['To investigate prospectively the effect of diclofenac sodium (DfNa) eye drops on corneal epithelial structure and function.', 'Seventeen patients with bilateral age-related cataract undergoing phacoemulsification combined with intraocular lens implantation were studied prospectively. After the surgery on both eyes, one eye each of these patients was assigned randomly to receive 0.1% DfNa eye drops three time daily (DfNa group), and the other eye served as control (control group). Vital stainings, tear function test, corneal sensitivity measurement, specular microscopy for corneal epithelium and endothelium, pachymetry, anterior fluorometry to measure epithelial barrier function, and laser flare-cell-metry were performed before and after surgery.', 'There were no statistically significant differences between the DfNa and control groups in any measurement examined except for laser cell-flare-metry, in which the DfNa group demonstrated a significantly lower flare value at day 7 postoperatively (compare with the preoperative level of 73% +/- 41% in the DfNa group, and 130% +/- 98% in the control group, P=0.035). Epithelial cells in the DfNa group showed slight elongation and increased permeability postoperatively; however, there were no statistically significant differences with the control group.'] Does effects of diclofenac eye drop on corneal epithelial structure and function after small-incision cataract surgery?