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How to succeed with
multifocal contact lenses
Course code: C-15605 O/CL
45
The prescribing of first generation multifocal contact lenses a decade ago was
Figure 1
Schematic to indicate the generic design principle
of a centre near multifocal contact lens
often a frustrating process, yielding low success rates amongst patients. Even
throughout the UK and Europe have begun
today, many practitioners are reluctant to fit multifocal lenses despite significant
to show favour towards multifocal lenses.6
improvements in materials, designs and parameter ranges, which provide
In the UK alone, this segment of the industry
better visual outcomes and more satisfied patients. This article reviews the
is growing at a rate of approximately 5,000
1
2
1
current status of multifocal contact lenses and guides practitioners on how
to reliably achieve high levels of success and satisfaction amongst wearers.
new wearers per quarter.6 Despite these
new fitting behaviours there is still a long
way to go before multifocal contact lenses
to correct presbyopia becomes ‘the norm’.
In the UK, the presbyopic population
A huge disparity exists between the
developed, segment of the contact lens for ‘reduced spectacle dependence’ and
What are the principles of current
multifocal contact lenses?
market.3 Contact lens options available the actual use of contact lenses in this
The latest generation of soft multifocal
for presbyopes include multifocal contact population.4 As a result, manufacturers
contact lenses are based on the principle
lenses, monovision, or a combination of have applied a range of optical principles
of simultaneous vision whereby multiple
single vision distance contact lenses with to produce different multifocal contact
powers are placed within the pupil at the
reading spectacles. In light of the potential lens corrections, which can be applied
same time. Therefore, light both from the
to both increase the number of patients to suit the individual eye or functional
distant and near portions of the lens is
who can benefit from contact lenses and to requirement, of the patient. Similarly,
focused onto the retina simultaneously.
generate additional revenue, it is interesting contact lens materials have evolved to
This description, however, tends to over-
to consider the lingering factors that prevent improve oxygen transmission (eg, silicone
complicate the reality, which is that
practitioners from tackling the ‘presbyopic hydrogels), reduce wetting angles, and
when a patient views a distant object
challenge’. For many practitioners, it resist deposition and dehydration, in
the image
may be that a previous ‘bad’ experience order to minimise the impact of dry eye.
by the area of relative positive power
limits their enthusiasm for multifocal The visual environment of the typical
(near zone). The reverse is true when
lenses. For others, it may be a fear of presbyope has also evolved at a rapid
viewing near objects. Thus, for any given
failure to achieve promised outcomes, or pace, with less emphasis on near work at
simultaneous lens design, the amount to
an uncertainty regarding what to expect a relatively close distance (40cm or closer)
which the image is ‘affected’ depends on
over the short-, medium- and long-term. in down gaze and greater emphasis on
a careful balance of the following factors:
represents the largest growing, yet least common
desire
amongst
presbyopes
Ever-increasingly, presbyopes enjoy better visual display units (VDU) and mobile
quality will be ‘affected’
• Relative size of the distance and near
health and increased vitality during the phones at a range of distances from
optic zones
middle years of life. The range of activities 40cm (and closer) to 80cm (and beyond).
• Blending, or non-blending, of the
carried out and attitudes towards physical
distance/near zone junction
There is a common view amongst
appearance have changed substantially over practitioners that correcting presbyopia
• Rate of blending of the distance/near
the past 20 years. These factors, along with with monovision requires less chair time
zone junction
other social trends, are likely to make visual and yields higher success rates compared
• Relative position of the near optic zone
correction options that are uninhibiting with multifocal contact lenses. However,
(centre-near vs. centre-distance and/or
and burden-free increasingly attractive. over the past two years, practitioners
concentric design)
5
11/02/11 CET
Dr Cameron Hudson BSc (Hons), PhD MCOptom
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clear vision (p<0.05) than monovision.7
emerging presbyopes. For many of these
• Near add power
Amongst early presbyopes, Woods et
individuals, contact lenses have been
• Aspheric optics
al.2 found superior subjective performance
the refractive correction of choice. They
• Centration and stability of the lens on
with the Air Optix Aqua Multifocal
are also far more aware of contact lenses
the eye
lens when compared with monovision.
and have far more varied visual needs
• Pupil size and ambient light
46
OT CET content supports Optometry Giving Sight
The performance and advantages of
Their most notable findings were the
than
one lens type over another cannot be
improvement in subjective ability to
baby boomers, these individuals are more
simply attributed to, for example, whether
change focus (p<0.001), watch television
likely to embrace technology eg, using the
a lens is centre distance vs. centre near
(p<0.001) and drive during the day (p<0.05)
Internet and mobile phones. Accordingly,
or whether a lens has a higher or lower
and at night (p<0.001) whilst wearing the
these individuals are more likely to be
add power. There are two commercially
multifocal lenses. Overall satisfaction with
motivated to preserve their functional
available centre-near silicone hydrogel
the lenses was also significantly better with
visual ability as well as their appearance.
multifocal contact lenses with aspheric
multifocal than monovision correction
Historically many practitioners may
optics (Figure 1), namely the PureVision
(p<0.01), leading the investigators to
resist correcting presbyopia until as late
Multi-Focal (Bausch & Lomb) and the Air
conclude that incorporation of subjective
a stage as possible. However, the key to
Optix Aqua Multifocal (CIBA Vision).
vision metrics into the fitting assessment
multifocal contact lens success is tackling
Such lenses achieve a different balance
2
improves the predictability of success.
the emerging presbyopic changes before
between distance and near vision due to
A broad conclusion that can be drawn
becoming overtly manifest. The ideal time
differences in the specific lens design.
from the literature is that multifocal
is when patients report that their ability to
For example, the Acuvue Oasys for
contact lenses are capable of providing a
‘change focus’ is reducing/slowing down.1
presbyopia (Johnson and Johnson Vision
superior level of subjective vision, whilst
Irrespective of the patient’s age, good
Care)
uses
monovision wearers obtain relative sparing
candidates for multifocal contact lenses
ring
design,
of near VA under high and low contrast
possess some level of dissatisfaction
conditions.
offer
a
centre-near
which
control
balance
of
according
is
the
to
concentric
believed
to
distance/near
ambient
light.
What do patients think about
multifocal contact lenses?
Several studies have investigated the
presbyopes.
Unlike
One proposed reason for
with their current correction in at
the subjective preference of multifocal
least part of their day-to-day life. Most
lenses is the minimal disruption to
importantly,
binocular vision due to preservation of
identify, and then seek to quantify,
stereoacuity and range of near vision.7,10,12
this level of dissatisfaction, as it will
2,7-11
practitioners
must
first
form the benchmark against which all
of multifocal contact lenses, specifically
Which patients are best suited to
multifocal contact lenses?
by
objective and subjective visual performance
established
alternative corrections are compared.
monovision.
The success of multifocal contact lenses
Objective assessments included visual
is largely dependent upon identifying
acuity
sensitivity
candidates who stand to gain tangible
Communicating effectively
and establishing realistic
expectations
(CS)7,8 whilst subjective assessments have
benefits from being less dependent on their
Failure with multifocal contact lenses is
centred on intent to purchase, satisfaction,
spectacles. Presbyopes aged between 50
often due to poor communication rather
and
responses.2,9-11
and 64 years are commonly referred to as
than the lens technology. The practitioner’s
When comparing the objective visual
‘baby boomers’, few of whom entered into
ability to establish ‘realistic expectations’
comparing
(VA)
them
and
to
contrast
questionnaire
performance
PureVision
of
monovision
Multi-Focal
and
contact lens wear at a young age. Thus
Gupta
many of this group may not possess the
et al.7 found significant differences in
motivation to commence wearing contact
the performance of the two modalities.
lenses. This is not to say, however, that they
Most
cannot succeed if given the opportunity.
notable
was
the
lens,
the
improvement
in high contrast distance and near VA
whilst
wearing
monovision
The greatest potential for success lies
(p<0.05),
with those individuals within generation
although they also found that the low
X. These are people born after the post-
addition multifocal lenses achieved better
world
stereoacuity (p<0.01) and near range of
between 1960-1970) and are the current
war
II
baby
boom
(typically
Figure 2
Binocular over-refraction using handheld trial
lenses
at the initial fitting stage is commonly cited
by lens manufacturers as one of the key
milestones in achieving success. However,
this should not constitute an opportunity
for the practitioner to repudiate all
responsibility for what is about to happen.
The practitioner’s choice of language can
47
have a large impact on the success/uptake
of multifocal lenses once fitted. Describing
the visual outcomes with terms such as
that is not as good as spectacles’ does
not provide the patient with either a
positive or necessarily realistic outlook
on what might be achieved. It is far better
to describe the visual outcomes using
terms such as ‘functional all-round vision’
or achieving ‘a better balance between
distance and near vision’. In the broadest
terms, practitioners should describe what
the patient stands to gain rather than what
they stand to lose (Table 1). This approach
will improve the likelihood of success
and offer patients a compelling reason
to proceed; the approach should be akin
to recommending varifocal spectacles
to a new wearer by being realistic about
expectations and having a positive outlook.
How do I know which lens power
to select initially?
There is no “one size fits all” approach to
Figure 3
Example case summary of a presbyopic multifocal contact lens fitting
chair time. In the same way that not all
in two stages; short-term (20-30 minutes)
patients will adapt to varifocal spectacles,
and long-term (1 week and beyond). In
it would be unrealistic to expect every
an ideal situation a practitioner would
patient to adapt to multifocal contact lenses.
be able to assess the best possible
However, by following the manufacturer’s
visual performance achievable shortly
fitting
guidelines,
can
after initial lens application, giving
1
The
an indication of success or failure,
guidelines
are
but in practice this is not the case.
practitioners
expect success rates of 72-79%.
manufacturer’s
fitting
derived from experience gained during lens
development, often involving hundreds,
if not thousands, of patients. Following
1
the manufacturers fitting guidelines also
serves as an important indicator of the
point at which no further adjustments to
lens power should be made, for example,
in the relatively small percentage of
instances
where
the
patient
doesn’t
achieve the visual outcome they require.
Short-term adaptation
A period of 20-30 minutes is usually
required for the lenses to stabilise and
for any initial physiological reaction (eg,
lacrimation) to pass. During this time is
it advisable that the patient leaves the
consulting room and be given opportunity
to perform a mixture of visual tasks eg,
looking into the distance, reading the
time on their watch, viewing their mobile
phone,
alternating
between
distance
multifocal contact lenses. Each lens has its
Adaptation
own ‘manufacturer approved’ set of fitting
Unlike most other types of contact lenses,
environment. Upon their return, patients
guidelines, which should be followed
multifocal lenses require a period of
should be encouraged to subjectively
for every new patient. Following the
adaptation in order for the practitioner
score their distance and near vision eg, on
manufacturer’s guidelines will increase
to obtain a true sense of the visual
a scale of 1-10, to provide the practitioner
the rate of success and reduce unnecessary
performance.13 Adaptation is best thought of
with a relative indication of their
and near vision tasks etc. in a real world
satisfaction. This is the recommended
Words/phrases to avoid
Words/phrases to use
Compromise
Functional vision
practitioner with a benchmark to work
Trade-off
Balance between distance and near
against in order to obtain the optimal
Not perfect
Re-prioritisation of vision
balance of distance and near vision when
Not as good as spectacles
Reduced dependence on reading glasses
refining the lens power. Furthermore,
Loss of crispness/slightly hazy/foggy
Likely to use your reading glasses 60-90% less
subjective grading of vision may be
Table 1
Guidance on communication when discussing multifocal contact lenses
clinical
standard2 and
provides
the
sensitive to small changes in lens power
that cannot be identified using objective
methods; equally, it has been shown that
11/02/11 CET
‘slightly compromised vision’ or ‘vision
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where objective vision appears reduced
or improved there may be no correlation
with a patient’s subjective opinion.13
Long-term adaptation
As for first time varifocal spectacle wearers,
48
patients who are new to multifocal contact
lenses commonly require a longer period
of adaptation to get used to their new
vision. This is where the real trial of the
Figure 4
Example case summary of an emerging presbyopic multifocal contact lens fitting
11/02/11 CET
lens begins. It is important to fulfil this
part of the lens fitting process as subjective
near vision is not close to an acceptable
the overwhelming majority (78%) chose to
performance of the lenses can change
level consider adding a small amount of
use both to combine the benefits of each.15
significantly from the initial findings.13
positive power to the distance component
Improving outcomes
Guidance note 1
It is important to check that the distance
vision is optimised. In general, this
process involves measuring the objective
VA and subjective opinion binocularly;
add as much plus power to the distance
prescription as the patient will accept,
up to the point where further plus power
causes a reduction in VA.14 This will
enable the add power to be kept to a
minimum. The process should be done
in good illumination. Begin with the
dominant eye and increase plus power
in 0.25D steps. Repeat this process for the
non-dominant eye. Use handheld trial
lenses to carry out the over-refraction and
avoid using a phoropter or trial frame
in the non-dominant eye (eg, +0.50D).1
Summary
Guidance note 3
significantly over the past decade and
Follow
the
manufacturer’s
fitting
guidelines, even if a patient isn’t achieving
high scores subjectively. Provided that the
patient is willing and that they objectively
achieve a standard of vision that from
a medico-legal perspective is deemed
acceptable,
encourage
an
extended
trial (4-7 days) and re-assess the visual
performance after this time. If, at the end
of the extended trial, there are no further
adjustments to the lens power, formulate
a succinct way to summarise what you
have achieved (Figures 3 and 4). This will
allow the patient to formulate in their own
mind about whether the vision achieved
justifies
the
lenses
being
dispensed.
(Figure 2). If minus lenses are required to
improve distance vision act cautiously.
Only reduce the plus power if there is a
distinct improvement in subjective vision.
Which method of correction do
presbyopes prefer?
Given that there is no single correction
Practitioners should be wary of chasing
that suits all presbyopes for all activities
contrast
over-
it is important that clinicians consider
refracting with minus powered lenses.
all options to satisfy an individual’s
improvements
when
Multifocal contact lenses have evolved
increasingly practitioners are fitting them.
However,
the
presbyopic
population
remains the least developed segment of
the contact lens market and thus presents
a very real opportunity to the industry.
Emerging presbyopes stand to gain the
most from multifocal contact lenses, as
they have greater familiarity with contact
lenses and possess a wider variety of
visual requirements than more established
presbyopes. Adopting a fitting strategy
that conforms to the manufacturers fitting
guidelines
will
improve
the
success
rate and reduce unnecessary chair time.
Practitioner communication, particularly
during the pre-fitting discussion, also
plays a significant role in the outcome
achieved. It takes practice to achieve
high and reliable success rates with
multifocal lenses. Practitioners should
seek guidance from experienced peers or
consult with contact lens manufacturers
for
fitting
guidance
and
education.
lifestyle and visual demands. This may
About the author
involve combining the benefits of several
Dr Cameron Hudson is the professional
is
correction options in order that the relative
services manager for CIBA Vision, UK.
optimised should near vision be assessed,
advantages and disadvantages can be
since small changes to the distance
maximised and minimised, respectively.
References
power can have a profound effect on
It has been demonstrated that when
See http://www.optometry.co.uk/clinical/
near vision.
Aim to keep the near add
spectacle-wearing presbyopes are given the
index. Click on the article title and then
power as low as possible. If subjective
opportunity to try multifocal contact lenses,
download “references”
Guidance note 2
Only
when
1,14
the
distance
power
PLEASE NOTE There is only one correct answer. All CET is now FREE. Enter online. Please complete online by midnight
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Course code: C-15561 O
Course code: C-15605 O/CL
1. Which of the following statements is FALSE?
a) Currently an estimated 700,000 people in the UK have dementia
b) Two thirds of people with dementia have Alzheimer’s disease
c) 90% of people with Alzheimer’s disease have visual function decline
d) Visual system disturbances can pre-date manifestations of dementia
1. Which age group of patients is LEAST represented within the
contact lens industry?
a. 20-27 years
b. 28-35 years
c. 35-45 years
d. 45 years and above
2. Which of the following is a typical visual symptom of Alzheimer’s
disease?
a) Difficulty with reading at near
b) Blurred vision, not due to refractive error or eye disease
c) Difficulty picking out objects in a group
d) All of the above
3. Alzheimer’s disease does NOT affect which of the following?
a) Tear ducts
b) Crystalline lens
c) Optic nerve
d) Retina
4. Motion processing is NOT associated with which of the following?
a) Dysfunction of magno- and konio-cellular processing
b) Dysfunction of form identification
c) Difficulty interpreting patterns
d) Mental confusions
5. Which of the following statements about assessing visual function in
Alzheimer’s disease is FALSE?
a) The Vistech chart reveals loss of high spatial frequency contrast sensitivity
b) Frequency doubling technology is preferred for testing visual fields
c) The City University test is preferred for assessing colour vision
d) Threshold visual fields are more suitable for monitoring co-morbidity with
glaucoma
6. Which of the following conditions requires an individual
possessing a driving licence to notify the DVLA?
a) Alzheimer’s disease
b) Parkinson’s disease
c) Glaucoma
d) All of the above
49
2. The performance of a simultaneous design multifocal contact lens
is dependent upon which of the following factors?
a. Relative size of the distance and near optic zones
b. Relative position of the near optic zones on the lens
c. Pupil size and ambient light
d. All of the above
3. According to Woods et al. which of the following statements reflects
patient opinion on multifocal contact lenses?
a. Patients generally prefer monovision over multifocal contact lenses
b. Patients generally prefer multifocal contact lenses over monovision
c. Multifocal contact lenses and monovision are liked equally
d. Neither multifocal contact lenses nor monovision are liked by patients
4. Which of the following terms would be MOST appropriate to use
when describing the visual outcome with multifocal contact lenses?
a. “They provide a slight loss of crispness”
b. “They provide functional vision for distance and near”
c. “They provide a compromise between distance and near”
d. “They provide vision which is not as clear as with spectacles”
5. When refining the multifocal contact lens power, practitioners
should:
a. Aim to provide the most plus distance refraction
b. Preferably use a phoropter
c. Assess vision monocularly
d. Assess vision in low room illumination
6. When given the opportunity to experience multifocal contact
lenses, what proportion of varifocal wearers preferred to combine
the benefits of both spectacles and contact lenses?
a. 35%
b. 78%
c. 54%
d. 63%
11/02/11 CET
Module questions