AIM: To evaluate factors associated with the development of strabismus after cataract extraction and primary intraocular lens implantation.METHODS: The medical records of 122 patients, aged 1.5mo to 9y, who had undergone cataract extraction with primary intraocular lens implantation between January 1993 and August 2011 were reviewed. Fourteen patients (17 eyes) with strabismus before cataract surgery were excluded. Patients were divided into those with congenital bilateral cataracts (64 patients, 128 eyes) and those with unilateral cataracts (44 patients, 44 eyes). The associations between the development of strabismus and age at cataract surgery, pre- and post-cataract extraction corrected distance visual acuity (CDVA), interocular CDVA difference, nystagmus, surgical method, and secondary cataract were evaluated.RESULTS: Factors significantly associated with the development of strabismus included age at cataract surgery (≤1y), preoperative mean CDVA ≤20/100, presence of nystagmus in the bilateral cataract group and postoperative interocular CDVA difference ＞20/70 in the unilateral group. Postoperative CDVA ≤20/100 and preservation of posterior capsule, and presence of secondary cataract were significant factors in both groups.CONCLUSION: Children with congenital cataracts should be monitored carefully after cataract surgery for the development of strabismus, especially when they underwent surgery at age ≤1y, and they have nystagmus, large postoperative interocular CDVA difference, poor preoperative and postoperative CDVA, preservation of the posterior capsule, or secondary cataract.