Ординатура / Офтальмология / Английские материалы / Glaucoma Surgery_Trope_2005

Figure 9.7 (See color insert) The Pars Plana ClipTM is anchored to the episclera with 8/0 silk sutures through the eyelets.

advance by dissecting off the epithelial half of the cornea through the midstroma with a 57 blade using only the endothelial half.

The half-thickness cornea graft is sutured to the episclera with interrupted 10/0 nylon sutures, to prevent postoperative erosion of the implant tube and Clip through the conjunctiva (Fig. 9.8).

Water-tight closure of Tenon’s capsule and conjunctival flap, in separate layers with a continuous 7/0 vicryl sutures is then performed (Fig. 9.9).

The superonasal sclerostomy and peritomy is closed in turn with 7/0 vicryl suture. In cases where an anterior chamber maintainer is used, this is now removed followed by hydration of the limbal wound with BSS. In cases where a pars plana infusion is used, the infusion cannula is removed with immediate closure of the

sclerostomy by the preplaced 7/0 vicryl suture.

Figure 9.8 (See color insert) Half thickness cornea graft is sutured to the episclera with inter rupted 10/0 nylon sutures to cover the tube and the Pars Plana ClipTM.

Figure 9.9 (See color insert) Water tight closure of Tenon’s capsule and conjuctival flap.

Top-up with filtered air can be injected on a short 30-gage needle through the inferotemporal limbal wound into the anterior chamber, or through the closed inferotemporal sclerostomy into the vitreous cavity, if the eye is soft.

Subconjunctival injection of steroid and antibiotic should be placed inferonasally.

4.RESULTS AND COMPLICATIONS OF PARS PLANA GDI

Various studies (8,10 15) in the last decade have reported the experience of combined GDI surgery with pars plana vitrectomy and pars plana tube insertion. These are summarized in Table 9.1. A wide variety of different glaucoma diagnosis were reported in these studies. In addition, variability in the definition of surgical success, difference in the surgical techniques, and the different types of GDI used make interpretation of the results difficult.

There are significant postoperative complications, some secondary to hypotony, shared with conventional GDI surgery with anterior chamber tube placement. Serous choroidal effusions were reported in 36% in one series (13). Suprachoroidal hemorrhage occurred in up to 6% of cases (15). In addition, complications specific to pars plana vitrectomy are also encountered, specifically, rhegmatogenous retinal detachment in 6 12% of cases (12,15). Patient should be fully informed about potential complications prior to surgery.

Nevertheless, satisfactory intraocular pressure control without further glaucoma surgery (with or without glaucoma medication) is achieved in 72.5 94% of the cases (8,10 15). Considering the severity of the glaucoma treated, these results show promise for the management of these selected cases of refractory glaucoma. Before proceeding with combined GDI surgery and pars plana tube insertion, considerations should be given to ensure that the advantages associated with the reduced risk of anterior segment problems outweighs the additional risk of posterior segment complications of the pars plana vitrectomy.

REFERENCES

1.Katz GJ, Higginbotham EJ, Lichter PR et al. Motomycin C versus 5 fluorouracil in high risk glaucoma filtering surgery. Ophthalmology 1995; 102:1263 1269.

2.The Fluorouracil Filtering Surgery Study Group. Five year follow up of the fluorouracil filtering surgery study. Am J Ophthalmol 1996; 121:349 366.

3.Patel A, Thompson JT, Michels RG, Quigley HA. Endolaser treatment of the ciliary body for uncontrolled glaucoma. Ophthalmology 1986; 93:825 830.

4.Trope GE, Ma S. Mid term effects of neodymium:YAG transcleral cyclophotocoagulation in glaucoma. Ophthalmology 1990; 97:73 75.

5.Schocket SS, Nirankari VS, Lakhanpal V et al. Anterior chamber tube shunt to an encircling band in the treatment of neovascular glaucoma and other refractory glaucomas; a long term study. Ophthalmology 1985; 92:553 562.

6.Lloyd MA, Sedlak T, Heuer DK et al. Clinical experience with the single plate Molteno

implant in complicated glaucomas: update of a pilot study. Ophthalmology 1992; 99:679 687.

7.Lloyd MA, Baervrldt G, Heuer DK et al. Initial experience with the Baerveldt implant in complicated galucomas. Ophthalmology 1994; 101:651 658.

8.Varma R, Heuer DK, Lundy DC et al. Pars plana Baerveldt tube insertion with vitrectomy in glaucomas associated with pseudophakia and aphakia. Am J Ophthalmol 1995; 119:401 407.

9.Siegner SW, Netland PA, Urban RC Jr et al. Clinical experience with the Baerveldt glaucoma drainage implant. Ophthalmology 1995; 102:1298 1307.

10.Grandham SB, Costa VP, Katz LJ et al. Aqueous tube shunt implantation and pars plana vitrectomy in eyes with refractory glaucoma. Am J Ophthalmol 1993; 116:189 195.

11.Smiddy WE, Rubsamen PE, Grajewski A. Vitrectomy for pars plana placement of a glaucoma seton. Ophthalmic Surg 1994; 25:532 535.

12.Kaynak S, Tekin NF, Durak I et al. Pars plana vitrectomy with pars plana tube implantation in eyes with intractable glaucoma. Br J Ophthalmol 1998; 82:1377 1382.

13.Luttrull JK, Avery RL, Baerveldt G, Easley KA. Initial experience with pneumatically stented Baerveldt implant modified for pars plana insertion for complicated glaucoma. Ophthalmology 2000; 107:143 150.

14.Joos KM, Lavina AM, Tawansy KA, Agarwal A. Posterior repositioning of glaucoma implants for anterior segment complications. Ophthalmology 2001; 108:279 284.

15.Sidoti PA, Mosny AY, Ritterband DC, Seedor JA. Pars plaa tube insertion of glaucoma drainage implants and penetrating Keratoplasty in patients with coexisting glaucoma and corneal disease. Ophthalmology 2001; 108:1050 1058.

fashioned to cover the scleral fistula. The scleral flap retards the aqueous outflow through the fistula and significantly reduces the risk of postoperative complications, in particular, over-filtration, flat anterior chamber (AC), hypotony, and suprachoroidal hemorrhage. Owing to its greater safety compared with full-thickness procedures, trabeculectomy has become the standard filtration procedure for glaucoma surgery. Although trabeculectomy adds to the safety of filtering surgery, reducing the risk of postoperative complications, it also slows and restricts aqueous drainage. The result is that trabeculectomy only infrequently achieves intraocular pressure (IOP) reduction into the low teens (10 12 mmHg) when compared with full-thickness procedures. Recent longitudinal studies have demonstrated the importance of achieving IOP levels into the low teens in patients with optic nerve head cupping and visual field loss (2). The ability to achieve these IOP levels with trabeculectomy became feasible when antimetabolites were used in conjunction with trabeculectomy. At present, the most effective antimetabolite in use is mitomycin C.

The higher success rate has come with a price. The effect of these antifibrotic agents is not confined to fibroblasts entering the area of bleb formation, but destroys cells in the surrounding conjunctiva and the surrounding blood vessels. Postoperatively, a thin-walled bloodless bleb forms, which is prone to hypotony, suprachoroidal hemorrhage (2), and leakage of aqueous through poor healing of the conjunctival incision and/or breaks in the bleb (positive Seidel) and risk of endophthalmitis (3,4). These are serious and sightthreatening complications and have led to a resurgence of interest in full-thickness procedures without the use of antimetabolites as a means of achieving low IOP levels. The full-thickness procedures most popular at this time are trabeculectomy but without suturing the lamellar scleral flap, the subscleral Scheie, the subscleral trephine procedure, and setons, because of their relative safety when compared with other full-thickness procedures. These full-thickness procedures have been modified and are performed under a small scleral flap which acts as a “ball valve,” restricts aqueous flow and protects the limbal conjunctiva.

2.SUBSCLERAL SCHEIE PROCEDURE

The subscleral Scheie procedure, first described by Soll in 1973 (5) is a modification of the procedure which was first described by Harold Scheie in 1958 (6). The procedure was subsequently modified and used with excellent results by Luntz et al. (7).

The operation interposes a lamellar flap of sclera between the classical Scheie fistula and the limbal conjunctiva. The scleral flap is designed to reinforce the conjunctiva at the limbus, to reduce the rate of aqueous flow through the fistula, in this way to reduce the incidence of over-filtration and minimize postoperative flat or shallow AC. By deflecting aqueous humor posteriorly, the flap also results in a more posterior and diffuse bleb (Fig. 10.1).

The scleral flap is not sutured as in trabeculectomy and this operation is a partially guarded full-thickness procedure as opposed to a trabeculectomy, which is a fully guarded procedure.

3.SURGICAL TECHNIQUE

A suitable area of conjunctiva is selected. The best site is virgin, untraumatized conjunctiva, preferably the upper nasal quadrant. Where conjunctival scarring is present, an area

Figure 10.1 Aqueous flow in subscleral Scheie.

of normal or near-normal conjunctiva is selected, but only in the superior conjunctiva. If the superior conjunctiva is severely scarred, this procedure is contraindicated and a seton should be used.

3.1.Conjunctival Flap (53 Magnification)

A limbus-based conjunctival flap is preferred to a fornix-based flap for this operation. Using Westcott scissor, a conjunctival incision 7 mm in width is made in the fornix, 7 mm behind and parallel to the surgical limbus. The incision is carried through the conjunctival tissue and Tenon’s to sclera, and scleral surface is laid bare. Hemostasis is obtained using a pencil bipolar cautery. Dissection is then carried forward using either a Westcott or Troutman scissors toward the surgical limbus, separating conjunctiva and Tenon’s fascia from sclera. As the limbus is approached, Tenon’s capsule and episcleral tissue fuse, and a disposable Beaver knife (#75 or #69) is used to dissect into the limbal area, dissecting just forward of the surgical limbus. The limbus-based conjunctival flap is rotated forward onto the cornea and held there by an assistant using a #28 Hoskins forceps (Katena).

3.2.Scleral Flap and Paracentesis (73 to 103 Magnification)

A scleral flap hinged at the limbus, extending posteriorly from the limbus for 1.5 mm and 5 mm in length, is marked out on the sclera beneath the conjunctival flap using the bipolar cautery. A 5 mm incision is made 1.5 mm posterior and parallel to the limbus along this marked-out area, extending through one-third of the scleral thickness, and each end of the incision is joined to the limbus by two radial incisions, also extending through one-third of the scleral thickness. Using a diamond blade, the scleral flap is dissected from the posterior incision to the limbus, raising a 1/3 thickness scleral flap, 5 mm in length and 1.5 mm in width, hinged at the limbus. A temporal paracentesis is made with a 158 superblade (Alcon).

Figure 10.3 Cautery to incision subscleral Scheie.

by using a jet of balanced salt solution (BSS) through the incision. Healon or a comparable viscoelastic is injected through the paracentesis incision to maintain the AC.

3.4.Closure (53 Magnification)

The conjunctival flap is rotated back into the fornix, covering the 1/3 thickness scleral flap which is not sutured. The incision in Tenon’s capsule is sutured with interrupted #10/0 nylon sutures using 10 interrupted sutures. Approximately 10 interrupted or continuous #10/0 nylon sutures unite the cut conjunctival edges. A drop of an antibiotic steroid combination is instilled into the conjunctival sac at the completion of surgery. BSS is injected through the temporal paracentesis incision to deepen the AC. The BSS egresses through the scleral fistula and fills the bleb. Ensure a negative Seidel using a Fluorescein strip. The steroid antibiotic combination is used for 1 10 days postoperatively, depending on the extent of postoperative iritis. As soon as the AC reaction is improved to a level of 1þ flare and no cells, and postoperative infection is no longer anticipated, this medication is replaced with a topical steroid for another month. By this time, the eye should be quiet and the patient can be weaned off the steroid drops. If the AC shallows postoperatively, homatropine 5% twice daily is added. The treatment of postoperative complications is reviewed elsewhere. Transient ocular hypertension may follow some fistulizing procedures, lasting from 2 days to 6 weeks. The reason for this is obscure, but may be related to postsurgical edema of the trabecular meshwork, to obstruction of the fistula by blood, to early failure of the bleb, or to the use of steroids or cycloplegics. If blood is a factor, the pressure will gradually drop to a normal postoperative level once the blood is resorbed. Massage used three to four times a day may be helpful during the ocular hypertensive period and the technique of massage is described elsewhere in this book.

Figure 10.4 Subscleral Scheie completed incision.

4.SUBSCLERAL TREPHINE

For the first half of the 20th century, corneal-scleral trephine, which is a full-thickness filtration, was the most popular procedure for the treatment of chronic open angle glaucoma. It fell into disuse when trabeculectomy became popular because of the smaller risk of complications with trabeculectomy. The corneal-scleral trephine operation was first described by Robert Elliot in 1909 (8). The procedure has become popular once again as fullthickness procedures have increased in popularity over the past few years. The modern corneal-scleral trephine procedure should be a partially guarded procedure performed under 1/3 thickness lamellar-scleral flap, similar to that described for subscleral Scheie.

5.SURGICAL TECHNIQUE

5.1.Conjunctival Flap (53 Magnification)

Using Westcott scissors, a conjunctival incision 7 mm in width is made in the fornix 7 mm behind and parallel to the surgical limbus. The conjunctival dissection is then carried out in the same way as described in the previous section for subscleral Scheie. When the surgical limbus is reached, the dissection is carried forward into the surgical limbus and just anterior to the vascular arcade in the corneal periphery.

5.2.The Scleral Flap (73 to 103 Magnification)

A 1.5 mm wide by 5 mm long 1/3 thickness scleral flap is raised in the same way as described in the previous section for the subscleral Scheie procedure, except that the