8.1.5 Adjunctive Treatments

8.1.5.1 Bleb Needling

Tissue remodeling and scarring response are two healing processes that occur after any surgery. In the case of glaucoma Þltration, aqueous humor is drained in the subconjunctival space before further routing to the drainage vessels. This space may be prone to the development of a Þbrosis, leading eventually to the growth of a Þbrous capsule around the surgical site, which may signiÞcantly reduce the absorption of aqueous humor (Fig. 8.18). This can lead to a signiÞcant increase in the IOP. To solve this problem, needling the Þltering bleb, with or without the use of adjunctive antimetabolites (such as Mitomycin C or 5-ßuorouracil) might be proposed to restore the function of the Þltering bleb and reduce the IOP. The needling is performed after instilling the topical anesthetic and placement of a lid speculum. The patient is instructed to look down and a 30-gauge needle mounted on a 1 mL syringe is introduced beneath the conjunctiva near the surgical site. The tip of the needle is advanced to gently enter in the Þbrous capsule or cysts in the TenonÕs layer, and then the tip is carefully moved back and forth to break the capsule and/or the cysts. Care is taken to not puncture the nearby running blood vessels or the overlying conjunctiva. Antimetabolites, e.g., 0.2 mg/mL Mitomycin C or 50 mg/mL 5-ßuorouracil, are injected (0.3 mL) during the needling procedure. The eye is then thoroughly rinsed using a sterile balanced salt solution for about 1 min to ßush any excess antimetabolite solution. Topical combined antibiotics and corticosteroids are

Fig. 8.18 Cystic bleb

given three times a day for a week. The IOP is checked 10Ð15 min after this procedure to assess efÞcacy of the treatment.

8.1.5.2 Nd:YAG Goniopuncture

Aqueous humor should ßow easily through the TDM. After the initial drop in IOP, any signiÞcant rise in pressure (above 20 mmHg) in the early postoperative period (~10 days) might be indicative of an impaired percolation through this membrane. A goniopuncture of the latter using a gonioscope and a Neodynium: Yittrium Aluminium Garnet (Nd:YAG) laser can be proposed to create minute perforations in the membrane to improve aqueous humor egress [21, 22]. The laser is set on free-running Q-switched mode, with an energy of 4Ð5 mJ. The laser spot is aimed at the membrane and a series of shots are given to create very Þne holes creating a direct route from the anterior chamber to the intrascleral and subconjunctival spaces. Postoperative management consists of topical antibiotics and corticosteroids for a few days.

8.1.6 Complications and Management

8.1.6.1 General

The complications that might occur in the course of nonpenetrating deep sclerectomy can be classiÞed into three groups. The Þrst group relates to the peroperative complications that happen during the dissection of the TDM, the implantation of the Þltering device (cylindrical collagen implant, viscoelastics, SK gel¨, T-Flux¨, etc.), or at any time during completion of the surgery. The second group reports the occurrences during the Þrst days after surgery, such as wound leaks, hypotony, shallow anterior chamber, choroidal detachment, hyphema, inßammation, infection, and ocular hypertony. The third group encompasses complications observed in the weeks or months after the Þltering procedure was performed and can comprises of problems related to the Þltering bleb, such as onset of Þbrosis of the bleb, encysted bleb, prolonged increase in the IOP, detachment of the DescemetÕs membrane, development of peripheral anterior synechia, or chronic hypotony.

8.1.6.2 Perioperative Complications

Perforation of the TDM can easily happen during the learning phase of this technique. A small perforation that does not reduce anterior chamber depth will not compromise surgery, which can be resumed normally. Larger perforations usually lead to the formation of a long tear, which is usually followed by immediate iris prolapse and subsequently a shallow or ßat anterior chamber. In this situation, a peripheral iridectomy should be performed after injection of low molecular weight viscoelastics to increase the anterior chamber depth. The superÞcial scleral ßap should then be tightly sutured with 6Ð8 interrupted 10-0 nonresorbable stitches and viscoelastics injected in the scleral space to limit the egress of aqueous humor (Fig. 8.19).

Blood might reßux from the drainage vessels, the collector channels through SchlemmÕs canal ostia when the episcleral venous pressure is higher than the IOP. Dissection of the TDM might be more difÞcult in this case. Blood reßux might be prevented by injecting some high molecular weight viscoelastics into the SchlemmÕs canal ostia with a Þne Grieshaber canula or by injecting some balanced salt solution into the anterior chamber to increase the IOP.

8.1.6.3 Early Postoperative Complications

A small wound leak or positive Seidel test may happen after insufÞcient wound closure. They generally seal by themselves, but in persistent cases a second wound closure should be performed to solve the problem.

The IOP on the Þrst postoperative day is generally low, in the range of 0Ð5 mmHg. This is a reliable

Fig. 8.19 SuperÞcial ßap closed with eight 10-0 Nylon sutures in case of trabeculo-DescemetÕs membrane perforation

indicator for a good dissection of the membrane. The pressure gradually increases to reach, 1 week after surgery, a plateau at around 9Ð12 mmHg. A wound leak or positive Seidel test should be considered in case of prolonged hypotony (over 1 week).

Owing to the nonpenetrating nature of deep sclerectomy, a completely ßat anterior chamber has never been reported after such a procedure. Yet a shallowing of the anterior chamber may be seen in patients with a signiÞcant drop in IOP. In this case, perforation of the TDM, wound leak, suprachoroidal hemorrhage, pupillary block, or malignant glaucoma should be ruled out.

Choroidal detachment is a rare complication after deep sclerectomy. In most of the cases, no speciÞc treatment is needed, the problem resolves spontaneously within a few days. In more serious cases, cycloplegics and anti-inßammatory drops should be given. In the most severe cases, drainage of the suprachoroidal space is proposed to prevent subsequent retinal and/or cornea damages. A small sclerectomy is performed in the lower quadrant, about 8Ð10 mm away from the limbus, to drain as much suprachoroidal ßuid as possible.

Hyphema may result from rupture of a small iris vessel or from a ßow of erythrocytes through the TDM. For this there is no speciÞc treatment and the problem will resolve spontaneously.

Inßammation is generally modest after nonpenetrating surgery, for the anterior chamber and the iris are left untouched. Inßammation can nevertheless be more pronounced in uveitic glaucoma, pseudoexfoliative glaucoma, pigmentary glaucoma, or traumatic glaucoma. Severe inßammation shall be addressed by extensive anti-inßammatory drugs, i.e., corticosteroids, which are tapered after the inßammation subsides, to prevent secondary steroid-induced ocular hypertony.

Infection of the bleb is a very rare event, which can be seen in patients with a compromised immunological system. An intensive regimen of topical broadspectrum antibiotics is prescribed and close monitoring of the eye structure is advocated to detect any extension of the infection, i.e., endophthalmitis.

Ocular hypertension can occur if the surgery is not performed correctly, when the TDM is not sufÞciently dissected, peeling of SchlemmÕs canal is not performed properly, in case of excessive viscoelastics remaining in the anterior chamber, large hemorrhage, or postoperative rupture of the membrane with subsequent iris prolapse. Nd:YAG laser goniopuncture might solve some of the problems related to the surgical technique. The pressure spikes shall resolve spontaneously a few

weeks after the surgery. In the most severe cases, a second surgery might be proposed.

8.1.6.4 Late Postoperative Complications

Postoperative tissue remodeling can induce important scarring of the subconjunctival space. Fibrosis of the conjunctiva or encysted Þltering bleb results from this scarring response and outßow of aqueous is impeded. Bleb needling with concomitant antimetabolites injection is recommended when on examination the bleb shows signs of Þbrosis and the IOP is elevated (>20mmHg). The subconjunctival cysts are treated the same way.

Sustained increase in the IOP may result from a decreased ßow through the TDM. An Nd:YAG laser goniopuncture is performed to enhance Þltration through the membrane. Extended Þbrosis of the Þltering space, the conjunctiva, or the superÞcial ßap may lead to an increase in IOP. Revision of the Þltering surgery may be

proposed to address this problem by reopening the scleral space and revising the superÞcial ßap.

A detachment of the DescemetÕs membrane may occur after nonpenetrating Þltering surgery. This complication is caused by the passage of aqueous humor from the scleral space into the sub-DescemetÕs space at the anterior edge of the DescemetÕs window. A bleb is visible on the posterior plane of the cornea, which corresponds to the separation of the DescemetÕs layer from its overlying stroma (Figs. 8.20 and 8.21). A decrease in the visual acuity is reported when the detachment extends over the visual axis. To solve this problem, a descemetopexy is performed after drainage of the underlying ßuid.

Intraoperative microruptures of the TDM, a large goniopuncture hole, or traumatic rupture of the TDM, are all associated with entrapment or incarceration of the iris, and will likely promote onset of peripheral anterior synechia. When the iris incarceration is important, outßow is compromised and the IOP increases (Figs 8.22 and 8.23). Laser peripheral anterior synechia lysis may be attempted

to reposition the iris back, or a secondary surgery could be performed to restore a normal Þltration.

A thin ischemic conjunctival bleb may lead to excessive Þltration, thus resulting in prolonged late chronic ocular hypotony with, in some occasions, hypotonyrelated maculopathy. Intraoperative antimetabolites (e.g., Mitomycin C) application might favor occurrence of this complication. Revision of the Þltering bleb and conjunctival graft is proposed to solve this problem.

References

1.Demailly P, Jeanteur-Lunel MN, Berkani M (1996) Non penetrating deep sclerectomy associated with collagen implant device in primary open angle glaucoma: middle term retrospective study. J Fr Ophtalmol 19:659Ð666

2.Fjodorov SN, Ioffe DI, Ronkina TI (1984) Deep sclerectomy: technique and mechanism of a new glaucomatous procedure. Glaucoma 6:281Ð283

3.Karlen M, Sanchez E, Schnyder CC et al (1999) Deep sclerectomy with collagen implant: medium term results. Br J Ophthalmol 83:6Ð11

4.Kozlov VI, Bagrov SN, Anisomova SY (1990) Deep sclerectomy with collagen. Eye Microsurg 3:44Ð46

5.Stegmann R (1995) Viscocanalostomy: a new surgical technique for open angle glaucoma. An Inst Barraquer 25: 225Ð232

6.Stegmann R, Pienaar A, Miller D (1999) Viscocanalostomy for open angle glaucoma in black African patients. J Cat Refract Surg 25:316Ð322

7.OÕDonoghue E, Batterbury M, Lavy T (1994) Effect on intraocular pressure of local anaesthesia in eyes undergoing intraocular surgery. Br J Ophthalmol 78:605Ð607

8.Sauder G, Jonas JB (2002) Topical anaesthesia for penetrating trabeculectomy. Graefes Arch Clin Exp Ophthalmol 240:739Ð742

9.Zabriskie NA, Ahmed II, Crandall AS et al (2002) A comparison of topical and retrobulbar anesthesia for trabeculectomy. J Glaucoma 11:306Ð314

10.Bill A, Svedbergh B (1972) Scanning electron microscopic studies of the trabecular meshwork and the canal of SchlemmÕs: an attempt to localize the main resistance to outßow of aqueous humour in man. Acta Ophthalmol (Copenh) 50:295Ð320

11.Ethier CR, Kamm RD, Palaszewski BA et al (1986) Calculation of ßow resistance in the juxtacanalicular meshwork. Invest Ophthalmol Vis Sci 27:1741Ð1750

12.Johnson M, Kamm RD (1983) The role of SchlemmÕs canal in aqueous outßow from the human eye. Invest Ophthalmol Vis Sci 24:320Ð325

13.Vaudaux J, Mermoud A (1998) Aqueous dynamics after deep sclerectomy: ex-vivo study. Ophthalmic Pract 16:204Ð209

14.Atesü H, Uretmen O, Anda• K et al (2003) Deep sclerectomy with a nonabsorbable implant (T-Flux): preliminary results. Can J Ophthalmol 38:482Ð488

15.LŸke C, Dietlein TS, Jacobi PC et al (2003) A prospective randomised trial of viscocanalostomy with and without implantation of a reticulated hyaluronic acid implant (SKGEL) in open angle glaucoma. Br J Ophthalmol 87: 599Ð603

16.Marchini G, Marraffa M, Brunelli C et al (2001) Ultrasound biomicroscopy and intraocular-pressure-lowering mechanisms of deep sclerectomy with reticulated hyaluronic acid implant. J Cataract Refract Surg 27:507Ð517

17.Shaarawy T, Nguyen C, Schnyder C et al (2003) Five year results of viscocanalostomy. Br J Ophthalmol 87:441Ð445

18.Sourdille P, Santiago PY, Villain F et al (1999) Reticulated hyaluronic acid implant in nonperforating trabecular surgery. J Cataract Refract Surg 25:332Ð339

19.Chiou AG, Mermoud A, Jewelewicz DA (1998) Postoperative inßammation following deep sclerectomy with collagen implant versus standard trabeculectomy. Graefes Arch Clin Exp Ophthalmol 236:593Ð596

20.Roth SM, Spaeth GL, Starita RJ et al (1991) The effects of postoperative corticosteroids on trabeculectomy and the clinical course of glaucoma: Þve-year follow-up study. Ophthalmic Surg 22:724Ð729

21.Mermoud A, Karlen ME, Schnyder CC et al (1999) Nd:YAG goniopuncture after deep sclerectomy with collagen implant. Ophthalmic Surg Lasers 30:120Ð125

22.Shaarawy T, Mansouri K, Schnyder C et al (2004) Long-

term results of deep sclerectomy with collagen implant. J Cataract Refract Surg 30:1225Ð1231

8.2Minimally Penetrating Glaucoma Surgery with the Ex-PRESS™ Miniature Shunt

8.2.1Introduction to Glaucoma Surgery with the Ex-PRESS™

Glaucoma is deÞned as a group of eye conditions that share either the common feature of progressive optic neuropathies (the open-angle variants) or the common feature of occludable drainage angles in the anterior chamber (the closed-angle variants). The primary goal of glaucoma therapy is to reduce IOP to the point where deterioration of the optic disk or visual Þelds ceases with a minimum of side effects or complications. The therapy currently available can be divided into three main groups: medical therapy, laser trabeculoplasty, and Þltering surgery.

In its essence, glaucoma surgery has always aimed to be minimally invasive, but recently nonpenetrating and minimally penetrating techniques have been proposed to improve the classic techniques further.

The Ex-PRESSª glaucoma implant is a miniature glaucoma shunt that was designed with the primary intention of offering a straightforward and safe drainage operation for the general ophthalmologist. The inventors (Belkin and Glovinsky) and the manufacturers (Optonol Ltd, Neve Ilan, Israel) initially suggested that the implant be inserted at the limbus under a conjunctival ßap [1Ð9]. This technique was soon abandoned for a safer and more efÞcient technique of implantation under a scleral ßap [10, 11]. This chapter will deal only with the use of Ex-PRESS implant under a scleral ßap because the implantation under a conjunctival ßap is not advised by the manufacturers. Furthermore, the great majority of the Ex-PRESS users worldwide are using it exclusively under a scleral ßap.

The Ex-PRESSª device is a nonvalved implant made of medical-grade implantable stainless steel (316L) identical to the material used for cardiac stents worldwide [4]. The Ex-PRESSª device and its material are FDA-approved for ophthalmic applications since 2002. Although it is metallic, the Ex-PRESSª is MRIsafe [4, 8]. The manufacturers advise not to do an MRI within 2 weeks after implantation to be on the safe side.

At present, two models of the Ex-PRESSª implants are available (Fig. 8.24). The basic design is of a 27-gauge (0.4 mm external diameter) tube, the length

Fig. 8.24 Ex-PRESSª. Top: Model P. Bottom: Model X. Both models are available in 50 and 200 mm inner bore diameter

of which varies from 2.4 to 3.0 mm. The internal diameter of the device is available in 50 or 200mm. The distal end can be bevelled and sharp or rounded off according to the device model (Fig. 8.24). The proximal end has a disk-like ßange that limits the device penetration into the anterior chamber (A/C). A spurlike projection is situated on the lower external surface of the tube to prevent extrusion once the device has been implanted. Both the ßange and the spur are angled to conform to the anatomy of the sclera and the distance between them corresponds to the scleral thickness at the limbus. The distal end has extra holes to provide alternative routes for the aqueous humor in case the main hole becomes obstructed.

The main concept of the Ex-PRESSª glaucoma implant is to allow a restricted aqueous humor ßow from the A/C to the subscleral and subconjunctival spaces (Fig. 8.25). The restricted internal diameter (50 or 200 mm) of the device provides a certain consistency and standardization to the Þltration procedure. In classic trabeculectomy, wide variations occurred not only with different surgeons but also in the hands of the same surgeon. These variations occur during sclerostomy that is done either by manual incisions or by punch. The Ex-PRESSª implantation does not require any tissue excision or removal whereas in trabeculectomy, a sclerostomy is mandatory and an iridectomy is performed by a great majority of surgeons.

Therefore, the Ex-PRESSª implantation can be described as minimally penetrating glaucoma surgery