Skin prick tests (SPT) are commonly used in daily allergological practice to assess skin reactivity to allergens. Multiple factors can contribute to non-optimal results of conventional wheal and flare measurement (CWFM) of SPT such as inaccurate measurements, observer-dependency and absence of traceability.

This study aims to evaluate the quantification of SPT by a novel High Speed Laser Doppler Imaging (HSL-DI) and to compare it with CWFM. First, SPT with birch and/or grass pollen extracts as well as positive and negative controls will be performed in 20 volunteers (11 atopics, 9 non-atopics) to establish the characteristics (cut-off, optimal reading time and allergen concentration) of HSL-DI analysis based on two parameters ("area" and "flow" measurement). In a second step, fifty patients will be tested with birch and grass pollen extracts at optimal allergen concentration and time window. Analysis of SPT by HSL-DI and CWFM will be compared.

Inclusion Criteria:

• age 18 to 65 years
• history of allergic rhinitis to birch pollen and/or grass pollen.

Exclusion Criteria:

• any medical condition (including pregnancy) that could influence the study (viral or bacterial airway infection, active allergic rhinitis)
• uncontrolled asthma (peak expiratory "flow" <80% of volunteer's best personal value)
• treatment with antihistamine medication less than two weeks before enrolment or during the trial.