Tear film thickness after treatment with artificial tears in patients with moderate dry eye disease

Purpose: This study was designed to investigate the effect of a single-drop instillation of different lacrimal substitutes on tear film thickness (TFT) assessed with optical coherence tomography in patients with mild to moderate dry eye disease. Methods: The study was performed in a randomized, doublemasked, controlled parallel group design. Patients received a single dose of either unpreserved trehalose 30 mg/mL and sodium hyaluronate 1.5 mg/mL (TH-SH, Thealoz Duo), unpreserved sodium hyaluronate, 0.15% (HA, Hyabak) or sodium chloride, 0.9% (NaCl, Hydrabak) eye drops. Sixty patients finished the study according to the protocol. TFT was measured with a custom-built ultrahighresolution Fourier domain optical coherence tomography system providing a resolution of 1.2 mm. Results: The mean TFT before treatment was 2.5 6 0.4 mm. Ten minutes after instillation, TFT significantly increased in the THSH group from 2.4 6 0.4 to 3.1 6 0.9 mm (P , 0.01) and in the HA group from 2.4 6 0.3 to 2.9 6 0.5 mm (P , 0.01), whereas no significant change was observed in the NaCl group (from 2.6 6 0.4 to 2.7 6 0.4 mm, P = 0.76). The increase in TFT remained statistically significant up to 240 minutes after administration of THSH. In contrast, the increase in TFT after administration of HA was only statistically significant at 10, 20, and 40 minutes after drop instillation. Conclusions: The findings of this study indicate that single instillation of TH-SH and HA eye drops increases TFT in patients with dry eye disease. The data also indicate longer corneal residence of the TH-containing eye drops. The effect of multiple instillation and long-term use of artificial tears on TFT warrants further investigation.