Tear Evaporation Rates in Sjögren Syndrome and non-Sjögren Dry Eye Patients

Purpose: To reinvestigate tear evaporation rates in Sjögren syndrome (SS) and non-Sjögren (non-SS) dry eye patients with a recently reported ventilated chamber evaporimeter system. Design: Prospective case-control study. Methods: A ventilated chamber evaporimeter system was used to measure tear evaporation rates. A DR-1 camera (Kowa, Nagoya, Japan) was used for tear lipid layer interference image acquisition. The Yokoi severity grading system was used for DR-1 image evaluation. Twenty-four aqueous tear deficiency (ATD) eyes of 21 consecutive patients with SS were studied (SS ATD group). Twenty-one ATD eyes of 12 non-SS patients (non-SS ATD group) were examined as control subjects. Results: Tear evaporation rates of the SS ATD group (5.9 ± 3.5 [10^-7 g/cm² per second]) were significantly higher than those of the non-SS ATD group (2.9 ± 1.8 [10^-7 g/cm² per second]; P = .0009). The severity grading of DR-1 tear interference images of the SS ATD group was significantly higher (P = .03), along with significantly worse meibomian gland expressibility and vital staining scores, compared with those of the non-SS ATD group. Conclusions: Tear evaporation rates were higher in eyes of the SS ATD group compared with the non-SS ATD group. Tear evaporation assessed in conjunction with tear lipid layer findings and meibomian gland expressibility provides an increased understanding in the differential diagnosis of dry eye states.