"Mongolian" comes from word "Mongoloid," an anthropological term used to denote one of the well-known but now discredited ethnological divisions of the Asiatic people. Mongolia today is a country landlocked between north-central China and southern Russia.
While politically-incorrect, the term "Mongolian slant" is mentioned here because that is what the steeper upward course of the Asian lower lid is called in Asia where surgery to lessen it was devised and is mainly practiced.
Many Asian lower eyelids follow a relatively straight course across the eye and then rise upward before joining with the upper eyelid at the outer corner of the eye.
Mongolian slant modification is designed to lessen this upward rise at the corner and make the eyes look bigger.
The procedure entails detaching part of the canthal tendon that achors the lid to the bone. It is performed from within an incision made through the back lining of the eyelid (conjunctiva) and so no visible scar is created on the skin. Dissolving sutures are used.
For the effect to be noticeable, the upward course of the lid needs to be moderate to extreme.
The procedure usually requires simultaneous performance of lateral canthoplasty.