What are the big double eyelid shapes in double eyelid surgery alone? However, for this type of eyes, if the outer side (lateral canthus surgery) or the inner side (medial canthus surgery) of the eyes are cut in parallel, the actual length of the eyes will become longer, the eyebrows will become narrower, and the eyes will look straighter and bigger. The operation of inner canthus or outer canthus does not have to be parallel to the double eyelids, but many people do it for better results. The double eyelid shape of the outer canthus is less than that of the inner canthus, so Xi 'an's Zhang Yong inner canthus is more recommended.