Centre for Eye and Vision Research (CEVR) 1 article published in JoVE Medicine A Protein Suspension-Trapping Sample Preparation for Tear Proteomics by Liquid Chromatography-Tandem Mass Spectrometry Jimmy Sung-Hei Tse*1, Ying-Hon Sze*1,2, Jimmy Ka-Wai Cheung1,2, King-Kit Li1, Thomas Chuen Lam1,2,3,4 1Centre for Myopia Research, School of Optometry, The Hong Kong Polytechnic University, 2Centre for Eye and Vision Research (CEVR), 3Research Centre for SHARP Vision (RCSV), The Hong Kong Polytechnic University, 4Research Centre for Chinese Medicine Innovation (RCMI), The Hong Kong Polytechnic University This protocol describes a method for collecting tear samples using Schirmer strips and an integrated quantitative workflow for discovering non-invasive tear protein biomarkers. The suspension trapping sample preparation workflow enables fast and robust tear sample preparation and mass spectrometric analysis, resulting in higher peptide recovery yields and protein identification than standard in-solution procedures.