Transcript ARE WE GETTING TOO SOFT?

PUTTING VIAGRA BACK INTO
RGP LENS PRACTICE
TONY PHILLIPS
THE DEMISE OF RGPs????
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In the 1990s, Nathan Efron forecast the
demise of RGP lenses by the year 2,000
Then 2001, 2002, 2003, 2004 etc, and, at
the latest count, 2010
Horror of horrors, could he actually be
correct?!
PHILIP MORGAN - WORLD
SURVEY Of PRESCRIBING HABITS
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The number of RGPs prescribed in the
USA is 7%, 8% in the UK and 5% in Hong
Kong.
In Australia, the figure is also 5% with
27% of these being prescribed for Ortho-k
and around three quarters of the rest
being for refits or where RGPs are
essential e.g. keratoconus, post-grafts,
trauma, etc
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So have we effectively already stopped
prescribing RGPs? Again, has Nathan’s
prediction already come true?
Yet in New Zealand the prescribing rate of
RGPs is 23% and in Holland is 39%
So what is it that they know that we
don’t?
Are we right - or are they???
WHAT I WANT TO COVER
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To remind ourselves why we should be
prescribing RGPs - and not lose the art!
Understand why the current situation has
arisen
Finally give you twenty-one ways in which
to improve your RGP practice!
THE REASONS FOR
PRESCRIBING RGPs
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Refitting of existing RGP wearers
Some conditions can ONLY be fitted with
RGPs e.g. karatoconics, post-grafts,
corneal trauma, etc.
RGP lenses may be easier to handle e.g.
narrow VIPs, enophthalmics, babies, etc.
Easier to maintain and last longer than
many soft lenses.
THE REASONS FOR
PRESCRIBING RGPs
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Some patients will get better acuity with RGPs
e.g. irregular astigmats, uncorrected small cyls
in soft lens wearers, etc.
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But is this no longer applicable since aspheric SCLs
are now available????
Nathan Efron - “Modern approaches using
aspheric optical designs result in vision with soft
lenses that is just as sharp as that which can be
achieved with soft lenses”
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Is this true?
RGPs and V.A.
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The results of one 2008 study stated:
“…the fitting of aspheric design soft contact
lenses does NOT result in superior visual acuity,
aberration control or subjective appreciation
compared with equivalent spherical soft lenses”
and –
“….all indicate that the aspheric abberationcontrolled design actually reduces vision”
And who said this????
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The man himself!
RGPs and VA
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In conclusion on VA and the aspheric lens debate, Trusit
Dave stated in the BCLA journal, 2008:
“If the patient has a high refractive error, spherical
aberration will play an important role in visual blur.
However, in higher prescriptions also be aware that
other factors such as lens movement and rotation will
also play a significant role in vision quality. Currently,
lenses that are designed to correct spherical aberration
have not been shown to be more effective than
conventional spherical lenses”
By implication, RGP’s will provide better visual quality than
most soft lenses
VA and RGPs
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Refractive Surgeon, Dr B Allan, writing in the UK
journal ‘Optometry Today’ (2008) stated:
“The best qualitative approximation of what
patients can expect from their vision post-LASIK
is what they can see in soft contact lenses. Most
post-LASIK patients do not have zero refractive
error and it is important to emphasise that some
sharpness may be lost. This is particularly
important for RGP wearers”
REASONS FOR PRESCRIBING
RGPs
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RGP lenses perform better physiologically
because there is:
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Less corneal coverage
Better retro-lens tear flow
Often greater oxygen permeability
Often better and sometimes the only
alternative in cases such as GPC, recurrent
SEALs, marginal dry eye, etc.
RGPs & ADVERSE REACTIONS
Annual incidence of microbial keratitis in different lens
types
RGPs & ADVERSE REACTIONS
Insight, September, 2008:
“Online/mail order purchase of contact lenses
carries five times the risk (of microbial keratitis):
2 Studies”
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Nathan Efron - textbook: “The incidence of
virtually all forms of adverse physiological events
is lower in RGP lenses versus soft lenses”.
THE REASONS FOR
PRESCRIBING RGPs
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RGP wearers appreciate the skill involved and
become loyal, happy patients
Alan Saks writing in Insight, September, 2008
wrote:
“Most days I see at least one long-term RGP
wearer with at least thirty to forty years of very
successful hard/RGP wear. They are generally
some of the most trouble-free, loyal and happy
patients one can ever hope to see. They make
going to work a pleasure”
THE REASONS FOR
PRESCRIBING RGPs
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RGP wearers rarely, if ever, reorder
through the internet
RGP bifocal and multifocal lenses generally
give better results in terms of clarity.
REASONS FOR PRESCRIBING
RGPs
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RGPs can be repolished or modified in power
within small limits
A good knowldge of RGPs is essential if you
contemplate doing ortho-k work
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As ancillary to this, if ortho-k is shown to slow down
or stop the progression of myopia it will hugely take
off.
Holden - approximately 30% of the world’s
population are myopic (1.92 billion)
REASONS FOR PRESCRIBING
RGPs
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RGPs are less affected by dryness and blinking:
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Edwards (2008)”The current investigation showed
that the tear film evaporation with soft contact lenses
in situ is significantly higher than that from the bare
optical surface”
Tomlinson (1994) “The reduction in visual
performance induced by the blink during soft toric
lens wear appears to last longer than that produced
in RGP lens wear”
SO WHY HAS THE PROBLEM
ARISEN?
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Inadequate University teaching
Difficulty in Universities getting
appropriate patients
Laboratories like volume and the simpler
lens type the better
Optometrists’ fear of charging reasonable
fees for their time
The longer adaptation period for RGPs
SO WHY HAS THE PROBLEM
ARISEN?
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Patient pressure
Perceived as quicker and easier for
practitioners and, particularly,:
if their own RGP knowledge is rather
mediocre and/or they don’t have
appropriate fitting sets and equipment.
FEES
In Jim Kokkinakis’s excellent
article in Mivision (March, 2009)
he pointed out that the sales
economy is hour glass shaped:
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The top 60% of the market seek
quality over cost
The lower 37% are cost driven
and
3% are internet purchasers
Very few are in the middle!
FEES
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The bottom part of the hour glass is divided between
the large corporations since all they can advertise is
how cheap they are. The quality of
the eye examination is
not vital to most patients.
Volume is paramount
The larger, top end of
the hour glass expect a
high standard of care
and represent a golden
opportunity for specialist,
professional image
practice including RGP fitting.
SO WHAT CAN BE DONE TO
IMPROVE THINGS?
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More help/enthusiasm from the Universities with
undergrad and post-grad courses. More RGP clinical
work
More help from the CCLSA e.g. travelling post-grad
courses on RGPs
Development of better wetting materials etc. by labs
Awareness by practitioners that it is their own interest to
learn more on the subject e.g. CCLSA Fellowship, and to
acquire the necessary equipment and fitting sets
IMPROVING YOUR RGP
PRACTICE
WHAT YOU CAN DO NOW!!
1. Improve your knowledge!
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How many of you have read a recent textbook or current paper(s) on RGP fitting?
There are several good text-books on the
market (well, at least one!)
2. Understand how to write a
prescription properly!
Please supply:
R. C3/7.80:8.30/8.50:8.80/9.90:9.80 -6.50D
Green XO ct 0.15 FOZD 7.40
et 0.16 – 018
VWB
Engrave ‘R’ and ‘XO’
3. Understand how to manipulate
the ‘numbers’ to achieve what you
want
With very little practice you can understand
how to change the curves and diameters
to achieve what you want.
Those attending the workshop will be
experts by the time they leave!
4. Reject the obvious potential
failures in the first place!
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High cyls but spherical corneas
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Those with corneal cyls but little or no refractive
cyl
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Those who work in very dusty atmospheres
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Those who spend a great deal of their time
doing contact sports
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Those who want intermittent wear only
5. Use the Correct Terminology
The correct or incorrect use of wording can have a
major effect on the patient’s perception.
Andrew Hogan in Optometry Pharma, 2008:
“… practitioners who see patients with central
serous chorioretinopathy should consider
recommending that they cease taking sildenafil
(Viagra) which will, of course, be a hard
decision”
Use the Correct Terminology
Imagine if you said to a patient:
“Your first choice is a soft lens. Compared to the
alternative, these are:
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Rather slippery, somewhat slimy
Will give you a slightly poorer standard of vision
Will be more expensive to wear
Will significantly increase your chance of a serious infection
Are more difficult to handle than the alternatives
Will tend to dry out more easily,” etc
How many would go for them?!!!
Use the Correct Terminology
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Avoid the word ‘Hard’
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Even avoid the use of the word ‘Rigid’
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Just talk about ‘Gas Permeable’ or ‘GP’ lenses
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If necessary, just say that GP lenses are like soft
lenses but just a more rigid material and with
specific advantages
6. If in doubt?
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Start with an RGP lens first. It’s much harder going from
a soft to an RGP than vice versa!
Also, most RGP wearers, if they are going to fail will
usually fail in the first month whereas SCL wearers may
take many months to show up as failures (e.g. from
mediocre VA, marginal dry eye, unstable toric, etc)
Better to start with an RGP and fail quickly than have
problems cropping up along the way over the next two
years with soft lenses before they give up
7. Use an anaesthetic at the fitting
appointment
The urban myth is that this gives a false
impression and can lead to corneal damage
Purslow et al, BCLA Jnl 2008 concluded that ;
“The use of Proxymetacaine prior to lens fitting
had no significant effect on redness or corneal
staining compared to a placebo drop and
subjects prefer its use for the procedure”
Use an anaesthetic at the fitting
appointment
Ed Bennett and Cristina Schnider, CL Spectrum
1993:
“A study performed at the Pacific University
College of Optometry showed that… no
significant physiological problems resulted from
the use of one drop of Proparacaine prior to lens
application at the fitting visit. In addition,
subjects who received the anaesthetic seemed
to adapt more rapidly to their lenses and to
display a more positive outlook throughout the
first month of lens wear.”
8. Generally, go larger in Total
Diameter
Initial comfort is often better with a larger
TD lens
Choice of diameter
Lindsay and Bruce recommend choosing the TD according
to the lid position
As most eyelids cover the upper part of the cornea and are
level or slightly below the lower limbus, most corneas
allow a larger TD to be selected.
Choice of Total Diameter
As stated before:
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Go for the largest TD possible
Aim for lid attachment if possible
Consider the effect of the eyelids
9. Fitting Sets
From the foregoing it will be essential to have:
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at least three TD sets e.g. 9.50, 10.00 and
10.50mm diameters
Toric sets e.g. 0.4 mm toricity
With time, sets of different BVPs and e values
And, most importantly:
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Know ALL the lens parameters and check them
for accuracy
10. Ensure the lens edge shape is
optimal
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The ideal edge should be rounded with a
tapered front surface (Donna La Hood, 1988).
A rounded front surface is more important than
a rounded back surface or square edge
Ensure the lens edge shape is
optimal
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A very simple quick way to check an edge
is with a piece of plasticene pressed into a
cube and your slit-lamp on the highest
magnification.
Ensure the lens edge shape is
optimal
11. Specify and check the centre
and edge thicknesses
Look up ct in tables and check!
12. Don’t err on the tight side
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Go for alignment or slightly steep (but not
a ‘tight’ edge!)
Don’t err on the tight side
Remember, a steep lens is not necessarily a
tight lens!
13. Get the correct Axial Edge
Clearance
Garry Andrasko in C L Spectrum (1989):
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Tricurves with narrow peripheral curves are
more comfortable than bicurves or tricurves with
wide peripheral curves
Lenses with high axial edge lift (> 0.15mm) are
less comfortable than lenses with a low edge lift
(0.08mm)
Blended lenses are more comfortable than nonblended lenses
14. Lenticulate
As a general rule, lenticulate all lenses over + and
– 5.00D
A lens of TD 9.80mm and BVP +7.00D would be
0.41mm in ct if non-lenticulated but 0.26mm ct
if ordered with an FOZD of 7.00, i.e. 60%
thinner.
This is significantly more comfortable and provides
significantly better oxygen transmission
15. Mimic any former lens design
It is often tempting to go to a ‘modern’ fitting or
your favourite design when refitting an existing
RGP or PMMA wearer.
By all means try to head in that direction but
generally speaking try to mimic what they
already have.
Bear in mind the effect of improved oxygen
transmission on corneal shape however!
16. Don’t get them back for the
first after-care too quick!
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Warn patients that there IS an adaptive period
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Warn them that this can be very variable
between individuals
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That initial adaptation will take two or three
weeks and sometimes a little longer to
completely forget that they’re in their eyes
Whilst telling them to report any obvious
symptoms, don’t get them back for after-care in
under two weeks. All they’ll do is whinge!
17. Stress hygiene and cleaning
Good hygeine is, of course, essential with
any form of contact lens.
The pitfalls of soft lens wear (dryness, GPC,
etc.) can be avoided by good cleaning
and, particularly, the use of Progent, say
monthly
18. Consider surface treated
lenses
The use of surface treated materials is
equivocal but may help in certain cases.
Remember that they cannot be repolished
or changed in power in most cases.
19. Do over K’s where necessary
to check for lens flexure
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This can affect VA’s and may indicate the
need for a toric design, especially in
against-the-rule corneas
In with-the-rule corneas go slightly flatter
if the lens flexes
In both cases the lens ct may need to be
increased slightly
20. Fees!
Charge an appropriate fee for all your time,
skill, equipment, ancillary staff. You’re
worth it!
And remember, soft lenses wearers are for
now, RGP wearers are for ever!
20. Fees
Remember that poor fitting fees is one of
the main reasons for the low
recommendation of contact lenses in this
country
You need to cover the fitting session, the
instruction session and at least three
after-cares i.e. around $3 - 400
21. Don’t pre-judge!
Keith Edwards (BCLA Jnl. 2002) tested a new B &
L RGP design on 51 subjects:
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96% wore the lenses successfully
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Two drop-outs were former soft lens wearers
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Two dropped out for visual problems (lenticular
astigmatism - but the research protocol did not
prevent their exclusion)
21. Don’t pre-judge!
Johnson and Schnider (1991) Int. C L Clin. carried
out a cross-over study where one group of new
patients were fitted with RGP lenses and the
other half with soft lenses. At the end of six
weeks they were swapped over.
In a forced choice, 60% preferred the soft lenses
and 40% the RGPs. However, 35% also wore
the RGPs quite successfully in terms of vision
and comfort and could have worn either. In
other words, 75% of the group could have
successfully worn the RGP lenses and 40%
actually preferred them
21. Don’t pre-judge!
They further noted:
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That all subjects preferred the RGPs for VA
That all subjects preferred the RGPs for handling
and cleaning simplicity
That the preference figure for RGPs of 40%
would undoubtedly have risen if the trial had
extended beyond six weeks
IN SUMMARY
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Improve your knowledge
Understand how to write prescriptions properly - and
do it!
Understand how to manipulate the numbers
Reject the obvious in the first place
Use the correct terminology with the patient
If in doubt, start with an RGP
Use an anaesthetic at the fitting appointment
Use a largish TD where possible
Make sure you have adequate and known fitting sets
Ensure the edge shape is optimal
IN SUMMARY
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Specify and check the ct and et
Don’t err on the tight side
Ensure the correct aec
Lenticulate where appropriate
Mimic any former lens design
Don’t get them back too quick
Stress hygiene and cleaning
Consider surface treated materials
Do over-k’s where necessary
Charge appropriate fees
Don’t pre-judge
CONCLUSION
So is it really worth going to all this trouble?
van der Worp (2002) stated:
“Even small improvements in
RGP fits influenced comfort of
wear significantly. It should
be noted that this could
potentially lead to drop out
among patients with acceptable
but not optimal fits”
CONCLUSION
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Brad Giedo in CL Spectrum, 2008
“If you are truly an advocate of GP lenses and you believe
the positive things that you tell your patients about
them, then you need to be willing to present GPs as a
first option. In my experience this is not how most of
you practice so I challenge you to make a conscious
effort to include GPs when you consider your initial lens
selection. Resist the urge to simply default to soft lenses.
You will find that there are many more opportunities to
fit GP lenses than you thought possible and you and
your patients will be better for it.”