To investigate the relationships between tear osmolarity and various parameters for ocular and systemic disease in primary Sjögren's syndrome.

The medical records of 53 patients with primary Sjögren's syndrome were reviewed. Tear osmolarity using a TearLab® (TearLab™ Corp., San Diego, CA, USA) osmometer as well as other dry eye parameters such as tear break-up time, ocular staining score (Sjögren's International Collaboration Clinical Alliance [SICCA] ocular staining score, SICCA score), Schirmer-I score, symptoms with Ocular Surface Disease Index (OSDI), and Visual Analog Scale (VAS) were obtained. Systemic laboratory data and medication history were also collected. The correlations between the parameters were analyzed using the Spearman's rank correlation test.

53 patients with a mean age of 54.1 ± 13.2 years and female predominance (96.23%) were enrolled. The majority of patients (28.3%) were receiving systemic therapy for severe Sjögren's syndrome. The tear osmolarity in Sjögren's syndrome patients was 307 ± 13.6 (mOsm/L). Higher tear osmolarity was associated with lower tear film break-up time (BUT) scores and with higher SICCA scores. Tear osmolarity and the Schirmer test results were not significantly related. Higher tear osmolarity was paradoxically associated with lower VAS scores and lower OSDI scores. Neither current medication nor the salivary gland focus score showed significant associations with tear osmolarity. Although tear osmolarity was not associated with the SSA-Ro or SSA-LA titer, serum immunoglobulin G (IgG) level and serum erythrocyte sedimentation rate (ESR) level showed positive correlations with tear osmolarity.

Tear osmolarity is positively correlated with the severity of dry eye and was associated with lower symptom severity. The significant associations of tear osmolarity with IgG and ESR suggest that high tear osmolarity may be correlated with autoantibody load and the systemic inflammatory state.