Tear osmolarity in Sjögren syndrome

The Schirmer test is one of the 2 ocular surface tests included in the current classification criteria for Sjögren syndrome (SS). Tear osmolarity may also be a useful test for the diagnosis of dry eye disease. The purpose of this study was to examine the relationship between tear osmolarity, the Schirmer test I, and dry eye symptoms in SS.

Patients with a diagnosis of SS were assessed for tear osmolarity with the TearLab Osmolarity System, tear production with Schirmer testing, symptoms with the Ocular Surface Disease Index (OSDI), and discomfort associated with each test.

Forty-nine patients with a mean age of 53.7 years and a female (92%) predominance were enrolled. The majority of patients (86%) were receiving systemic therapy for severe SS. Higher tear osmolarity was moderately associated with lower scores on the Schirmer test I (ρ = -0.39, P < 0.01) and OSDI (ρ = -0.45, P < 0.01). Schirmer test I results and lower OSDI scores were not correlated significantly (ρ = 0.20, P = 0.17). Tear osmolarity testing was significantly less painful than Schirmer testing (P < 0.01).

Signs and symptoms of dry eye in SS patients were not strongly correlated. An unexpected finding was that higher tear osmolarity was associated with lower symptom severity. Tear osmolarity testing in the clinical setting was feasible and was associated with significantly less discomfort than Schirmer testing in patients with severe SS.