WOUND CONSTRUCTION PROBLEMS

Incisions problems are similar in both sclerocorneal and clear corneal incisions and can be due to inaccuracy in wound construction including:

1.The external incision unsuitably located anteriorally or posteriorally

2.The internal incision unsuitably located anteriorally or posteriorally

3.Premature entry into the anterior chamber

4.The incision too deep or too shallow

5.Incision width inadequate or too broad

There may be unforeseen problems including:

1.Torn roof or floor

2.Premature entry into the anterior chamber

3.Detachments of Descemet’s membrane

4.Wound burns

INACCURACY IN WOUND

CONSTRUCTION

SCLEROCORNEAL (FROWN)

If the external incision is too close to the limbus, the tunnel may be of inadequate length to create a watertight sutureless closure. Similarly, if the internal incision is too short there will be an inadequate corneal lip, making watertight closure difficult. In these situations one to three 10-0 nylon sutures placed radially and tied adequately to prevent fluid egress should provide satisfactory wound integrity. If a fluid leak continues after refilling the AC to a normal intraocular pressure, the conjunctiva should be closed tightly over the wound. A 10-0 nylon suture will work well. Then, should there be continued leakage, a filtering bleb will form and back pressure will be adequate to prevent postoperative hypotony or a flat anterior chamber. All sutures should be trimmed on the knot and rotated to bury the knot in the sclera or conjunctivae to prevent postoperative patient discomfort.

CLEAR CORNEA

Similar to the discussion above, an external incision that is too anterior or an internal incision that is too posterior will result in a short corneal tunnel, and watertight closure and wound strength cannot be assured. Wound leak could lead to hypotony, IOL dislocation, or endophthalmitis. The 10-0 nylon sutures are mandatory to strengthen the wound and prevent fluid egress. Stromal hydration should be utilized as an adjunct to the creation of a watertight incision.

SCLEROCORNEA AND CLEAR CORNEA

If the external incision is too posterior, the tunnel will be unnecessarily long, making manipulation of the phaco tip difficult. The long area of tissue contact with the phaco tip can cause sufficient heat transfer to result in wound burn. In this situation the wound can be abandoned and a properly constructed incision can be created in a different anatomic location. Another approach would be to create two 1-mm incisions in the roof of the wound parallel to the tunnel sides. This will, in effect, unroof the posterior aspect of the tunnel, creating a functionally shorter tunnel, and making manipulation of the phaco tip easier. A suture closure will be necessary to tack down the now mobile posterior incisional roof.

If the internal incision is too anterior, it will extend too far into clear cornea. This will cause the phaco tip to enter the AC too anteriorally, making phaco difficult. It is difficult to direct the phaco tip downward to perform phaco, forcing the phaco to take place in the cul de sac opposite the incision. In addition, the phaco tip will distort the cornea, creating striae and poor visibility. These problems substantially increase the risk of creating tears in the posterior capsule during the procedure. In clear corneal incisions, especially if created superiorally, the incision may invade the visual axis with significant postoperative corneal edema and irregular astigmatism causing permanent visual impairment. This situation may be worsened by a concomitant Descemet’s detachment. Once this condition becomes apparent, the least traumatic approach is to abandon the incision immediately, before trauma to the stroma, Descemet’s membrane, and endothelium occurs. A new incision can be made near the abandoned one, and with attention to placement of the internal incision these problems can be avoided.

Finally, a clear corneal wound should have a square configuration to ensure a watertight closure. If a 3.4- mm blade is employed, the tunnel must be longer to be watertight. If the wound is placed superiorly, where the corneal diameter is narrower, there is a greater likelihood that the internal incision will invade the visual axis. Superior placement should be avoided. If absolutely necessary, a smaller width should be used. This will shorten the length of the incision.

INTERNAL INCISION TOO

POSTERIOR—PREMATURE ENTRY

INTO THE ANTERIOR CHAMBER

This problem most commonly occurs while creating the tunnel dissection into the cornea during construction of the sclerocorneal incision. The angle of the dissection instrument may become too deep en-

tering the AC. This can also occur during keratome entry if the keratome is directed iris parallel but too close to the limbus. It will then pierce Descemet’s membrane too posteriorally. The lack of a good internal corneal lip to divert the exit of BSS may allow the exiting irrigation fluid to capture the iris and thus cause iris prolapse. The trauma to the iris will cause pigment loss and dispersion and damage to the blood–aqueous barrier. Difficulty with insertion of the phaco tip may lead to the tip catching the iris and creating a subincisional iris dialysis with or without hemorrhage. The proximity of the phaco tip to the iris may cause iris chafe. Damage to angular blood vessels and the iris root may lead to hemorrhage and hyphema. If the premature entry is not too posterior, a small peripheral iridotomy may be accomplished to prevent iris prolapse and trauma. The procedure may be completed. However, if the entry is very posterior, with immediate iris prolapse and difficulty with insertion of the phaco tip due to it becoming embedded in iris, it would be prudent to abandon and suture the wound and create another anatomically correct one in a new location.

INCISION TOO DEEP

A deep sclerocorneal incision will expose the ciliary body, which occurs most commonly during the initial incision in the sclera. If the ciliary body or choroid is visualized, the incision should be sutured and abandoned. If the dissection of the tunnel is seen to extend into the ciliary body, the dissection should be redirected so that it is shallower. If it cannot be redirected, the incision should be sutured and abandoned.

Deep incisions are uncommon in clear cornea. They will usually result in premature AC entry and a short tunnel. The floor of the tunnel will be thin and may tear. Descemet’s detachments may occur. Suture closure will usually be necessary.

INCISION TOO SHALLOW

If the roof is too thin, it can tear or a buttonhole can form. A torn roof can be closed with sutures. Usually it is watertight. However, a buttonhole may lead to a leaking wound, which may be impossible to close. If the thin roof causes a buttonhole, and the surgeon is able to recognize the problem prior to anterior chamber entry, the incision should be abandoned before entry. If entry to the anterior chamber has already occurred, fluid egress through the buttonhole will make it visible. The buttonhole can be closed with an X suture in an attempt to create downward pressure. Conjunctivae should also be sutured over the buttonhole to limit fluid egress. A filtering bleb may be the outcome, but this will prevent fluid leak and possible

hypotony. If all else fails, a partial-thickness autologous scleral patch or bank scleral patch can be sewn over the buttonhole to create a watertight patch.

INCISION WIDTH INCORRECT

The incision may be too wide or too narrow. If it is too wide, there will be excessive fluid egress. The anterior chamber will be shallow and difficult to maintain. By necessity, the irrigation bottle must be raised so that excessive irrigation fluid inflow will create turbulence with resultant anterior chamber trauma. Trampolining of the posterior capsule during phaco may lead to tears with vitreous loss. If the phaco tip passes too easily through the incision and anterior chamber depth is difficult to maintain, the amount of fluid egress through the wound should be evaluated. If the wound is too wide, one or two sutures should be used to partially close it. This will then stabilize the anterior chamber and allow an uneventful procedure.

If the incision is too narrow, it will be difficult to insert the phaco tip. The wound will be seen to stretch to allow phaco tip entrance. Binding of the wound to the phaco tip sleeve will cause excessive eye movement when the phaco tip is advanced or retracted. Crimping of the sleeve may diminish BSS inflow and cooling, leading to wound burn. The phaco tip may catch Descemet’s membrane on the anterior wound lip and create a Descemet’s detachment.

If the above is seen to occur, it is simple to remedy the situation by enlarging the tunnel and/or the anterior chamber entry with a suitable keratome.

UNFORESEEN PROBLEMS IN

WOUND CONSTRUCTION

In addition to the unforeseen problems discussed here, a torn roof or floor and premature entry can also occur. They have been discussed above.

CONJUNCTIVAL HYDRATION

In the near-clear and sclerocorneal incisions, if there is inadequate conjunctival pyritomy, escaping fluid from the wound can flow into Tenon’s fascia. This will progressively hydrate the conjunctivae, creating potentially massive swelling. The resultant pooling of fluid within the confines of the edematous conjunctivae will progressively impair visualization of events within the anterior chamber during the procedure. The remedy for this problem is simple but demands early detection. At the first sign of conjunctival hydration, the phaco tip should be withdrawn, the pyritomy should be enlarged, and a conjunctival incision should be created with Westcott scissors 1 to 2 mm posteriorally to allow fluid egress. This must