SOFT TORIC CONTACT
Vision and Comfort with Soft Torics
ease of fit and so many design and material options, soft torics are an excellent
choice for astigmats.
soft torics really become so easy? Actually, the answer is "Yes." No longer should
practitioners experience long, sleepless nights contemplating the extended chair
time they need to fit soft toric contact lenses. Fear of multiple follow-up visits
eating away at your schedule should no longer exist. The reason? Soft torics are
painlessly easy to fit. The available lens materials, wear schedule options, lens
designs and powers provide practitioners with a more-than-adequate opportunity for
Improve Your Patients' Vision
toric lenses are absolutely necessary for proper vision care. Over the past five
years, we've experienced a steady increase in the overall number of soft toric fits.
However, the number of soft toric contact lens wearers continues to fall well below
the number of patients who have correctable astigmatism. Considering the many contact
lens wearers who have cylinder values greater than –0.75D, we're still missing
a tremendous opportunity.
Each time we perform a refraction and the final result reveals cylinder, we should
consider a toric contact lens. Proactive approaches to soft toric fitting will not
only help patients see more clearly, but will increase the value of our practices.
With the vast improvements in manufacturer technology, better lens reproducibility
and various design options of today's lenses, all practitioners should take
advantage of giving patients the best vision possible.
You can and should
consider any of the past arguments against the use of soft toric lenses in favor
of spherical lenses as obsolete by today's standards. Visual fluctuation, limited
cylinder powers and lack of different lens designs are no longer excuses to avoid
fitting astigmatic patients. Contact lens manufacturers realize the importance of
creating products that allow practitioners to fit soft toric lenses with extreme
confidence. So stop worrying about failure and lost chair time, and don't make "20/happy"
the endpoint visual acuity for your astigmatic patients. Soft toric contact lenses
are a reasonable and viable option for the regular
astigmatism patient. So let the fitting process begin.
Soft Toric Fitting Basics
are a few basic guidelines for a successful soft toric fit:
of soft toric candidates do well with median base curve values (8.3mm to 8.7mm).
With-the-rule and against-the-rule (ATR) astigmats tend to have more success than
do oblique astigmats.
Choose the replacement plan that best suits the patient. Options range from daily
disposable to traditional conventional plans.
Choose material options based on patient needs and ocular health.
Perform a careful refraction, which will save time during the fitting process.
Use diagnostic sets to choose initial lenses or order diagnostic lenses empirically.
Adjust for rotation using the LARS method.
Begin with a spherical over-refraction, but don't settle for "20/happy." if
necessary, move to a spherocylindrical over-refraction.
Educate the patient and set expectations properly. Explain the tremendous benefit
in vision that you are providing with the use of toric lenses.
makes soft toric fitting so easy? The answer lies in the pre-fit knowledge that
we now have. Accurate keratometry readings, an accurate refraction, detailed history
and careful slit lamp examination help determine the proper diagnostic lens. And
because of appropriate pre-fit preparation (determining lens design, material, replacement
schedule, etc.), the diagnostic lens often becomes the dispensed lens. This technique
takes all guesswork out of the process. In turn, the actual fitting may take only
Choosing a Lens Design
vary, thus giving practitioners the opportunity to match the appropriate lens to
each individual patient. Following are some of the lens options from a few major
offers a range of lenses that can generally cover most corneas. For example, the
Vertex Toric provides consistent, reliable results for relatively average corneal
shapes. This back-surface toric is currently offered only in an 8.6mm base curve.
Because the average corneal curve is generally from 43.00D to 45.00D, the Vertex
Toric works well most of the time.
corneas that may be a little too steep or too flat for the Vertex lens, the Frequency
55 Toric is available
in base curves of 8.4mm and 8.7mm. The Frequency 55 Toric is also a back-surface
toric. The Proclear Toric provides yet another option and features an 8.8mm base
curve for flatter corneas. CooperVision also offers the Ocular Sciences Biomedics
55 Toric with a standard base curve of 8.7mm.
offers the Focus Monthly Toric in base curves of 8.9mm and 9.2mm. Although these
values would indicate adequate correlation with flatter corneas, I find that this
lens tends to perform well for both flat ranges and for more average curvature ranges
(43.00D+). Another option from CIBA is the Focus Dailies Toric. It features a standard
base curve of 8.6mm. It's available in only 90-degree and 180-degree axes and cylinder
power of –0.75D. Practitioners won't find any laser markings on these lenses
because they're simply prepackaged at axis 90 or 180.
& Lomb offers the SofLens 66 Toric, which has the highest water content
of the lenses in this article (with the exception of Focus Dailies Toric) at 66
percent. It features a back-surface toric design and is available with an 8.5mm
base curve and up to –2.75D of cylinder. The FDA recently approved the Purevision
Toric for use in the United States. This is a low-water content, high Dk/t lens.
Initial parameters may be limited, but I expect B&L to expand them fairly quickly.
currently offers two toric lens options. The Acuvue Toric has a dual thin zone design,
which helps reduce lens interaction with the lower lid. This lens comes in a standard
base curve of 8.7mm. I find this lens particularly useful when fitting ATR corneas.
The newest toric lens on the market is the Acuvue Advance for Astigmatism. This
lens has an accelerated stabilization design and comes in an 8.6mm base curve. The
stabilizing design is based on accelerated slope of thickness zones that prevent
unbalanced interaction with the lids. The theory is that when the lens is stabilized
and in position, it works with the lids during the blink rather than against them.
This design is unlike prism-ballasted lenses that can dislodge when interacting
with the lower lid. Both toric designs feature a UV blocker.
Choosing a Lens Material
toric lenses are appropriate for patients of virtually any age, selecting the lens
material is important. Even the healthiest of patients can eventually present with
dry eye symptoms after lens wear. End-of-day comfort continues to be a major
hurdle for practitioners and patients to overcome. The lenses I've mentioned each
have a different material matrix and vary quite dramatically in water content.
Feedback in our
clinic continues to show a reduction in contact lens dropouts secondary to dry eye.
CooperVision is helping our battle against dry eyes with the Proclear Toric. A blend
of 62 percent water content along with phosphorylcholine has earned the lens an
indication for dry eye from the FDA and through patient satisfaction.
Toric and Frequency 55 Toric have water content values of 55 percent each, as does
the Ocular Sciences Biomedics 55 Toric. As when fitting any Group IV lenses, choose
patients wisely in terms of lipid content in the tear film. Patients who tend to
produce excess amounts of lipid may fare better in a non-ionic material such as
Vision has a simple solution to lens protein and lipid buildup: Simply throw the
lenses away after each use. The Focus Dailies Toric uses a 69 percent water content
material as well as the CIBA Light Stream Technology. Patients tend to find this
lens comfortable, and many find the opportunity to dispose of lenses after one use
very appealing. I tend to fit this lens particularly for the age range of 12 years
to 25 years, although obviously not exclusively. Any patient who has an active lifestyle
is an excellent candidate for daily disposable lenses.
SofLens 66 Toric is a Group II material that blends the comfort of a higher water
content lens with the more deposit-resistant non-ionic matrix. I use this lens on
patients of just about any age, with careful attention to tear lake. Patients who
have excellent tear lake and overall tear quality generally do well wearing the
Soflens 66 Toric. The silicone hydrogel (balafilcon) Purevision Toric is our first
continuous wear toric lens to receive approval. Once launched, its 30-day continuous
wear schedule may prove a wonderful new option for soft toric wearers.
two toric lens options drastically differ in material makeup. The Acuvue Toric consists
of a Group I lens material that has a water content of 58 percent, while the new
Acuvue Advance for Astigmatism adopts the Hydraclear matrix popularized by the Acuvue
Advance spherical lens. The Acuvue Advance for Astigmatism manages to control comfort
as a result of its silicone hydrogel material (galyfilcon A) with Hydraclear.
High Cylinder Options
the lenses discussed thus far have upper cylindrical values of –1.75D to –2.75D,
varying with each manufacturer. Cylinder values over –2.00D have always proven
a topic of discussion. Do soft torics provide stable vision at higher cylinder powers?
Should you use prism ballast or thin zones? Must you go to a conventional lens?
Are GPs the best option? We'll continue to debate the answers to all of these questions,
but following are a few lenses that are available and work well for me.
two lens types that not only correct high astigmats, but offer patients a frequent
planned replacement lens. The Frequency 55 Toric XR is a back-surface toric that
has a cylinder range from –2.75D to –5.75D in 0.50D steps. Axis values
range from zero to 180 degrees in five-degree steps. Another option for even higher
amounts of cylinder is the Preference Toric XR. Cylindrical values range from –2.75D
to –9.75D Axis values also range from zero to 180 degrees in five-degree steps.
This is usually dispensed as a quarterly replacement lens.
Choose Replacement Schedules with
lens replacement schedules vary greatly from patient to patient. Practitioners have
different views on how far to stray from manufacturer recommendations. I personally
stay fairly close to them. Because of the vast availability of disposable lenses,
practitioners often overlook the importance of the micromanagement that may be necessary
for long-term success. Quite often comfort is the reason for patient success or
The lenses I've
discussed include daily replacement, two-week replacement, one-month replacement
including 30-day continuous wear and three-month replacement. With the variety of
anterior segment complications that exist, you must choose the final lens type with
careful consideration for each patient.
The Future of Soft Torics
with Acuvue Advance for Astigmatism and soon the PureVision Toric, a wave of silicone
hydrogel toric lenses is soon to come. Higher Dk/t values will provide yet another
improvement in lens design, and more lenses may join PureVision as overnight or
continuous wear toric options this year.
In addition, lens
stabilization will continue as a focus of improvement for lens manufacturers. Expect
others to follow Vistakon in an attempt to create novel lens designs to help
achieve better stabilization and less visual fluctuation.
conclusion, make soft toric lens fitting a primary service in your practice.
Patients will appreciate your expertise as well as the clear vision you have
provided to them. When the refraction reveals significant astigmatism,
reach for the toric lens.
lens parameters appeared in Vol. 22 No.2 of Tyler's Quarterly Soft Contact Lens
Parameter Guide, March 2005, and the Contact Lenses and Solutions Summary.
X-Cel, Gelflex and Westcon also manufacture toric soft lenses that are widely
Devlin is the Cornea and Contact Lens Resident at The Eye Institute of The Pennsylvania
College of Optometry and is the Chief of Refractive Services for a private ophthalmological
practice in Elkins Park, PA
Contact Lens Spectrum, Issue: June 2005