Tear sample collection in ocular allergy

Purpose To evaluate four different methods of tear collection in healthy participants. Methods Four methods used for tear collection were evaluated in both eyes of 20 healthy participants. Methods tested: capillary tubes (CT), capillary tubes with instillation of saline (CT saline), Schirmer's Tear Test Strips (STTS) and Polyvinyl Alcohol sponges (PVA). Volume, duration of collection, participant-reported discomfort, concentration and mass of histamine were evaluated. Results With CT saline the largest volume was collected in the shortest time. A significantly higher concentration of histamine was found in samples collected with STTS compared to CT saline (p = 0.04) and PVA (p = 0.02). CT and CT saline were associated with no or mild discomfort in 95% and 90%, STTS and PVA with moderate or severe discomfort in 70% and 85%. Conclusion For collection of tear fluid for the measurement of histamine the CT saline method was found to be a technically easy and quick method of obtaining sufficient volumes of tear fluid, with low discomfort for participants.