professional judgment based on evidence, patient anatomy and
physiology, refractive status, lifestyle and parental influence.
The benefits of ortho-k are mainly the parental involvement
in the handing and maintenance of the lenses and having
the daytime free from contact lens wear, which is especially
beneficial when involved in swimming and other sports
and activities at school. The main limitation is the range of
refractive error correctable with ortho-k. Because the effect
on peripheral refraction is based on the inherent myopic
error, low myopes (below 1.00D) might not have an effective
enough topographic change to deliver the peripheral myopic
defocus required. Also, correction of myopia above -4.50D or
significant astigmatism can be difficult with ortho-k. In these
cases over-spectacles can be worn, mindful that the reason for
fitting is to reduce myopic progression rather than solely the
vision correction.
Flitcroft 24 compared the odds ratios of myopic control
against the widely-understood odds of stroke and heart
attack associated with high blood pressure. It is medically
unacceptable to leave a hypertensive person uncontrolled, with
a systolic blood pressure over 160, as this would increase the
odds of stroke by 3.2 times when compared to a normotensive.
Myopes between -3.00 and -5.75D experience a similar,
3-fold increase in the risk of retinal detachment over
Figure 6 Children rarely see handling as a barrier to contact
lens wear
Figure 5 Soft multifocal, centre-distance contact lenses correct
a wide range of myopic prescriptions including astigmatism
Centre-distance soft multifocal contact lenses can be
prescribed across a full range of prescriptions, including for
astigmatism. A near addition of +2.00D or greater will provide
a myopic image shell that is in front of the peripheral retina
and so provide a mechanism of myopia control. This is often a
good first choice lens option for many patients and higher adds
or different lens designs can be customised later to optimise
peripheral defocus.
Public awareness of ortho-k for myopia control in China and
the Far East has preconditioned some parents towards this lens
modality whereas soft contact lenses dominate the contact
lens markets in the western world. It is highly likely that many
patients, parents and professionals in the UK will choose a soft
multifocal as the lens of choice.
Children’s acceptance of soft lenses in terms of handling and
comfort is well documented 20 , as are the positive psychological
benefits of soft contact lens wear 21 . Concerns over the effect on
loss of contrast sensitivity associated with multifocal contact
lenses is rarely cited by younger children but may be more
of a problem to older teenagers. Most studies show dropout
rates to be in the order of 30%, which is less than the normal
contact lens wearing population.
Is it safe to fit children with contact lenses?
Contact lens wear is not risk free. Both ortho-k 22 and daily
wear soft lenses 23 carry an increased risk of microbial keratitis
over no lens wear. Children wearing contact lenses have been
shown to have similar risks to adults wearing the same lenses
but this increased risk should be balanced against the benefits
of reducing myopia.
emmetropes and low myopes. For myopes over -6.00D the
relative risk is nearly 22 times.
Any concerns about microbial infection need to be addressed
through repeated reinforcement at aftercare to minimise the
risk but the risk of developing microbial keratitis from contact
lens wear is significantly less than the risk of developing sight
threatening complications associated with high myopia.
An additional benefit of fitting contact lenses to children is
the impact on the child’s wellbeing. Wearing contact lenses
instead of spectacles has been shown to improve sporting
and academic ability as well as improving the social and
psychological development of a child 21 . These are less tangible
benefits but can be very significant when considering fitting a
child with contact lenses.
When to start?
Figure 7 High myopia carries with it a 22-times increased risk
of retinal detachment
Continued overleaf
January 2017 | etCETera
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