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, double-masked, 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 ultrahigh-resolution Fourier domain optical coherence tomography system providing a resolution of 1.2 mu m. Results: The mean TFT before treatment was 2.5 +/- 0.4 mu m. Ten minutes after instillation, TFT significantly increased in the TH-SH group from 2.4 +/- 0.4 to 3.1 +/- 0.9 mu m (P < 0.01) and in the HA group from 2.4 +/- 0.3 to 2.9 +/- 0.5 mu m (P < 0.01), whereas no significant change was observed in the NaCl group (from 2.6 +/- 0.4 to 2.7 +/- 0.4 mu m, P = 0.76). The increase in TFT remained statistically significant up to 240 minutes after administration of TH-SH. 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.