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

saline solution, which is generally kept 1 m above the stretcher, so that while the goniotomy is introduced, the chamber angle remains completely filled and wellformed and the iris is displaced slightly backward, thus leaving the chamber angle area, on which the procedure must be performed, wholly uncovered.

Briefly, the original and useful aspects of the Worst technique are the following:

1.The lens is applied and fastened to the sclera by means of stitches (Fig. 15.7).

2.The chamber angle between the lens and the cornea is liquid and permanently free of air.

3.There is continuous irrigation of the chamber angle through the goniotome, with no chamber angle loss.

Technique

1.General anesthesia

2.The Worst lens is fixed to the episcleral plane with four stitches inserted in the four holes of the scleral support of the lens (Fig. 15.7). The stitches can be more easily inserted into the holes if the contact lens is previously applied, held with the hand, and properly centered on the cornea. The opening through which the goniotome will be introduced should be located at the edge of the meridian, opposite the area chosen for goniotomy. At the same time, the areas of the sclera where each stitch will be made are well marked through the holes by means of a punch for lacrimal ducts.

The stitches are made with only one suture, as shown by Fig. 15.8. The crossing of the threads at the center

Fig. 15.8a–c Goniotomy performed with the Worst lens. a Goniotomy in the inferior nasal quadrant; the goniotome is introduced through the inferior temporal area and shifted from 9 to 6 o’ clock. b Superior nasal goniotomy. The goniotome

penetrates through the inferior temporal area and is displaced from 12 to 9 o’ clock. c If a third goniotomy is required, it is performed in the temporal area, by inserting the goniotome into the nasal limbus at 9 and shifting it from 5 to 1 o’ clock

of the cornea is held with a clamp and cut with scissors, thus leaving the four stitches ready to be passed through the holes of the scleral support of the lens in order to tie them later. As shown in Fig. 15.8a, the fifth U-shaped stitch is then passed and its two edges are inserted into the oval-shaped hole in the lens, which has been designed for inserting the goniotome. This thread allows the goniotome to be located between its two branches, so that pulling it, when introducing the goniotome, facilitates the maneuver. The goniotome is introduced, guided by the microscope, and the Barkan membrane or pathological mesodermal tissue is removed from the chamber angle. The steps to be followed are shown in Fig. 15.8.

Goniotomy is followed by a hyphema of varying degrees of severity, which indicates that the goniotomy has been performed at the appropriate place. This hyphema reverses in a few hours.

Atropine 1% eye drops are instilled and both eyes are occluded with a dressing. Twenty-four hours after surgery, the eye is examined and the occlusion removed. Generally, the hyphema is found to have disappeared.

Goniopuncture

Scheie (1961) applied the technique of goniopuncture on 36 eyes with juvenile glaucoma and 52 eyes with infantile glaucoma. His results were encouraging: IOP was normalized in 57% of eyes by one or more goniopunctures. The longest follow-up period was 11 years and the shortest 1 year.

Trabeculotomy for Chamber Angle Type I

In 1959, Dellaporta [24], studying the pathological anatomy specimens of 100 eyes subject to cyclodialysis, found that the trabecular meshwork had become detached in the area of the anterior chamber where the spatula was introduced: he therefore proposed the trabeculodialysis technique. He communicated his results to Burian [25], who, in 1960, made the first ab externo trabeculotomy in a case with glaucoma and Marfan syndrome. Allen and Burian [26] described the technique used experimentally in enucleated human eyes: a conjunctival flap is made with a good dissection, and then, advancing on the sclerocorneal limbus, an incision is made perpendicular to the limbus, and a stitch is passed through each margin so that it is slightly open,

thus leaving the Schlemm canal uncovered in order to channel it with a trabeculotome specially designed for this purpose.

In the same year, Smith [27, 28], in England, made a trabeculotomy canalizing the Schlemm canal by two incisions similar to those made by Burian, with a nylon thread. After passing it through, it is pulled from both ends and in this way what was an arch becomes a cord with the resulting destruction of the meshwork.

Similar techniques were used by Walter and Kanagasundaran [29] and Strachan [30], the latter using a tear-duct dilator as an instrument.

In 1966, the most important contribution to the operation was made by Harms [31–33], who made a scleral lamellar dissection (like Cairns, for the trabeculectomy procedure) in the area of the Schlemm canal, advancing slightly into the transparent cornea. With an incision perpendicular to the limbos, they revealed the Schlemm canal, sectioned its outer wall, and canalized it.

In 1969, the Lyon [34] school with Paufique, Sourdille, and Ortiz-Olmedo, presented the results of trabeculotomy with the same technique as Harms to the Ophthalmology Congress in Paris. Ortiz-Olmedo provided a complete review of trabeculotomy in his doctoral thesis.

In 1971 [35], Dannheim performed trabeculotomy on 300 eyes of adult patients with different types of glaucoma, but he also studied infants. He considered trabeculotomy to be a technique carrying quite a low risk of operative and postoperative complications in comparison with fistulizing methods. Its effect in controlling intraocular pressure is no worse than that of classical operating procedures. In these cases performed in adults, the IOP was regulated only between 20 and 24 mmHg. Today, however, to reach a target pressure, this is not sufficient to stop the damage caused by glaucoma from progressing.

From results obtained in 86 eyes, Luntz [36] considered trabeculotomy to be superior to goniotomy. In the same year, in another paper [37], he reported obtaining a success rate of 93.4% in 75 eyes of 47 children.

In 1979, Rothkoff et al. [38] performed trabeculotomy on seven eyes of five children with follow-up for periods ranging from 18 months to 4 years. They recommend trabeculotomy for both early diagnosed cases and children with late-onset congenital glaucoma. Their results, even in children over 1 year of age, are good, matching the report made by McPherson in 1973 [39].

Fig. 15.9 Trabeculotomy. Pathological anatomy. Trabeculotomy made in a patient with choroid melanosarcoma, before enucleation, after an injection of glutaraldehyde in the anterior chamber, with the patient’s permission. At the left part,

the Schlemm canal can be seen in communication with the anterior chamber through the continuity solution made in the trabecular meshwork. At the right part, with greater magnification, the zone in the square in the left figure

Fig. 15.10 Trabeculotomy. Pathological anatomy. In the other eye of a patient with intraocular tumor, a trabeculotomy was made before enucleation, with the patient’s consent. The Schlemm canal is in communication with the anterior chamber.

This is from the final part of the trabeculotomy; the point of the instrument has lifted the endothelium and the Descemet membrane at the right at a greater magnification

Fig. 15.11 a Piece from a 6-month-old child with unilateral retinoblastoma. The parents’ consent was given to do a trabeculectomy before enucleation. When the Cocher tweezers were placed before the constriction of the optic nerve to section it, glutaraldehyde was injected intraocularly in the anterior chamber. The trabecular meshwork can be seen clearly and the internal wall of the Schlemm canal, turned and supported on the anterior face of the iris. This shows up the internal part of the external wall of the Schlemm canal. Three external collectors can be seen in this which exit toward the sclera: 1 External wall of the Schlemm canal shown by the trabeculotomy.

2 Prominent scleral spur. 3 Internal wall of Schlemm’s canal and trabecular meshwork rolled up. 4 Anterior surface of the iris. 5 Ciliary processes. In the square, two external collectors divided by septa. b, c These are the external Schlemm collectors, corresponding to the black squares in the previous figure. In the first, there is a septum dividing them, and in the one on the right there are two. The specimen of normal and pathological (congenital glaucoma) anatomy are the first ones done and were made by Dr. R. Sampaolesi and Dr. C. Argento at the Institute of Bioneurology directed by Dr. Juan Tramesani. The technician who made the inclusion was Mrs. Isable Farias

Figure 15.11 clearly shows the trabecular meshwork and the internal wall of the Schlemm canal turned and supported on the anterior face of the iris. This method shows the internal part of the external wall of the Schlemm canal. Six external collectors can be seen here exiting toward the sclera. Figure 15.11b and c show the openings of the collectors with greater magnification.

General Points About Surgery

In order to perform a trabeculotomy, it is first necessary to experiment on cadaveric eyes in order to have a clear idea of the necessary size of the scleral flap, the positioning of the incision in relation to the surgical limbus, the difficulties in finding the Schlemm canal, and the problems canalizing it. A surgical microscope is always necessary and it is preferable to use microscopes that give 30–40 diameters or special microscopes such as the Harms microscope, developed

by Zeiss (Oberkochen, Germany), which also helps greatly increase the amount of light per unit of surface.

Instruments

Harms probe is shown in Fig. 15.12a. Each arm is 0.3 mm in diameter; the arm that is not introduced is a guide for the surgeon to follow for the position of the arm introduced. Makensen added a handle to Harms trabeculotome (Fig. 15.12b).

The right and left trabeculotomes, from the Lyon school, made by Moria, are shown in Fig. 15.12c and are 0.2 mm in diameter; each of them is a conical probe with a handle that forms a 130° angle so as not to get in the way when operating with a microscope. There are special needles for intubating Schlemm’s canal. Figure 15.12d shows the Beaver knife, which is very useful for dissecting the scleral flap.

Harms Technique

At first Harms dried the dissected scleral lamina to give the patients the possibility of a filtering bleb if the trabeculotomy did not work. But when it was seen that the trabeculotomy worked on its own, they stopped drying the scleral flap and sutured it.

Figure 15.13 shows the dissection of an elliptical conjunctival flap whose the ends do not reach the limbus (1); in the middle part of the flap, toward the corneoscleral limbus, the dissection enters the corneal tissue. The limits of the scleral flap incision can also be seen in this figure, made in three stages and measuring

2×3 mm. In 2, the scleral flap is already lifted and supported by two threads of virgin silk. The incision was made in the center of the bed and perpendicular to the limbus. In 3, the opening of the Schlemm duct and the Vannas scissors that penetrate and section of the outer wall of the duct can be seen. In 4, the deep arm of Harms probe penetrates the Schlemm canal. In 5, a chalaziontype curette pushes the round end of the Harms probe and presses the whole of it inside. In 6, a needle-holder takes the upper arm of the Harms probe and performs the trabeculotomy on the right side. The same is done for the left part. In 7, the stitch can be seen closing the scleral incision, and in 8, the scleral and conjunctival

incisions are closed. One interesting detail is that, to help introduce the probe, the point of a closed tweezers should be used to depress the opposite lip of the incision perpendicular to the limbus.

The Lyon School Technique

Paufique, Sourdille, and Ortiz-Olmedo (1969) use the following technique (Fig. 15.14a). In 1, the conjunctival flap can be seen and the dissection of the small 2×4- mm scleral flap with a scleral depth two-thirds of the scleral thickness in 2. In 3, the incision perpendicular to the limbus can be seen showing the opening of the Schlemm canal, which is shown marked with a dotted line. Part 4 shows the Moria trabeculotome being

introduced, which is then rotated until the trabeculotomy is produced. The same maneuver is made on the left side. In 5, the incision to find the Schlemm canal is closed. The scleral and the conjunctival incision are being closed in 5, and both flaps in 6.

Figure 15.14b shows the series of steps for introducing the trabeculotome into the Schlemm canal, breaking the trabecular meshwork and extracting the trabeculotome. It is fundamental that this should follow the curvature of the limbus and that the maneuver should be made in a tangential plane so that it is located at half the depth of the anterior chamber. The trabecular meshwork breaks suddenly, and so it is important that neither the cornea nor the iris be touched.

We have used both the Harms and Paufique techniques with the same results.

Fig. 15.14 a Trabeculotomy. The Lyon School technique. 1 Conjunctival flap. 2 Scleral flap. 3 Scleral incision perpendicular to the limbus, disclosing the Schlemm canal. 4 Introduction of the trabeculotome, then repeated on the left side. 5 Closing

the scleral incision. 6 Replacement and closing of scleral and conjunctival flaps. b The delicate introduction of the trabeculotome and its extraction

Making the Scleral Flap

The small scleral flap is important in performing trabeculotomy. We make three incisions beginning with the incisions perpendicular to the limbus, 2.5 mm in length, and then we join them with the parallel incision. We use a Beaver handle with interchangeable blades. This scleral flap has a rectangular shape of approximately 2.5 mm in its two incisions perpendicular to the limbus and 4 mm in the incision parallel to the limbus. This rectangular shape lets the trabeculotome penetrate more easily into the opening of the Schlemm canal. For the point to penetrate, it must be supported on the side opposite the side it will enter, with the sclera depressed slightly, and then it is slid to thread the Schlemm canal.

Location of the Incision and Looking for the Schlemm Canal

We consider it very important to use transillumination (the Minsky maneuver), supporting the transilluminator on the cornea protected by the conjunctival flap (Fig. 15.15). In this way the limbus zone where the Schlemm canal is situated can be clearly seen.

The incision is made perpendicular to the limbus in the area indicated by the transillumination, 3–4 mm in length. With a diamond knife or razor blade and working with the greatest magnification, it gradually

deepens until an upper black triangle appears that corresponds to the Schlemm canal and a larger mother-of- pearl triangle with horizontal bands, the upper part of which corresponds to the scleral spur (Fig. 15.16a). The trabeculotome is inserted in the upper black triangle corresponding to the Schlemm canal (Fig. 15.16b).

The trabeculotome lifts the trabecular meshwork without breaking it on the left side (Fig. 15.17a). The trabeculotome enters the Schlemm canal (Fig. 15.17b) and breaks the trabecular meshwork and enters the anterior chamber (Fig. 15.17c). After the trabeculotomy, the anterior chamber remains perfectly formed (Fig. 15.17d).

We close the vertical incision with a stitch of virgin silk and the scleral flap with three stitches of the same material, which is also used for closing the conjunctiva.

After the trabeculotomy, a small hyphema should appear in the anterior chamber that does not reach the edge of the pupil (Fig. 15.18). A larger hyphema means that a cyclodialysis has been performed instead of a trabeculotomy. A German author also described this sign after we reported it.

The suction of the contact lens when the observation is made makes blood pass from the interior of the Schlemm canal to the anterior chamber. This is the proof that the operation has been performed correctly and that the aqueous humor is in communication with the episcleral venous system through the Schlemm canal (Fig. 15.19).

Fig. 15.15a,b The Minsky maneuver (transillumination). a Diagram. a Clear zone corresponding to the trabecular meshwork. b Zone of shade where the Schlemm canal must be sought. c Dark zone caused by choroidal pigmentary epithe-

lium. d Friedenwald artery (artery of the Schlemm canal). Schl C the Schlemm canal. b Photograph of the Minsky maneuver in an eye with congenital glaucoma

Fig. 15.16 a Finding the Schlemm canal. The incision is made perpendicular to the limbus in the area indicated by the transillumination. It is made 3–4 mm long using the diamond knife or razor blade and working with greater magnification,

going slowly deeper until in the vertical oval left by the incision can be seen the upper black triangle, corresponding to the Schlemm canal and the lower pearly triangle with horizontal bands corresponding to the scleral spur.

Fig. 15.17a–d The trabeculotome lifts the trabecular meshwork without breaking it on the left side (a), the trabeculotome enters the Schlemm canal (b), and it breaks the trabecular mesh-

Fig. 15.18 After the whole trabeculotomy, a small hyphema should appear in the anterior chamber that does not reach the edge of the pupil. When a larger hyphema is seen, a cyclodialysis has been performed instead of a trabeculotomy. When there is no hyphema, the trabeculotomy was not made at the right place

work and the trabeculotome enters the anterior chamber (c). After the trabeculotomy, the anterior chamber remains perfectly formed (d)