INTRODUCTION: The proteins found in tears play an important role in maintaining 
the ocular surface and changes in tear protein components may reflect changes in 
the health of the ocular surface. Proteomics provides a comprehensive approach 
for cataloguing all the proteins of the tear proteome, which will help to 
elucidate disease pathogenesis, make clinical diagnoses and evaluate the 
influence of medications on the structure, composition and secretion of tear 
proteins. In this study, an alternative proteomic strategy was investigated to 
explore the human tear proteome.
MATERIALS AND METHODS: Tear samples were obtained from patients who had 
pterygium and were collected on the first day and third day after pterygium 
surgery. Tears pooled from 6 patients were used in the analysis. Reverse-phase 
high-pressure liquid chromatograph (RPHPLC) was used as the first step to 
separate intact proteins into 21 peaks. Each fraction was then tryptic-digested 
and analysed by nanoLC-nano-ESI-MS/MS to characterise the protein components in 
each fraction.
RESULTS: In total, 60 tear proteins were identified with high confidence, 
including well-known abundant tear proteins, and tear-specific proteins such as 
lacritin and proline-rich proteins. Among them, proline-rich protein 5 was found 
for the first time in tear fluid. A large number of plasma proteins were also 
observed in tear fluid.
CONCLUSIONS: The results showed that the proteomic strategy used in this study 
was successfully applied to analyse tear proteome.