AIM: To compare the efficacy of povidone iodine with different concentration and exposure time in preparation for cataract surgery. The effect of PI on reducing the conjunctival bacterial load before cataract surgery was observed. The effect of PI on the ocular surface was also valued. In order to provide a theoretical support for clinical standardization of PI, the optimum concentration and irrigation time of PI were screened.

METHODS: From June 2015 to June 2017 cataract surgery was performed in 270 cases 270 eyes. According to the concentration(0.5%, 0.1%, 0.05%)of the PI the patients were randomly divided into three groups(A, B, C,). Group A was randomly divided into three subgroups(A1, A2, A3)respectively according to different irrigation time: 30s, 1min and 2min. group B and group C were divided to subgroups similar to group A. In all groups, the conjunctiva was flush irrigate with 3ML of PI of the respective concentration. Conjunctival specimens were obtained before PI irrigation and after PI irrigation. The change of conjunctival sac bacterial flora and bacterial culture positive rate were studied. Tear break up time(BUT), cornea fluorescein staining(CFS)were evaluated 3d preoperative and 1d, 3d, 1wk, 1mo, 3mo postoperative.

RESULTS:(1)The change of conjunctival sac bacterial flora. A total of 12 species of conjunctival sac bacteria were cultured before PI irrigation including 9 Gram positive bacteria and 3 Gram negative bacteria. A total of 4 species of conjunctival sac bacteria were cultured after PI irrigation including 2 Gram positive bacteria and 2 Gram negative bacteria.(2)Comparison of the positive rate of bacterial culture in conjunctival sac. Positive conjunctival sac culture for 15 eyes before PI irrigation, 5 eyes show positive after washing, the amount of positive bacteria culture was lower(P<0.05).(3)No endophthalmitis was found in all patients at the last follow-up. The BUT in all groups except the groups of 0.5g/L, 30s and 5g/L, 2min were restored to preoperative level at 3mo after surgery, The BUT in group 0.5g/L, 30s was restored to preoperative level 1mo after surgery, while the BUT in groups 5g/L, 2min, was still not restored to preoperative level 3mo after surgery. The CFS in all groups recovered to preoperative level at 1mo after surgery.

CONCLUSION: 0.5g/L PI with 30s irrigation time may effectively reduce the conjunctival sac bacteria. Compared with other groups, its damage to the eye surface is smaller. It is safe and effective in preparation for cataract surgery.