Canthoplasty or Lateral Canthopexy for Young People?

Great question.
These are highly specialized procedures used for or as part of very specialized reconstructive and aesthetic reconstructive surgery. Unless there is a history of prior surgery, trauma, or congential eyelid abnormality, it is highly improbable that it would make no sense for you to go into someone's office and ask for this surgery. The truly scary thing is that someone might just acceede to your request. Some of the most difficult reconstructive surgeries I have done have been trying to restore the preoperative appearence of relatively young people who for what ever reason had "cosmetic" canthal surgery. Some surgical changes are flat out irreversible. If you are not truely body dysmorphic now, a surgery like this will definitely push you over the edge.

Canthopexy and canthoplasty are performed on young or old people, it just depends on what the presenting issues are. When the procedures are done, they make the eye more almond shaped and raise up the outer corner of the lower eyelid.

Answer: Barring any unusual circumstances for routine lower eyelid blepharoplasty, a canthoplasty is generally unnecessary. When a skin muscle flap is employed for a lower eyelid blepharoplasty, a lateral canthopexy may be utilized to secure the lower lid margin and prevent retraction or rounding of the lower lid margin. If a very young person presents with lower lid fat herniation with no skin redundancy, a transconjunctival blepharoplasty is usually indicated. In a middle aged person with skin redundancy, I prefer the use of a skin muscle flap. In most cases, I do perform a lateral canthopexy to secure the lid margin. One must be careful, however, in performing a lateral canthopexy to avoid lymphatic obstruction leading to chemosis (swelling of the conjunctiva).

I do not routinely perform canthopexy or canthoplasty in young patients. These patients usually have good lower eyelid tone that does not warrant doing these procedures.

WHY would a young person need EITHER one?
These operations are usually used to tighten the corner of the eye either when there is lid laxity OR when a downward lower lid pull is anticipated with lid laxity. I cannot find a reason why this operation would be done in a young person and certainly NOT for self-esteem since they are associated with increasing lateral eye slant.
More information is needed.

It would be rare to perform canthal tightening in a young person.  The problem with a canthopexy is that it will elevate the lateral corner of the eye and make you look either asian or at least "different" from your normal identity.