Abstract: Objective To study the effect of distilled water and dextran and hypromellose eye drops on corneal epitheliuem in ultrasound biomicroscopy. Methods Sixty-three patients admitted to our hospital for ultrasound biomicroscopy from January to April 2012 were randomly divided into distilled water group(n=30, 46 eyes) and dextran and hypromellose eye drop group(n=33, 37 eyes). Distilled water was used as an ultrasound agent in patients of distilled water group, and dextran and hypromellose eye drops were used as an ultrasound agent in patients of dextran and hypromellose eye drop group. Corneal tissue was stained with fluorescein and scored at 10 min and 24 h after ultrasound biomicroscopy. Corneal epithelium defect was assessed. Results The scores of corneal tissue fluorescein staining were significantly lower in dextran and hypromellose eye drop group than in distilled water group at 10 min after ultrasound biomicroscopy(P< 0.05). No significant difference was observed in corneal tissue fluorescein staining between the two groups at 24 h after ultrasound biomicroscopy(P> 0.05) although it was improved. Conclusion Ultrasound biomicroscopy is risky to cause corneal epithelium injury. As an ultrasound agent, dextran and hypromellose eye drops can protect corneal epithelium against injury and alleviate uncomfortable symptoms after ultrasound biomicroscopy.