Background: We examined the effect of surgical repair on the pattern of refractive errors in Korean patients with congenital blepharoptosis. Methods: We reviewed the clinical records of 54 patients with congenital blepharoptosis who attended our hospital from 2006 to 2012 and underwent a detailed refractive examination before and after ptosis repair surgery. Among them, 21 of the patients whose refractive data was available for both before and after the surgery were included in order to observe the effect of ptosis repair surgery on refractive error characteristics. The astigmatism groups were divided into three subgroups: with-the-rule (WTR), against-the-rule (ATR), and oblique astigmatism (OA). We also evaluated the severity of astigmatism. Results: Before surgery, the ptotic eyes had more severe astigmatism and a greater percentage of OA than the fellow eyes. The changes in astigmatism magnitude before and after surgery were not significant, but the proportion of subjects with OA increased significantly. In ptotic eyes, amblyopia was found in 14 eyes (20.9 %). 3 eyes (4.5 %) were from solely occlusive visual stimulus deprivation due to severe ptosis, and 11 eyes were from refractive errors. Among refractive errors, amblyogenic astigmatism made up to the largest proportion of patients (8 patients, 11.9 %). Conclusions: Ptotic eyes had more severe astigmatism and more OA than fellow eyes. Amblyogenic astigmatism was more common in ptotic eyes. A change in astigmatism toward the OA axis was significantly detected after surgery, and that can be possible amblyogenic cause. Therefore, the correction of astigmatism before and after ptosis repair surgery is very important to prevent amblyopia.