Objective To observe the incidence of visual axis opacification after pediatric intraocular lens surgery with two different vitrectomy instruments.Methods In a retrospective case series study,the records of children less than 8 years of age who underwent intraocular lens surgery for congenital and developmental cataract in Shandong Eye Institute were retrospectively reviewed.Posterior capsulotomy and anterior vitrectomy were performed with 18-gauge coaxial vitrectomy instruments between June 2003 and June 2006,while pars plana sutureless 25-gauge instruments were used between July 2006 and June 2008.A Chi-square test was used to compare the two methods for the occurrence of visual axis opacification.Results Ninteen children with bilateral cataract and 16 with unilateral cataract underwent posterior capsulotomy and anterior vitrectomy with 18-G coaxial vitrectomy instruments,while 19 children with bilateral cataracts and 12 with unilateral cataract underwent surgery with 25-G vitrectomy instruments.The occurrence of postoperative visual axis opacification was 15％(8/54) and 2％(1/50),respectively.There was a statistically significant difference between the two methods (x2=5.393,P＜0.05).With 18-G vitrectomy instruments,3 eyes had intraocular lenses implanted in the sulcus during surgery and 14 eyes developed iris synechia postoperatively.On the contrary,with 25-G instruments all eyes had well-centered intraocular lenses in the capsule bag and mild iris synechia formation was only observed in 2 eyes.Conclusion Compared to 18-G vitrectomy instruments,posterior capsulotomy and anterior vitrectomy with 25-G instruments decreased the incidence of postoperative visual axis opacification during initial intraocular lens surgery.In addition,modified pars plana sutureless 25-G vitrectomy systems appeared to be safer and more effective.