title: Correlation between tear film osmolarity, dry eye disease, and rheumatoid arthritis.
abstract: OBJECTIVE
  The aim of this study was to evaluate the reliability of tear film osmolarity as a diagnostic tool for detecting dry eye disease (DED) in patients with rheumatoid arthritis (RA). The second aim was to determine whether there is a relationship between tear film osmolarity, a commonly used RA score, and diagnostic blood tests for RA.
  
  
  METHODS
  A group of 74 patients with RA but without any previously established diagnosis of DED at University Hospital Wurzburg was examined. A Modified Dry Eye Severity Score was calculated based on tear film osmolarity, Schirmer test, tear film break-up time, ocular surface disease index questionnaire, corneal fluorescein staining, conjunctival lissamine green staining, and meibomian gland grading score. RA assessment included disease activity score (DAS) 28-erythrocyte sedimentation rate (ESR) scoring and serum levels of C-reactive protein (CRP) and rheumatoid factor (RF).
  
  
  RESULTS
  Tear film osmolarity showed a high coefficient of determination and correlation when regressed to Modified Dry Eye Severity Score (R = 0.727, P < 0.001). Using a cutoff point of 316 mOsmol/L, there was significant correlation between DAS28-ESR values and tear film osmolarity (P = 0.016). Spearman correlation coefficients between osmolarity and CRP or RF were not significant (CRP: r = -0.104, P = 0.353; RF: r = 0.138, P = 0.226).
  
  
  CONCLUSIONS
  Tear film osmolarity highly correlates with a modified dry eye severity scale in patients with RA with previously unknown DED. Tear film hyperosmolarity >316 mOsmol/L is correlated significantly with a commonly used DAS of RA (DAS28-ESR) but not with serum markers such as CRP and RF. Patients with RA with a high DAS28-ESR score show higher prevalence of tear film hyperosmolarity.
authors.affiliation: *Department of Ophthalmology, University Hospital, Bochum, Germany; †Department of Ophthalmology, University Hospital, Wuerzburg, Germany; ‡Department of Rheumatology and Clinical Immunology, Department of Internal Medicine II, Wuerzburg, Germany; and §Department of Ophthalmology, University Hospital, Duesseldorf, Germany.
authors.forename: Marc
authors.initials: M
authors.lastname: Schargus
authors.forename: Franziska
authors.initials: F
authors.lastname: Wolf
authors.forename: Hans-Peter
authors.initials: HP
authors.lastname: Tony
authors.forename: Tobias
authors.initials: T
authors.lastname: Meyer-Ter-Vehn
authors.forename: Gerd
authors.initials: G
authors.lastname: Geerling
mesh_terms: D000368:Aged; D001172:Arthritis, Rheumatoid / Q000175:diagnosis*; D015415:Biomarkers / Q000097:blood; D001799:Blood Sedimentation; D002097:C-Reactive Protein / Q000378:metabolism; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D015352:Dry Eye Syndromes / Q000175:diagnosis*; D005260:Female; D015590:Fluorophotometry; D006801:Humans; D008297:Male; D008875:Middle Aged; D009994:Osmolar Concentration; D015203:Reproducibility of Results; D013194:Staining and Labeling / Q000379:methods; D011795:Surveys and Questionnaires; D013666:Tears / Q000737:chemistry*
chemical_list: D015415:Biomarkers; D002097:C-Reactive Protein