Preliminary Study In Antibacterial Effect On Conjunctival Sac And Influence On Corneal Epithelium Of 5% Povidone-iodine Before Cataract Extraction

Postoperative infectious endophthalmitis is a rare but severe postoperative complication after cataract extraction surgery.Once happened,it would cause serious damage to patients'vision.It is very important to study and make effort to prevent postoperative infectious endophthalmitis.Previous studies have demonstrated the primary pathogens causing postoperative infectious endophthalmitis were the bacteria and fungus existing in the conjunctival sac and eyelid.The pathogens enter the anterior chamber and vitreous humor through the surgery incision during and after the surgery.They could reproduce very fast in the vitreous humor in a short time,which damage the surgery eye severely.Previous investigators have found an effective approach to prevent the happening of postoperative infectious endophthalmitis—-reducing the amount of pathogens in the conjunctival sac during the perioperative period.The surgeons have made effort to decrease the occurrence rate of postoperative infectious endophthalmitis through preventing methods.Making conjunctival sac flushing using povidone-iodine has been demonstrated an effective method to decrease the bacteria of ocular surface and the occurrence rate of endophthalmitis.It has become a conventional process and been written in many clinical guidelines.There were not enough guidelines or evidences of evidence-based medicine about the dosing and exposure time of povidone-iodine nowadays.The side effect and irritation of povidone-iodine are related to the dosing and exposure time.Thus,to choose an appropriate dosing and exposure time is very important,which could get a better disinfection effect and less side effect.Objective To investigate the efficacy and adverse reactions of 5%povidone-iodine in removing bacteria from conjunctival sac at different contact time.Methods Randomized controlled studies were used.420 patients underwent cataract surgery in our hospital from December 2017 to June 2018 were selected.Non-surgical eyes(420 eyes)were selected as the study subjects and divided into 4 groups randomly:30s group,1min group,2min group and 3.5min group.On the day of surgery,domestic 5%povidone iodine was used to flush the conjunctival sac for 30s,1min,2min and 3.5min,respectively.The conjunctival sac specimens were collected for bacterial culture and bacterial identification before and after flushing the conjunctival sac with povidone-iodine.The positive rate of bacterial culture and bacterial growth in each group were compared.The patients'ocular surface was observed and the incidence of corneal epithelial injury was recorded at 1hour and 1day after surgery.The positive rates of bacterial culture and corneal epithelial injury in each group were compared by Pearson chi-square test.Results After excluding 20 patients with suspected specimens contamination,400patients(400 non-surgical eyes)were enrolled,including 191 males and 209 females,with an average age of 66.8 years.Before flushing the conjunctival sac,the positive rates of bacterial culture in 30s group,1min group,2min group and 3.5min group were 44.8%(43/96),43.3%(39/90),43.1%(47/109)and 43.8%(46/105),respectively,with no statistically significant difference(X~2=0.066,P=0.996).After flushing,the positive rates of conjunctival sac bacteria culture in the 4 groups were 29.2%(28/96),31.1%(28/90),13.8%(15/109)and13.3%(14/105),respectively.The differences between 30s group and 2.0min group(X~2=7.308,P=0.007),1.0min group and 2.0min group(X~2=8.760,P=0.003),30s group and 3.5min group(X~2=7.606,P=0.006),1.0min group and 3.5min group(X~2=9.063,P=0.003)were statistically significant,respectively.At 1 hour after surgery,there were cases of mild corneal epithelial injury in each group:the rates of each group were 16.7%(16/96),18.9%(17/90),20.2%(22/109)and 34.3%(36/105),respectively,The differences between 30s group and3.5min group(X~2=8.118,P=0.004),1.0min group and 3.5min group(X~2=5.804,P=0.016),2.0min group and 3.5min group(X~2=5.383,P=0.020)were statistically significant,respectively.At 1 day after surgery,there was no new injury occurred,the incidence of mild corneal injury in each group was 3.1%(3/96),5.6%(5/90),9.2%(10/109),and 15.2%(16/105),respectively.The statistically significant differences among the 4 groups were 30s group and3.5min group(X~2=8.597,P=0.003),1.0min group and 3.5min group(X~2=4.728,P=0.030).The corneal epithelial injury healed completely at the review 1 week after surgery.Conclusion The preoperative bacterial load of conjunctival sac was more effectively reduced in the 2min and 3.5min groups than in the 30s and 1min groups,and the 2min group is superior to the 3.5min group in the occurrence of corneal epithelial injury at 1 hour after surgery.The conjunctival sac irrigated with 5%povidone iodine for 2min was effective and safe,which can be an alternative measure.