Inner and outer canthoplasty are procedures designed to adjust the horizontal width of the eye or the area of the eye that is exposed. An epicanthoplasty involves adjusting the epicanthal fold (medial canthal skin fold)—a skin fold at the inner corner of the eye commonly found in people of Asian descent—to expose the inner corner of the eye. Surgery to address this is performed to extend the inner corner of the eye toward the nose, making the eyes appear larger. Outer canthoplasty is a procedure that adjusts the outer part of the eye to change its horizontal width or overall appearance. Since these incisions are made at the inner and outer corners of the eye, it is important to consider factors such as scarring, the tendency for the eyes to revert to their original shape, and the possibility of asymmetry between the left and right sides. Indications vary depending on the original distance between the eyes, the degree of the epicanthal fold, and facial balance; excessive widening can result in an unnatural appearance, so careful judgment is required. Results and scar healing vary significantly from person to person. This information is for informational purposes only and does not constitute a diagnosis. Please consult a specialist before undergoing any procedure.
[Source] https://my.clevelandclinic.org/health/symptoms/22413-monolid-eyes