Several external incisions of the lower eyelid to gain access to the infraorbital rim and orbital floor have been described. The major difference between them is the level at which the incision is placed in the skin of the eyelid and the level at which the muscle is thansected to expose the orbital septum/periosteum. Each incision has advantages and disadvantages. The approach shown here, however, is a standard approach that encompasses all of the techniques used in the others. It is most commonly called subciliary incision, but is also known as infraciliary or blefharoplasty incision. This incision is merely a lower lid incision at a higher level that in the lower lid incision, made just below the eyelashes. The main advantage of this incision is the imperceptible scar that it creates. Further, it can be extended laterally for additional exposure of the entire lateral orbital rim.
Once the skin is incised, the surgeon has three options. The first is to dissect between the skin and the muscle until the orbital rim is reached, at which point another incision through muscle and periosteum is made to the bone. The second option is to incise through muscle at the same level as the skin incision and dissect down just anterior to the orbital septum to the orbital rim. The third option is a combination of these in which subcutaneous dissection toward the rim proceeds for a few millimeters followed by incision through the muscle at a lower level, producing a step-incision, then following the orbital septum to the rim.
Although all three options are advocated by several surgeons, each has advantages and disadvantages. The first option, in which a subcutaneous dissection to the level of the infraorbital rim is made, leaves an extremely thin skin flap. This flap is technically difficult to elevate, and accidental "buttonhole" dehiscence can occur. A further problem that may occasionally be seen is a slight darkening of the skin in this area after healing. Presumably, the skin flap becomes avascular and essentially acts as a skin graft. An increase in the incidence of ectropion has also been noted by some investigators with this approach. Entropion and lash problems have occasionally been experienced after this "skin only" flap.
The second option, in which the dissection is made between muscle and orbital septum, is technically less difficult. Care must be taken, however, because the thin orbital septum can be easily violated, causing periorbital fat to herniate into the wound. In practice, this is more a nuisance than a problem. The skin and muscle flap, however, presumably maintains a better blood supply to the skin, and pigmentation of the lower lid has not been seen.
The third technique, in which a layered dissection is used, avoids the disadvantages of the others. The main advantage of the "stepped" incision through skin and muscle is that the pretarsal fibers of the orbicularis oculi can be kept attached to the tarsal plate, presumably assisting in maintaninig the position of the eyelid and its contact with the globe postoperatively.
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