Hello! What you are describing is called scleral show and you are correct about the terminology canthal tilt. Typically, excess scleral show on the lower outer aspect of the eyes is caused by too much lower eyelid laxity (as with aging), a lower eyelid that is too tight (usually due to over-resection of lower eyelid skin during a lower eyelid lift procedure, i.e. a blepharoplasty), or simply due to genetics/development. To correct this, a small procedure called a canthoplasty can be performed. It is a relatively minor procedure and can sometimes be performed in the office. I would recommend seeing an oculoplastic surgeon for this as their expertise is in eyelids. Hope that helps and wish you all the best!