Abstract
Purpose: :
Dry eye disease (DED) is a prevalent, chronic condition with varied signs and symptoms, including reduced tear film stability, ocular surface damage, as well as elevated levels of inflammatory cytokines and cell surface molecules such as human leukocyte antigen DR (HLA-DR). The lack of a "gold standard" test and patient heterogeneity necessitates research into repeatability and correlation of new biomarkers and conventional objective and subjective endpoints to further the development of dry eye therapies.
Methods: :
A non-drug, non-randomized study was designed to enroll 120 subjects at screening based on Ocular Surface Disease Index (OSDI) and corneal staining (CS). They were stratified into four groups: Normal (OSDI<13 and CS=0), mild DED (OSDI≥13 and CS<4), moderate DED (OSDI≥13 and CS between 4 and 7) and severe DED (OSDI≥13 and CS>7). Study eye was defined as the eye with more severe corneal staining at screening. Eligible subjects were evaluated at Day 0 and Day 7 during which a series of clinical objective and subjective tests were performed along with tear collection for protein biomarker analysis and impression cytology to assess HLA-DR expression.
Results: :
Among 33 tear protein analytes, 29 had correlations greater than 0.6 between the 2 eyes at baseline and 23 had correlations greater than 0.6 between the 2 visits for the study eye. The correlation for HLA-DR expression in conjunctival cells between the 2 eyes was 0.92 at baseline and 0.7 between visits. For those subjective and objective endpoints (CS, conjunctival staining, Schirmer’s Test, tear break up time (TBUT), Ocular Protection Index (OPI), osmolarity, OSDI), the correlations between visits ranged from 0.68 to 0.94 except for tear osmolarity (0.34) and TBUT (0.56). Among many correlations examined between different clinical tests the only ones greater than 0.5 were corneal staining vs. TBUT and corneal staining vs. OSDI. A small number of protein markers showed moderate correlations (>0.45) with objective tests for dry eye.
Conclusions: :
We demonstrated in this study that many current subjective and objective clinical assessments of dry eye were well correlated between visits. The strong correlations of tear protein markers between two eyes or between two visits indicated good reliability of the marker and detection technology. In conclusion, a small number of protein markers in tear have the potential to be a dry eye disease biomarker.
Keywords: clinical (human) or epidemiologic studies: outcomes/complications • clinical research methodology • proteomics