Conjunctivitis (seasonal & perennial allergic)


Type I hypersensitivity (IgE-mediated) reaction to specific airborne allergens.
Conjunctival mast cell degranulation liberates histamine and other inflammatory mediators into the tissues and tear film, causing dilatation of conjunctival vessels (→red eye), increased permeability of blood vessels (→oedema), itch
Seasonal allergic conjunctivitis (hay fever conjunctivitis) (SAC)

  • caused by seasonal allergens, especially grass pollen
  • onset of symptoms associated with seasonal production of allergens, e.g. tree pollen: spring; grasses: early summer; weeds and fungal spores: late summer
  • condition not sight-threatening, but reduces quality of life and is associated with a significant economic burden

Perennial allergic conjunctivitis (PAC)

  • caused by non-seasonal allergens such as house dust mite or animal dander
  • symptoms throughout the year; may be seasonal exacerbations
  • less common and usually less severe than SAC

Often associated with allergic rhinitis (between 30–71% of patients with allergic rhinitis also have allergic conjunctivitis or conjunctival symptoms).

Predisposing factors

Atopic disposition (40% of population, of which only around half manifest allergic disease)
Personal history of allergic disease (hay fever, asthma, eczema, food or drug allergy)
Family history of allergic disease
Exposure to allergens

Symptoms of seasonal & perennial allergic conjunctivitis

Red eye
Itching of eye (main symptom)
Watering of eye
May be associated with sneezing and watery nasal discharge
SAC: symptoms seasonal with climatic variations
PAC: symptoms perennial but variable; seasonal exacerbations may occur

Signs of seasonal & perennial allergic conjunctivitis

Lids: mild to moderate oedema (peri-orbital oedema in severe cases)
Bulbar and tarsal conjunctiva: chemosis (oedema), hyperaemia and diffuse papillary reaction
Cornea: uninvolved

Differential diagnosis

Vernal or Atopic Keratoconjunctivitis (cornea usually involved)
Other allergic conjunctivitis

Management by optometrist

Practitioners should work within their scope of practice, and where necessary seek further advice or refer the patient elsewhere

Non pharmacological

Identify allergen(s). Requires thorough history and possible use of symptom diary matching to pollen calendars
Advise avoidance of allergen(s)
Cool compresses for symptomatic relief
Advise against eye rubbing (causes mechanical mast cell degranulation)
(GRADE*: Level of evidence=low, Strength of recommendation=strong)


Ocular lubricants for symptomatic relief
(GRADE*: Level of evidence=low, Strength of recommendation=strong)

Various topical treatment options are available but there is insufficient evidence to recommend the use of one type of medication over another; however the choice of drug may be determined by compliance, cost, and availability of preservative-free formulation (if required). The twice daily dosing regime of dual-action antihistamines may be beneficial in contact lens wearers and in school-age children.

  • topical mast cell stabilisers, e.g. gutt. sodium cromoglicate 2%, gutt. lodoxamide 0.1%
  • topical antihistamine e.g. gutt. antazoline 0.5% (the only available over-the counter preparation [Otrivine-Antistin] also contains xylometazoline 0.05%)
  • topical antihistamine + mast cell inhibitor, e.g. gutt. olopatadine 0.1%, gutt. ketotifen 0.025%
  • topical NSAID e.g. gutt. diclofenac sodium 0.1%

(GRADE*: Level of evidence=moderate, Strength of recommendation=strong)

Systemic antihistamine (e.g. tabs cetirizine or loratadine once daily)

  • could be used as an adjunct to topical treatment and may be effective also for other symptoms of hay fever, e.g. allergic rhinitis

(GRADE*: Level of evidence=low, Strength of recommendation=strong)

Management category

B2: alleviation or palliation; normally no referral
B1: if conventional therapy fails, consider referral to Clinical Immunologist for consideration of sub-lingual or other form of immunotherapy

Possible management in secondary care or local primary/community pathways where available

Additional guidance may be available

(Not normally referred)

Evidence base

*GRADE: Grading of Recommendations Assessment, Development and Evaluation (

Sources of evidence

Bielory BP, O’Brien TP, Bielory L. Management of seasonal allergic conjunctivitis: guide to therapy. Acta Ophthalmol 2012;90:399–407.

Bilkhu PS, Wolffsohn JS, Naroo SA, Robertson L, Kennedy R. Effectiveness of nonpharmacologic treatments for acute seasonal allergic conjunctivitis. Ophthalmology 2014;121(1):72-8

Calderon MA, Penagos M, Sheikh A, Canonica GW, Durham SR: Sublingual immunotherapy for allergic conjunctivitis: Cochrane systematic review and meta-analysis. Cochrane Database Syst Rev. 2011;7:CD007685

Castillo M, Scott NW, Mustafa MZ, Mustafa MS, Azuara-Blanco A. Topical antihistamines and mast cell stabilisers for treating seasonal and perennial allergic conjunctivitis. Cochrane Database Syst Rev.2015;6:CD009566

del Cuvillo A, Sastre J, Montoro J, Jáuregui I, Dávila I, Ferrer M, Bartra J, Mullol J, Valero A. Allergic Conjunctivitis and H1 Antihistamines. J Investig Allergol Clin Immunol. 2009;19,Suppl.1:11-18

Leonardi A, Silva D, Perez Formigo D, Bozkurt B, Sharma V, Allegri P, Rondon C, Calder V, Ryan D, Kowalski ML, Delgado L, Doan S, Fauquert JL. Management of ocular allergy. Allergy. 2019;74(9):1611-1630

Zhang SY, Li J, Liu R, Lao HY, Fan Z, Jin L, Liang L, Liu Y. Association of Allergic Conjunctivitis With Health-Related Quality of Life in Children and Their Parents. JAMA Ophthalmol. 2021;139 (8):830-837.


What are Seasonal and Perennial Allergic Conjunctivitis?

Seasonal Allergic Conjunctivitis (SAC) is the part of hay fever that affects the eye and is one of the most common eye problems, affecting about one fifth of adults. It is caused when something called an allergen lands on the eye surface and sets off an allergic reaction. Allergens usually travel through the air. Grass pollen is the most common of these and is at its highest levels in the summer months. The allergic reaction releases histamine into the tears and on to the surface of the eye, causing redness and swelling of the conjunctiva (the clear membrane covering the white of the eye), watering and itching. People with SAC often have allergic symptoms affecting the nose, throat and sinuses, and they may also have asthma, eczema and food or drug allergy. SAC can be unpleasant and cause people to lose time at work or school, but it does not harm the sight.

How are Seasonal and Perennial Allergic Conjunctivitis managed?

It can be treated with anti-allergy drops or antihistamines in eye drop form. Antihistamine tablets can also be helpful, and these will usually control hay fever also. Perennial Allergic Conjunctivitis (PAC) is rarer than SAC but produces similar symptoms. The main difference is that it is a reaction to an allergen that is present throughout the year, such as house dust mite. Its treatment is similar.

Conjunctivitis (Seasonal and Perennial Allergic)
Version 15
Date of search 08.12.22
Date of revision 23.02.23
Date of publication 29.03.23
Date for review 07.12.24
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