Ординатура / Офтальмология / Английские материалы / The Glaucomas Volume 1 Pediatric Glaucomas_Sampaolesi, Zarate_2009

Postsurgical Gonioscopy

The most frequent gonioscopic results after trabeculotomy are shown together in Fig. 15.20. These are very clear modifications to the structure of the chamber angle, which until now we had not been used to seeing in congenital glaucoma surgery.

If the trabeculotomy was done correctly, the trabecular meshwork is preserved in the point where the trabeculotome entered. The breakage of the mesh can be seen on either side of this zone, with chains of membrane with neater edges in the zone next to the Descemet membrane and more untidy edges next to the spur (1, Fig. 15.20). The spur is seen as a clearer, whiter and mother-of-pearl formation in the area of the trabeculotomy (2, Fig. 15.20). Generally, three goniosynechiae can also be seen in well-done trabeculotomies. A small central goniosynechia (3, Fig. 15.20) can be seen at the point where the trabeculotome entered, i.e., with the trabecular meshwork complete, reaching up to the spur or even to the height of the trabecular meshwork at the level of the Schlemm canal. This goniosynechia may result from the reaction of the trabecular meshwork tissue of the internal wall of the Schlemm canal against the insult suffered by the external wall. At the right and left ends of the trabeculotomy, two other triangular and wider goniosynechiae can be seen (4 and 5, Fig. 15.20), reaching up to the Schwalbe line. These may have a similar origin to the one just described and also receive the injury that the point of the trabeculotome causes to the outer wall of the angle and sometimes to the rear wall of the Descemet membrane and the endothelium. If the Moria trabeculotome is used, this problem is more common,

since there is less monitoring of its depth and, since the trabecular meshwork breaks sharply, the surgeon does not want the trabeculotome to go deeper and tends to move it upward.

In the Schlemm area, the edges of the breaking of the trabecular meshwork can be seen and, further in, the outer wall of the duct. The near edge of the Schwalbe line can always be seen more easily and the one nearer the spur is more difficult to see and sometimes does not exist.

Instead of the breakage of the Schlemm canal, it is usual to see blood deposited behind it, shaped like the duct (6, Fig. 15.20). Sometimes, when performing an early gonioscopy, a thread of blood comes out of this part, mixing with the aqueous humor (7, Fig. 15.20).

The spur can be clearly seen in all cases. It is pearly white, more obviously than in the regions that have not been operated. The trabeculotomy area in its near ends sometimes ends in a rounded shape.

The Descemet membrane in the zone of the trabeculotomy often presents small radial folds perpendicular to the Schwalbe line (Fig. 15.20). This may result from the Descemet membrane having less support when the trabecular meshwork has been broken. Sometimes these folds retain a little of the blood that came out during the surgery, which may last 15–20 days; therefore, we assume that there is slight filtration between the Descemet membrane and its adjacent parenchyma. These lamellar remains of blood are located below the Descemet membrane and remains for a long time, 6–8 months or more; we are reminded of what is seen after a cyclodialysis in which the Descemet membrane is accidentally dried with the spatula, so that blood penetrates the space. In the center of the corneal tissue,

Fig. 15.20 Postsurgical gonioscopy. 1 Schlemm canal open. 2 Spur more visible than normally. 3 Central goniosynechiae, reaches the spur. 4, 5 Triangular lateral goniosynechiae, reaching the Schwalbe line. 6 Coagulated blood inside the Schlemm canal. 7 Liquid blood comes out of one end of the the Schlemm

below the untouched trabecular meshwork, an elongated shadow can be seen (9, Fig. 15.20), corresponding to the external incision.

In the zone corresponding to the opening of the trabecular meshwork, the last circular fold of the iris retreats (10, Fig. 15.20). This element is constantly found and must be very important in the mechanism involved in the intraocular pressure decreasing. We rarely see:

1.Depigmentation of the trabecular meshwork in the breakage area, as occurs in pigmentary glaucoma.

2.Iris root dialysis.

3.Cyclodialysis.

4.Iris prolapse with large synechiae in the incision area as a result of the breakage of the internal wall of the trabecular meshwork at this point during the operation.

5.Some 5 or 6 months after doing the trabeculotomy, in a very few cases, pigmentation is seen advancing from the angle toward the posterior face of the cornea.

Figures 15.21 and 15.22 show other chamber angles after trabeculotomy.

canal and mixes with the aqueous humor during gonioscopy. 8 Folds in the Descemet membrane. 9 Scleral incision showing through the cornea. 10 Retreat of the last circular fold of the iris

Action of Atropine in Children

After a Trabeculotomy

If atropine is instilled 15 days after surgery, the ocular pressure drops, as can be seen in Fig. 15.23a, and, looking at the chamber angle, the area of the Schlemm canal opens up and the chamber deepens (Fig. 15.23b).

Mechanism of Action of the Trabeculotomy

It is difficult to explain precisely what mechanism the operation uses, but it is clearly the breakage of the trabecular meshwork that opens the way for the aqueous humor to enter the Schlemm canal and removes its resistance. The retreat of the last circular fold of the iris that is seen in all cases is remarkable.

During trabeculotomy, Abudi and Manzitti propose an implant of amniotic membrane to prevent postoperative adhesion under the scleral flap, in order to maintain a functional bleb after surgery (V.R. Abudi and K. Manzitti, personal communication).

Surgery for Refractory Congenital Glaucoma Type II

Combined Surgery: Trabeculotomy and Trabeculectomy for Chamber Angle Type II

Introduction

In 1971, after trabeculotomy was proposed by Harms and Paufique for congenital glaucoma, I started using the technique in primary congenital glaucomas. By 1975, 30% of congenital glaucoma patients on whom I had performed trabeculotomy had come back to my office with high IOP with pathological values and their axial length had continued to grow, as evidenced by echometry. Therefore, in 1975 I thought of the possibility of combining trabeculotomy and trabeculectomy in a single session in these refractory glaucomas. The results were successful.

When a new examination of the chamber angle was performed in those refractory glaucomas in which the first trabeculotomy had not been successful (i.e. IOP had failed to be regulated and the axial length continued to grow), I found that all these refractory glaucomas had the same type of angle (Type II) and so I changed the surgical indications.

In the second edition of my book Glaucoma [41] (p 754), I wrote, “I started to perform this combined technique in 1975 for congenital glaucomas which, in the first two years of age, had type 2 chamber angle (apparent high insertion of the iris), markedly increased axial length, and tears in Descemet’s membrane and endothelium, since in this type of glaucoma trabeculotomy alone failed to regulate the IOP. I also extended this indication to secondary congenital glaucomas such as Axenfeld’s syndrome, Rieger’s syndrome, etc.”

In 1988, my paper, “Congenital glaucoma. Longterm results after surgery” [42], was published, reporting 32 trabeculectomies and 29 combined surgeries, performing trabeculotomy and trabeculectomy in a single session. The follow-up after surgery ranged from 10 to 17 years.

In 1998, Mandal [43] published a paper titled “Surgical results of combined trabeculotomy-trabeculectomy for developmental glaucoma. Primary combined trabeculotomy and trabeculectomy in a single session.” They reported the results obtained over 5 years in a sample of 120 patients with a follow-up of at least 6 months. They concluded that “primary combined trabeculotomy and trabeculectomy is safe, effective, and sufficiently predictable to be considered the first choice of surgical treatment in primary congenital glaucoma.” In 2003, the same author [44] presented a new paper titled “Outcome of surgery on infants younger than 1 month with congenital glaucoma.” It reported a sample of 47

eyes of 25 consecutive newborn patients with congenital glaucoma who underwent single-session combined trabeculotomy and trabeculectomy between 1990 and 2000. They concluded that “primary combined trabe- culotomy-trabeculectomy offers a variable surgical option in infants that have cloudy corneas at birth as a result of congenital glaucoma. It is associated with favorable visual outcome and a low rate of anesthetic complications in an Indian population.”

In 2000, Meyer et al. [45], in their paper, “Trabekulotomie bei Kongenitalem Glaukom. Ein Vergleich zur Goniotomie” (Trabeculotomy in congenital glaucoma. A comparison with goniotomy), reported the results obtained in 37 trabeculotomy cases in which they had to perform combined trabeculotomy + trabeculectomy 14 times in order to regulate the IOP and stop eye growth. In this article, they quote my first paper of 1988 as follows: “Sampaolesi’s criteria is to do combined surgery: trabeculotomy with trabeculectomy as a standard procedure in refractory congenital glaucomas and in secondary congenital glaucomas (for example: Axenfeld’s, Rieger’s Syndromes, etc.). This is the reason why we thought it very important to include his criteria into this evaluation.”

The paper by Kiefer et al. [46], “Correlation of postoperative axial length growth and intraocular pressure in congenital glaucoma. A retrospective study in trabeculotomy and goniotomy,” concluded that “axial length measurement can help to ascertain halting or progression of congenital glaucoma and thus is considered an important parameter for congenital glaucoma follow-up. The nomogram of axial length growth over age compiles data published by Sampaolesi in a paper published in 1981: ‘Ocular echometry in the diagnosis of congenital glaucoma.’” This paper presents a graph where the authors show the normal growth curve reproduced from my paper, with the pathological growth curve of the refractory congenital glaucomas of their population superimposed on it.

The population studied included 61 eyes belonging to 44 children, 26 males and 18 females, with the fol-

-lowing features:

- 27 unilateral cases: 14 males and 13 females. - 17 bilateral cases: 12 males and 5 females.

43 eyes (70%) with chamber angle type I that under- - went trabeculotomy.

18 eyes (30%) with chamber angle type II that underwent combined surgery (trabeculotomy + trab-

- eculectomy).

32 trabeculotomies and 29 combined surgeries (trabeculotomy + trabeculectomy) were performed.

Meyer et al. [45] had similar results in a population of -37 eyes:

- 23 eyes (62%) that underwent trabeculotomy. 14 eyes (38%) that underwent combined surgery.

In our first paper on the combined operation, the proportion between simple trabeculotomy and combined operation (trabeculotomy + trabeculectomy) was as follows: 65% trabeculotomies and 35% combined operation. Indeed, if we compare both results it is encouraging to find consistency in the results obtained in Argentina and Europe with surgical techniques for congenital glaucoma.

Combined Surgery Trabeculotomy

and Trabeculectomy in the Same

Surgical Session

Until 1995, I managed to find the Schlemm canal in the first phase of surgery with the Harms and Paufique technique. After creating a 4×3-mm square scleral flap, two vertical incisions were made perpendicular to the limbus and adjacent to the outer and inner margin of the scleral bed at the level of the Schlemm canal (Fig. 15.24). After trabeculotomy on the right

Fig. 15.24a–d Combined trabeculectomy and trabeculotomy operation. In a and b, after making the first step of the conjunctival and scleral flap, as in the common trabeculotomy operation (See Fig. 15.15, 1 and 2), instead of making one incision to look for the Schlemm’s canal, two are made, one on each side. In c and d, we look for Schlemm canal and make the right trabeculotomy through the right incision and the left one

through the left incision. Then an incision is made parallel to the limbus that joins the two ends nearest the limbus of the previous incisions and the anterior chamber is entered. Then the piece of the trabecular meshwork is removed, sectioning it at the spur, the trabeculotomy piece is removed, a peripheral iridectomy is done, and we finish by stitching the scleral and conjunctival flaps

and left sides, a third incision is made parallel to the limbus above the Schlemm canal and two further incisions perpendicular to the first one in order to remove the trabeculectomy specimen, which includes the Schlemm canal in the central area, where the trabeculectomy has been made. Finally, the sclera is cut below the Schlemm canal, a peripheral iridectomy is made, the scleral flap is closed with two sutures, and the conjunctiva is secured to the limbus.

Combined Surgery with Kozlov’s Technique for Finding the Schlemm Canal

in the First Step

From 1995, when we were introduced to Kozlov’s nonpenetrating deep sclerectomy, we changed the technique shown in Fig. 15.24 for Kozlov’s modified technique. The surgical steps we follow to find the Schlemm canal are reported in the following figures [47] (Figs. 15.25, 15.26).

A second trapezoidal scleral flap is dissected (Figs. 15.27, 15.28, 15.29, 15.30). This second scleral

flap is created carefully so that it includes the external wall of the Schlemm canal (Figure 15.31). In the blood of the Schlemm canal coming from the Friedenwald artery, there is a whiteness that corresponds to the aqueous humor.

Trabeculotomy on the right side (Fig. 15.32a) is the same as on the left side. The trabeculectomy piece is extracted, as are the inner wall of the Schlemm canal, the Schwalbe line, and the outermost part of the cornea (Fig. 15.32b).

The trabeculectomy piece is dissected (Fig. 15.33a). In Fig. 15.32b and c, a diagram is drawn over the piece so that the ophthalmologist can easily find the scleral spur, the inner wall of the Schlemm canal, the juxtacanalicular tissue, and the corneoscleral trabecular meshwork.

While tweezers hold the trabeculectomy piece to be extracted, we pass a trabeculotome, which shows the persistence of the Barkan membrane that has to be removed before extracting the trabeculectomy piece (Fig. 15.34). The cut must pass behind it. The scleral flap is then closed, followed by the conjunctiva.

Fig. 15.32 a Trabeculotomy on the right side and b the left side. b Extraction of the trabeculectomy piece, the inner wall of the Schlemm canal, the Schwalbe line, and the outermost part of the cornea. SP scleral spur, I.W. Schl inner wall of the Schlemm canal, Schw the Schwalbe’ line

Fig. 15.33 a Dissection of the trabeculectomy piece. b Shown over the piece is a diagram so that the ophthalmologist can easily find the scleral spur, the inner wall of the Schlemm canal,

the juxtacanalicular tissue and the corneoscleral trabecular meshwork. SP scleral spur, I.W. Schl inner wall of the Schlemm canal, Schw the Schwalbe line