Data extraction
Data were extracted using pre-defined data fields from each study by two investigators independently. If there were inconsistencies between two investigators, a third reviewer would extract results and engage in discussion until a consensus was reached. VA reported as log MAR VA were extracted as the primary outcome. Second outcomes including glaucoma, strabismus, nystagmus and VAO were extracted. The results of postoperative visual performance at last visit were extracted from studies with multiple postoperative follow-up data. As for the retrospective studies, age-matched outcome would be extracted if reported. Continuous data reported as mean ± SD were extracted directly. Those data reported as median and interquartile ranges would be converted into mean and SD based on the formula25.