The role of neopterin in rheumatoid arthritis-related dry eye

Purpose To compare the relationship between serum and tear neopterin levels of patients diagnosed with rheumatoid arthritis-related dry eye syndrome and evaluate correlation of measured parameters with rheumatoid arthritis activity and dry eye syndrome severity. Method In this cross-sectional study, serum and tear levels of neopterin were measured in 57 patients with rheumatoid arthritis and 31 healthy individuals. Participants were divided three groups diagnosed with RA without dry eye (Group 1), or RA having dry eye (Group 2), and healthy controls. OSDI, tear osmolarity, Schirmer I test, and TBUT were evaluated for dry eye. Serum and tear neopterin levels were measured and compared between all groups and healthy controls. Results Significant difference was observed in serum and tear neopterin levels between control and patients, no significant difference was detected between group1 and 2. Comparison of dry eye parameters between groups revealed that Schirmer's I test and TBUT scores were significantly higher, and tear osmolarity and OSDI scores were significantly lower in the control group compared to groups 1,2 (p < 0.001). Statistically low significant correlation was found between tear and serum neopterin levels for all participants (p = 0.003, R S = 0,316). No significant correlation was found between other parameters of dry eye, RA activity and neopterin level. Conclusions The findings of this study indicate that cellular immune activation may not be the only mechanism underlying non-Sjögren's RA-related dry eye. Tear neopterin can be used to indicate the presence of ocular surface disease caused by RA, supporting the presence of extra-articular manifestations.