Tear film breakup time (TBUT) at baseline and at days 7 and 30 after surgery. (A) All patients undergoing cataract surgery. (B) Subgroup of patients with dry eye before cataract surgery. (C) Subgroup of patients without dry eye before cataract surgery. *P ≤ 0.0475; **P ≤ 0.0168 compared with control group; error bars represent standard error mean.