BACKGROUND
The most important factor in optimizing success with a new GP
wearer is optimizing the initial experience they have with GP lenses.
With the many benefits and applications of GP lenses including
excellent quality of vision, astigmatic correction, correction of
presbyopia, impact on the progression of myopia in young people, and
the visual benefits for the irregular cornea patient, GP lenses should
be an integral part of EVERY practice which provides contact lens care
to patients. However, there is often a fear by new contact lens wearers
about having a foreign body on the eye and, in some cases, they have
been told that gas permeable (GP) lenses are uncomfortable. Likewise,
many practitioners are hesitant to fit GP lenses for fear out of how
the patient will react to lens wear, possible perceived complexities in
lens design and fitting and perhaps increased chair time. All of these
concerns are understandable but, with today's GP lenses, should not
necessarily be a problem. This can be managed, and adaptation
optimized, via the following four step plan: 1) Communicating GPs to
the patient, 2) Use of a topical anesthetic, 3) Optimize initial
vision, and 4) Comfortable lens design.
FOUR STEP INITIAL COMFORT PROGRAM
1. Communicating GP Lenses to Your Patient.
It is important to first note that patients depend upon the
prescribing practitioner to assist them in deciding which contact lens
would be best for them. If the practitioner is not interested in this
as a viable option to patients - either via their nonverbal behavior or
their verbal comments - patients are very likely to detect this and be
dissuaded from GP lenses. Conversely, if the practitioner is interested
in this option and feels it is indicated, patients will likely agree.
This philosophy was confirmed in a study conducted at the
University of Missouri-St. Louis and Pacific University Colleges of
Optometry. New GP wearing subjects were divided into three
groups for their GP fitting experience. At the diagnostic
fitting visit one group observed a video of a practitioner
communicating GP lenses to a patient using such terms as "discomfort",
"pain", and "feels like something is always on the eye". In
addition, it was evident in his nonverbal behavior that he was not a GP
advocate. The second group observed a doctor who used neutral
terms such as "lens awareness" and "lid sensation" while emphasizing
that the long-term comfort of GP lenses if typically very
good. However, his nonverbal communication was not positive
(i.e., unenthusiastic). The third group of subjects observed
a practitioner who discussed adaptation using the same terminology as
the previous practitioner but was enthusiastic about GPs as a viable
contact lens correction option. The results of this
one month study showed that 6 of 19 subjects in Group One dropped out;
2 of 17 in Group Two dropped out and 0 of 13 subjects in Group Three
dropped out. In addition, the subjects in Group Three were
much more compliant in submitting their daily questionnaires.
It is evident that avoiding strong terminology and offering
GPs as a viable option is important. I always assume that my patients
may have heard that GPs are uncomfortable and, using the aforementioned
terminology, emphasize that today's designs exhibit better initial
comfort than their predecessors while providing excellent vision and
good long-term comfort. The Contact Lens Manufacturers Association
(CLMA) has recently adopted the term "GP" as opposed to "rigid gas
permeable" which is advantageous when discussing this option with
potential wearers.
2. Use of a Topical Anesthetic at the Fitting Visit
The use of a topical anesthetic immediately prior to the
initial application of GP lenses will increase the initial comfort and
reduce apprehension. This is especially beneficial for first-time
contact lens wearers as well as soft lens wearers who are being
refitted into GP lenses. In fact, with the latter group it is not
uncommon to hear comments that the lens awareness with GP lenses is not
as much as they would have predicted while the vision is excellent.
Several studies have found that the use of a topical
anesthetic prior to lens insertion results in a more positive
perception of adaptation and a higher success rate. In a one month 80
subject study, 38 of 40 subjects who had an anesthetic at the fitting
visit successfully completed the study; 32 of 40 subjects who did not
have an anesthetic completed the study. In addition, there has been no
evidence to indicate that anesthetic use prior to GP fitting increases
corneal staining. In addition, although topical anesthetic application
is typically limited to the initial application of GPs only, patients
rarely complain of excessive awareness after subsequent applications of
GP lenses. The most important time period in the mind of the
apprehensive first-time GP lens wearer is the first few minutes after
lens application. If the comfort is optimized via the use of a topical
anesthetic, this can be a powerful tool in creating a satisfied and
successful GP wearer. It is important, however, for the anesthetic
effect to wear off while the patient is wearing the lenses such that
they can gradually experience awareness and achieve a realistic
lid-edge sensation.
3. Good Initial Vision
If the first pair of lenses a GP wearing patient applies is in
their prescription and, therefore, they experience the most powerful
benefit of GP lenses - good vision - it is certainly possible that
their perception of initial awareness will be less.
Therefore, although diagnostic fitting has the benefits of practitioner
confidence about the final lens parameters, whenever possible, ordering
lenses empirically or fitting out of a GP inventory provides patients
with this benefit. In fact, it can result in a "Wow factor"
which is especially important with patients being refit from soft
lenses as a result of poor vision. Empirical fitting is
increasingly successful as a result of continuing advances in
manufacturing technology resulting in more consistent edges, ultra-thin
profiles and aspheric or pseudo-aspheric peripheries.
Obviously, there are patients in which diagnostic fitting is
necessary including segmented translating presbyopic lenses, irregular
cornea fitting and patients interested in corneal reshaping.
Likewise, initially fitting several patients into spherical designs
will give the fitting practitioner confidence in GP design, fitting and
evaluation, making the later empirical fitting easier and more
successful.
4. Comfortable Lens Design
Several factors are important in a GP lens design that will be
comfortable initially. These include the following:
- Ultra-Thin Design. All CLMA member
laboratories have ultra-thin designs which are approximately .03 -
.05mm thinner than standard designs. This results in a lens
that is 30 - 40% less mass and more likely to exhibit a lid attachment
fitting relationship. The exceptions to ultra-thin use would
be patients with moderate-to-high corneal astigmatism (i.e., ≥
1.50D) in which flexure can be problematic.
- Alignment Fitting Relationship.
Evaluating the lens-to-cornea fitting relationship with fluorescein and
striving for an alignment fit is important. In high corneal
astigmatism (often ≥ 2.50D), the use of a bitoric design is
typically indicated for this reason.
- Large Overall Diameter. The continuing
introduction of large diameter (typically 10 - 12mm) designs which
result in lid attachment, good centration and reduced movement with the
blink as compared to more conventional smaller designs.
- Avoid Excessive Edge Clearance. With
fluorescein there should be slightly greater edge clearance than
centrally. If excessive pooling is present peripherally
several problems may result including corneal desiccation via funneling
the peripheral tear film under the lens edge, decentration via
increased lid interaction with the lens edge and reduced initial
comfort.
- Consistent Edge Design. A rolled
tapered smooth edge is very important for initial comfort.
Fortunate with the current manufacturing methods, defective edges is a
rare problem.
- Use of Lenticulation When Indicated.
The use of a plus lenticular on all high minus power (often ≥
-5D) and a minus lenticular on all low minus power (≤ -1,50D)
and all plus power designs is important to optimize centration and,
therefore, initial comfort.
Avoid terms such as "discomfort" and "pain".
Substitute terms such as "lens awareness" and "lid sensation" when
describing GP lenses.
Use a topical anesthetic prior to the initial application of
GP lenses on all new GP wearing patients.
Whenever possible, the first lenses that are fit to new GP wearing
patients are - via empirical or inventory fitting - is in their
prescription.
The use of an ultra-thin design will often optimize comfort;
a larger overall diameter, low-medium edge clearance and a lenticular
(when indicated) may also optimize initial comfort.
SUGGESTED READINGS
1) Bennett ES. Patient Selection, Evaluation and
Consultation. In Bennett ES, HOM MM. Manual of Gas
Permeable Contact Lenses. Elsevier, St. Louis, MO, 2004: 58-85.
2) Bennett ES, Stulc S, Bassi CJ, et al. Effect of
patient personality profile and verbal presentation on successful rigid
contact lens adaptation, satisfaction and compliance. Optom Vis
Sci 1998;75:500-505.
3) Bennett ES, Smythe J, Henry VA, et al. The effect of
topical anesthetic use on initial patient satisfaction and overall
success with rigid gas permeable contact lenses. Optom Vis
Sci 1998;75:800-805.
4) Quinn TG. Maximizing comfort with RGPs. Contact Lens Spectrum 1997;12(3):21.
5) Schnider CM. Anesthetics and RGPs: crossing the controversial line. Rev Optom 1996;133:41-43.
6) Szczotka LB. RGP parameter changes: how much change
is significant? Contact Lens Spectrum 2001;16(4):18.
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