The clinical relevance of an allergen-specific sensitization is proven e.g., by allergen challenge tests in clinical routine. Several protocols for different challenge tests such as nasal (NPT), bronchial (BPT) or conjunctival provocation test (CPT) have been proposed. Beneath others, the CPT is broadly used in both clinical trials and routine because of its feasibility.

However, there is no internationally harmonized standard regarding the clinical interpretation of CPT results as well as a lack of validation of a specific outcome score. Therefore, this trial aims to investigate and validate a new scoring system for CPT results in order to provide this test as a useful method in future clinical trials.

Of 33 patients who had been initially screened, ten patients did not fulfill all of the inclusion criteria mentioned hereafter. Thus, 23 patients aged 18 to 67 years having a birch and/or grass pollen allergy were included in the analysis. The study is in line with the Declaration of Helsinki and is approved by the responsible ethics committee (FF 118/2012 (4 December 2012); Landesärztekammer Hessen, Frankfurt, Germany). All participating patients are informed of the nature and objectives of the study and signed an informed consent document.

The CPT is conducted using standardized and registered allergen extracts (ALK- Abelló, Hørsholm, Denmark). At the first visit, a titrated quantitative CPT (tqCPT) is performed according to a standardized protocol. In case of a positive test result, CPT-results are to be confirmed at a re-challenge one week later. The final CPT takes place 3 to 4 weeks after the 2nd (confirmatory) challenge for analyzing the primary objective of the trial: reproducibility of the CPT symptom score. Furthermore, objective evaluation of the clinical reactions after the tqCPT is documented using a MATLAB software program to calculate the degree of redness in percent. This is then correlated with the (subjective) main investigators' evaluations and with the external observer's evaluations.

Inclusion Criteria:

• moderate to severe allergic rhinoconjunctivitis (ARC) symptoms in preceding two years -intake of anti-allergic medication in the preceding two years -positive test result in skin prick test (SPT) (wheal size at least 3 mm larger than the negative control). -
• retrospective global symptoms score (≥5 out of 12)

Exclusion Criteria:

• acute diseases of the eye or of the nose/nasal sinuses,
• persistent allergy
• intake of concomitant (antiallergic) medication prior to CPT-challenges
• CPT score ≥3 during the examination of the control (non-challenged eye) at baseline