GENERAL PRINCIPLES

The goal of eyelid reconstruction is to repair a defect in such a way that the globe will be protected, the eyelids will not obstruct vision, and the appearance will be as normal as possible. Plastic surgery in most areas of the body involves skin rearrangement, as well as that of associated structures. The associated structures in the eyelid area include the conjunctiva, the eyelashes, the brow, and the lacrimal system.

In general, a malignancy should be removed completely without regard to reconstruction. The reconstructive procedure would then be devised after the tumor is completely removed. However, in some cases a complete removal of the tumor might result in a situation in which the eyelids cannot be reconstructed. Therefore, the globe would not be protected. In this instance, the surgeon should realize that complete removal of the tumor would necessitate loss of the eye. Sometimes the eye must be sacrificed, with the potential of saving a life, in order to completely eradicate the tumor. However, this situation should be recognized prior to surgical removal of the tumor so that other avenues of treatment can be considered.

Since the first edition of this book, newer technology has emerged for tissue dissection. Laser surgery for soft tissue dissection has become popular because it allows hemostasis while dissection is occurring. The author has found that radiosurgery gives the best combination of precision cutting with good hemostasis and, therefore, uses this modality as the primary technique for tissue dissection. It allows tumor removal with so little heat damage to cells that accurate frozen section analysis of tumor margins is possible. The author uses the Ellman Surgitron Dual Frequency (177) and all references of settings will be to that model.

Radiosurgery is the passage of high frequency radio waves through tissue for the purpose of dissection. By using the appropriate waveform and wave frequency, the surgeon can create skin incisions and deep tissue dissection with little destruction of the surrounding structures. Excellent hemostasis during dissection is achieved by using the correct waveform and proper electrode. Minimal tissue destruction and good hemostasis result in minimal swelling and bruising with excellent wound healing.

The principle of radiosurgery is that a 4 MHz radio wave passes through tissue from an active electrode to a passive electrode. Household alternating current is electrically converted (rectified) to direct current and the oscillations are increased. The term radio wave was chosen because the 4 MHz frequency is just above the AM radio band and below FM. The resistance of the tissues causes volatilization of the cells at the tip of the electrode. This narrow path of cell destruction creates a smooth incision with minimal lateral cell damage.1

Several factors affect the amount of lateral heat generated. By changing these parameters, the amount of cutting and coagulation can be varied. Increasing the diameter of the electrode, the intensity of the power and the time the electrode is in contact with the tissues causes more lateral heat. Both the waveform and the frequency of the current affect the amount of lateral heat generated. The fully rectified filtered waveform, which is a continuous wave, causes the least amount of lateral heat. By interrupting the continuous flow to varying degrees, the amount of lateral heat can be increased. (178, 179) The lateral heat is inversely proportional to the frequency. The advantage of this very high frequency is that cutting and hemostasis can be produced with much less lateral heat and tissue destruction than other electrical instruments that use a much lower frequency.

SKIN INCISIONS

Varying the waveform and the type of electrode allows the surgeon to perform different maneuvers with facility and minimal bleeding. For skin incisions, the author uses the A-8 wire electrode (0.18 mm [0.007 in]) at a setting of 40 on the Dual Frequency Surgitron. The waveform is fully rectified, filtered, and is designated as ‘cut’ on the unit. This is the continuous wave that gives the least lateral heat. The wounds heal the same as with a scalpel.

The A-10 electrode is thinner (0.1 mm [0.004 in]) and gives even less lateral heat. It can also be used for fine skin incisions. It can be very useful for the removal of malignant lesions where microscopic evaluation of the margins is required. The setting is ‘cut’ with a power of 40. With this technique, the pathologists are unlikely to find tissue damage that might interfere with an accurate evaluation of the margins (181, 182).

SOFT TISSUE DISSECTION

Smooth cutting with hemostasis is the value of radiosurgery when dissecting tissue below the skin. To obtain the best hemostasis, the author uses the fully rectified (‘cut/coag’) or partially rectified(‘hemo’) setting. The ‘hemo’ setting gives the better hemostasis but if the tissue is too firm some hemostasis may have to be sacrificed to get better cutting. The author’s preferred electrode is the Empire Needle. This electrode is fully insulated except for the tip, which is cone shaped. Cutting is best done with the tip, but hemostasis can be obtained by touching the side of the cone to the bleeding vessel. Larger bleeding vessels can be coagulated with the bipolar forceps. The bipolar setting, which has a lower frequency of 1.7 MHz, with a power of 50–70 is used when the bipolar forceps are needed.

FLAPS

Skin elasticity increases with age, and larger defects are more easily reconstructed in the elderly than in the young. Since eyelid tissue is thin and very flexible, it will be pulled in the direction of the scar. When rotating a flap of skin in the eyelid area, the surgeon must pay attention to the direction of forces that will occur during healing. For instance, if a flap is advanced from the cheek to the lower eyelid, one can expect the postoperative forces to pull the lower eyelid inferiorly or cause an ectropion.

When suturing skin to skin or repairing the tarsal margin, the edges may be approximated exactly without being everted. However, tension should be taken off the wound edges. Otherwise, the edges will pull apart, and significant scarring can occur.

GRAFTS

If direct closure or advancement and rotation flaps are not sufficient to fill in a defect, a skin graft can be used. When using a skin graft, the best color and texture match can be obtained with a full-thickness graft from another eyelid or the retroauricular area. If eyelid skin is to be used, it will usually come from the upper eyelid where the skin is more abundant. However, in some cases, excess lower lid skin would have to be removed and could be transplanted as a full thickness skin graft. When taking skin from the upper lid, a line should be drawn in the upper lid crease, the excess skin gathered together, and a second line drawn on the other side of the excess skin. An ellipse should be formed and a thin skin flap removed. This is essentially the technique for a ‘skin only’ upper lid blepharoplasty (180).

If retroauricular skin is to be used, the amount of graft needed is outlined in the retroauricular area (183). The crease in the retroauricular area should run through the center of the graft. Local anesthetic is injected to balloon up the skin, and a skin graft is taken (184, 185).

The author uses the A-8 electrode on a ‘hemo’ or ‘cut/coag’ mode to make the skin incision (184). Once the skin incision is completed, an Empire Needle is used to remove the skin from the donor site. By using a ‘hemo’ setting on a power of 70, there will be the least amount of bleeding. However, if the tissue is too tough, a ‘cut/coag’ or ‘cut’ mode is used on a power of 40. If bleeding is brisk, the bipolar forceps are effective in achieving good hemostasis.

Since a scar is not obvious in this area, closure may be done with absorbable sutures to eliminate the step of suture

Principles of Radiosurgery 75

removal. If the defect is large and there is significant tension on the closure, the author uses 4-0 polyglactin 910 as buried sutures. Skin is closed with 4-0 chromic in interrupted fashion. If the wound is not under tension, 4-0 chromic alone can be used as the skin closure (186).

The graft must then be trimmed of all subcutaneous tissue until the thinnest possible skin is obtained. It is better to make a few unintentional ‘buttonholes’ in attempting to trim the skin very thin than to leave too much subcutaneous tissue that could inhibit the growth of new vessels into the graft (187).

The skin on the ear itself is thinner than skin over the adjacent temporal bone. It is, therefore, important to place the thinner skin of the graft in the recipient bed so that it will be closer to the eyelid margin. This will give a better match of skin texture, since the eyelid skin is thinnest near the lid margin and becomes thicker as it approaches the orbital rim. There should be drainage holes to allow for the egress of subcutaneous fluid. Several 6-0 mild chromic or 6- 0 fast absorbing plain sutures can be used in the central area of the graft to attach it firmly to the recipient bed. The graft should be trimmed so that there is approximately 1 mm (0.05 in) of graft overlapping the recipient skin on all sides, since no significant shrinkage is anticipated. The skin edges are then closed with a running or interrupted 6-0 fast absorbing plain gut or 6-0 mild chromic suture (188–191).

A bolster may be used to keep the graft firmly attached to the recipient bed, by exerting mild pressure on the graft. The author’s preference is a roll of nonstick material such as Telfa. The thickness of the roll is determined by the size and the position of the graft. Either absorbable or non-absorbable sutures can be used in a mattress fashion. The needle is passed through the skin about 2 mm (0.1 in) away from the graft. It is then passed over the bolster and

through skin on the other side of the graft. The second pass is 2 mm away from the graft opposite to the first pass. When the knot is tied, the mattress suture now holds the graft against the recipient bed (192–195). Bolsters are often cumbersome if they are close to the eye and tying the mattress sutures might evert the lid margins. For this reason, it is preferable to use multiple absorbable sutures to tack the graft to the recipient bed when the graft is close to the lid margin.

The author frequently uses full thickness grafts to fill eyelid defects. The negatives are that the graft might be elevated, bumpy, or a poor color match. The positives are that it can be taken while the frozen sections are being examined by the pathologist, and it is often easier to perform than a complicated flap.

If neither eyelid skin nor retroauricular skin is available for a free graft, skin from the supraclavicular area or the underside of the upper arm can be used. If full thickness skin is not available, a split-thickness graft can be used. However, in this case 25% shrinkage and a poor color and texture match should be anticipated. Since their use is so limited in eyelid reconstruction, details of split-thickness grafts will not be given in this text.