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substantially ‘damaged’ (see OT, August
Management Options for UK Optometrists Part 4
General eye irritation and allergic conjunctivitis
13 2010). Such compromise will likely be
Course code: C-14569 O/AS/SP/IP
(fTBUT) values then cause ocular surface
associated with a change in the goblet cells, such that a vicious cycle can result in mucin deficiency that destabilises the tear film; very short fluorescein tear break-up time desiccation and a worsening of the staining. Immediately
under
the
33
conjunctiva
are numerous nerve fibre terminals that endow the conjunctiva with sensitivity to mechanical stimuli as well as to sensitivity to tactile stimuli of the bulbar conjunctiva is rather lower than that of the central cornea, but has also indicated that sub-normal sensitivity is associated with a higher than normal eyeblinking.4 This sensitivity is, in some way, linked to the function of the trigeminal nervous
Professor Michael J. Doughty, PhD This article considers the aetiology and demographics of general conjunctival irritation, including seasonal allergic conjunctivitis (SAC) and perennial allergic conjunctivitis (PAC). In terms of patient management, assessment
system that forms organised fibre bundles slightly
deeper
in
the
sub-epithelial
connective tissue (Figure 1). Therefore, an acute response to an irritant might
and follow-up, guidelines need to be carefully considered for each type
stimulate
of condition as does the finer details of legislation relevant to the use of
reflex lacrimation), while a longer-term
different drugs in eye brighteners, decongestants, decongestant / topical
consequence of chronic irritation appears
antihistamines, and oral antihistamines, as well as mast cell stabilisers.
to be a reduction in conjunctival sensitivity
Special consideration will be given to access to topical ocular antihistamines
that also results in increased eyeblinking.
and a topical NSAID by additional supply (AS level) optometrists.
The sub-epithelial connective tissue
excessive
eyeblinking
(and
(parenchyma) is richly supplied with
Aetiology of ocular irritation and reactions to external allergens
lacrimation and eyeblinking are likely, as
blood
this system attempts to clear the tear film
distinctive smooth muscle surrounding
Patients can report a variety of symptoms
of the cause. There will also be changes in
them and the venules more likely to
associated with tear film deficiencies,
the complex structure of the conjunctival
have a fenestrated endothelial lining
often loosely referred to as ‘dry eye’ (see
epithelium tissue and the connective tissue
(Figure 1). All the blood vessels are likely
OT, July 16 2010). Slightly different
immediately underlying it (Figure 1).
innervated by the autonomic nervous
Most of the healthy conjunctival surface
system (ANS), with the sympathetic
symptoms,
including
‘discomfort’
or
vessels,
the
arterioles
having
‘itchiness’, can also be experienced in
is
patients not having dry eye disease (DED);
within the layers of which are goblet cells
arterioles and the parasympathetic nervous
all, however, are sensory responses to
providing mucin that forms the basal
system
anything abnormal and/or threatening
aspect of the tear film layer.
The surface
venules. It is unknown how the balance
to the conjunctiva. If the exposure to
of the conjunctiva can change such that
of these ANS effects is altered if there
irritants (eg, organic fumes) or allergens
it will ‘stain’ with fluorescein if slightly
is a change in conjunctival sensitivity.
(eg,
compromised and with rose bengal if more
pollen)
persists,
then
increased
composed
of
non-squamous
1-3
cells
(adrenergic)
The
system
(cholinergic)
parenchyma
dominating controlling
also
the the
contains
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irritants. Recent research confirms that the
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vessels, means that substantial and rapid changes in fluid flow to and from these vessels can occur, which results in changes to the fluid content of the parenchyma. It is such changes that are responsible for the (sometimes) dramatic changes in the
34
external appearance of the conjunctiva and eyelid marginal skin, when there is an acute response to an irritant or allergen. A progressive impairment of this lymphatic system is also thought to be responsible for the development of conjunctivochalasis,5 perhaps better known by the acronym lid-
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parallel-conjunctival-folds
or
LIPCOF.
Overall, all of the components outlined here are involved in response of the eye to external irritation as well as to allergens. The
general
response
is
traditionally
Figure 1 Schematic diagram to illustrate the complexity of the conjunctiva. From Bergmanson JPG, Doughty MJ (2005) in Clinical Contact Lens Practice (Bennett ES, Weissman BA, eds). Lippincott, Williams & Wilkins, Philadephia. Chapter2, pp. 12-39
associated with the innate immune system
inflammatory cells, whether these be
system, the distinguishing symptom often
the natural complement of mast cells
noted is that of ‘itching’. This can often
is also reflected in the use of both non-
or additional white blood cells (eg,
result in the patient wanting to rub (rather
eosinophils) that have migrated from the
than ‘scratch’) their eyes. A patient with
capillaries into the tissue in response to
acute-onset allergic reaction may indeed
irritation;3 both cell types are special in
have an overwhelming desire to rub their
that they generally contain granules which
eyes and, in the process, actually worsen
can release inflammatory mediators such
their condition leading to redness and
as histamine and certain prostaglandins.
puffiness of the eyelid margins and even
Medicines and non-medical products for managing general eye irritation and allergic conjunctivitis
These inflammatory mediators generally
the bulbar conjunctiva. This secondary
With
cause dilatation of the blood vessels and
response is mediated by the lymphatic
conjunctival system, there is no single
also mediate the sensory responses to
system within the parenchyma. These can
approach to pharmacological management
irritation. Some patients may complain of
be seen as having similar size to blood
of general eye irritation and allergic
general ‘irritation’ or ‘discomfort’ or even
vessels (Figure 1) or, at least at some
conjunctivitis. Furthermore, the legislation
‘smarting’ of the eyes, as opposed to saying
locations under the conjunctiva, as very
relevant to the range of products available
that their eyes are ‘dry’, although some
2,5
substantial in size (volume) (Figure 2).
has changed substantially in recent years.
patients experiencing progressive allergy
The electron micrograph (Figure 2)
Eyewashes and eye ‘brighteners’ are general
reactions to eye drop preservatives (eg,
illustrates just how loosely packed the
sales list (GSL), with the latter being an
benzalkonium chloride) may report ‘dry
parenchyma is, especially in the vicinity
alternative
eyes’. If the irritant is actually an allergen ie,
of a dilated lymphatic vessel.
This
containing topical ocular decongestants or
is triggering the specific immune response
attribute, along with the specialised loops
a decongestant and antihistamine. A topical
system rather than the innate non-specific
in the endothelial lining of the lymphatic
mast cell stabiliser has been recently added
2
and the allergic response with a more specific immunoglobulin E (IgE)-activated system. These distinctions are far from clear by modern-day perspectives and this specific as well as specific pharmacological interventions to manage the wide spectrum of presentations for this group of conditions.
numerous
to
components
pharmacy
to
the
(P)-medicines
to the GSL category (as well as
(even though the latter can
being available as a P-medicine),
still be efficacious). Older
and
topical
remedies included use of
ocular antihistamines have been
“true” astringent (eg, very
discontinued, oral antihistamines
hypertonic solutions such as
are available as GSL products and as
5% saline), but modern-day
P-medicines.
individuals with a mild-to-
P-medicine
Non-therapeutically
trained optometrists may access all
moderate
the above-mentioned products by
are most unlikely to tolerate
way of wholesale trading and then
the use of such products.
may sell and supply them to their patients at the recommended retail price. With
the
Additional
Supply
(AS)
legislation changes in 2005, optometrists with appropriate training may access prescription-only
medicines
(PoM)
including mast cell stabilisers, most of the topical ocular antihistamine eye drops and a non-steroidal anti-inflammatory drug of
(NSAID).
The
Optometrists
relevant
clinical
College
management
guideline (CMG) is ‘Seasonal Allergic Conjunctivitis;
Perennial
Allergic
Conjunctivitis’ which notes the major role optometrists can play in pharmacological management of these conditions with referral to an ophthalmologist not required.
Figure 2 Very high magnification (electron microscope) image of part of a sub-conjunctival lymphatic vessel with distinctive loops on the very irregular lymphatic lining that appears only loosely attached to the numerous round bundles of collagen fibrils that make up the parenchyma. From Doughty MJ, Bergmanson JPG (2003) Optometry 74: 485-500. a
non-specific
irritant
conjunctivitis.
The external appearance of the eye will indicate that the conjunctiva is reacting slightly to irritants and a very mild ‘red eye’ develops (Figure 3). There should be no discharge of a mucopurulent nature but some lacrimation (or even slight epiphora) may be present perhaps along with little white mucous strands in the lower fornix
Astringent eyewashes and eye drops and topical ocular decongestants
(as the goblet cells can discharge slightly
Once-common causes of ocular irritation
sign of oedema (puffiness) etc. with the
were smoke-filled rooms (now reduced
degree of bulbar conjunctiva hyperaemia
with changes in workplace legislation)
usually being low. In addition, there
but either traffic exhaust fumes or perhaps
will usually be little or no signs of ocular
barbecue smoke or indoor grills are
surface compromise (eg, significant ocular
the likely replacements, in addition to
surface staining with sodium fluorescein)
numerous other indoor airborne micro-
but fTBUT values may be reduced.
in response to general irritation). In many such presentations, there will be little
particulates causing mucous membrane irritation.
These
irritants
film is a logical first step to management,
sometimes referred to as volatile organics
either by avoidance or with the use of
and associated with conditions such as
eyewashes or lotions. Such remedies have
‘sick building syndrome’. A recreational
mild ‘astringent’ action, a term indicating
exposure
chemicals
that there is a slightly greater cleansing
(eg, swimming pools) can also cause
action than a simple isotonic (0.9%) saline
chlorinated
35
irritation
Reduction of tear film irritant levels can therefore be effectively achieved by the use of eyewashes containing plant extracts such as Hamamelis (witch hazel) (eg, GSL Optrex Eye Lotion),6 and are generally most effective if performed with patience and using an eye-cup, at the end of the working day or after the recreational exposure to irritants. Patients can also use eye drops containing the same ingredients or dilute zinc sulphate (0.25%). If simply washing out the irritant is not successful, the next logical step is to use drugs that actually work on the superficial blood vessels to reverse the changes that have been induced ie, reduce hyperaemia and discomfort.7,8 If the cause can be established as essentially a minor irritant, then the use of brighteners or decongestants is appropriate. A number of products are available, which are designed to attenuate these mild reactions regardless of the actual nature of the stimuli; these are labelled as
Reducing the level of irritants in the tear
are
to
latter
ocular
Figure 3 Very mild ‘red eye’ associated with chronic environmental workplace irritation where some conjunctival blood vessels are notably dilated.
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eye drops) were introduced in the 1950s to
children (ie, those less than 12 years of age),
replace the use of adrenaline (epinephrine)
and the current recommendation is that the
1:1000 eye drops as a vasoconstrictor
combination product Otrivine-Antistin is
Eye drops containing
not for use in children at all, or should be
phenylephrine were discontinued in the
half the dose recommended for an adult.
(decongestant).
9
UK in 2003, but may be accessible over the
36
Internet along with eye drops containing other drugs such as tetrahydrozoline or oxymetazoline. At the concentrations used, the adrenergic drugs act as vasoconstrictors on the smooth muscles of the more superficial vessels of the conjunctiva, to
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whiten the general appearance of the eye.10
the use of topical ocular decongestants is whether there is rebound vasodilation with overuse.14,15 This can be part of a general irritation
response
of
the
conjunctiva
that includes a follicular reaction and it may thus be considered as an ophthalmic ‘medicamentosa’. Safety issues are both ocular and systemic. Overuse, in an attempt
last for at least an hour to help relieve
to alleviate all signs and symptoms of any
symptoms such as irritation, mild burning
acute red eye with these products, could
and photophobia,10,11 and reduce reflex
allow a (mild) infectious conjunctivitis to
products
progress,16 and even dilute solutions may
introduced
produce a slight pupillary dilation.10,17 While
to also produce a “calming effect on
only slight pupil dilation has been measured
blepharospasm” associated with ocular
with the use of combination products (with
irritation,11 and this logically applies to the
an antihistamine),18,19 an additive effect
current UK combination of xylometazoline
might be due to mild cholinergic blocking
with
Combination
antihistamines
were
and antazoline (Otrivin-Antisine). Their combination
with
antihistamine,
an
astringent such as zinc sulphate,9 or a coloured dye such as brilliant blue,6,13
to minor eye irritations” or to “reduce
below), but a recurrent issue that arises with
rapid in onset (ie, within a minute) and
lacrimation.
“for the relief of redness of the eye due
of these products relates to safety (see
The effect of these products should be
11,12
Figure 4 Packaging for an ophthalmic brightener product to indicate use and precautions
The primary reason for limiting the use
may provide extra relief and added cosmesis (eg, Eye Dew Dazzling eye drops). The recommended doses for symptomatic relief and cosmesis (ie, whitening of the eye) vary widely. They have been assessed
actions of the antihistamine. Even slight pupil dilation in at-risk individuals could be associated with acute-onset angle closure glaucoma.20 Such an adverse reaction is definitely not wanted, and is the reason for the small print warning on some of these products that they “should not be used in patients with glaucoma” or a far more vague warning about ‘eye disease’ (Figure 4); some small print warnings include the
redness so making the eyes brighter with
and used at anything from one to eight
type “Do not use for more than 72 hours
whiter whites” (Figure 4). These products
drops per day in each eye, but current
except under the advice and supervision
contain low concentrations (sometimes
perspectives are that such products should
of a ‘doctor’ or ‘physician’”. Overall,
not specified) of drugs that primarily act
not be used ‘as needed’ for long periods
therefore, all such decongestant-containing
as alpha-1 adrenergic agonists on the
and that the number of uses per day should
products should be used with caution and
blood vessel smooth muscles. Drugs such
be limited, eg, ‘do not use more than three
should not be recommended for use in
as naphazoline (eg, Murine eye drops,
times per day’ (Figure 4). As can be seen on
patients who are known to have a narrow
or Eye Dew Sparkling eye drops) and
the pack of a contemporary GSL product,
anterior chamber angle. Pupillary dilation
xylometazoline
these eye drops are not intended for use in
is more likely to be evident under lower
(eg,
Otrivine-Antisitine
LEGAL
BOTTLE
(DRUG)
STATUS
SIZE (mL)
now deregulated, with the responsibility
PRODUCT NAMES
for safe use being transferred to the user.
This
responsibility
comes
in
the form of the small print on the
antazoline
P
10
OTRIVINE-ANTISTINE
sodium cromoglicate
GSL
10
CLARITYN
sodium cromoglicate
P
5 or 10
OPTICROM, VIVICROM EYE DROPS, CROMOLUX EYEDROPS, CLARITEYES, OPTREX ALLERGY EYE DROPS, OPTREX ALLERGY RELIEF EYE DROPS, HAY-CROM HAY-FEVER RELIEF EYE DROPS, BOOTS HAYFEVER RELIEF EYEDROPS, POLLENASE ALLERGY EYE DROPS, DOMINION PHARMA HAYFEVER EYE DROPS, VANTAGE ALLERGY RELIEF EYE DROPS
1
packing and product inserts (Figure 4).
sodium cromoglicate
P
30 x 0.3
CATACROM (preservative-free)
sodium cromoglicate
PoM
13.5
OPTICROM, HAY-CROM EYE DROPS, VIVIDRIN EYE DROPS, CUSILYN EYE DROPS, SODIUM CROMOGLICATE EYEDROPS (generic)
Mast cell stabilisers For
chronic
and
recurrent
allergic
conjunctivitis, part of an appropriate management approach is the use of ‘mast
cell
stabilisers’,21
with
several
drugs marketed in the UK (eg, sodium cromoglicate, lodoxamide and nedocromil sodium). There are others with a combined action of being mast cell stabilisers and antihistamines drugs
(eg,
(H1-receptor ketotifen,
blocking)
olopatadine).
Illustrated in Figure 5 is the corneal surface, at extremely high magnification, to show the presence of extremely small ‘fuzzy balls’ of pollen grains amidst a background of the pre-corneal mucin. The
lodoxamide
P
5
ALOMIDE ALLERGY EYE DROPS
lodoxamide
PoM
10
ALOMIDE
nedocromil
PoM
5
RAPITIL
ketotifen2
PoM
5
ZADITEN
be from animal dander, dust mite excreta,
olopatadine2
PoM
5
OPATANOL
workplace processes, from furniture and
azelastine
PoM
8
OPTILAST
stick to the epithelial surface mucus
emedastine
PoM
5
EMADINE
coating. Due to the persistent exposure,
epinastine3
PoM
5
RELESTAT
emedastine
PoM
5
EMADINE
epinastine3
PoM
5
RELESTAT
density of these very small (circa 1μm in diameter) pollen grains is in excess of 1000,000 per mm2, and these resist washing with saline. Other micro-particulates might
carpeting etc., all of which can tenaciously
it should make sense therefore that the use of a mast cell stabiliser may well be needed, along with twice-daily astringent eye washes, to reduce the allergen load on the ocular surface. Indeed, the idea
Table 1 UK marketed mast cell stabilisers and topical ocular antihistamines. 1 antihistamine in combination with a decongestant, xylometazoline; 2 considered to have dual action as mast cell stabiliser and antihistamines; 3 not on additional supply list
for use of a mast cell stabilizer is to try to
levels of illumination and in blue-eyed
Overall, while some ocular irritation
be achieved, there should be a reduction
individuals and probably is more likely
can develop with overuse, these products
in the tear film levels of inflammatory
when there is significant compromise
have an excellent safety record and this
mediators despite the continued presence
of
is why some
of the allergen. With repeated contact of
the
corneal
epithelial
surface.
20
of
these
products are
37
reduce or even prevent the mast cells from discharging histamine and prostaglandins (degranulation)
following
their
IgE-
mediated activation by allergens. If this can
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especially sodium cromoglicate, can be
antihistamines can be used to manage SAC,29-
used to manage a range of types of allergic
31
conjunctivitis, and have an extraordinary
the faster onset in reduction of symptoms,
good safety record in that local adverse
ie, a patient can start using these at the
effects reports are both unusual and perhaps
first exposure to allergens and can expect
actually due to the benzalkonium chloride
useful effects within minutes to hours (as
preservative. As a broad principle, therefore,
opposed to days with a mast cell stabiliser).
there are no restrictions to the use of sodium
It is unclear, however, whether the overall
cromoglicate eye drops other than known
longer-term tolerance to airborne allergens
allergy to the drug or the preservative
is better when comparing use of topical
benzalkonium chloride, regardless of patient
antihistamines to mast cell stabilisers. The
age. For a named patient, preservative-free
antihistamines all have some restrictions
(unit dose) sodium cromoglicate eye drops
on use, with the various products having
are available through a specialist hospital
warnings that they are not indicated for use
pharmacy, eg, Moorfields Eye Hospital.
on children below the age of three or four
the ocular surface with allergens, the mast
The commoner indications for the use
years, largely because appropriate efficacy
cells (as well as other inflammatory cells)
of sodium cromoglicate eye drops are for
and safety data has not been provided for
can be expected to migrate towards the
chronic conditions such as SAC and PAC.
conjunctival surface.3 These cells can then
such use. Considerable assessments have
The available P-medicines can be used for
respond progressively faster and more
been made on their safety, with particular
most presentations and are designed to
extensively even for the same allergen load.
attention being paid to the ocular surface.
improve tolerance to the external allergens
Certain types of deposits on contact
There is no obvious ‘drying’ effect from
such that symptoms are reduced in severity.
as
use of these drugs on the corneal and
However, if symptoms are dramatically
allergens.22 These mast cell stabilizers
conjunctival epithelium (eg, as evidenced
reduced in response to sodium cromoglicate
should reduce mast cell degranulation in
by sodium fluorescein staining) but patients
eye drops (or another mast cell stabilizer),26
a dose-dependent fashion,23 and may also
with chronic allergic conjunctivitis are
then substantial activation of the mast cells
reduce migration of white blood cells.24
more likely to have low grade staining and
has not occurred, and such a patient could
Sodium cromoglicate eye drops are
lower fTBUT values.32 Patients who already
likely be managed with occasional use of
have DED may be more likely to show
widely available as P-medicines and
moisturisers, brighteners or an eye wash.
such staining or punctuate epitheliopathy.
even as a GSL product (see Table 1). All
The optometrist with training to AS level
However, it should not be forgotten that
of these cromoglicate products can be
may chose to manage other conditions such
the ocular reaction to allergens could
accessed by optometrists, along with a
as vernal keratoconjunctivitis (VKC)27 or
produce significant morbidity. Lastly, it
P-medicine in the form of lodoxamide. To
adult atopic keratoconjunctivitis (AKC)28
should be noted that patients can prefer
increase tolerance to allergens, these drops
with PoM mast cell stabiliser products.
different antihistamine eye drops despite
need to be used regularly (ie, four times
They can also access the dual acting drugs,
their overall ocular discomfort,30,33 with
per day) and continuously for the entire
ie, ketotifen and olopatadine, as well as
the
period for which exposure to the allergen
selective antihistamines (eg, azelastine and
to be due to the pH of the eye drops.
is expected. This might be seasonal (eg,
emedastine), all of which can be used in
pollen) or perennial (eg, animal dander,
a similar manner to a mast cell stabilizer
indoor allergens etc.). It may take a week
with certain caveats. The most important of
Oral antihistamines and related products
or so before a reasonable tolerance to
these is that they are not generally indicated
For patients with more substantial SAC,
allergens is achieved, thus the potential
for use in young children (see below).
ocular symptoms are more than likely to
need for eye washes, decongestants or
Another drug, epinastine, is marketed
be accompanied by non-ocular symptoms.
topical ocular antihistamines to initially
as eye drops in the UK but not on the
These may range from sneezing, nasal
manage these conditions. These drugs,
additional supply list. These topical ocular
congestion and rhinitis, to a general irritation
25
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38
Figure 5 Pollen grains (the small round balls with irregular surfaces) adhering to pre-corneal mucus layer on the corneal epithelial surface of a cow eye, as viewed at extremely high magnification with the scanning electron microscope
lenses
may,
in
themselves,
act
with their principal advantage being
differences
in
acceptability
likely
(itching, burning sensations) of the
routine
periocular skin (extending onto
medication
the eyelid skin). The periocular
patient use of anti-depressants (eg,
response to allergens may prompt
monoamine oxidase inhibitors,
a patient to want to rub their eyes,
MAOIs) being a notable contra-
and the nasal symptoms can be
indication. In addition, medicines
rather disconcerting as well. It is
for
logical, therefore, to use an oral
relevant to the special use of
antihistamine to reduce the non-
another
ocular symptoms, which may also
hydroxyzine.
reduce the need to repeatedly instill
for use in glaucoma has already
mast cell stabiliser or antihistamine
been described and is of greater
eye
importance in elderly patients
too.
Suitable
antihistamine-containing products include
chlorphenamine,
acrivastine, cetirizine.
32,34
azelastine, Orally
clemstine,
loratidine
assessments,
anxiety
and
administered
Figure 6 Patient information leaflet accompanying product containing an older oral antihistamine (chlorphenamine)
are
oral 34
oral
history
and with
particularly antihistamine,
The
precaution
with a shallow anterior chamber; slight cholinergic blocking effects are notable with some older ‘sedating’ oral antihistamines. There is also a general
antihistamines are used to ‘dry up’
pharmacy chains. The dose used will
warning about limiting alcohol use and
secretions (eg, a runny nose) and therefore,
likely be an important determinant of both
‘Do not drive or operate heavy machinery
for some patients, can actually reduce ocular
the overall efficacy and the likelihood of
if the tablets make you feel drowsy’.
symptoms of watery and itchy eyes too.
adverse reactions / side effects; indeed
Patients’ lifestyles should therefore be
Older drugs such as chlorphenamine have
the use of oral antihistamines can be
considered
been classed as ‘sedating antihistamines’
associated with ‘dry eye’ symptoms.37,38
particular
for many years,35 with each of the newer
With the reduced regulation of these
Last, but not least, consideration needs to
2nd generation drugs being successively
drugs for the management of common
be given to patient age. Most of these oral
presented as ‘non-sedating’; there is a
conditions such as SAC and PAC, the
antihistamines can be used in children,
further drug that is considered to have
responsibility for safe use has been largely
with a general recommendation that a
even lesser-sedating effects, but it should
transferred to the user, as with the use of
lower dose should be used as compared to
be borne in mind that a condition such as
decongestants. Various precautions apply,
adults. P-medicine and GSL oral solutions
seasonal allergic rhinitis (with congestion)
and while most are relevant to the older
of most of the antihistamines are also
may in itself cause a form of drowsiness
antihistamines (still available in large packs
available to facilitate this low dosing (ie,
36
(ie, a ‘thick’ or ‘stuffed’ head feeling).
as P-medicines, rather than small GSL
half a spoonful for a child), eg, Allerief
Oral antihistamines are indicated for use
packs), these still need to be considered
(chlorphenamine), Benadryl Allergy Oral
on a QDS basis for older antihistamines
by the optometrist recommending their
Syrup (cetirizine), Benadryl for Children
to once daily for newer antihistamines.
use or even supplying them to their
Allergy Solution, Clarityn Allergy Syrup
Current products include the P-medicines
patients. Some of these precautions are on
(loartidine), Piriteze Allergy Syrup, Zirtek
of Allercalm, Hayleve, Piriton, Pollonase
the packaging, but more typically are in
Allergy Solution and Zirtek Allergy Relief
Antihistamine Tablets (chlorphenamine),
the ‘small print’ on a Patient Information
for Children (cetirizine).
Tavegil (clemastine), Benadryl Allergy
Leaflet inside the packaging (Figure 6).
Beyond considering the use of oral
Relief (acrivastine), Zirtek and Piriteze
As opposed to warnings of substantial
antihistamines as part of management of the
Allergy Tablets (cetirizine), plus the P /
risk of severe side effects, many of these
ocular effects of SAC and PAC, optometrists
GSL drug Clarityn Allergy (loratidine).
precautionary notes relate to possible
should also be aware of numerous over-
There are also a number of small pack
effects of the antihistamines on the
the-counter (OTC) nasally-administered
(seven tablets) products available as GSL
actual bioavailability of the medication.
products for patients for whom the nasal
products manufactured by the major
Optometrists should already be taking
congestion and inflammation is more of
before oral
39
recommending
antihistamine
a
product.
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4
a problem. These OTC products include
entail instillation of eye drops (either a
stabilizer should be continued until the
nasal decongestants such as phenylephrine
decongestant, mast cell stabilizer or a topical
papillae are greatly reduced, preferably
0.5% (eg, Fenox), xylometazoline 0.1 %
ocular antihistamine) 5 to 10 minutes prior
as
(Otrivine Adult Nasal), xylometazline 0.05
to morning lens insertion. After lens wear, a
fluorescein (see OT May 21, 2010).49,50
% (Otrivine Child Nasal) or oxymetazoline
patient could then instill further eye drops.
Most resolution should take two to four
0.05 % (Afrazine). OTC nasal products
It would not be unexpected for such a
weeks, after which the dosing could be
containing sodium cromoglicate (Vividrin
patient to instill the eye drops in the middle
reduced to TDS or even BDS for a further
Nasal
well
of the day with the lens in place. However,
two to three weeks to ensure complete
as a number of products containing
this is not generally recommended for
resolution of mild-to-moderate CLPC.
corticosteroids (see article 6 in this series).
soft lens wearers because these eye
For contact lens wearers with allergies,
A last option, available to AS-trained
drops are preserved with benzalkonium
the use of oral antihistamines might prove
Spray)
are
available,
as
OT
documented
with
problematic as a result of the ‘drying’ effect
Not withstanding, for contact lens wearers
which could reduce tear secretion,51 and
form, which works to reduce production
it has been reported that shorter-term
would be expected to be greater with the
of prostaglandins (see article 6 in this
BDS use of olopatadine eye drops could
older sedating antihistamines. Therefore,
series). There are only vague guidelines as
reduce symptoms, redness and papillary
it might be beneficial to simply avoid use
to when these eye drops might be used for
reactions,42 while the extended use of
of the older drugs and to recommend a
SAC, but they should reduce inflammation
decongestant (tetrahydrozoline) eye drops
2nd generation drug such as cetirizine.
and redness while having little impact
BDS had no obvious beneficial effects on
Slight
These
superficial punctate keratitis (SPK), follicles,
contact lens wear, could be managed
eye drops, which are preserved with
vasodilation etc.43 Sodium cromoglicate
with the as-needed use of a contact lens
thimerosal, should be considered perhaps
eye drops QDS use has been assessed in
rewetting drop (see OT July 16 2010).
as an adjunct medication to be used
contact lens wearers,44-46 and, especially
alongside mast cell stabilisers as well as oral
for RGP lens wearers, has been reported
Summary
or topical antihistamines. Recommended
to be effective and without significant side
Irritation or allergic reactions of the eye
dosing with diclofenac eye drops is QDS.
effects for up to 18 months. For nedocromil
are commonplace, and it is rarely possible
eye drops, the situation is different since
to prevent exposure. Optometrists have
the eye drops have a yellow colour and so
a range of simple options available
As noted earlier, certain deposits on contact
could stain a hydrogel lens matrix;47 the
to them to manage these conditions
lenses may serve as allergens leading to the
product use should also be limited to 12
as part of providing a comprehensive
development of Contact Lens Papillary
weeks. Currently, the various UK marketed
eye
Conjunctivitis (CLPC) or the more severe
products clearly state that they should not
Giant Papillary Conjunctivitis (GPC). In
be used whilst wearing contact lenses.
addition, contact lens wearers may also
The principle of management of CLPC
Professor Doughty has been teaching
suffer from SAC or PAC and individuals
is similar to that for many other ocular
ocular pharmacology, as well as many
with these conditions are perhaps more
allergies,22 with a period of discontinuation
aspects of ocular physiology and eye
likely to develop CLPC.41 With care,
of contact lens wear recommended as part
disease, for over 25 years and authored
many of the options outlined above can
of the management, and the treatment
books on the subject. He has held the
be
on symptoms such as itching.
29,39,40
Allergy and contact lens wear
considered,
both
for
maintaining
(see
16
and
diclofenac (PoM Voltarol Multi) in eye drop
chloride
July
assessed
2010).
optometrists, is access to the NSAID
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OT CET content supports Optometry Giving Sight
dryness,
care
service
whilst
to
continuing
their
patients.
About the Author
is usually with a mast cell stabiliser.
post of Research Professor at Glasgow-
contact lens wear in those with ocular
A discontinuation of lens wear should
Caledonian
University,
discomfort reactions to external irritants
result in reduction in the severity of the
of
Sciences,
or allergens, and for managing CLPC.
condition over several days, often allowing
48
advocate
resumption of contact lens wear within
a conservative approach for daily lens
a few weeks. With contact lens wear
wearers with allergies, which would
discontinued, a QDS regimen of a mast cell
Some
practitioners
might
Vision
Department since
1995.
References See www.optometry.co.uk and search ‘references’
Course code: C-14569 O/AS/SP/IP
1. Which of the following symptoms is typically experienced by those suffering acute-onset allergic conjunctivitis? (a) Dryness (b) Itching (c) Scratchy feeling (d) All of the above
7. Which of the following is TRUE about eye drops containing antihistamines? (a) They are approved for use by patients of all ages (b) They are not recommended for use in young children (c) They should not be used along with decongestants or brighteners (d) They can be used safely in all elderly patients
2. Which of the following is TRUE about bulbar conjunctival lymphatic vessels? (a) They are very small and are controlled by the corneal nerves (b) They have distinctive sets of smooth muscle cells around them (c) They have a specialised endothelial lining facilitating rapid fluid exchange (d) They are only altered when there are specific IgE-mediated reactions
8. For moderate severity of contact lens-induced papillary conjunctivitis (CLPC) causing lens discomfort, the most appropriate therapy would be: (a) Use of diclofenac eye drops QDS (b) Use of a decongestant eye drops up to 3 times per day (c) Use of a topical antihistamine as-needed whilst continuing lens wear (d) Discontinue lens wear and use lodoxamide eye drops QDS
3. Which of the following is TRUE about Hamamelis extracts? (a) They are included in eye drops as vasoconstrictors (b) They have specific dilation-mediating effects on conjunctival mast cells (c) They have astringent actions equivalent to saline 5% solutions (d) They can be expected to cleanse and sooth the eye
9. Which of the following is TRUE about orally-administered antihistamines? (a) They cannot be legally supplied to patients by optometrists (b) They should not be used concurrently with antihistamine eye drops (c) They are widely available as P-medicines that can be sold by all optometrists (d) They all have the potential to cause substantial drowsiness
4. Which of the following can be found in products labelled as ophthalmic decongestants? (a) naphazoline (b) xylometazoline (c) tetrahydrozoline (d) all of the above 5. Which of the following is TRUE about rebound vasodilation? (a) It is a possible effect of overuse of brightener eye drops (b) It occurs when the conjunctival vessels over-react to environmental allergens (c) It is mediated by IgE effects on the conjunctival lymphatic vessels (d) It is the cause of slight mydriasis associated with use of a decongestant 6. Which of the following is TRUE about topical ocular mast cell stabilisers? (a) They are designed to provide immediate relief in allergic conjunctivitis (b) They can be used effectively on an as-needed basis along with saline eyewashes (c) They should reduce the severity of symptoms in both SAC and PAC (d) They are currently only indicated for use in adults with SAC
10. How does Ketotifen, as PoM Zaditen eye drops, work? (a) Effect on alpha-1 adrenergic receptors in conjunctival arterioles (b) By combined stabilising effects on mast cells, white blood cells and eosinophils (c) Effect on specific histamine H2 receptors on conjunctival venules (d) As a non-steroidal anti-inflammatory drug to reduce prostaglandin synthesis 11. Which of the following is TRUE about airborne pollen grains and other micro-particulates? (a) They can enter the tear film and stick to the ocular surface epithelia (b) They are usually too large to mix with the tear film (c) They are generally inert and will not activate the specific immune system (d) They should usually be easily washed from the ocular surface by the tears 12. Soft contact lens wear can usually be continued with the use of which of the following? (a) Astringent eye drops (b) Topical ocular decongestants (c) Topical ocular mast cell stabilisers (d) None of the above
PLEASE NOTE There is only one correct answer. All CET is now FREE. Enter online. Please complete online by midnight on November 17 2010 - You will be unable to submit exams after this date – answers to the module will be published on www.optometry.co.uk
41
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