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General eye irritation and allergic conjunctivitis: management options for UK optometrists part 4: course code: C-14569 O/AS/SP/IP.

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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 and follow-up, guidelines need to be carefully considered for each type of condition as does the finer details of legislation relevant to the use of different drugs in eye brighteners, decongestants, decongestant / topical antihistamines, and oral antihistamines, as well as mast cell stabilisers. Special consideration will be given to access to topical ocular antihistamines and a topical NSAID by additional supply (AS level) optometrists.

Aetiology of ocular irritation and reactions to external allergens

Patients can report a variety of symptoms associated with tear film deficiencies, often loosely referred to as 'dry eye' (see OT, July 16 2010). Slightly different symptoms, including 'discomfort' or 'itchiness', can also be experienced in patients not having dry eye disease (DED); all, however, are sensory responses to anything abnormal and/or threatening to the conjunctiva. If the exposure to irritants (eg, organic fumes) or allergens (eg, pollen) persists, then increased lacrimation and eyeblinking are likely, as this system attempts to clear the tear film of the cause. There will also be changes in the complex structure of the conjunctival epithelium tissue and the connective tissue immediately underlying it (Figure 1).

Most of the healthy conjunctival surface is composed of non-squamous cells within the layers of which are goblet cells providing mucin that forms the basal aspect of the tear film layer. (1-3) The surface of the conjunctiva can change such that it will 'stain' with fluorescein if slightly compromised and with rose bengal if more substantially 'damaged' (see OT, August 13 2010). Such compromise will likely be 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 (fTBUT) values then cause ocular surface desiccation and a worsening of the staining.

Immediately under the conjunctiva are numerous nerve fibre terminals that endow the conjunctiva with sensitivity to mechanical stimuli as well as to irritants. Recent research confirms that the 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 system that forms organised fibre bundles slightly deeper in the sub-epithelial connective tissue (Figure 1). Therefore, an acute response to an irritant might stimulate excessive eyeblinking (and reflex lacrimation), while a longer-term consequence of chronic irritation appears to be a reduction in conjunctival sensitivity that also results in increased eyeblinking.

The sub-epithelial connective tissue (parenchyma) is richly supplied with blood vessels, the arterioles having distinctive smooth muscle surrounding them and the venules more likely to have a fenestrated endothelial lining (Figure 1). All the blood vessels are likely innervated by the autonomic nervous system (ANS), with the sympathetic (adrenergic) system dominating the arterioles and the parasympathetic nervous system (cholinergic) controlling the venules. It is unknown how the balance of these ANS effects is altered if there is a change in conjunctival sensitivity. The parenchyma also contains inflammatory cells, whether these be the natural complement of mast cells or additional white blood cells (eg, eosinophils) that have migrated from the capillaries into the tissue in response to irritation; (3) both cell types are special in that they generally contain granules which can release inflammatory mediators such as histamine and certain prostaglandins. These inflammatory mediators generally cause dilatation of the blood vessels and also mediate the sensory responses to irritation. Some patients may complain of general 'irritation' or 'discomfort' or even 'smarting' of the eyes, as opposed to saying that their eyes are 'dry', although some patients experiencing progressive allergy reactions to eye drop preservatives (eg, benzalkonium chloride) may report 'dry eyes'. If the irritant is actually an allergen ie, is triggering the specific immune response system rather than the innate non-specific system, the distinguishing symptom often noted is that of 'itching'. This can often result in the patient wanting to rub (rather than 'scratch') their eyes. A patient with acute-onset allergic reaction may indeed have an overwhelming desire to rub their eyes and, in the process, actually worsen their condition leading to redness and puffiness of the eyelid margins and even the bulbar conjunctiva. This secondary response is mediated by the lymphatic system within the parenchyma. These can be seen as having similar size to blood vessels (Figure 1) or, at least at some locations under the conjunctiva, as very substantial in size (volume) (Figure 2). (2,5)

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The electron micrograph (Figure 2) illustrates just how loosely packed the parenchyma is, especially in the vicinity of a dilated lymphatic vessel. (2) This attribute, along with the specialised loops in the endothelial lining of the lymphatic 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 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-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 associated with the innate immune system 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 is also reflected in the use of both nonspecific as well as specific pharmacological interventions to manage the wide spectrum of presentations for this group of conditions.

Medicines and non-medical products for managing general eye irritation and allergic conjunctivitis

With numerous components to the conjunctival system, there is no single approach to pharmacological management of general eye irritation and allergic conjunctivitis. Furthermore, the legislation relevant to the range of products available has changed substantially in recent years. Eyewashes and eye 'brighteners' are general sales list (GSL), with the latter being an alternative to pharmacy (P)-medicines containing topical ocular decongestants or a decongestant and antihistamine. A topical mast cell stabiliser has been recently added to the GSL category (as well as being available as a P-medicine), and while P-medicine topical ocular antihistamines have been discontinued, oral antihistamines are available as GSL products and as P-medicines. Non-therapeutically trained optometrists may access all the above-mentioned products by way of wholesale trading and then 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 (NSAID). The relevant College of Optometrists clinical 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.

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Astringent eyewashes and eye drops and topical ocular decongestants

Once-common causes of ocular irritation were smoke-filled rooms (now reduced with changes in workplace legislation) but either traffic exhaust fumes or perhaps barbecue smoke or indoor grills are the likely replacements, in addition to numerous other indoor airborne microparticulates causing mucous membrane irritation. These latter irritants are sometimes referred to as volatile organics and associated with conditions such as 'sick building syndrome'. A recreational exposure to chlorinated chemicals (eg, swimming pools) can also cause 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 (as the goblet cells can discharge slightly in response to general irritation). In many such presentations, there will be little sign of oedema (puffiness) etc. with the degree of bulbar conjunctiva hyperaemia usually being low. In addition, there will usually be little or no signs of ocular surface compromise (eg, significant ocular surface staining with sodium fluorescein) but fFBUT values may be reduced.

Reducing the level of irritants in the tear film is a logical first step to management, either by avoidance or with the use of eyewashes or lotions. Such remedies have mild 'astringent' action, a term indicating that there is a slightly greater cleansing action than a simple isotonic (0.9%) saline (even though the latter can still be efficacious). Older remedies included use of "true" astringent (eg, very hypertonic solutions such as 5% saline), but modern-day individuals with a mild-to-moderate ocular irritation are most unlikely to tolerate the use of such products. 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 "for the relief of redness of the eye due to minor eye irritations" or to "reduce redness so making the eyes brighter with whiter whites" (Figure 4). These products contain low concentrations (sometimes not specified) of drugs that primarily act as alpha-1 adrenergic agonists on the blood vessel smooth muscles. Drugs such as naphazoline (eg, Murine eye drops, or Eye Dew Sparkling eye drops) and xylometazoline (eg, Otrivine-Antisitine eye drops) were introduced in the 1950s to replace the use of adrenaline (epinephrine) 1:1000 eye drops as a vasoconstrictor (decongestant)? Eye drops containing phenylephrine were discontinued in the UK in 2003, but may be accessible over the 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 whiten the general appearance of the eye. (10)

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Figure 4
Packaging for an ophthalmic brightener product to
indicate use and precautions

Reduces redness making
eyes brighter, with whiter
whites.

STERILE

Do not use if seal is
broken.

Directions:

Adults: One or two drops
in each eye, do not use
more than 3 times a day.
Do not use in children
under 12 years.

Do not use:

* If you have any eye
disease or have had eye
surgery.

* If you are being treated for
high blood pressure
depression, heart
disease, diabetes, thyroid
disorders or Parkinson's
disease.

* During pregnancy.

* Whilst wearing contact
lenses.

* If you are sensitive to any
of the ingredients.
Discard within 4 weeks of
opening.

Keep out of reach of
children.


The effect of these products should be rapid in onset (ie, within a minute) and last for at least an hour to help relieve symptoms such as irritation, mild burning and photophobia, (10,11) and reduce reflex lacrimation. (11,12) Combination products with antihistamines were introduced to also produce a "calming effect on blepharospasm" associated with ocular irritation, (11) and this logically applies to the current UK combination of xylometazoline 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) 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 and used at anything from one to eight drops per day in each eye, but current perspectives are that such products should not be used 'as needed' for long periods and that the number of uses per day should be limited, eg, 'do not use more than three times per day' (Figure 4). As can be seen on the pack of a contemporary GSL product, these eye drops are not intended for use in children (ie, those less than 12 years of age), and the current recommendation is that the combination product Otrivine-Antistin is not for use in children at all, or should be half the dose recommended for an adult.

The primary reason for limiting the use of these products relates to safety (see below), but a recurrent issue that arises with 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 to alleviate all signs and symptoms of any acute red eye with these products, could allow a (mild) infectious conjunctivitis to progress, (16) and even dilute solutions may produce a slight pupillary dilation. (10,17) While only slight pupil dilation has been measured with the use of combination products (with an antihistamine), (18,19) an additive effect might be due to mild cholinergic blocking 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 type "Do not use for more than 72 hours except under the advice and supervision of a 'doctor' or 'physician'". Overall, therefore, all such decongestant-containing products should be used with caution and should not be recommended for use in patients who are known to have a narrow anterior chamber angle. Pupillary dilation is more likely to be evident under lower levels of illumination and in blue-eyed individuals and probably is more likely when there is significant compromise of the corneal epithelial surface. (20)

Overall, while some ocular irritation can develop with overuse, these products have an excellent safety record and this is why some of these products are now deregulated, with the responsibility for safe use being transferred to the user. This responsibility comes in the form of the small print on the packing and product inserts (Figure 4).

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 (Hi-receptor blocking) drugs (eg, ketotifen, 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 density of these very small (circa l[micro]m in diameter) pollen grains is in excess of 1000,000 per [mm.sup.2], and these resist washing with saline. Other micro-particulates might be from animal dander, dust mite excreta, workplace processes, from furniture and carpeting etc., all of which can tenaciously stick to the epithelial surface mucus coating. Due to the persistent exposure, 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 for use of a mast cell stabilizer is to try to reduce or even prevent the mast cells from discharging histamine and prostaglandins (degranulation) following their IgE-mediated activation by allergens. If this can be achieved, there should be a reduction in the tear film levels of inflammatory mediators despite the continued presence of the allergen. With repeated contact of the ocular surface with allergens, the mast cells (as well as other inflammatory cells) can be expected to migrate towards the conjunctival surface. (3) These cells can then respond progressively faster and more extensively even for the same allergen load.

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Certain types of deposits on contact lenses may, in themselves, act as allergens. (22) These mast cell stabilizers should reduce mast cell degranulation in a dose-dependent fashion, (23) and may also reduce migration of white blood cells. (24)

Sodium cromoglicate eye drops are widely available as P-medicines and even as a GSL product (see Table 1). All of these cromoglicate products can be accessed by optometrists, along with a P-medicine in the form of lodoxamide. To increase tolerance to allergens, these drops need to be used regularly (ie, four times per day) and continuously for the entire period for which exposure to the allergen is expected. This might be seasonal (eg, pollen) or perennial (eg, animal dander, indoor allergens etc.). It may take a week or so before a reasonable tolerance to allergens is achieved, thus the potential need for eye washes, decongestants or topical ocular antihistamines to initially manage these conditions. These drugs, especially sodium cromoglicate, can be used to manage a range of types of allergic conjunctivitis, (25) and have an extraordinary good safety record in that local adverse effects reports are both unusual and perhaps actually due to the benzalkonium chloride preservative. As a broad principle, therefore, there are no restrictions to the use of sodium cromoglicate eye drops other than known allergy to the drug or the preservative benzalkonium chloride, regardless of patient age. For a named patient, preservative-flee (unit dose) sodium cromoglicate eye drops are available through a specialist hospital pharmacy, eg, Moorfields Eye Hospital.

The commoner indications for the use of sodium cromoglicate eye drops are for chronic conditions such as SAC and PAC. The available P-medicines can be used for most presentations and are designed to improve tolerance to the external allergens such that symptoms are reduced in severity. However, if symptoms are dramatically reduced in response to sodium cromoglicate eye drops (or another mast cell stabilizer), (26) then substantial activation of the mast cells has not occurred, and such a patient could likely be managed with occasional use of moisturisers, brighteners or an eye wash.

The optometrist with training to AS level may chose to manage other conditions such as vernal keratoconjunctivitis (VKC) (27) or adult atopic keratoconjunctivitis (AKC) (28) with PoM mast cell stabiliser products. They can also access the dual acting drugs, ie, ketotifen and olopatadine, as well as selective antihistamines (eg, azelastine and emedastine), all of which can be used in a similar manner to a mast cell stabilizer with certain caveats. The most important of these is that they are not generally indicated for use in young children (see below).

Another drug, epinastine, is marketed as eye drops in the UK but not on the additional supply list. These topical ocular antihistamines can be used to manage SAC , (29-31) with their principal advantage being the faster onset in reduction of symptoms, ie, a patient can start using these at the first exposure to allergens and can expect useful effects within minutes to hours (as opposed to days with a mast cell stabiliser).

It is unclear, however, whether the overall longer-term tolerance to airborne allergens is better when comparing use of topical antihistamines to mast cell stabilisers. The antihistamines all have some restrictions on use, with the various products having warnings that they are not indicated for use on children below the age of three or four years, largely because appropriate efficacy and safety data has not been provided for such use. Considerable assessments have been made on their safety, with particular attention being paid to the ocular surface. There is no obvious 'drying' effect from use of these drugs on the corneal and conjunctival epithelium (eg, as evidenced by sodium fluorescein staining) but patients with chronic allergic conjunctivitis are more likely to have low grade staining and lower fTBUT values. (32) Patients who already have DED may be more likely to show such staining or punctuate epitheliopathy. However, it should not be forgotten that the ocular reaction to allergens could produce significant morbidity. Lastly, it should be noted that patients can prefer different antihistamine eye drops despite their overall ocular discomfort, (30,33) with the differences in acceptability likely to be due to the pH of the eye drops.

Oral antihistamines and related products

For patients with more substantial SAC, ocular symptoms are more than likely to be accompanied by non-ocular symptoms. These may range from sneezing, nasal congestion and rhinitis, to a general irritation (itching, burning sensations) of the periocular skin (extending onto the eyelid skin). The periocular response to allergens may prompt a patient to want to rub their eyes, and the nasal symptoms can be rather disconcerting as well. It is logical, therefore, to use an oral antihistamine to reduce the nonocular symptoms, which may also reduce the need to repeatedly instill mast cell stabiliser or antihistamine eye drops too. Suitable oral antihistamine-containing products include chlorphenamine, clemstine, acrivastine, azelastine, loratidine and cetirizine. (32,34) Orally-administered antihistamines are used to 'dry up' secretions (eg, a runny nose) and therefore, for some patients, can actually reduce ocular symptoms of watery and itchy eyes too. Older drugs such as chlorphenamine have been classed as 'sedating antihistamines' for many years, (35) with each of the newer 2nd generation drugs being successively presented as 'non-sedating'; there is a further drug that is considered to have even lesser-sedating effects, but it should be borne in mind that a condition such as seasonal allergic rhinitis (with congestion) may in itself cause a form of drowsiness (ie, a 'thick' or 'stuffed' head feeling). (36)

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Oral antihistamines are indicated for use on a QDS basis for older antihistamines to once daily for newer antihistamines. Current products include the P-medicines of Allercalm, Hayleve, Piriton, Pollonase Antihistamine Tablets (chlorphenamine), Tavegil (clemastine), Benadryl Allergy Relief (acrivastine), Zirtek and Piriteze Allergy Tablets (cetirizine), plus the P / GSL drug Clarityn Allergy (loratidine). There are also a number of small pack (seven tablets) products available as GSL products manufactured by the major pharmacy chains. The dose used will likely be an important determinant of both the overall efficacy and the likelihood of adverse reactions / side effects; indeed the use of oral antihistamines can be associated with 'dry eye' symptoms. (37,38)

With the reduced regulation of these drugs for the management of common conditions such as SAC and PAC, the responsibility for safe use has been largely transferred to the user, as with the use of decongestants. Various precautions apply, and while most are relevant to the older antihistamines (still available in large packs as P-medicines, rather than small GSL packs), these still need to be considered by the optometrist recommending their use or even supplying them to their patients. Some of these precautions are on the packaging, but more typically are in the 'small print' on a Patient Information Leaflet inside the packaging (Figure 6).

As opposed to warnings of substantial risk of severe side effects, many of these precautionary notes relate to possible effects of the antihistamines on the actual bioavailability of the medication. Optometrists should already be taking routine medical history and medication assessments, with patient use of anti-depressants (eg, monoamine oxidase inhibitors, MAOIs) being a notable contraindication. In addition, medicines for anxiety are particularly relevant to the special use of another oral antihistamine, hydroxyzine. (34) The precaution for use in glaucoma has already been described and is of greater importance in elderly patients with a shallow anterior chamber; slight cholinergic blocking effects are notable with some older 'sedating' oral antihistamines. There is also a general warning about limiting alcohol use and 'Do not drive or operate heavy machinery if the tablets make you feel drowsy'. Patients' lifestyles should therefore be considered before recommending a particular oral antihistamine product.

Last, but not least, consideration needs to be given to patient age. Most of these oral antihistamines can be used in children, with a general recommendation that a lower dose should be used as compared to adults. P-medicine and GSL oral solutions of most of the antihistamines are also available to facilitate this low dosing (ie, half a spoonful for a child), eg, Allerief (chlorphenamine), Benadryl Allergy Oral Syrup (cetirizine), Benadryl for Children Allergy Solution, Clarityn Allergy Syrup (loartidine), Piriteze Allergy Syrup, Zirtek Allergy Solution and Zirtek Allergy Relief for Children (cetirizine).

Beyond considering the use of oral antihistamines as part of management of the ocular effects of SAC and PAC, optometrists should also be aware of numerous over-the-counter (OTC) nasally-administered products for patients for whom the nasal congestion and inflammation is more of a problem. These OTC products include nasal decongestants such as phenylephrine 0.5% (eg, Fenox), xylometazoline 0.1% (Otrivine Adult Nasal), xylometazline 0.05 % (Otrivine Child Nasal) or oxymetazoline 0.05 % (Affazine). OTC nasal products containing sodium cromoglicate (Vividrin Nasal Spray) are available, as well as a number of products containing corticosteroids (see article 6 in this series).

A last option, available to AS-trained optometrists, is access to the NSAID diclofenac (PoM Voltarol Multi) in eye drop form, which works to reduce production of prostaglandins (see article 6 in this series). There are only vague guidelines as to when these eye drops might be used for SAC, but they should reduce inflammation and redness while having little impact on symptoms such as itching. (29,39,40) These eye drops, which are preserved with thimerosal, should be considered perhaps as an adjunct medication to be used alongside mast cell stabilisers as well as oral or topical antihistamines. Recommended dosing with diclofenac eye drops is QDS.

Allergy and contact lens wear

As noted earlier, certain deposits on contact lenses may serve as allergens leading to the development of Contact Lens Papillary Conjunctivitis (CLPC) or the more severe Giant Papillary Conjunctivitis (GPC). In addition, contact lens wearers may also suffer from SAC or PAC and individuals with these conditions are perhaps more likely to develop CLPC. (41) With care, many of the options outlined above can be considered, both for maintaining contact lens wear in those with ocular discomfort reactions to external irritants or allergens, and for managing CLPC.

Some practitioners might advocate a conservative approach for daily lens wearers with allergies, which would entail Instillation of eye drops (either a decongestant, mast cell stabilizer or a topical ocular antihistamine) 5 to 10 minutes prior to morning lens insertion. After lens wear, a patient could then instill further eye drops. It would not be unexpected for such a patient to instill the eye drops in the middle of the day with the lens in place. However, this is not generally recommended for soft lens wearers because these eye drops are preserved with benzalkonium chloride (see OT July 16 2010).

Not withstanding, for contact lens wearers it has been reported that shorter-term BDS use of olopatadine eye drops could reduce symptoms, redness and papillary reactions, (42) while the extended use of decongestant (tetrahydrozoline) eye drops BDS had no obvious beneficial effects on superficial punctate keratitis (SPK), follicles, vasodilation etc. (43) Sodium cromoglicate eye drops QDS use has been assessed in contact lens wearers, (44-46) and, especially for RGP lens wearers, has been reported to be effective and without significant side effects for up to 18 months. For nedocromil eye drops, the situation is different since the eye drops have a yellow colour and so could stain a hydrogel lens matrix; (47) the product use should also be limited to 12 weeks. Currently, the various UK marketed products clearly state that they should not be used whilst wearing contact lenses.

The principle of management of CLPC is similar to that for many other ocular allergies, (22) with a period of discontinuation of contact lens wear recommended as part of the management, and the treatment is usually with a mast cell stabiliser. (48) A discontinuation of lens wear should result in reduction in the severity of the condition over several days, often allowing resumption of contact lens wear within a few weeks. With contact lens wear discontinued, a QDS regimen of a mast cell stabilizer should be continued until the papillae are greatly reduced, preferably as assessed and documented with fluorescein (see OT May 21, 2010). (49,50) Most resolution should take two to four weeks, after which the dosing could be reduced to TDS or even BDS for a further two to three weeks to ensure complete resolution of mild-to-moderate CLPC.

For contact lens wearers with allergies, the use of oral antihistamines might prove problematic as a result of the 'drying' effect which could reduce tear secretion, (51) and would be expected to be greater with the older sedating antihistamines. Therefore, it might be beneficial to simply avoid use of the older drugs and to recommend a 2nd generation drug such as cetirizine. Slight dryness, whilst continuing contact lens wear, could be managed with the as-needed use of a contact lens rewetting drop (see OT July 16 2010).

Summary

Irritation or allergic reactions of the eye are commonplace, and it is rarely possible to prevent exposure. Optometrists have a range of simple options available to them to manage these conditions as part of providing a comprehensive eye care service to their patients.

Module questions

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

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

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

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

7. Which of the following is TRU E 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

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

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

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

References

See www.optometry.co.uk and search 'references'

Professor Doughty has been teaching ocular pharmacology, as well as many aspects of ocular physiology and eye disease, for over 25 years and authored books on the subject. He has held the post of Research Professor at Glasgow-Caledonian University, Department of Vision Sciences, since 1995.
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

ACTIVE INGREDIENT     LEGAL    BOTTLE      PRODUCT NAMES
(DRUG)                STATUS   SIZE (mL)

antazoline (1)        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

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)

lodoxamide            P        5           ALOMIDE ALLERGY EYE DROPS

lodoxamide            PoM      10          ALOMIDE

nedocromil            PoM      5           RAPITIL

ketotifen (2)         PoM      5           ZADITEN

olopatadine (2)       PoM      5           OPATANOL

azelastine            PoM      8           OPTILAST

emedastine            PoM      5           EMADINE

epinastine (3)        PoM      5           RELESTAT

emedastine            PoM      5           EMADINE

epinastine (3)        PoM      15          RELESTAT
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Title Annotation:CONTINUING EDUCATION & TRAINING
Author:Doughty, Michael J.
Publication:Optometry Today
Article Type:Report
Geographic Code:4EUUK
Date:Oct 15, 2010
Words:5847
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