The use of environmental exposure chambers in studies related to ocular surface effects.

PURPOSE OF REVIEW: The potential of allergen challenges using environmental exposure facilities in allergic conjunctivitis drug development and more recently its implication on the diagnosis of the united airways concept have been emphasized in the recent literature. This study aims to present an overview of new and important data in this field. RECENT FINDINGS: Standardized methodologies for ocular surface assessment during allergen challenges were described. The Total Ocular Symptom Score (TOSS) is the main validated questionnaire used for the assessment of ocular surface during allergen challenges. It combines patient and investigator assessments for more accurate conjunctival response and was extensively used in clinical research and daily practice. Environmental Exposure Chambers (EECs) studies aim to conduct tight-controlled challenges to a stable and well defined allergen airborne concentration, closer to natural exposure to evaluate the efficacy of nonpharmaceutical and antiallergic treatments. Recent studies showed a good correlation between ocular symptoms elicited by EEC and those assessed during natural exposure. These validated methods allow to investigate the efficacy of novel pharmacotherapies for allergic conjunctivitis and allergen immunotherapy (AIT) in a real-world model of allergen exposure. SUMMARY: This study aims to summarize novel data regarding the impact of EECs in studying pathophysiology and drug efficacy in the context of existing clinical protocols related to ocular surface effects. In this regard, studies comparing conjunctival response during natural and EEC exposures in patients with pollen-induced conjunctivitis aimed to demonstrate better outcomes in tight-controlled exposures mimicking natural exposure. Because allergen challenges are widely implemented in allergy treatment, this article will focus on the most important outcomes and the evolution of treatments for allergic conjunctivitis.

Technical standards in allergen exposure chambers worldwide - an EAACI Task Force Report.

Allergen exposure chambers (AECs) can be used for controlled exposure to allergenic and non-allergenic airborne particles in an enclosed environment, in order to (i) characterize the pathological features of respiratory diseases and (ii) contribute to and accelerate the clinical development of pharmacological treatments and allergen immunotherapy for allergic disease of the respiratory tract (such as allergic rhinitis, allergic rhinoconjunctivitis, and allergic asthma). In the guidelines of the European Medicines Agency for the clinical development of products for allergen immunotherapy (AIT), the role of AECs in determining primary endpoints in dose-finding Phase II trials is emphasized. Although methodologically insulated from the variability of natural pollen exposure, chamber models remain confined to supporting secondary, rather than primary, endpoints in Phase III registration trials. The need for further validation in comparison with field exposure is clearly mandated. On this basis, the European Academy of Allergy and Clinical Immunology (EAACI) initiated a Task Force in 2015 charged to gain a better understanding of how AECs can generate knowledge about respiratory allergies and can contribute to the clinical development of treatments. Researchers working with AECs worldwide were asked to provide technical information in eight sections: (i) dimensions and structure of the AEC, (ii) AEC staff, (iii) airflow, air processing, and operating conditions, (iv) particle dispersal, (v) pollen/particle counting, (vi) safety and non-contamination measures, (vii) procedures for symptom assessments, (viii) tested allergens/substances and validation procedures. On this basis, a minimal set of technical requirements for AECs applied to the field of allergology is proposed.