven in 10
tell us they found the lenses more comfortable. The remainder tell us they're about
as comfortable in their old lenses, and because silicone hydrogel lenses are more
expensive, they'll stay with what they've been wearing.
In our practice, we make
certain to prescribe the lens care solutions we want our patients to use with their
silicone hydrogel lenses. When patients return for follow-up, we ask them to confirm
that they're using what we recommended. That way, we uncover the patient who switched
to an inexpensive solution that was on sale at a discounter, which often increases
the chances of ocular irritation.
Fortunately, silicone hydrogel
lenses are fully compatible with the leading no-rub solutions that render lens care
a snap. We do, however, recommend rubbing lenses when you clean them; it's simply
more effective than just soaking lenses in a no-rub multipurpose solution. Silicone
hydrogel lenses have often been called "lipid lovers" due to silicone's tendency
to attract deposits. However, with proper care and frequent replacement schedules,
lipid deposits have not been a significant problem in our practice.
Understand the benefits
One of the key benefits to silicone hydrogel lenses is increased
patient satisfaction, which means patient retention a key practice benefit.
It is remarkable that each year approximately three million people come in to contact
lens wear, but as many as 2.7 million contact lens patients drop out. That's an
incredible loss of practice revenue.
At the same time, many practitioners lack a good understanding
of how prevalent dropouts are or how damaging this loss can be to practice
income. Often a doctor doesn't know about a drop out. We frequently see patients
who come over from another practice because they are interested in a more comfortable
lens, but their current doctor didn't suggest any other options.
From an economic standpoint, silicone hydrogel lenses bear a higher
profit margin than conventional hydrogel lenses. That's clearly a practice benefit.
We also are able to price ourselves competitively and to offer direct-delivery.
Patients can pick up their replacement lenses from our office, but it's beneficial
to our practice not to warehouse lenses. It's also more convenient for patients
to have replacement lenses shipped directly to their homes or offices.
Silicone hydrogel lenses also ease our patient load. With fewer
problems of red, irritated eyes brought on by oxygen deficiency, we have fewer unscheduled
the end, silicone hydrogel lenses provide more oxygen and a balance of properties
that add up to better health benefits and patient satisfaction and better
benefits for the eyecare practice, too!
Dr. Smick serves
as chief of primary care services at the Clayton Eye Center in Morrow, Ga.
Optometric Management, Issue: February 2006