Ординатура / Офтальмология / Английские материалы / The Art and the Science of Cataract Surgery_Boyd, Barraquer_2000

Removal of the Lens Nucleus

and Cortex. Insertion of IOL

The surgeon proceeds with extracapsular cataract extraction and insertion of an IOL using his/her preferred technique.

Iridectomy (10x Magnification)

Following insertion of the IOL a peripheral iridectomy is made within the trabeculectomy opening ensuring that the base of the iridectomy is wider than the trabeculectomy opening (Fig. 173-A). This is achieved by grasping the iris near its root at the center of the trabeculectomy opening, bringing it out of the eye and moving to the left, cutting

midway across the iris from the right side with a Vannas or DeWecker scissors, and then moving the iris to the right and completing the iridectomy cut.

Closure of the Cataract-Trabeculec- tomy Incision (5x Magnification)

Closure is achieved using interrupted 10-0 nylon sutures, one interrupted suture on either side of the trabeculectomy opening leaving the trabeculectomy opening and adjacent scleral bevel unsutured (Fig. 181). The interrupted sutures are placed through the full thickness of the scleral flap at the limbus and through the posterior scleral incision (Fig. 181). The sutures are not tightly tied,

but tied to achieve tissue apposition without «crimping» the scleral flap and are «buried» in the sclera. It is desirable to inflate the anterior chamber with balanced salt solution to achieve a good positive intraocular pressure before tying these sutures.

An alternative is to use one horizontal suture through the scleral flap and scleralcorneal bevel on either side of the trabeculectomy opening.

Closure of the Conjunctivo-Tenons’

Flap (5X Magnification)

An uninterrupted 10-0 nylon suture running from the limbal sclera to conjunctiva closes the conjunctival incision. These sutures should be tightly tied, particularly if an antimetabolite is used.

Phacoemulsification With

Trabeculectomy

This procedure is shown in Figs. 182 through 187.

Conjunctivo-Tenons’ Flap

(5x-7x Magnification)

A 6 mm fornix-based flap is raised in the same way as described previously for the combined extracapsular extraction and trabeculectomy. Luntz’ technique when using antimetabolites is that if mitomycin is to be

used it is applied before raising the conjunctival flap.

Scleral-Corneal Incision (7x-10x

Magnification)

Luntz performs a 1/2-thickness vertical scleral groove, 5.5 mm or 6.0 mm cord length, depending on the diameter of the IOL to be used, or 3.5 mm cord length if a foldable IOL is used, which is cut in the exposed sclera in the superior half of the globe, 1.5 mm posterior to the limbus using a crescent blade or diamond blade (Fig.182). The crescent knife then dissects under the anterior lip of the groove to within the corneal vascular arcade extending the dissection on either side to the limits of the incision (Fig. 182).

Using a Superblade, a paracentesis incision is made at the 9:00 o’clock and 3:00 o’clock meridians.

A 2.5 mm keratome is inserted into the scleral-corneal incision at the 12:00 o’clock meridian advancing the keratome to the edge of the incision just anterior to the corneal vascular arcade (Fig. 183). The tip of the keratome is pushed toward the anterior chamber, it is withdrawn slightly and the anterior chamber is penetrated with the keratome tip 45º to the iris plane. At this point, the keratome tip is raised so that the keratome advances fully into the anterior chamber parallel to the iris plane producing a 2.5 mm «tunnel» incision (Figs. 183, 177 Insets).

Corneal «Tunnel» Incision and

Separate Trabeculectomy

(7x-10x Magnification)

For cataract and glaucoma surgery the 3.0 - 3.5 mm tunnel intracorneal incision placed in the temporal cornea can be used with a trabeculectomy performed separately and superiorly (Fig. 187).

Capsulorhexis, Phacoemulsification, Nucleofractis, Infusion/ Aspiration and IOL Insertion (10x-15x Magnification)

Using the scleral corneal tunnel incision (Fig. 184), the surgeon performs the above procedures according to his/her preferred method.

Figure 184: Combined Phacoemulsification Cataract Extraction - Trabeculectomy Procedure - Step 4

This figure shows the final configuration of the combined Phacoemulsification Cataract Extraction - Trabeculectomy incision. (See Figure 175 B for the corresponding cross section view). The scleral-corneal incision has been extended for its full length. In this figure, a cord length of 6mm is illustrated. The IOL is then inserted. Trabeculectomy (W) is performed by removing an approximately 2mm by 2mm block of the scleral-corneal bevel down to the scleral spur (see Figure 179). Iridectomy is performed (I). The sclera is shown lifted here to reveal the scleral tunnel (T) (its margins denoted by dotted lines). Initial scleral groove incision (S).

Trabeculectomy is not performed prior to lens removal in order to maintain a watertight «tunnel» incision for the phacoemulsification.

The 2.5 mm tunnel incision is enlarged to a 6 mm incision for insertion of a 6 mm IOL. If a 5 mm IOL is used, a 5 mm incision is made; and if a foldable lens is used the incision can be reduced to 3.5 mm.

Trabeculectomy (10x-15x

Magnification)

Following insertion of the IOL the anterior chamber is filled with viscoelastic and a trabeculectomy is made within the scleral bevel of the tunnel incision using the same technique as described in Figs. 175 and 179. The next step is an iridectomy insuring that the iridectomy base is wider than the trabeculectomy opening, as previously described (Fig. 184).

Closure of the Incision

(5x Magnification)

An interrupted 10-0 nylon suture is placed through the scleral incision on either side of the trabeculectomy as described in Fig. 185. The trabeculectomy and adjoining scleral-corneal bevel is left open without sutures. The knots should be buried. The scleral flap can also be left unsutured but Luntz has found a high incidence of postoperative bleeding and hyphema in these eyes. The 3.5mm incision or the 6 mm scleral flap are left unsutured only if the surgeon anticipates that freer drainage of aqueous through the trabeculectomy opening will be required early in the postoperative period. However, the disadvantage of an unsutured scleral flap, particularly the 6 mm scleral flap, is that the anterior chamber may be shallow or flat in the immediate postoperative period. To overcome this problem, one or two releasable 10-0 nylon sutures should be used (Figs. 186 A-B). These have the advantage that the anterior chamber is very unlikely to shallow postoperatively, because the scleral incision is partially sutured, and, at the same time, the sutures can be easily removed in the postoperative period if and when more drainage through the filtering procedure is required. The releasable sutures are placed as follows: the 10-0 nylon suture (Luntz prefers a CU-5 needle) is loaded backwards in the needle holder. The suture is placed through the posterior lip of the scleral incision and then through the anterior lip of the incision (posterior lip of the trabeculectomy flap) and exteriorized through the anterior lip. A second bite is taken at the limbus and into adjacent cornea in a radial direction and is exteriorized. A third bite is then taken at the point where the suture exits from the cornea, and this bite in

the cornea is horizontal to the limbus (Fig. 186). The free end of this nylon suture entering into the posterior lip of the scleral incision is held with tying forceps. Three throws are made, and the tying forceps then engages the portion of the suture that is exteriorized between the anterior lip of the scleral incision and the limbus. This portion of the suture is then pulled through the three loops held in the other tying forceps, and a bow knot is tightened, apposing the two lips of the scleral incision. The free end of the nylon suture from the bow tie is cut, and the free end of the nylon suture on the cornea is cut. The radial and horizontal suture in the cornea eliminates a free end of nylon suture on the cornea behaving as a windshield wiper. Two such releasable nylon sutures are placed in the incision at the same locations as shown for the interrupted sutures in Fig. 185. (The above technique is the method described by

Allan E. Kolker, M.D.).

Conjunctival Closure

(5x Magnification)

The conjunctiva is closed with an uninterrupted 10-0 nylon suture as previously described.

(Editor’s Note: in patients with glaucoma and cataract, one of the most difficult problems to deal with is the management of the small pupil. This important subject is discussed separately in this same chapter.)

Antimetabolites in Combined

Procedures

Luntz believes that antimetabolites should be used routinely in combined cataract and trabeculectomy as the result is better.

Choice of Antimetabolite

Surgeons in general will vary in their choice of an appropriate antimetabolite depending on the age of the patient and their own personal experience. For the combined cataract and trabeculectomy procedure, Luntz uses mitomycin-C routinely, as the results of the procedures are better with the use of an antimetabolite. There is a remote possibility of teratogenesis and the development of cancer many years following application of this drug. For this reason, and particularly so in children, an informed consent is required before Mitomycin-C is applied.

When using Mitomycin, Luntz’ preferred technique is to soak a Weck cell sponge into a solution of 0.4% Mitomycin-C. The soaked Weck cell sponge is placed on the conjunctival surface at the site selected for surgery. It is held on the conjunctiva for oneminute and then replaced with a freshly soaked Weck cell sponge for a further oneminute, and this is repeated a third or fourth time giving a total application time of three or four minutes. Following this, the conjunctival surface is vigorously lavaged with balanced salt solution to remove all traces of the drug.

Some surgeons have used a topical application of 5-FU intraoperatively with a Weck cell sponge soaked in the drug, similar to the way Mitomycin-C is used. The effectiveness of this method is still undecided.

Results of Combined Cataract

Surgery and Trabeculectomy

In Luntz’ experience, the results of combined cataract surgery and trabeculectomy have been consistently good. In a study combining extracapsular cataract extraction with posterior chamber intraocular lens implant and trabeculectomy, 38 eyes were followed for up to 46 months, with a mean of 16.4 months. The average preoperative intraocular pressure was 20.5 mm Hg and the average postoperative pressure was 14.5 mm Hg, a statistically significant change. The mean number of medications preoperatively was 2.3 and postoperatively at the end of the follow-up period this had still dropped to a mean of 1.42.

There was no significant change in the visual field graded from the preoperative to the postoperative level. Visual acuity, which averaged 20/120 preoperatively, improved to an average of 20/50 postoperatively.

Simmons et al (1992), have also reported good results with few complications using extracapsular cataract extraction with posterior chamber intraocular lens and trabeculectomy (as well as phacoemulsification and trabeculectomy -Editor).

In Luntz’ studies, the complications associated with combined ECCE and trabeculectomy (and (phacoemulsification and trabeculectomy) were surprisingly few and of no greater severity than would have been

expected from the cataract surgery or the glaucoma surgery alone. Intraoperative complications specific to the combined operation were not observed. The complications that were seen were similar to those associated with a trabeculectomy or extracapsular cataract extraction alone.

Immediate postoperative problems consisted of corneal edema of mild degree which rapidly resolved, and iritis which caused no long-term problems. Contrary to what was anticipated, the performance of a radial iridectomy and its repair by suturing the iris when this procedure was chosen by the surgeon did not cause an increase in the

level of postoperative iritis. None of the patients had shallow or flat anterior chambers postoperatively, which can be attributed to good apposition and closure of the cataract wound.

When using antimetabolites, if a significant leak from the conjunctival wound does occur this will in most cases require surgical repair. Surgical repair entails resuturing the incision. In severely affected eyes, the conjunctiva at the site of the leak becomes friable and normal conjunctiva is rotated from the fornix or moved across as a flap from the adjacent temporal or nasal conjunctiva.

PHACOEMULSIFICATION AND IOL IMPLANTATION IN THE PRESENCE OF OPAQUE CORNEA

Overview

Most of the concepts and techniques presented on this subject are based on the extensive clinical experience and research of Professor Miguel Angel Padilha, of Brazil. For many years, a triple procedure involving a corneal transplant, cataract extraction and intraocular lens implantation regularly entailed an open sky extracapsular cataract extraction. This technique exposed the open eye for a long period of time, while the surgeon performed the anterior capsulotomy, extraction of the cataract nucleus, aspiration of the cortical material and the implantation of the intraocular lens. Only then is the donor’s cornea placed and adequately sutured. During this period, the eye is subjected to considerable risk, including the greatly feared complication of expulsive hemorrhage.

Padilha’s Timing and Technique

When the cornea is opaque to the extent of preventing visualization of the anterior chamber, no other alternative is left than to proceed with the surgical timing and steps

described above: a corneal trephining first, followed by open sky extracapsular extraction, intraocular lens implantation and suturing the donor cornea to the recipient’s cornea to complete the operation.

If the cornea is reasonably transparent, allowing the surgeon to visualize the structures of the anterior chamber (Fig. 188) Padilha’s procedure of choice is removal of the cataract by phacoemulsification first which is a pressurized, much safer system, continued by IOL implantation and last, completing the penetrating graft, as first recommended by Enrique Malbran, M.D., from Argentina in 1995.

Step 1: Incomplete trephining of the moderately opaque cornea reaching half depth (Fig. 188). Step 2: Viscoelastic is injected into the anterior chamber through a side port incision. A Valvulated self-sealing scleral tunnel incision 2 mm posterior to the limbus, is performed, as shown in Fig. 40-B. Step 3: CCC with a bent needle used as a cystotome and long Kelman-McPherson forceps, preceded by injection of viscoelastic (Figs. 97, 44, 45). Step 4: The remaining phases of phacoemulsification are completed in a routine way, followed by the implantation of an PMMA or foldable intraocular lens, depending on the experience of the surgeon (Fig. 189). A miotic agent is injected intracamerally. Step 5: Padilha checks the hermetic closure of the sclero-corneal tunnel. The wound may or may not be closed with a horizontal suture depending on how sure the