The epicanthal fold, less commonly called the Mongoloid fold, is a distinctively Asian facial feature present in, essentially, all people of east and southeast Asian inheritance. While occasionally seen in other populations outside of Asia, its presence there is more often considered an anomaly rather than a normal anatomic feature.

Epicanthoplasty, sometimes called medial canthoplasty, is an operation designed to remove or minimize the epicanthal fold. There are well over fifty methods that have been described and at least ten or twenty still in common use, which indicates that there are limitations in all and that the "ideal" procedure has yet to be developed.

Most patients undergoing double eyelid surgery do not require epicanthoplasty. If the epicanthal fold is small or even moderate in size, retaining it helps to preserve ethnic identity and make the newly creased lids appear more harmonious with the rest of the facial features.

If, however, the epicanthal fold in unusually well-developed, it can cover so much of the inner corner of the eye that the eye may appear too short horizontally, cross-eyed in certain positions of gaze, and too widely spaced. In such patients, epicanthoplasty can lengthen the horizontal eyelid opening to make the eye look bigger and more alert.

Some patients with even small epicanthal folds may still request epicanthoplasty if seeking more aggressive "Westernization."

As noted above, epicanthoplasty remains a problematic operation, in part because its anatomic cause is not well understood.

The procedure requires making multiple incisions in some of the most delicate and visible skin on the face, creating a network of tiny skin flaps, and sometimes removing skin, steps which create scarring in the highly exposed skin between the eye and nose.

While makeup may help to camouflage the scarring as it fades over several years, not all patients feel comfortable with the end result.

While surgeons continue to explore techniques to minimize these limitations, less invasive techniques are usually less successful.

The operation is offered much more frequently in Asia than in the United States.