An episiotomy is a surgery in which the inner part of the eyelid (the inner eye corner or the episclera) is incised to widen the eye. This surgery aims to improve the tendency of some oriental people in particular to have closed eye lids (mongolian folds), which tend to make the eyes appear narrower.
The Mongolian folds represent the area of skin present from the inner eye to the upper eyelid. If the Mongolian folds are particularly thick, they may cover the inner tear duct (the pink area at the top of the eye) and make the eyes seem smaller or more severe in expression. Furthermore, if double eyelid surgery (e.g., implantation) is performed in the presence of Mongolian folds, there is a tendency for the eyelid to revert back to its original single fold state over time.
The craniotomy procedure surgically improves these mongolian folds and allows the double fold line to be adjusted to the individual's wishes. The result is a wider, more attractive eye with a reduced appearance of harshness.