Ординатура / Офтальмология / Английские материалы / Step by Step Minimally Invasive Glaucoma Surgery_Garg, Melamed, Bovet, Pajic, Carassa, Dada_2006

342 Step by Step Minimally Invasive Glaucoma Surgery

It is extremely important to check the preand postoperative pressures in the two eyes at the same times.

COMPLICATIONS

Complications During the Operation

Complications specifically connected with this combined operation consist in the rupture of the Descemet’s membrane. This happens if the timing already described is not respected and if the second flap is done before operating on the cataract.

Postoperative Complications

The most frequent postoperative complication with this technique is an increase of pressure, more or less long-term, with the collapse or closing up/healing on the site of the operation. Our technique uses an autograft of the sclera, soaked in Mitomycin C which inhibits all fibrocyte proliferation. This produces the best results and the lowest costs in the long term

REFERENCES

1.Arenas E. The routine use of mytomycine in trabeculectomy ab externo using a modified drill technique. Highlights of Ophthamol.World Atlas Series Vol. 2 1993;236-37.

2.Baumgartner JM, Bovet J, Baumgartner A. Etude de la stabilisation de la plaie opératoire et de la rapidité de la récupération fonctionnelle dans la chirurgie de la cataracte:Comparaison des résultat entre quatre techniques chirurgicales différentes. Ophtalmologie 1995;9:624–25.

3.JM Baumgartner, J Bovet, A Baumgartner. Deep Sclerectomy or trabeculectomy in outpatient eye surgery. SOE Budapest (abstract) June 97.

Bimanual Microphaco and Deep Sclerocanalostomy 343

4.J Bovet. Catarefractive Surgery: A next Step to Phakonit. In: A. Garg (Ed): Mastering the Art of Bimanual Microincision Phaco. Jaypee Brothers Medical Publishers, New Dehli 2005.

5.J Bovet, et al. Combined Glaucoma and cataract surgery (phacotrabeculectomy). Instruction course ( abstract) SOE, Budapest, European Ophthalmic Society, 1997.

6.J Bovet, et al. L’anesthésie topique en chirurgie oculaire et sa préparation In: A.B. Safran, T. Landis, P. Dayer (Eds): Les Dimensions de la douleur en ophtalmologie. Paris Masson 1998;166-73.

7.J Bovet, et al. Deep Phaco Glaucoma tunnel. ESCRS, video Nice 1998.

8.J Bovet. Deep lamellar sclerectomy, what’s new Eye Advance Mumbay India (abstract) Chairman Keiki Mehta, August 2004.

9.J. Bovet. Combined Sclerectomy and Phaco in Topical and conjunctival Bubble Anaesthesia. Island Ophthalmology, Puerto Rico (abstract) 1999.

10.Chiou AGY, et al. An ultrasound biomicroscopic study of eyes after deep sclerectomy with collagen implant. Ophthalmology 1998;105,4:104-08.

11.Gianoli F, et al. Combined surgery for cataract and glaucoma: phacoemulsification and deep slcerectomy compared with phacoemulsification. J Cataract and Refractive Surgery 1999;25:340-46.

12.Krasnov MM. Externalisation of Schlemm’s canal (sinusotomy) in glaucoma. Br J Ophthalmol 1968;52:15761.

13.Lebuisson DA, Bovet JJ. Le concept opératoire pour patients ophtalmologiques ambulants in Laroche L, Lebuisson DA, Montard M Chirurgie de la cataracte chap 6 pp61-74ed Masson 1996.

14.Massy J, Gruber D, Muraine M, Brasseur G. Nonpenetrating Deep Sclerectomy: collagen implant and viscocanalostomy procedures. Bylsma S. Int Ophthalmol Clin. 1999 Summer; 39(3):103-19.

344 Step by Step Minimally Invasive Glaucoma Surgery

15.Metha KR. The new phaco cleaves techniques for hard cataracts. J intraocular Implant and Refractive Society India 1996;1:74-75.

16.Molnar L, Beuchat J, Bovet M, Bumbacher JF. Chanson, JC Corne, C de Courten, F Failla, A Merz, F Paccolat, P Rabineau, F Rossi, F Simona, C Tabatabay, E Thorthon (Switzerland). Swiss multicentre study group for phacotrabeculectomy: current state ESRC Gothenburg, Sweden, (abstract) 10-13 October 1996.

17.Stegmann RC. Viscocanalostomy : a new surgical technique for open angle glaucoma. An Inst Barraque, Spain 1995;25:229-32.

18.Sampaolesi R. Glaucoma, Editorial Médica Panamericana, Buenos Aires, 1991; 2nd edition, pp. 525-26.

19.Tanibara H, Negi A, Akimoto M, et al. Surgical effects of trabeculectomy ab externo on adults eyes with primary open angle glaucoma and pseudoexfoliation syndrome. Arch Ophthalmol 1993;111:1653-61.

346 Step by Step Minimally Invasive Glaucoma Surgery

INTRODUCTION

Standard nonpenetrating glaucoma surgery (NPGS) currently consists of different methods, the most popular of which are deep sclerectomy and viscocanalostomy.1,2 The goal of NPGS is to create a surgical procedure as efficient as trabeculectomy but with less complications.3-6 The main idea of NPGS is to target the portion of the aqueous outflow pathway responsible for the main resistance to outflow, and to create filtration through the thin trabeculo-Descemet’s membrane.

The uveoscleral pathway was described more than 30 years ago.7 It was also termed unconventional outflow route (as opposed to the conventional or trabecular meshwork outflow) and showed to be responsible for up to 50 percent of aqueous humour drainage in monkey eyes.7 The aqueous percolates through the tissue spaces of the ciliary muscle into the supraciliary and suprachoroidal spaces.

We have observed that by tightly suturing the scleral flap, bigger amounts of the percolating aqueous could be forced through the remaining sclera into the uveoscleral outflow.8 Deep sclerectomy with collagen implant (VDSCI) is a modification of deep sclerectomy that was devised with the goal of increasing aqueous outflow via the uveoscleral pathway. By dissecting part of the deep sclera, the drainage of aqueous humour into the suprachoroidal space should be enhanced. Aqueous in the supra-choroidal space may hypothetically reach the uveoscleral outflow, and it could also induce a chronic ciliary body detachment thus reducing aqueous production.

At the same time, we aimed to reduce dependency on subconjunctival outflow to minimize the size of the filtering bleb and bleb-related discomfort and complications.

Very Deep Sclerectomy 347

We furthermore aimed to gain further knowledge in the mechanisms of function of NPGS that are not yet properly understood.

GENERALITIES

Indications for NPGS include primary or secondary openangle glaucoma, and exclude neovascular and closed-angle glaucoma. The procedure is particularly well adapted for patients with myopia due to the slow and gradual postoperative pressure reduction and the smaller subconjunctival filtering bleb size which enhances the comfort of wearing a contact lens.

SURGICAL TECHNIQUE

Retrobulbar, peribulbar or topical anesthesia can be used at the discretion of the surgeon. With peribulbar or retrobulbar block, the smallest amount of anesthetic should be used to allow rotation of the globe and thus give good exposure for the deep sclerectomy dissection. The initial steps for VDSCI are identical to those for standard DSCI, for which we give a short description here.

Conjunctiva and Tenon’s capsule are opened on 8-10 mm either at the limbus or at the fornix. Some light wetfield cauterization should be performed on the sclera as necessary at this stage.

A superficial scleral flap measuring 5 × 5 mm and including 1/3 of the scleral thickness (about 300 μm) is first delineated using a metal blade and then dissected with a crescent ruby blade (Huco vision SA, St-Blaise, Switzerland). In order to be able to later dissect the corneal stroma down to Descemet’s membrane, the scleral flap is dissected 1 to 1.5 mm into clear cornea. A sponge soaked in mitomycin-C, 0.02 percent, is used at this stage in

348 Step by Step Minimally Invasive Glaucoma Surgery

patients at high-risk of scarring (i.e. age below 60; melanoderma patients; previous history of conjunctival surgery; long standing history of glaucoma treatment; previous uveitis; or trauma).

Deep sclero-keratectomy is done by performing a second deep scleral flap (4 × 4 mm). The two lateral and the posterior deep scleral incisions are made using a 15-degree diamond blade. The deep flap is smaller than the superficial one leaving a margin of sclera on the three sides. This will allow a tighter closure of the superficial flap in cases of a preoperative perforation of the TDM. The deep scleral flap is then dissected horizontally. The remaining scleral layer should be as thin as possible (50 to 100 μm).

Reaching the anterior part of the dissection, Schlemm’s canal is unroofed and the sclero-corneal dissection is prolonged anteriorly into clear cornea for 1 to 1.5 mm in order to remove the sclero-corneal tissue behind the anterior trabeculum and the Descemet’s membrane. When the anterior dissection between the corneal stroma and Descemet’s membrane is completed, the deep scleral flap is cut anteriorly using the diamond knife.

At this stage of surgery, the very deep scleral dissection is performed. In the posterior quadrant of the sclera, two very deep flaps (each 1.5 × 1.5 mm) of the remaining 5-10 percent of sclera are excised and the choroid is exposed. A thin bridge of deep scleral tissue is left between the two flaps in order to prevent a possible choroidal prolapse (Figs 21.1 and 21.2).

At that last stage of the procedure, there should be a diffuse percolation of aqueous through the remaining trabeculo-Descemet’s membrane. The juxtacanalicular trabeculum and Schlemm’s endothelium are then removed. To avoid a secondary collapse of the superficial flap over the TDM and the remaining scleral layer, a collagen implant

350 Step by Step Minimally Invasive Glaucoma Surgery

is placed in the center of the scleral bed over the remaining bridge of deep sclera and secured inside the scleral bed with a single 10/0 nylon suture. The superficial scleral flap is then repositioned into place, and closed with two loose 10/0 nylon sutures. Conjunctiva and Tenon’s capsule are closed in two layers with a running 8/0 Vicryl suture.

PRELIMINARY RESULTS

In a prospective randomized trial that involved 50 patients we looked at the intraocular pressure lowering effect and safety of the new method of very deep sclerectomy with collagen implant (VDSCI, 25 patients) and compared it to standard deep sclerectomy with collagen implant (DSCI, 25 patients). The two groups were well matched with respect to gender, age, race, and glaucoma type. Mean preoperative IOP was 21.5 mmHg (±7.4) in the VDSCI and 22.7 mmHg (±4.4) in the DSCI group. After a mean followup of 6 months, the two procedures produced similar outcomes with respect to IOP (Fig. 21.3), success rates, reduction of medication use, and safety. On the first postoperative day IOP fell to 4.4 in the VDSCI and 5.6 mmHg in the DSCI group, a positive prognostic sign for IOP control as shown by Shaarawy and co-workers.9 Mean IOP at six months’ follow-up was 12.0 mmHg in the VDSCI and 12.5 in the DSCI eyes.

The safety profile of the new procedure has also been favorable with significantly fewer patients requiring postoperative MMC (3 VDSCI vs. 10 DSCI eyes) and only two eyes in the VDSCI group developing a choroidal detachment versus none in the DSCI group. There were no significant postoperative complications in this series. No shallow or flat anterior chamber, no-bleb-related endophthalmitis, and no surgery-induced cataract was observed in either group. There was one case of a malignant

Very Deep Sclerectomy 351

Fig. 21.3: IOP over time for VDSCI and DSCI groups. There was no significant difference at any point at time. Mean follow-up period was 6.5 months (maximum 12 months)

glaucoma in a patient of African origin in the DSCI group. Goniopuncture with the Nd:YAG laser was performed

on 3 VDSCI-treated eyes and 5 DSCI-treated eyes.

High frequency ultrasound biomicroscopy (UBM), as developed by Pavlin and Foster,10 provides in vivo detailed anatomic evaluation of the anterior segment of the eye. Using ultrasound biomicroscopy, it was possible to observe greater uveoscleral outflow in VDSCI eyes as measured by suprachoroidal effusion in 80 percent of VDSCI vs. 20 percent of DSCI patients (Figs 21.4 to 21.7). Mean subconjunctival bleb size was smaller in VDSCI eyes compared to DSCI eyes (9.1 vs. 29.6 mm3).

POSTOPERATIVE MANAGEMENT

As in standard NPGS, the first postoperative weeks are crucial for the success of the new procedure. Experience has shown that the appropriate postoperative management can have the same magnitude of influence on the surgical outcome as surgery itself. The following regimen for postoperative check-up is recommended as a guideline: