Conjunctival allergen provocation test : guidelines for daily practice

Abstract

Conjunctival allergen provocation test (CAPT) reproduces the events occurring by instilling an allergen on the ocular surface. This paper is the compilation of a task force focussed on practical aspects of this technique based on the analysis of 131 papers. Main mechanisms involved are reviewed. Indications are diagnosing the allergen(s)-triggering symptoms in IgE-mediated ocular allergy in seasonal, acute or perennial forms of allergic conjunctivitis, especially when the relevance of the allergen is not obvious or in polysensitized patients. Contraindications are limited to ongoing systemic severe pathology, asthma and eye diseases. CAPT should be delayed if receiving systemic steroids or antihistamines. Local treatment should be interrupted according to the half-life of each drug. Prerequisites are as follows: obtaining informed consent; evidencing of an allergen by skin prick tests and/or serum-specific IgE dosages; being able to deal with an unlikely event such as acute asthma exacerbation, urticaria or anaphylaxis, or an exacerbation of allergic conjunctivitis. Allergen extracts should be diluted locally prior to administration. Positive criteria are based on itching or quoted according to a composite score. An alternative scoring is based on itching. CAPT remains underused in daily practice, although it is a safe and simple procedure which can provide valuable clinical information.The conjunctival allergen provocation test (CAPT), also known as conjunctival allergen challenge (CAC), is a conjunctival provocation test (CPT) used to evaluate the inflammatory effects on the external ocular surface after the topical application of an allergen in a presumed sensitized patient. The aim was to objectively evaluate the reactivity to specific allergens at the mucosal surface (1).As stated in a recent Position Paper on Ocular Allergy, CAPT is a method for investigating the ocular surface IgE-mediated hypersensitivity disorders. It is used to determine or confirm which allergen(s) triggers the ocular symptoms, using the eye as a model to evidence a specific reactivity to allergen(s) (2). Conjunctival allergen provocation test is also a tool for investigating allergic inflammation mechanisms and biomarkers of the ocular surface, as well as its treatments. Recently, it has been used as a surrogate test of mucosal reactivity in other allergic diseases, namely rhinitis, asthma, food and latex allergy (3-5).Allergy 72 (2017) 43-54

A randomized, double‐blind, placebo‐controlled, dose‐finding trial with Lolium perenne peptide immunotherapy

“…The clinical effect was assessed using the CPT, which has been shown to be a reliable surrogate marker in the diagnosis of SAR and in the prediction of allergic rhinoconjunctivitis symptoms during the season in patients treated with preseasonal SLIT tablets 19, 20…”

Liposomal Eye Spray Is as Effective as Antihistamine Eye Drops in Patients with Allergic Rhinoconjunctivitis Induced by Conjunctival Provocation Testing

“…All patients had to have a positive CPT (stage II or higher, according to Table 1) in order to be enrolled in the study. Exclusion criteria related to the CPT were allergy symptoms already present at the time of the CPT, other ocular disorders except for refraction anomalies, wearing of contact lenses for the 72 h prior to the CPT, and ongoing antiallergic therapy that might interfere with the CPT [19]. …”

“…Therefore, we analyzed liposomes as a potential nonpharmacological treatment option to topical antihistamines by assessing their respective onsets of action as well as their capability of reducing allergy symptoms after a conjunctival provocation test (CPT). Through artificial allergen exposure, the CPT serves as a model for the allergy season by triggering typical symptoms of ARC [18, 19]. Current guidelines recommend carrying out the CPT either before initiating allergen immunotherapy (AIT) to determine the allergens which induce the symptoms or conducting the CPT throughout the course of AIT to monitor its therapeutic effect [20].…”

Reliability of a New Symptom Score in a Titrated Quantitative Conjunctival Provocation Test Supported by an Objective Photodocumentation

“…Recently, a task force initiative of the EAACI outlined recommendations for conducting the conjunctival allergen provocation test in daily practice and has proposed a test protocol as well as positivity criteria [18]. However, no harmonized and clinically validated evaluation method exists on the national or international level [18, 23, 24]. The various protocols are highly heterogeneous with regard to the documentation and interpretation of evoked conjunctival symptoms [14, 17, 19, 21, 24, 25].…”

“…According to the new position paper [18], it is essential for assessing the reproducibility of the CPT to use subjective and objective criteria as well.…”