The move from winter to spring is widely celebrated: few can help but have their spirits lifted by the sight of trees coming into leaf and flowers starting to bloom.
But the advent of warmer weather also brings with it a rise in pollen levels, which can trigger hay fever in those predisposed to the condition.
This week Asha Fowells runs through some of the more common ocular symptoms of this disorder: seasonal allergic conjunctivitis and dry eye syndrome.
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Seasonal allergic conjunctivitis is relatively straightforward to manage, and while uncomfortable and often inconvenient, it is pleasingly unlikely to cause any complications.
There are several self-care measures that sufferers can put into place to try and ease their symptoms:
- avoid rubbing eyes as the action causes further mast cell degranulation, which in turn triggers histamine release and worsening or prolonged symptoms
- minimise exposure to the allergen by staying indoors with windows shut if possible and regularly vacuuming and damp dusting, and wearing wraparound sunglasses if outside, though going outdoors should ideally be avoided in the early morning, evening and at night when the pollen count is at its peak
- eschew contact lens wearing in favour of glasses until symptoms resolve
- place a cold compress such as face flannel soaked in cool water or a refrigerated gel-filled eye mask over the eyes to reduce oedema and redness.
Treatment is usually two-fold, involving rapid relief of symptoms followed by preventative therapy. The former is generally best achieved using an oral or topical antihistamine.
The choice between these two options should be dictated by the patient’s preference, given that there is insufficient evidence supporting any one course of treatment over another.
Factors that warrant consideration include the patient’s age, dosing regimen, contact lens use, cost and, if the patient is a woman of childbearing age, whether she is pregnant or breastfeeding.
Several antihistamine eye drop preparations are available on prescription – azelastine, emedastine, epinastine, olopatidine and ketotifen are the main ingredients used – and the product packaging should be checked before dispensing as various licensing restrictions are in place.
The antihistamine antazoline is available over-the-counter but only in combination with the vasoconstrictor xylometazoline, which requires careful recommendation or sale as the sympathomimetic is contraindicated or cautioned in a number of conditions and should not be used for longer than seven consecutive days.
Of the oral antihistamines, a non-sedating one is usually recommended in the interests of not affecting attendance at work or school, and minimising the impact on the performance of skilled tasks such as driving.
Again, there is little to choose between the different drugs in terms of effectiveness: loratidine and cetirizine are widely used because of their OTC availability, low cost and once daily dosing, levocetirizine, mizolastine and fexofenadine are the same in terms of dosing but are prescription-only, and mizolastine has been implicated in QT-interval prolongation and is therefore not usually regarded as a first line treatment option.
It is worth noting that at the time of writing, products containing desloratadine, acrivastine or bilastine are not licensed for the treatment of seasonal allergic conjunctivitis, even on prescription.
Antihistamines – both topical and systemic – are used for preventative treatment in addition to being employed for rapid relief, but mast cell stabilisers are also an option.
Sodium cromoglicate, nedocromil sodium and lodoxamide are all available in eye drop form and are effective at controlling symptoms over a long period of time, but the need to instil drops four times a day is offputting for some.
This class of drug can be used in conjunction with antihistamines, which can be particularly valuable when waiting for a mast cell stabiliser to take effect and for those who do not maintain control on monotherapy.
If symptoms persist, the mast cell stabiliser and/or antihistamine may be switched for an alternative within the same drug class, though it is also prudent to reconsider the diagnosis.
Resistant cases require referral to an immunologist, and may involve specialist management options such as corticosteroids, immunosuppressants and immunotherapy.
Come back tomorrow for more information on dry eye syndrome.