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.