Investigation of tear osmolarity in early rheumatoid arthritis: relation to disease activity

Abstract Objective To investigate the frequency of dry eye (DE) by measuring tear osmolarity (TO) with the recently introduced TearLab system (TearLab Corp, San Diego, Calif.) in patients with early rheumatoid arthritis (ERA) and the relationship between the severity of DE and ERA disease activity. Design Prospective study Participants Sixty-four eyes of 64 newly diagnosed and untreated patients with ERA were enrolled in this study. Methods TO measurements, tear break-up time (TBUT), and Schirmer tests were performed. ERA disease activity was evaluated according to the disease activity score 28 (DAS28). The patients were divided into 3 groups according to DAS28 scores as follows: mild (DAS28 ≤ 3.2), moderate (3.2 < DAS28 ≤ 5.1), and severe (DAS28 > 5.1). Results DE was identified in 46 (71.8%) patients with ERA according to the TO values. There were significant differences among these groups concerning TO ( p = 0.001) and TBUT ( p = 0.005) scores, whereas there was no significant difference between these groups regarding Schirmer scores ( p = 0.200). In addition, DAS28 values were positively correlated with TO values ( r = 0.710, p < 0.001), negatively correlated with Schirmer scores, ( r = –0.251, p = 0.045), and negatively correlated with TBUT scores ( r = –0.335, p = 0.007) among all patients. Conclusions Our study demonstrated a relationship between the ERA disease activity and severity of DE by using TO measurements with the TearLab system. Therefore, TO measurement could be added to other classical DE tests for diagnosing DE and for assessing the degree of disease activity of ERA.