Ординатура / Офтальмология / Английские материалы / Glaucoma Surgery_Trope_2005

In most cases, leaking stops after a week and after discontinuing steroid therapy. Rarely, surgical intervention is necessary to repair the wound leak.

7.2.2.Inflammation

The degree of inflammatory reaction following nonpenetrating surgery is usually less than that seen with trabeculectomy. This is due to the fact that the AC is not penetrated and an iridectomy is not performed. Inflammation is treated with topical steroids for 6 weeks.

7.2.3.Hypotony

Early hypotony without perforation is an excellent indicator of good surgical dissection. Low postoperative IOP is expected in the early postoperative period because of the surgically induced increase in outflow facility. Ideally, the TDM should always offer enough resistance to prevent anterior-chamber collapse; flat anterior chambers are not expected with successful nonpenetrating filtering surgery.

On the first postoperative day, mean IOP after nonpenetrating filtering surgery usually measures 5 mmHg (19,20). IOP usually increases over the next few days without specific treatment.

7.3.Postoperative Increase in IOP

Because the main site of postoperative aqueous-humor outflow resistance after nonpenetrating filtering surgery is located at the TDM level, this complication should not occur if the dissection of the membrane has been performed correctly. Early postoperative IOP spikes are due to the following causes.

1.Insufficient surgical dissection. In such cases, the operative site can possibly be revised. A revision though is usually difficult, many surgeons opt for a re-operation in a different site.

2.Hemorrhage in the scleral bed. This usually spontaneously resolves without treatment within a few days.

3.Excess viscoelastic remaining in the AC, mainly after combined surgery or AC reformation with a microperforation. This usually resolves in a few days.

4.Postoperative rupture of the TDM with iris prolapse, secondary to increased IOP from eye rubbing, Valsalva’s maneuver, and so on. This should be managed with miotics and gonio Yag laser to the prolapsed iris. If this does not work, surgical iridectomy is indicated.

5.Peripheral anterior synechia (PAS) formation at the site of the filtering window, often secondary to intraoperative microperforation.

6.Steroid induced IOP increase within the first postoperative weeks.

Overall, IOP spikes are unusual postoperative complications and should be managed according to each specific cause.

7.4.Late Postoperative Complications

7.4.1.Late Rupture of the TDM

The risk of membrane rupture decreases with time because the postmembrane outflow resistance slowly builds for several weeks. However, rupture can occur after ocular trauma or after goniopuncture. With rupture, iris prolapses into the tear leading to a

distorted pupil and darkening of the subconjunctival area. If the IOP remains under control, no further treatment is needed. However, if the iris prolapse blocks the aqueous-humor outflow and the IOP rises, medical or surgical therapy including gonio laser or surgical iridectomy and AC reformation should be performed.

7.4.2.Descemet’s Detachment

Descemet’s membrane detachment is a rare complication after nonpenetrating filtering surgery. We estimate it occurs in about 1 out of 250 300 operated eyes. With viscocanalostomy, detachment is related to misdirected viscoelastic injection. The detachment is noticed during the procedure or generally shortly afterwards. After deep sclerectomy, this complication may be explained by the passage of aqueous humor from the scleral space to the sub-Descemet space at the anterior edge of Descemet’s window, secondary to increased intrableb pressure from trauma, encysted bleb, and vigorous ocular massage. This is usually a transient complication, but if it becomes prolonged, Descemetopexy has been tried successfully in such cases.

7.4.3.Peripheral Anterior Synechia

The iris may adhere to trabeculo-Descemet’s window and form PAS (21) in the following situations: intraoperative microperforation with microiris prolapse; iris entrapment into a goniopuncture hole, which usually occurs rapidly after laser treatment, and rupture of the TDM (e.g., blunt trauma) with subsequent iris prolapse. There may be an associated increase in IOP if there is insufficient aqueous-humor flow through the membrane. Yag laser lysis should be attempted to remove the iris from the osteum. If this fails, medical or surgical treatment should be considered.

7.4.4.Scleral Ectasia

In the literature, there is a single reported case (22) of scleral ectasia following deep sclerectomy in a12-year-old girl with chronic arthritis complicated with glaucoma secondary to a chronic uveitis. As rare as it is, this complication should be considered in patients with high myopia and chronic uveitis, especially in association with rheumatoid or juvenile arthritis. The use of antimetabolites intraor postoperatively may also increase the risk of this complication.

8.RESULTS OF NPGS

Prospective nonrandomized trials of deep sclerectomy (23 27) and viscocanalostomy (28 30) provide sufficient evidence that the procedure can reduce IOP to acceptable levels. Randomized controlled trials (15,31 35) comparing NPGS with trabeculectomy have a consensus on the superior safety profile of NPGS. On efficacy, we have controversial reports. This disparity in results can be attributed to a number of factors, namely the fundamental differences between various NPGS techniques, the long-learning curves, and the use of goniopunctures to achieve target IOPs. One should keep in mind though as he browses between results that it is all about technique. Issues related to which technique is superior to which in the wide spectrum of NPGS is of paramount importance. The fact of an existing long learning curve could not be over-stated. It is neither meaningful nor scientifically sound to compare one’s last twenty cases of trabeculectomy to one’s first twenty

deep sclerectomies. What is valid is that with its apparent mechanisms of function that seems to target specific pathological structure in glaucoma, NPGS is quite promising.

It would be prudent to remember that from the weight of evidence that we have available, it is of absolute importance to achieve proper depth of dissection, to use implants, and to perform goniopuncture whenever target IOPs are not achieved.

REFERENCES

1.Zimmerman TJ, Kooner KS, Ford VJ, Olander KW, Mandlekorn RM, Rawlings EF et al. Trabeculectomy vs. nonpenetrating trabeculectomy: a retrospective study of two procedures in phakic patients with glaucoma. Ophthalmic Surg 1984; 15:734 740.

2.Zimmerman TJ, Kooner KS, Ford VJ, Olander KW, Mandlekorn RM, Rawlings FE et al. Effectiveness of nonpenetrating trabeculectomy in aphakic patients with glaucoma. Ophthalmic Surg 1984; 15:44 50.

3.Mermoud A. Sinusotomy and deep sclerectomy. Eye 2000; 14:531 535.

4.Johnson DH, Johnson M. How does nonpenetrating glaucoma surgery work? Aqueous outflow resistance and glaucoma surgery. J Glaucoma 2001; 10:55 67.

5.Kozlov VI, Bagrov SN, Anisimova SY, Osipov AV, Mogilevtsev VV. Deep Sclerectomy with collagen. Eye Microsurg 1990; 3:44 46.

6.Stegmann R, Pienaar A, Miller D. Viscocanalostomy for open angle glaucoma in black African patients [see comments]. J Cataract Refract Surg 1999; 25:316 322.

7.Mermoud A, Schnyder CC, Sickenberg M, Chiou AG, Hediguer SE, Faggioni R. Comparison

of deep sclerectomy with collagen implant and trabeculectomy in open angle glaucoma. J Cataract Refract Surg 1999; 25:323 331.

8.Hamel M, Shaarawy T, Mermoud A. Deep sclerectomy with collagen implant in patients with glaucoma and high myopia. J Cataract Refract Surg 2001; 27:1410 1417.

9.Drolsum L. Deep sclerectomy in patients with capsular glaucoma. Acta Ophthalmol Scand 2003; 81:567 572.

10.Tixier J, Dureau P, Becquet F, Dufier JL. Deep sclerectomy in congenital glaucoma. Preliminary results. J Fr Ophtalmol 1999; 22:545 548.

11.Kozlov VI, Bagrov SN, Anisimova SY, Osipov AV, Mogilevtsev VV. Nonpenetrating deep sclerectomy with collagen. Eye Microsurg (In Russian) 1990; 3:157 162.

12. Detry Morel M. Non penetrating deep sclerectomy (NPDS) with SKGEL implant and/or 5 fluorouracile (5 FU). Bull Soc Belge Ophtalmol 2001; 280:23 32.

13.Shaarawy T, Nguyen C, Schnyder CC, Mermoud A. Comparative study between deep scle rectomy with and without collagen implant: long term follow up. Br J Ophthalmol 2004; 88(1):95 98.

14.Mermoud A, Karlen ME, Schnyder CC, Sickenberg M, Chiou AG, Hediguer SE et al. Nd:Yag goniopuncture after deep sclerectomy with collagen implant. Ophthalmic Surg Lasers 1999; 30:120 125.

15.Gandolfi S, Quaranta L, Cimino L, Bettelli S. Deep sclerectomy versus trabeculectomy. Prospective Randomized Clinical trial. 4 Year interim analysis. Proceedings of the Second International Congress on Glaucoma Surgery, Luxor, Egypt, 2003.

16.Karlen ME, Sanchez E, Schnyder CC, Sickenberg M, Mermoud A. Deep sclerectomy with collagen implant: medium term results [see comments]. Br J Ophthalmol 1999; 83:6 11.

17.Mermoud A, Schnyder CC, Sickenberg M, Chiou AG, Hediguer SE, Faggioni R. Comparison of deep sclerectomy with collagen implant and trabeculectomy in open angle glaucoma [see comments]. J Cataract Refract Surg 1999; 25:323 331.

18.Sanchez E, Schnyder CC, Mermoud A. Comparative results of deep sclerectomy trans formed to trabeculectomy and classical trabeculectomy. Klin Monatsbl Augenheilkd 1997; 210:261 264.

19.Shaarawy T, Karlen M, Schnyder C, Achache F, Sanchez E, Mermoud A. Five year results of deep sclerectomy with collagen implant. J Cataract Refract Surg 2001; 27:1770 1778.

20.Ambresin A, Shaarawy T, Mermoud A. Deep sclerectomy with collagen implant in one eye compared with trabeculectomy in the other eye of the same patient. J Glaucoma 2002; 11:214 220.

21.Kim CY, Hong YJ, Seong GJ, Koh HJ, Kim SS. Iris synechia after laser goniopuncture in a patient having deep sclerectomy with a collagen implant. J Cataract Refract Surg 2002; 28:900 902.

22.Milazzo S, Turut P, Malthieu D, Leviel MA. Scleral ectasia as a complication of deep sclerectomy. J Cataract Refract Surg 2000; 26:785 787.

23.Sanchez E, Schnyder CC, Sickenberg M, Chiou AG, Hediguer SE, Mermoud A. Deep sclerectomy: results with and without collagen implant. Int Ophthalmol 1996; 20:157 162.

24.Karlen ME, Sanchez E, Schnyder CC, Sickenberg M, Mermoud A. Deep sclerectomy with collagen implant: medium term results. Br J Ophthalmol 1999; 83:6 11.

25.Hamard P, Plaza L, Kopel J, Quesnot S, Hamard H. Deep nonpenetrating sclerectomy and open angle glaucoma. Intermediate results from the first operated patients. J Fr Ophtalmol 1999; 22:25 31.

26.Shaarawy T, Karlen M, Schnyder C, Achache F, Sanchez E, Mermoud A. Five year results of deep sclerectomy with collagen implant. J Cataract Refract Surg 2001; 27:1770 1778.

27.Yamin M, Quentin CD. Results and complications after deep sclerectomy. Ophthalmologe 2002; 99:171 175.

28.Sunaric Megevand G, Leuenberger PM. Results of viscocanalostomy for primary open angle glaucoma. Am J Ophthalmol 2001; 132:221 228.

29.Wishart MS, Shergill T, Porooshani H. Viscocanalostomy and phacoviscocanalostomy: long term results. J Cataract Refract Surg 2002; 28:745 751.

30.Shaarawy T, Nguyen C, Schnyder CC, Mermoud A. Five year results of viscocanalostomy in Caucasians. Br J Ophthalmol 2003; 87(4):441 445.

31.Carassa R. Viscocanalaostomy versus trabeculectomy: a 12 months prospective randomized study. American Society of Cataract and Refractive Surgery, Boston, USA, 2000.

32.Netland PA. Nonpenetrating glaucoma surgery. Ophthalmology 2001; 108:416 421.

33.Jonescu Cuypers C, Jacobi P, Konen W, Krieglstein G. Primary viscocanalostomy versus trabeculectomy in white patients with open angle glaucoma: a randomized clinical trial. Ophthalmology 2001; 108:254 258.

34.Luke C, Dietlein TS, Jacobi PC, Konen W, Krieglstein GK. A prospective randomized trial of viscocanalostomy versus trabeculectomy in open angle glaucoma: a 1 year follow up study. J Glaucoma 2002; 11:294 299.

35.El Sayyad F, Helal M, El Kholify H, Khalil M, El Maghraby A. Nonpenetrating deep sclerect omy versus trabeculectomy in bilateral primary open angle glaucoma. Ophthalmology 2000; 107:1671 1674.

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2.SURGICAL TECHNIQUE

2.1.Anesthesia

We prefer performing glaucoma implant surgery under local anesthesia. Our preference is for retrobulbar anesthesia, but this surgery can be done utilizing subtenons and even local anesthetic jelly if required.

2.2.Conjunctival Incision

The single plate implant may be inserted superonasally or superotemporally, between the superior rectus and the medial or lateral rectus muscles. A limbal or fornix-based incision can be utilized. We prefer fornix-based conjunctival incisions. The conjunctiva is ballooned up at the limbus by the injection of balanced salt solution (BSS). If the conjunctiva is adherent to the sclera for a distance .1 mm as a result of previous surgery, a different site needs to be chosen for the placement of the implant. The fornix-based conjunctival flap is then formed by incising the conjunctiva at the limbus for a length of 12 mm. A relieving incision of 5 mm is then made parallel to the upper border of medial or lateral rectus muscle, depending on which quadrant the implant is to be inserted. The two edges of the cut limbal conjunctiva are identified for reattachment, by placing two marker sutures at their extremities. This allows for accurate reattachment at the conclusion of the insertion of the implant. The conjunctiva is then undermined, by opening with Westcott scissors between sclera and conjunctiva. The dissection extends posteriorly for about 10 12 mm. A pocket is thereby created for the insertion of the drainage plate. The posterior widespread dissection is to be avoided, as the space created should not be larger than the diameter of the plate. This can be achieved by pushing a Weck cell sponge into the area designated for the plate, creating a limited space, and thereby decreasing the chances for hypotony in the immediate post-operative period, particularly when using a nonvalved implant (3). If a Baerveldt implant is to be used, isolation of the medial or lateral rectus muscle, as well as the superior rectus muscle, is achieved by the use of muscle hooks. This needs to be done as the lateral and medial wings of the implant need to be placed beneath the muscles. Prior to the insertion of the implant, two 8/0 silk sutures on Alcon cu5 needles are inserted through the two anterior suture holes located on all the implants (Fig. 7.1). The steep curve of the needles enables the exit path of the needle to be very close to its entry, allowing for accurate placement of the anterior edge of the implant distance wise from the limbus. A less curved needle would exit a greater distance from the plate, moving it forward towards the limbus.

2.3.Plate Attachment

The Ahmed and Molteno implants may be slid back into the pocket created between Tenons-conjunctiva and sclera, by using a curved Harms tying forceps placed on either side of the silicone tube, at its junction with the plate, and gently pushing the plate posteriorly into the previously created pocket (Fig. 7.2). The Baerveldt implant requires retraction of the superior and medial or lateral rectus muscles, so that the wings of the implant can be placed underneath two of these muscles, depending on which quadrant the implant is being placed. The plate is then fixed to the sclera with the preplaced 8/0 silk sutures. The anterior edge of the plate should be 8 10 mm from the limbus (Fig. 7.3)

Tip 1: If a preplaced suture is not used prior to placing the plate into the conjunctival pocket, it is still possible to suture the plate to sclera. However, in this situation, first place the plate into position. Then, place the first suture into the sclera 10 mm from the limbus in

Figure 7.3 (See color insert) Placing sutures through sclera 8 10 mm from limbus.

front of one of the holes on the leading edge of the plate. Then, pass the blunt side of the suture (the side with the suture) through the lower plate hole while holding the plate to exit through the upper opening last, that is, backwards. Tie the suture and repeat the process with the second hole. This maneuver prevents inadvertent scleral perforation that can occur if the suture is passed from plate into sclera.

Tip 2: If fibrosis or poor visualization prevents access to one or the other plate holes, it is still possible to firmly tie the plate by passing a suture through the anterior lip of one of the newer silicone Ahmed valves. The lip is soft enough to easily pass a sharp needle through it to facilitate plate adhesion to sclera.

2.4.Valve Priming

Using the Ahmed implant, the implant should be examined and primed prior to implantation. Priming is accomplished by injecting 1 cc of BSS or sterile water through the drainage tube and valve using a 30 gage cannula. The BSS should be seen to flow through the valve to ensure that it is open prior to inserting the implant. The valve site should not be touched with forceps, as this may lead to damage resulting in failure of valve function.

2.5.Tube Preparation and Patch Graft

2.5.1.Tube Stent

If a Baerveldt or Molteno implant is being used, then prior to insertion of the plate, a 3/0 supramid suture is placed into the silicone tube from its opening onto the plate (Fig. 7.1). A section of 3/0 supramid suture 15 20 mm in length is cut, and one end is grasped with a tying forceps and gently inserted into the silicone tube from the opening on the plate side. The suture is inserted for a distance of 6 10 mm into the tube. This suture will be used as a temporary valve to be removed during the post-operative period (2).

2.5.2.Patch Graft

Prior to the trimming and insertion of the tube, donor or preserved sclera or pericardium used to cover the tube is brought onto the operative field and cut to size, so that it will cover

Figure 7.4 (See color insert) Pericardium cut to cover tube from plate to limbus.

the tube from its insertion into the anterior chamber to its attachment to the plate (Fig. 7.4). The graft is sutured to the sclera prior to the insertion of the tube into the anterior chamber. This is done by suturing one side of the graft and preplacing the sutures into the other side but leaving them untied, so that the graft can be retracted to one side leaving access to the underlying tube (Fig. 7.5). Preplacing the sutures allows the graft to be fixated into place immediately after the tube is inserted into the anterior chamber. Furthermore, if hypotony occurs, as it occasionally does after tube insertion, having preplaced the sutures eliminates the need to insert sutures into an hypotonous eye, which can be difficult. The sutures used for the graft are 10/0 nylon sutures placed at the anterior and posterior corners of the graft.

Tip 1: If a seton is inserted in the infero-temporal quadrant, cover the tube with half thickness donor cornea. Cornea, being clear, has a much better cosmetic appearance than

Figure 7.5 (See color insert) Pericardium retracted to side following insertion of preplaced sutures. Suture preplaced around silicone tube.

sclera that is cosmetically unacceptable in this potentially exposed areas because of its white color.

2.5.3.Tube Suture

It is important to fixate the tube to the sclera. This is done by passing a 10/0 suture through sclera beneath the tube, again left untied, until the tube has been inserted, at which time this preplaced suture should be tied to fixate the tube to the sclera (Fig. 7.5). Be careful not to tie this suture too tightly as you may block aqueous flow; however, this is highly unlikely with the use of a 10/0 nylon suture.

2.5.4.Tube Trimming

Prior to inserting the silicone tube into the anterior chamber, it needs to be trimmed. The length of tubing to be inserted depends on the condition being treated. Usually, the tube should be 1 3 mm in length in the anterior chamber. However, if neovascular glaucoma is being treated, the tube needs to be longer to avoid blockage by fibrous tissue. The tube should extend almost to the pupil margin. As this measurement is done over the exterior of the cornea, one should ensure that no traction is placed on the tube when estimating the future internal length, as this will result in a shorter than desired result. The tube is then cut with a scissors, the blades facing upwards to ensure a bevel on the tube that is facing upwards and away from the iris preventing it from blocking the tube (Fig. 7.6).

Prior to inserting the tube, a paracentesis should be done at the lateral aspect of the limbus with a microsharp blade (Fig. 7.7). This allows for reformation of the anterior chamber, if this become necessary during insertion of the tube, as well as possible manipulation of the tube with an iris repositor, again if this become necessary. A 22 or 23 gage needle is then used to enter the anterior chamber. The needle is inserted immediately posterior to the limbus, unless peripheral anterior synechiae are present, as seen in neovascular glaucoma, in which case the needle needs to be inserted anterior to the peripheral anterior synechiae, thus avoiding obstruction of its insertion into the anterior chamber (Fig. 7.8). The needle is inserted parallel to the iris and mid-way between iris and

Figure 7.6 (See color insert) Cutting of tube with scissor blades facing upwards to ensure bevel of tube is facing up.