Eyelid Crease Functionality
Eyes with natural double eyelids (i.e., congenital supratarsal folds) have relatively thin and highly elastic skin. When the eyes are closed, the natural folds exhibit a very subtle, extremely thin line at which a fold forms when the eyes open. The dynamics of a fold formation involve a crease that becomes more defined as the eyes open, and fainter as the eyes close. This is what is known as a “dynamic” fold. A surgically created fold should mimic this feature. Unfortunately, in some surgical cases, a conspicuous indentation results at the fold even with the eyes closed. This is the most common indication that a fold has been surgically produced. Poorly executed surgeries typically result in a “static” fold, a noticeable fold that remains whether the eyes are closed or open.
In the natural fold, the eyelid skin connects to the underlying eye-elevating levator muscle via a bridge-like extension of the levator aponeurosis. This indirect connection enables the dynamic fold to take place. To properly emulate this key feature, the surgeon must utilize a loop suture technique or mobilize local tissue in order that the eye elevating component (levator aponeurosis) does not directly connect to the skin. These two mechanisms (suture technique and vector calibrated open technique respectively) allow the eyelid muscle to pull on the loops or the mobilized local tissue and not the skin itself, producing a fold that most resembles a natural fold.