ORIGINAL STUDY
Use of Autologous Scleral Graft in Ahmed Glaucoma Valve Surgery Alvit Wolf, MD,* Yair Hod, MD,* Gila Buckman, MD,* Nili Stein, MPH,w and Orna Geyer, MD*
Purpose: To compare the efficacy of an autoscleral free-flap graft versus an autoscleral rotational flap graft in Ahmed glaucoma valve (AGV) surgery. Patients and Methods: Medical records (2005 to 2012) of 51 consecutive patients (51 eyes) who underwent AGV surgery with the use of either an autoscleral free-flap graft or an autoscleral rotational flap graft to cover the external tube at the limbus were retrieved for review. The main outcome measure was the incidence of tube exposure associated with each surgical approach.
grafting has the advantage of being sterile, immunologically safe, readily available, and least costly. Aslanides et al13 described the efficacy of autologous sclera as a patch graft in GDD surgery. Their study was limited, however, by the small number of patients and a short period of follow-up. The purpose of this study was to report the long-term efficacy of autologous sclera as the primary patch graft for covering the tube in Ahmed glaucoma valve (AGV) surgery.
Results: Twenty-seven consecutive patients (27 eyes) received a free-flap graft and 24 consecutive patients (24 eyes) received a rotational flap graft. The mean follow-up time was 55.6 ± 18.3 months for the former and 24.2 ± 5.0 months for the latter (P < 0.0001). Two patients in the free-flap group (8.9%) developed tube exposure at 24 and 55 months postoperatively compared with none of the patients in the rotational flap group. Graft thinning without evidence of conjunctival erosion was observed in 15 patients (55%) in the free-flap group and in 7 patients (29.1%) in the rotational flap group. Conclusions: The use of an autoscleral rotational flap graft is an efficacious technique for primary tube patch grafting in routine AGV surgery, and yielded better results than an autoscleral freeflap graft. Its main advantages over donor graft material are availability and lower cost. Key Words: glaucoma drainage devices (GDD), tube exposure, patch graft, autologous sclera
(J Glaucoma 2016;25:365–370)
T
ube exposure is an occasional complication of glaucoma drainage device (GDD) surgery. It is of clinical concern because it predisposes the eye to endophthalmitis.1 The standard method to prevent this complication is the use of a patch graft to cover the external silicone tube of the GDD. Various tissues have been advocated as graft material, including human sclera,2 pericardium,3,4 dura mater,5 fascia lata,6 cornea,7,8 amniotic membrane,9 and porcine intestinal submucosa (KeraSys).10 All of these materials require the use of donor tissue and carry the risk of immune-mediated patch melting11 or transmission of infectious diseases.12 Availability and cost are additional concerns. Autologous scleral patch Received for publication March 6, 2014; accepted January 7, 2015. From the Departments of *Ophthalmology; and wCommunity Medicine and Epidemiology, Carmel Medical Center, affiliated to the Rapaport Faculty of Medicine, The Technion, Haifa, Israel. Disclosure: The authors declare no conflict of interest. Reprints: Orna Geyer, MD, Head, Department of Ophthalmology, Carmel Medical Center, 7 Michal Street, Haifa 34362, Israel (e-mail: [email protected]). Copyright r 2015 Wolters Kluwer Health, Inc. All rights reserved. DOI: 10.1097/IJG.0000000000000232
J Glaucoma
Volume 25, Number 4, April 2016
FIGURE 1. Intraoperative photographs illustrating the autoscleral free-flap technique. A, One half of the scleral thickness rectangular flap (57 mm) is taken from the sclera remote from the site planned for valve insertion and just anterior to the rectus muscle insertion, parallel to the limbus. B, The scleral flap is placed over the exposed part of the tube and secured to the underlying sclera with 4 interrupted 10-0 nylon sutures. Figure 1 can be viewed in color online at www.glaucomajournal.com.
www.glaucomajournal.com |
Copyright r 2016 Wolters Kluwer Health, Inc. All rights reserved.
365
Wolf et al
J Glaucoma
PATIENTS AND METHODS Patients This retrospective interventional case series of consecutive patients who underwent AGV surgery with autoscleral patch grafting to cover the subconjunctival portion of the tube was approved by the Institutional Review Board (IRB no. 350). Written informed consent was obtained from all patients before surgery. All procedures were performed by 1 surgeon (O.G.) between April 2005 and May 2012. A free scleral patch flap was performed in all patients before January 2010. Beginning January 2010, the practice was changed and all patients scheduled to undergo AGV surgery in our department received a pedunculated flap.
Surgical Technique All the study subjects underwent implantation of an AGV model FP7 (New World Medical Inc., Rancho Cucamonga, CA) under general anesthesia. The position of the AGV insertion site was in the superior or inferior quadrant, depending on the conjunctival mobility and the presence of previous surgical conjunctival scarring. The surgical procedure was similar for superior and inferior valves. The surgical technique used for eyes that had free scleral flap patches began with a limbal peritomy in the quadrant located 180 degrees away from the site planned for shunt insertion. In the event that the scleral thickness was inappropriate (ie, too thin), scleral tissue was taken from a different site but still remote from the site planned for valve insertion. The conjunctiva and Tenon’s capsule were dissected posteriorly, exposing the sclera. Hemostasis was achieved with a bipolar cautery. A 5 7 mm scleral flap was outlined with a caliper in the area just anterior to the rectus muscle insertion and parallel to the limbus. The sclera graft was dissected at half the scleral thickness along marked dimensions and removed with a no. 15 blade (Fig. 1A). The graft was transferred to BSS solution and kept there until use. The conjunctiva and Tenon’s capsule were sewn into place with 8-0 Vicryl sutures. In the quadrant planned for shunt insertion (at a site remote from the
Volume 25, Number 4, April 2016
one from which the flap was harvested), a fornix-based conjunctival flap was created, forming a pocket for the insertion of the Ahmed valve plate. The plate of the implant was inserted into the sub-tenon pocket and secured to the sclera at a distance of 8 to 10 mm posterior to the surgical limbus using a 9-0 Prolene horizontal mattress suture. The tube was trimmed to extend 2 mm beyond the limbus into the anterior chamber, with the bevel facing the cornea. The tube was inserted into the anterior chamber through a corneoscleral track created with a 23 G needle. The preprepared scleral patch graft was placed with the narrow part (5 mm) parallel and over the exposed part of the tube anteriorly to where the tube entered the sclera to ensure coverage. The patch was then secured to the sclera using 4 interrupted 10-0 nylon sutures (Fig. 1B). The conjunctiva and Tenon’s capsule were sewn into place with 10-0 nylon sutures to fully cover the scleral graft. The surgical method used for eyes that had the rotational scleral flap patch began with implantation of the AGV by the same surgical technique as that for the free scleral flap. After insertion of the tube into the anterior chamber, a lamellar scleral flap was created from the sclera adjacent to the tube and extending either temporally or nasally to it. The sclera in this area was marked to fashion a 55 mm rotational flap parallel to the limbus. The scleral flap, which was half the scleral thickness, was cut along the marked dimensions with the end adjacent to the tube that was still attached to the original scleral bed. The flap was then rotated over the tube and secured to the underlying sclera on the opposite side of the tube with 10-0 Vicryl sutures (Fig. 2). The conjunctiva was reopposed with 8-0 Vicryl sutures. Topical antibiotics were used at the end of the procedure. The postoperative regimen included topical ciprofloxacin eye drops 4 times per day (qid) for 1 week and topical prednisolone acetate 1% eye drops qid that was usually tapered over 6 to 8 weeks. Antiglaucoma medications were added when necessary. Information collected from patients’ medical records included age, sex, any existing systemic condition (diabetes mellitus, hypertension), type of glaucoma, previous ocular surgery, preoperative intraocular pressure (IOP), glaucoma medications, surgical variables (date of procedure, implant location, and type of patch graft used), and follow-up data (IOP values and glaucoma medications at the most recent clinical visit). The main outcome measures were tube exposure and characteristics of the graft and the sclera at the harvest site.
Statistical Analysis
FIGURE 2. Intraoperative photograph illustrating the autoscleral rotational flap technique. The flap (5 5 mm) is created from the sclera adjacent to the tube, rotated over the tube, and secured to the underlying sclera on the opposite side of the tube with 10-0 Vicryl sutures. Figure 2 can be viewed in color online at www. glaucomajournal.com.
The statistical analysis was performed with the IBM SPSS statistics 32 software. Comparisons between the freeflap and rotational flap groups were performed using the w2 test for the categorical variables, whereas the independent t test or the Mann-Whitney test was applied for the continuous variables. The systemic and ocular characteristics of patients with and without graft thinning were compared for potential risk factors for graft thinning. Because 2 cases with tube exposure had patch graft thinning for a long period of time before the actual onset of exposure, they were included in the graft thinning group and their data were included up to the point of exposure. Evaluation of the association between characteristics of the participants and patch thinning was performed with the univariate logistic regression analyses. A P-value of r0.05 was considered statistically significant in our analyses.
366 | www.glaucomajournal.com Copyright r 2015 Wolters Kluwer Health, Inc. All rights reserved. Copyright r 2016 Wolters Kluwer Health, Inc. All rights reserved.
J Glaucoma
Volume 25, Number 4, April 2016
Autocleral Graft for Ahmed Valve
RESULTS A total of 51 consecutive patients (51 eyes) underwent AGV implant surgery with autologous scleral patch grafting. Twenty-seven patients (27 eyes) had the free-flap technique and 24 patients (24 eyes) had the rotational flap approach. There were no intraoperative complications in either group. No patient was lost to follow-up during the course of the study. The patients’ baseline characteristics, operative details, and follow-up data are presented in Table 1. No significant differences in any of the demographic or baseline clinical features were observed between treatment groups. The mean follow-up time for the rotational flap group (24.2 ± 5.0 mo) was significantly shorter than the mean follow-up time for the free-flap group (55.6 ± 18.3 mo, P < 0.0001) because the former had not been performed in our department until
TABLE 1. Baseline Demographic, Ocular Characteristics, Operative and Postoperative Details of Patients Undergoing AGV Implantation With Autologous Scleral Patch Grafts
Free Flap No. patients (eyes) Mean age ± SD (y) Range Male [no. patients (%)] Diabetes [no. patients (%)] Hypertension [no. patients (%)] Glaucoma diagnosis [no. patients (%)] Primary open angle Neovascular Uveitic Silicone oil Iridocorneal endothelial syndrome Other Previous ocular surgery [no. patients (%)] Glaucoma Retinal Cataract Mean preoperative IOP ± SD (mm Hg) Mean no. preoperative glaucoma medications ± SD Valve location [no. patients (%)] Superotemporal Superonasal Inferotemporal Inferonasal Follow-up (mean ± SD) (mo) Median Range Postoperative mean IOP ± SD (mm Hg), at the last follow-up visit Postoperative mean no. glaucoma medications ± SD, at the last follow-up visit*
Rotational Flap
27 (27) 24 (24) 59.3 ± 15.6 62.0 ± 14.3 22-86 20-80 12 (44.4) 9 (37.5) 10 (37.0) 9 (37.5) 10 (37.0) 8 (33.3)
P 0.526 0.615 0.973 0.782 0.895*
14 8 1 2 1
(51.9) (29.6) (3.7) (7.4) (3.7)
1 (3.7) 24 (88.9)
12 6 2 1 1
(50) (25) (8.3) (4.2) (4.2)
2 (8.3) 17 (70.8)
18 (66.7) 12 (50) 4 (14.8) 0 19 (70.4) 11 (45.8) 32.5 ± 7.57 32.9 ± 7.74 3.48 ± 1.19 3.39 ± 0.78
0.160 0.227 1.113 0.076 0.854 0.531 0.490
16 (59.3) 6 (22.2) 4 (14.8) 1 (3.7) 53.5 ± 19.3
17 (70.8) 6 (25.0) 1 (4.2) 0 24.2 ± 5.0
55.1 12.0-97.8 19.04 ± 9.8
26.3 15.2-31.7 17.4 ± 4.8
0.468
2.35 (1.2)
1.46 (0.98)
0.007
< 0.0001
*Primary open-angle glaucoma versus other. AGV indicates Ahmed glaucoma valve; IOP, intraocular pressure.
Copyright
r
January 2010. There was no significant difference in postoperative mean IOP between groups (P = 0.468). The rotational flap group used significantly fewer glaucoma medications after the surgery (P = 0.007). Graft thinning in which the shunt tube was clearly visible through the conjunctiva without evidence of conjunctival erosion was observed in 7 patients in the rotational flap group and in 15 patients in the free-flap group. Table 2 summarizes the risk factors for graft thinning. The number of postoperative glaucoma medications and the flap type were the significant factors associated with graft thinning (P = 0.016 and 0.058, respectively). Age, sex, implant location, type of glaucoma, number of previous ocular surgeries, preoperative IOP, preoperative glaucoma medications, postoperative IOP, diabetes mellitus, and hypertension were not related to patch thinning. None of the patients in the rotational flap group developed tube exposure. Two patients (8.9%) in the freeflap group and who had previous patch thinning developed conjunctival erosion and tube exposure. One of those cases was a 60-year-old pseudophakic female with a long-standing history of primary open-angle glaucoma and status post 3 trabeculectomies. Her AGV was located in the superotemporal quadrant, and a free scleral flap patch had been used. Tube exposure had occurred 24 months after her initial surgery. Prompt surgical revision with a new free-flap graft was performed with no further complications during the subsequent 36 months of follow-up. The second case was a 32-year-old diabetic pseudophakic male who was postvitrectomy and trabeculectomy and who underwent AGV surgery with a free scleral flap patch implanted in the superotemporal quadrant of the right eye. Tube exposure occurred 55 months following surgery. A revision surgery was performed with a new free-flap graft, and no reexposure was observed at the 1-year follow-up visit. There were no complications at the harvest site in either group. Choroidal “blue” showing through the thin sclera region where the flap was created was observed in 9 patients of the free-flap graft group but, notably, in none of the patients in the rotational flap group
DISCUSSION Placement of a patch graft over the anterior part of a tube to reduce the risk of erosion through the overlying conjunctiva is an integral part of GDD surgery. Different homologous or heterologous materials1–10 have been used for grafting with satisfactory outcomes. Availability and cost may, however, be barriers to the routine use of those grafts, and the autoscleral patch is an excellent alternative. In 1999, Aslanides et al13 reported on 16 patients who underwent a GDD implant with autologous “free” or “rotational” scleral flap patching, and those authors detected no cases of tube erosion during the 14 months of follow-up. To the best of our knowledge, the current study is the first to demonstrate the long-term efficacy of autologous sclera as a primary patch graft to reduce tubal exposure in glaucoma shunt surgery. We had used free autoscleral patch grafts in AGV surgery since 2005, and it was our impression that the extra intraoperative manipulation required for harvesting the graft from a different quadrant than the one used for implant insertion substantially increased the time of surgery. We reasoned that a rotational flap created from the sclera immediately adjacent to the tube would shorten the
2015 Wolters Kluwer Health, Inc. All rights reserved.
www.glaucomajournal.com |
Copyright r 2016 Wolters Kluwer Health, Inc. All rights reserved.
367
Wolf et al
J Glaucoma
Volume 25, Number 4, April 2016
TABLE 2. Characteristics of Participants and Association With Patch Thinning*
Patch Status Age (mean ± SD) (y) Sex [n (%)] Female Male Diabetes [n (%)] No Yes Hypertension [n (%)] No Yes Glaucoma diagnosis [n (%)] Open angle Other Previous ocular surgeries [n (%)] No Yes Preoperative IOP (mm Hg) Postoperative IOP (mm Hg) No. preoperative glaucoma medications (median) No. postoperative glaucoma medications (median) Valve location [n (%)] Superotemporal Other Flap type [n (%)] Rotational Free
Nonthinning (n = 29)
Thinning (n = 22)
OR (95%CI)
P
62.1 ± 15.9
58.5 ± 13.8
0.98 (0.95-1.02) 0.98 (0.32-3.03)
0.407
17 (56.7) 12 (57.1)
13 (43.3) 9 (42.9)
21 (65.6) 8 (42.1)
11 (34.4) 11 (57.9)
20 (60.6) 9 (50.0)
13 (39.4) 9 (50.0)
17 (65.4) 12 (48.0)
9 (34.6) 13 (52.0)
7 (70.0) 22 (53.7) 33.14 ± 7.7 16.68 ± 4.7 3.3 ± 0.94 1.57 ± 1.0
3 (30.0) 19 (46.3) 32.14 ± 7.5 20.27 ± 10.3 3.64 ± 1.09 2.36 ± 1.26
16 (48.5) 13 (72.2)
17 (51.5) 5 (27.8)
17 (70.8) 12 (44.4)
7 (29.2) 15 (55.6)
0.973 2.62 (0.82-8.43)
0.101
1.54 (0.48-4.90)
0.465
0.49 (0.16-1.51)
0.210
2.02 (0.46-8.90)
0.483
0.98 1.07 1.45 1.89
(0.91-1.06) (0.98-1.17) (0.79-2.63) (1.1-3.24)
0.645 0.137 0.083 0.016
2.76 (0.80-9.52)
0.102
3.04 (0.95-9.71)
0.058
*Univariate logistic regression analyses. CI indicates confidence interval; IOP, intraocular pressure; OR, odds ratio.
operative time and we therefore introduced that approach in our AGV surgery in 2010. After adopting this surgical technique the operative time decreased significantly. There were no cases of tube exposure in the rotational flap group. Two cases (8.9%) of tube exposure developed at 24 and 55 months postoperatively in the free-flap group, but the follow-up time in the rotational flap was shorter and it is possible that exposure events could have developed in the that group with longer follow-up. On the basis of the rates of exposure in the meta-analysis of publications that predicted a 0.09% incidence of exposure per month,14 we would theoretically expect to find an exposure rate of 2.1% at the end of 24 months of follow-up in the rotational flap group, Nevertheless, the type of patch may not be solely responsible for the increased risk of exposure, because tube erosion is a multifactorial process that is influenced by numerous factors, among them are blepharitis, use of multiple hypotensive medications, implant position, and number of previous surgeries. We could not examine the contribution of blepharitis as it was not noted in all the records. Multiple hypotensive medications cause instability of tear film and loss of goblet cells, leading to poor ocular surface status and thereby possibly increasing the likelihood of tube exposure.15 In our study, there was no significant difference in the number of preoperative glaucoma medications between the 2 study groups. Postoperatively, however, the patients in the free-flap group required significantly more glaucoma medications than those in the rotational flap group. It is possible that the free-flap patch technique might alter the positioning of the tube, causing reduction in aqueous humor outflow, whereupon more glaucoma medication would be needed to control the postoperative IOP.
Another factor that was postulated as a reason for tube exposure is the location of the implant in the inferior quadrant due to the relatively shorter lower fornix and poor healing.16 In our study, the low number of participants who underwent inferior quadrant implantation of the device makes it difficult to draw any conclusions about this relationship. Of note, the implants had been placed in the superior quadrant in the 2 cases of tube exposure in the current study. Previous ocular surgeries induced either conjunctival thinning or scarring that may contribute to the processes underlying tube exposure. Indeed, Byun et al17 found that ocular surgical history was a risk factor for tube exposure. However, we found similar rates of previous ocular surgeries for both the free-flap and rotational flap groups, thus past ocular surgeries may not be solely responsible for tube exposure in the free-flap group. Different graft materials have been used to prevent tube exposure in GDD surgery, with the pericardium, sclera, dura mater, and cornea comprising the established coverage tissues,18–20 but tube erosion has still been observed with various incidences. Smith et al11 described 1 case of tube exposure at 6 months in a group of 18 eyes with dura grafts (5.5%) and 1 case of tube exposure at 15 months in a group of 23 eyes with sclera grafts (4.3%). Raviv et al3 reported no exposure events in a group of 44 eyes with pericardium grafts with an average follow-up of 10.2 months. Lama and Fechtner4 recorded 2 cases (22.2%) among a group of 9 patients who developed tube exposure 4 and 5 months after surgery with pericardium grafts. Lankaranian et al21 reported a 16% exposure rate in a group of 31 patients with single-thickness pericardium
368 | www.glaucomajournal.com Copyright r 2015 Wolters Kluwer Health, Inc. All rights reserved. Copyright r 2016 Wolters Kluwer Health, Inc. All rights reserved.
J Glaucoma
Volume 25, Number 4, April 2016
patch grafts who were followed-up for a mean of 18.6 months. Those authors, however, did not observe any tube erosion in 59 patients who were treated with doublethickness pericardium patch grafts and were followed-up for a mean of 21 months. Muir et al22 published a 41-month follow-up report on 1411 patients who underwent GDD implantations: those authors recorded a 5% tube exposure rate in 39 eyes with single-thickness pericardium patch grafts and no exposure in 14 patients with double-thickness pericardium patch grafts. They also found a 7% tube exposure rate in 43 patients who received eye bank sclera and a 5% tube exposure rate in 18 patients with Tutoplast sclera. Wigton et al23 reported a 8.9% exposure rate in a group of 101 patients with pericardium patch grafts during follow-up of 331 days compared with a 1.9% exposure rate in 161 patients with cornea patch grafts who were followedup for 440 days. Geffen et al24observed a 33.5% wound dehiscence rate and an 8.9% device exposure rate in a group of 158 subjects with corneal patch grafts who were followed up for a median of 43.5 months. The exposure rate of 8.9% (2/27 cases) in our free-flap group is within the range reported in the literature. None of the patients in our rotational flap group experienced tube exposure. We observed thinning of the patch graft that rendered the shunt tube clearly visible through the conjunctiva without evidence of conjunctival erosion in both groups. The free flap had higher rate of patch thinning compared with the rotational flap (55.5% vs. 29.1% respectively), and we consider that this finding may have been confounded by the longer follow-up time of the free-flap group. The results of an assessment of an association between follow-up time and the likelihood of patch thinning were insignificant, indicating that the duration of follow-up had no influence on the differences in patch thinning rates between the 2 groups. Similarly, the length of follow-up was unrelated to the incidence of patch thinning in Smith et al’s11 study, which found similar rates of patch thinning with pericardium and sclera grafts (26%) despite twice the length of follow-up in the latter group (66 vs. 33 mo, respectively). We found that a higher number of postoperative topical glaucoma medications was related to patch thinning (P = 0.016). To the best of our knowledge, this association has not been previously reported. It is possible that the inflammatory changes in the conjunctiva induced by the antiglaucoma drugs25 may lead to patch melt. We also found that a free-flap graft was associated with a greater likelihood of thinning than a rotational flap graft (P = 0.05). It is possible that the latter finding may be related to the structural characteristics of the patch material. Specifically, an autologous free-flap patch is harvested from a different quadrant in the same eye and lacks adequate blood supply, therefore making it prone to melt with progressive thinning after transplantation. The rotational flap is created from the sclera immediately adjacent to the tube, it has 1 portion that remains attached to the host sclera, and it maintains the vascular supply, thereby reducing the likelihood of patch melt. The preparation of the rotational flap is technically easy. The surgical maneuvers involved in these techniques are familiar to glaucoma surgeons and are similar to those performed in fashioning the trabeculectomy flap. This technique has been used successfully in the reconstruction of leaking trabeculectomy blebs,26 in the treatment of scleral melt after pterygium surgery,27 and in the repair of tube exposure after GDD implantation.28 Great care must Copyright
r
Autocleral Graft for Ahmed Valve
be taken when harvesting sclera to prevent iatrogenic staphylomas or choroidal injuries. We did not encounter any intraoperative or postoperative complications at the site where the flap was created. However, a choroidal “blue” show through the thin sclera at the harvesting site was observed in 9 patients in the free-flap graft group. This region was well covered by the lid and did not cause a cosmetic concern. We presume that the larger areas of sclera dissected for the free flap compared with the rotational flap might be the cause for sclera translucency. Although both incidences of tube exposure in our study occurred in the free-flap group, we did achieve successful results by repairing tube exposure with a new free-flap graft. Furthermore, we had favorable results with the use of an autoscleral patch in 2 pediatric patients who received a second AGV (they were not reported here as this study included adult patients with first AGV). We believe that the autoscleral rotational patch affords several advantages. First, the risks of an immunologic reaction are eliminated by using the patient’s own tissue. Second, the rotational flap allows the importation of blood supply, thereby reducing the likelihood of graft melting and tube exposure. Third, the color of the patch is similar to that of the recipient sclera, and the cosmetic result is excellent. Finally, the tissue is readily available, it eliminates the requirement for allografts, and it saves costs. The freeflap autograft is more prone to melting and tube exposure than the rotational flap, and thus has no advantage over other allografts except cost. However, when the sclera immediately adjacent to the tube is not available for harvesting (eg, due to scleral thinning or scarring), a free-flap graft is a viable option. The retrospective design of this study is a potential source of bias. The inclusion of consecutive cases, the longer term follow-up, and the absence of losses to followup, however, provide a clear picture of outcomes for the studied procedures. In conclusion, our experience demonstrates that the use of an autoscleral rotational flap is a valuable technique for primary tube patch grafting in routine AGV surgery. Its main advantages over donor graft options are availability and low cost. We recommend its usage as an alternative tissue option in GDD surgery.
REFERENCES 1. Krebs DB, Liebmann JM, Ritch R, et al. Late infectious endophthalmitis from exposed glaucoma setons. Arch Ophthalmol. 1992;110:174–175. 2. Zeppa L, Romano MR, Capasso L, et al. Sutureless human sclera donor patch graft for Ahmed glaucoma valve. Eur J Ophthalmol. 2010;20:546–551. 3. Raviv T, Greenfield DS, Liebmann JM, et al. Pericardial patch grafts in glaucoma implant surgery. J Glaucoma. 1998;7:27–32. 4. Lama PJ, Fechtner RD. Tube erosion following insertion of a glaucoma drainage device with a pericardial patch graft. Arch Ophthalmol. 1999;117:1243–1244. 5. Brandt JD. Patch grafts of dehydrated cadaveric dura mater for tube-shunt glaucoma surgery. Arch Ophthalmol. 1993;111: 1436–1439. 6. Tanji TM, Lundy DC, Minckler DS, et al. Fascia lata patch graft in glaucoma tube surgery. Ophthalmology. 1996;103: 1309–1312. 7. Rojanapongpun P, Ritch R. Clear corneal graft overlying the seton tube to facilitate laser suture lysis. Am J Ophthalmol. 1996;122:424–425.
2015 Wolters Kluwer Health, Inc. All rights reserved.
www.glaucomajournal.com |
Copyright r 2016 Wolters Kluwer Health, Inc. All rights reserved.
369
Wolf et al
8. Spierer O, Rachmiel R, Lazar M, et al. Double use of corneal graft for Descemet stripping automated endothelial keratoplasty and coverage of glaucoma drainage device tube. J Glaucoma. 2012;21:490–492. 9. Anand A, Sheha H, Teng CC, et al. Use of amniotic membrane graft in glaucoma shunt surgery. Ophthalmic Surg Lasers Imaging. 2011;42:184–189. 10. Nagi KS, Cumba RJ, Bell NP, et al. Short-term outcomes of KeraSys patch graft for glaucoma drainage devices: a case series. J Ophthalmol. 2013;2013:784709. 11. Smith MF, Doyle JW, Ticrney JW Jr. A comparison of glaucoma drainage implant tube coverage. J Glaucoma. 2002;11:143–147. 12. Mehta JS, Franks WA. The sclera, the prion, and the ophthalmologist. Br J Ophthalmol. 2002;86:587–592. 13. Aslanides IM, Spaeth GL, Schmidt CM, et al. Autologous patch graft in tube shunt surgery. J Glaucoma. 1999;8:306–309. 14. Stewart WC, Kristoffersen CJ, Demos CM, et al. Incidence of conjunctival exposure following drainage device implantation in patients with glaucoma. Eur J Ophthalmol. 2010;20:124–130. 15. Trubnik V, Zangalli C, Moster MR, et al. Evaluation of risk factors for glaucoma drainage device-related erosions: a retrospective case-control study. J Glaucoma. 2013. [Epub ahead of print]. 16. Pakravan M, Yazdani S, Shahabi C, et al. Superior versus inferior Ahmed glaucoma valve implantation. Ophthalmology. 2009;116:208–213. 17. Byun YS, Lee NY, Park CK. Risk factors of implant exposure outside the conjunctiva after Ahmed glaucoma valve implantation. Jpn J Ophthalmol. 2009;53:114–119. 18. Gedde SJ, Schiffman JC, Feuer WJ, et al. Tube Versus Trabeculectomy Study Group. The tube versus trabeculectomy study: design and baseline characteristics of study patients. Am J Ophthalmol. 2005;140:275–287.
J Glaucoma
Volume 25, Number 4, April 2016
19. Christakis PG, Tsai JC, Zurakowski D, et al. The Ahmed Versus Baerveldt Study: design, baseline patient characteristics, and intraoperative complications. Ophthalmology. 2011;118: 2172–2179. 20. Barton K, Gedde SJ, Budenz DL, et al. Ahmed Baerveldt Comparison Study Group. The Ahmed Baerveldt Comparison Study methodology, baseline patient characteristics, and intraoperative complications. Ophthalmology. 2011;118: 435–442. 21. Lankaranian D, Reis R, Henderer JD, et al. Comparison of single thickness and double thickness processed pericardium patch graft in glaucoma drainage device surgery: a single surgeon comparison of outcome. J Glaucoma. 2008;17:48–51. 22. Muir KW, Lim A, Stinnett S, et al. Risk factors for exposure of glaucoma drainage devices: a retrospective observational study. BMJ Open. 2014;4:e004560. 23. Wigton E, Swanner CJ, Joiner W, et al. Outcomes of shunt tube coverage with glycerol preserved cornea versus pericardium. J Glaucoma. 2014;23:258–261. 24. Geffen N, Buys YM, Smith M, et al. Conjunctival complications related to Ahmed glaucoma valve insertion. J Glaucoma. 2014;23:109–114. 25. Baudouin C, Pisella PJ, Fillacier K, et al. Ocular surface inflammatory changes induced by topical antiglaucoma drugs: human and animal studies. Ophthalmology. 1999;106:556–563. 26. Mandal AK. Management of the late leaking filtration blebs. A report of seven cases and a selective review of the literature. Indian J Ophthalmol. 2001;49:247–254. 27. Esquenazi S. Autogenous lamellar scleral graft in the treatment of scleral melt after pterygium surgery. Graefes Arch Clin Exp Ophthalmol. 2007;245:1869–1871. 28. Lee ES, Kang SY, Kim NR, et al. Split-thickness hinged scleral flap in the management of exposed tubing of a glaucoma drainage device. J Glaucoma. 2011;20:319–321.
370 | www.glaucomajournal.com Copyright r 2015 Wolters Kluwer Health, Inc. All rights reserved. Copyright r 2016 Wolters Kluwer Health, Inc. All rights reserved.
Use of Autologous Scleral Graft in Ahmed Glaucoma Valve Surgery Alvit Wolf, MD,* Yair Hod, MD,* Gila Buckman, MD,* Nili Stein, MPH,w and Orna Geyer, MD*
Purpose: To compare the efficacy of an autoscleral free-flap graft versus an autoscleral rotational flap graft in Ahmed glaucoma valve (AGV) surgery. Patients and Methods: Medical records (2005 to 2012) of 51 consecutive patients (51 eyes) who underwent AGV surgery with the use of either an autoscleral free-flap graft or an autoscleral rotational flap graft to cover the external tube at the limbus were retrieved for review. The main outcome measure was the incidence of tube exposure associated with each surgical approach.
grafting has the advantage of being sterile, immunologically safe, readily available, and least costly. Aslanides et al13 described the efficacy of autologous sclera as a patch graft in GDD surgery. Their study was limited, however, by the small number of patients and a short period of follow-up. The purpose of this study was to report the long-term efficacy of autologous sclera as the primary patch graft for covering the tube in Ahmed glaucoma valve (AGV) surgery.
Results: Twenty-seven consecutive patients (27 eyes) received a free-flap graft and 24 consecutive patients (24 eyes) received a rotational flap graft. The mean follow-up time was 55.6 ± 18.3 months for the former and 24.2 ± 5.0 months for the latter (P < 0.0001). Two patients in the free-flap group (8.9%) developed tube exposure at 24 and 55 months postoperatively compared with none of the patients in the rotational flap group. Graft thinning without evidence of conjunctival erosion was observed in 15 patients (55%) in the free-flap group and in 7 patients (29.1%) in the rotational flap group. Conclusions: The use of an autoscleral rotational flap graft is an efficacious technique for primary tube patch grafting in routine AGV surgery, and yielded better results than an autoscleral freeflap graft. Its main advantages over donor graft material are availability and lower cost. Key Words: glaucoma drainage devices (GDD), tube exposure, patch graft, autologous sclera
(J Glaucoma 2016;25:365–370)
T
ube exposure is an occasional complication of glaucoma drainage device (GDD) surgery. It is of clinical concern because it predisposes the eye to endophthalmitis.1 The standard method to prevent this complication is the use of a patch graft to cover the external silicone tube of the GDD. Various tissues have been advocated as graft material, including human sclera,2 pericardium,3,4 dura mater,5 fascia lata,6 cornea,7,8 amniotic membrane,9 and porcine intestinal submucosa (KeraSys).10 All of these materials require the use of donor tissue and carry the risk of immune-mediated patch melting11 or transmission of infectious diseases.12 Availability and cost are additional concerns. Autologous scleral patch Received for publication March 6, 2014; accepted January 7, 2015. From the Departments of *Ophthalmology; and wCommunity Medicine and Epidemiology, Carmel Medical Center, affiliated to the Rapaport Faculty of Medicine, The Technion, Haifa, Israel. Disclosure: The authors declare no conflict of interest. Reprints: Orna Geyer, MD, Head, Department of Ophthalmology, Carmel Medical Center, 7 Michal Street, Haifa 34362, Israel (e-mail: [email protected]). Copyright r 2015 Wolters Kluwer Health, Inc. All rights reserved. DOI: 10.1097/IJG.0000000000000232
J Glaucoma
Volume 25, Number 4, April 2016
FIGURE 1. Intraoperative photographs illustrating the autoscleral free-flap technique. A, One half of the scleral thickness rectangular flap (57 mm) is taken from the sclera remote from the site planned for valve insertion and just anterior to the rectus muscle insertion, parallel to the limbus. B, The scleral flap is placed over the exposed part of the tube and secured to the underlying sclera with 4 interrupted 10-0 nylon sutures. Figure 1 can be viewed in color online at www.glaucomajournal.com.
www.glaucomajournal.com |
Copyright r 2016 Wolters Kluwer Health, Inc. All rights reserved.
365
Wolf et al
J Glaucoma
PATIENTS AND METHODS Patients This retrospective interventional case series of consecutive patients who underwent AGV surgery with autoscleral patch grafting to cover the subconjunctival portion of the tube was approved by the Institutional Review Board (IRB no. 350). Written informed consent was obtained from all patients before surgery. All procedures were performed by 1 surgeon (O.G.) between April 2005 and May 2012. A free scleral patch flap was performed in all patients before January 2010. Beginning January 2010, the practice was changed and all patients scheduled to undergo AGV surgery in our department received a pedunculated flap.
Surgical Technique All the study subjects underwent implantation of an AGV model FP7 (New World Medical Inc., Rancho Cucamonga, CA) under general anesthesia. The position of the AGV insertion site was in the superior or inferior quadrant, depending on the conjunctival mobility and the presence of previous surgical conjunctival scarring. The surgical procedure was similar for superior and inferior valves. The surgical technique used for eyes that had free scleral flap patches began with a limbal peritomy in the quadrant located 180 degrees away from the site planned for shunt insertion. In the event that the scleral thickness was inappropriate (ie, too thin), scleral tissue was taken from a different site but still remote from the site planned for valve insertion. The conjunctiva and Tenon’s capsule were dissected posteriorly, exposing the sclera. Hemostasis was achieved with a bipolar cautery. A 5 7 mm scleral flap was outlined with a caliper in the area just anterior to the rectus muscle insertion and parallel to the limbus. The sclera graft was dissected at half the scleral thickness along marked dimensions and removed with a no. 15 blade (Fig. 1A). The graft was transferred to BSS solution and kept there until use. The conjunctiva and Tenon’s capsule were sewn into place with 8-0 Vicryl sutures. In the quadrant planned for shunt insertion (at a site remote from the
Volume 25, Number 4, April 2016
one from which the flap was harvested), a fornix-based conjunctival flap was created, forming a pocket for the insertion of the Ahmed valve plate. The plate of the implant was inserted into the sub-tenon pocket and secured to the sclera at a distance of 8 to 10 mm posterior to the surgical limbus using a 9-0 Prolene horizontal mattress suture. The tube was trimmed to extend 2 mm beyond the limbus into the anterior chamber, with the bevel facing the cornea. The tube was inserted into the anterior chamber through a corneoscleral track created with a 23 G needle. The preprepared scleral patch graft was placed with the narrow part (5 mm) parallel and over the exposed part of the tube anteriorly to where the tube entered the sclera to ensure coverage. The patch was then secured to the sclera using 4 interrupted 10-0 nylon sutures (Fig. 1B). The conjunctiva and Tenon’s capsule were sewn into place with 10-0 nylon sutures to fully cover the scleral graft. The surgical method used for eyes that had the rotational scleral flap patch began with implantation of the AGV by the same surgical technique as that for the free scleral flap. After insertion of the tube into the anterior chamber, a lamellar scleral flap was created from the sclera adjacent to the tube and extending either temporally or nasally to it. The sclera in this area was marked to fashion a 55 mm rotational flap parallel to the limbus. The scleral flap, which was half the scleral thickness, was cut along the marked dimensions with the end adjacent to the tube that was still attached to the original scleral bed. The flap was then rotated over the tube and secured to the underlying sclera on the opposite side of the tube with 10-0 Vicryl sutures (Fig. 2). The conjunctiva was reopposed with 8-0 Vicryl sutures. Topical antibiotics were used at the end of the procedure. The postoperative regimen included topical ciprofloxacin eye drops 4 times per day (qid) for 1 week and topical prednisolone acetate 1% eye drops qid that was usually tapered over 6 to 8 weeks. Antiglaucoma medications were added when necessary. Information collected from patients’ medical records included age, sex, any existing systemic condition (diabetes mellitus, hypertension), type of glaucoma, previous ocular surgery, preoperative intraocular pressure (IOP), glaucoma medications, surgical variables (date of procedure, implant location, and type of patch graft used), and follow-up data (IOP values and glaucoma medications at the most recent clinical visit). The main outcome measures were tube exposure and characteristics of the graft and the sclera at the harvest site.
Statistical Analysis
FIGURE 2. Intraoperative photograph illustrating the autoscleral rotational flap technique. The flap (5 5 mm) is created from the sclera adjacent to the tube, rotated over the tube, and secured to the underlying sclera on the opposite side of the tube with 10-0 Vicryl sutures. Figure 2 can be viewed in color online at www. glaucomajournal.com.
The statistical analysis was performed with the IBM SPSS statistics 32 software. Comparisons between the freeflap and rotational flap groups were performed using the w2 test for the categorical variables, whereas the independent t test or the Mann-Whitney test was applied for the continuous variables. The systemic and ocular characteristics of patients with and without graft thinning were compared for potential risk factors for graft thinning. Because 2 cases with tube exposure had patch graft thinning for a long period of time before the actual onset of exposure, they were included in the graft thinning group and their data were included up to the point of exposure. Evaluation of the association between characteristics of the participants and patch thinning was performed with the univariate logistic regression analyses. A P-value of r0.05 was considered statistically significant in our analyses.
366 | www.glaucomajournal.com Copyright r 2015 Wolters Kluwer Health, Inc. All rights reserved. Copyright r 2016 Wolters Kluwer Health, Inc. All rights reserved.
J Glaucoma
Volume 25, Number 4, April 2016
Autocleral Graft for Ahmed Valve
RESULTS A total of 51 consecutive patients (51 eyes) underwent AGV implant surgery with autologous scleral patch grafting. Twenty-seven patients (27 eyes) had the free-flap technique and 24 patients (24 eyes) had the rotational flap approach. There were no intraoperative complications in either group. No patient was lost to follow-up during the course of the study. The patients’ baseline characteristics, operative details, and follow-up data are presented in Table 1. No significant differences in any of the demographic or baseline clinical features were observed between treatment groups. The mean follow-up time for the rotational flap group (24.2 ± 5.0 mo) was significantly shorter than the mean follow-up time for the free-flap group (55.6 ± 18.3 mo, P < 0.0001) because the former had not been performed in our department until
TABLE 1. Baseline Demographic, Ocular Characteristics, Operative and Postoperative Details of Patients Undergoing AGV Implantation With Autologous Scleral Patch Grafts
Free Flap No. patients (eyes) Mean age ± SD (y) Range Male [no. patients (%)] Diabetes [no. patients (%)] Hypertension [no. patients (%)] Glaucoma diagnosis [no. patients (%)] Primary open angle Neovascular Uveitic Silicone oil Iridocorneal endothelial syndrome Other Previous ocular surgery [no. patients (%)] Glaucoma Retinal Cataract Mean preoperative IOP ± SD (mm Hg) Mean no. preoperative glaucoma medications ± SD Valve location [no. patients (%)] Superotemporal Superonasal Inferotemporal Inferonasal Follow-up (mean ± SD) (mo) Median Range Postoperative mean IOP ± SD (mm Hg), at the last follow-up visit Postoperative mean no. glaucoma medications ± SD, at the last follow-up visit*
Rotational Flap
27 (27) 24 (24) 59.3 ± 15.6 62.0 ± 14.3 22-86 20-80 12 (44.4) 9 (37.5) 10 (37.0) 9 (37.5) 10 (37.0) 8 (33.3)
P 0.526 0.615 0.973 0.782 0.895*
14 8 1 2 1
(51.9) (29.6) (3.7) (7.4) (3.7)
1 (3.7) 24 (88.9)
12 6 2 1 1
(50) (25) (8.3) (4.2) (4.2)
2 (8.3) 17 (70.8)
18 (66.7) 12 (50) 4 (14.8) 0 19 (70.4) 11 (45.8) 32.5 ± 7.57 32.9 ± 7.74 3.48 ± 1.19 3.39 ± 0.78
0.160 0.227 1.113 0.076 0.854 0.531 0.490
16 (59.3) 6 (22.2) 4 (14.8) 1 (3.7) 53.5 ± 19.3
17 (70.8) 6 (25.0) 1 (4.2) 0 24.2 ± 5.0
55.1 12.0-97.8 19.04 ± 9.8
26.3 15.2-31.7 17.4 ± 4.8
0.468
2.35 (1.2)
1.46 (0.98)
0.007
< 0.0001
*Primary open-angle glaucoma versus other. AGV indicates Ahmed glaucoma valve; IOP, intraocular pressure.
Copyright
r
January 2010. There was no significant difference in postoperative mean IOP between groups (P = 0.468). The rotational flap group used significantly fewer glaucoma medications after the surgery (P = 0.007). Graft thinning in which the shunt tube was clearly visible through the conjunctiva without evidence of conjunctival erosion was observed in 7 patients in the rotational flap group and in 15 patients in the free-flap group. Table 2 summarizes the risk factors for graft thinning. The number of postoperative glaucoma medications and the flap type were the significant factors associated with graft thinning (P = 0.016 and 0.058, respectively). Age, sex, implant location, type of glaucoma, number of previous ocular surgeries, preoperative IOP, preoperative glaucoma medications, postoperative IOP, diabetes mellitus, and hypertension were not related to patch thinning. None of the patients in the rotational flap group developed tube exposure. Two patients (8.9%) in the freeflap group and who had previous patch thinning developed conjunctival erosion and tube exposure. One of those cases was a 60-year-old pseudophakic female with a long-standing history of primary open-angle glaucoma and status post 3 trabeculectomies. Her AGV was located in the superotemporal quadrant, and a free scleral flap patch had been used. Tube exposure had occurred 24 months after her initial surgery. Prompt surgical revision with a new free-flap graft was performed with no further complications during the subsequent 36 months of follow-up. The second case was a 32-year-old diabetic pseudophakic male who was postvitrectomy and trabeculectomy and who underwent AGV surgery with a free scleral flap patch implanted in the superotemporal quadrant of the right eye. Tube exposure occurred 55 months following surgery. A revision surgery was performed with a new free-flap graft, and no reexposure was observed at the 1-year follow-up visit. There were no complications at the harvest site in either group. Choroidal “blue” showing through the thin sclera region where the flap was created was observed in 9 patients of the free-flap graft group but, notably, in none of the patients in the rotational flap group
DISCUSSION Placement of a patch graft over the anterior part of a tube to reduce the risk of erosion through the overlying conjunctiva is an integral part of GDD surgery. Different homologous or heterologous materials1–10 have been used for grafting with satisfactory outcomes. Availability and cost may, however, be barriers to the routine use of those grafts, and the autoscleral patch is an excellent alternative. In 1999, Aslanides et al13 reported on 16 patients who underwent a GDD implant with autologous “free” or “rotational” scleral flap patching, and those authors detected no cases of tube erosion during the 14 months of follow-up. To the best of our knowledge, the current study is the first to demonstrate the long-term efficacy of autologous sclera as a primary patch graft to reduce tubal exposure in glaucoma shunt surgery. We had used free autoscleral patch grafts in AGV surgery since 2005, and it was our impression that the extra intraoperative manipulation required for harvesting the graft from a different quadrant than the one used for implant insertion substantially increased the time of surgery. We reasoned that a rotational flap created from the sclera immediately adjacent to the tube would shorten the
2015 Wolters Kluwer Health, Inc. All rights reserved.
www.glaucomajournal.com |
Copyright r 2016 Wolters Kluwer Health, Inc. All rights reserved.
367
Wolf et al
J Glaucoma
Volume 25, Number 4, April 2016
TABLE 2. Characteristics of Participants and Association With Patch Thinning*
Patch Status Age (mean ± SD) (y) Sex [n (%)] Female Male Diabetes [n (%)] No Yes Hypertension [n (%)] No Yes Glaucoma diagnosis [n (%)] Open angle Other Previous ocular surgeries [n (%)] No Yes Preoperative IOP (mm Hg) Postoperative IOP (mm Hg) No. preoperative glaucoma medications (median) No. postoperative glaucoma medications (median) Valve location [n (%)] Superotemporal Other Flap type [n (%)] Rotational Free
Nonthinning (n = 29)
Thinning (n = 22)
OR (95%CI)
P
62.1 ± 15.9
58.5 ± 13.8
0.98 (0.95-1.02) 0.98 (0.32-3.03)
0.407
17 (56.7) 12 (57.1)
13 (43.3) 9 (42.9)
21 (65.6) 8 (42.1)
11 (34.4) 11 (57.9)
20 (60.6) 9 (50.0)
13 (39.4) 9 (50.0)
17 (65.4) 12 (48.0)
9 (34.6) 13 (52.0)
7 (70.0) 22 (53.7) 33.14 ± 7.7 16.68 ± 4.7 3.3 ± 0.94 1.57 ± 1.0
3 (30.0) 19 (46.3) 32.14 ± 7.5 20.27 ± 10.3 3.64 ± 1.09 2.36 ± 1.26
16 (48.5) 13 (72.2)
17 (51.5) 5 (27.8)
17 (70.8) 12 (44.4)
7 (29.2) 15 (55.6)
0.973 2.62 (0.82-8.43)
0.101
1.54 (0.48-4.90)
0.465
0.49 (0.16-1.51)
0.210
2.02 (0.46-8.90)
0.483
0.98 1.07 1.45 1.89
(0.91-1.06) (0.98-1.17) (0.79-2.63) (1.1-3.24)
0.645 0.137 0.083 0.016
2.76 (0.80-9.52)
0.102
3.04 (0.95-9.71)
0.058
*Univariate logistic regression analyses. CI indicates confidence interval; IOP, intraocular pressure; OR, odds ratio.
operative time and we therefore introduced that approach in our AGV surgery in 2010. After adopting this surgical technique the operative time decreased significantly. There were no cases of tube exposure in the rotational flap group. Two cases (8.9%) of tube exposure developed at 24 and 55 months postoperatively in the free-flap group, but the follow-up time in the rotational flap was shorter and it is possible that exposure events could have developed in the that group with longer follow-up. On the basis of the rates of exposure in the meta-analysis of publications that predicted a 0.09% incidence of exposure per month,14 we would theoretically expect to find an exposure rate of 2.1% at the end of 24 months of follow-up in the rotational flap group, Nevertheless, the type of patch may not be solely responsible for the increased risk of exposure, because tube erosion is a multifactorial process that is influenced by numerous factors, among them are blepharitis, use of multiple hypotensive medications, implant position, and number of previous surgeries. We could not examine the contribution of blepharitis as it was not noted in all the records. Multiple hypotensive medications cause instability of tear film and loss of goblet cells, leading to poor ocular surface status and thereby possibly increasing the likelihood of tube exposure.15 In our study, there was no significant difference in the number of preoperative glaucoma medications between the 2 study groups. Postoperatively, however, the patients in the free-flap group required significantly more glaucoma medications than those in the rotational flap group. It is possible that the free-flap patch technique might alter the positioning of the tube, causing reduction in aqueous humor outflow, whereupon more glaucoma medication would be needed to control the postoperative IOP.
Another factor that was postulated as a reason for tube exposure is the location of the implant in the inferior quadrant due to the relatively shorter lower fornix and poor healing.16 In our study, the low number of participants who underwent inferior quadrant implantation of the device makes it difficult to draw any conclusions about this relationship. Of note, the implants had been placed in the superior quadrant in the 2 cases of tube exposure in the current study. Previous ocular surgeries induced either conjunctival thinning or scarring that may contribute to the processes underlying tube exposure. Indeed, Byun et al17 found that ocular surgical history was a risk factor for tube exposure. However, we found similar rates of previous ocular surgeries for both the free-flap and rotational flap groups, thus past ocular surgeries may not be solely responsible for tube exposure in the free-flap group. Different graft materials have been used to prevent tube exposure in GDD surgery, with the pericardium, sclera, dura mater, and cornea comprising the established coverage tissues,18–20 but tube erosion has still been observed with various incidences. Smith et al11 described 1 case of tube exposure at 6 months in a group of 18 eyes with dura grafts (5.5%) and 1 case of tube exposure at 15 months in a group of 23 eyes with sclera grafts (4.3%). Raviv et al3 reported no exposure events in a group of 44 eyes with pericardium grafts with an average follow-up of 10.2 months. Lama and Fechtner4 recorded 2 cases (22.2%) among a group of 9 patients who developed tube exposure 4 and 5 months after surgery with pericardium grafts. Lankaranian et al21 reported a 16% exposure rate in a group of 31 patients with single-thickness pericardium
368 | www.glaucomajournal.com Copyright r 2015 Wolters Kluwer Health, Inc. All rights reserved. Copyright r 2016 Wolters Kluwer Health, Inc. All rights reserved.
J Glaucoma
Volume 25, Number 4, April 2016
patch grafts who were followed-up for a mean of 18.6 months. Those authors, however, did not observe any tube erosion in 59 patients who were treated with doublethickness pericardium patch grafts and were followed-up for a mean of 21 months. Muir et al22 published a 41-month follow-up report on 1411 patients who underwent GDD implantations: those authors recorded a 5% tube exposure rate in 39 eyes with single-thickness pericardium patch grafts and no exposure in 14 patients with double-thickness pericardium patch grafts. They also found a 7% tube exposure rate in 43 patients who received eye bank sclera and a 5% tube exposure rate in 18 patients with Tutoplast sclera. Wigton et al23 reported a 8.9% exposure rate in a group of 101 patients with pericardium patch grafts during follow-up of 331 days compared with a 1.9% exposure rate in 161 patients with cornea patch grafts who were followedup for 440 days. Geffen et al24observed a 33.5% wound dehiscence rate and an 8.9% device exposure rate in a group of 158 subjects with corneal patch grafts who were followed up for a median of 43.5 months. The exposure rate of 8.9% (2/27 cases) in our free-flap group is within the range reported in the literature. None of the patients in our rotational flap group experienced tube exposure. We observed thinning of the patch graft that rendered the shunt tube clearly visible through the conjunctiva without evidence of conjunctival erosion in both groups. The free flap had higher rate of patch thinning compared with the rotational flap (55.5% vs. 29.1% respectively), and we consider that this finding may have been confounded by the longer follow-up time of the free-flap group. The results of an assessment of an association between follow-up time and the likelihood of patch thinning were insignificant, indicating that the duration of follow-up had no influence on the differences in patch thinning rates between the 2 groups. Similarly, the length of follow-up was unrelated to the incidence of patch thinning in Smith et al’s11 study, which found similar rates of patch thinning with pericardium and sclera grafts (26%) despite twice the length of follow-up in the latter group (66 vs. 33 mo, respectively). We found that a higher number of postoperative topical glaucoma medications was related to patch thinning (P = 0.016). To the best of our knowledge, this association has not been previously reported. It is possible that the inflammatory changes in the conjunctiva induced by the antiglaucoma drugs25 may lead to patch melt. We also found that a free-flap graft was associated with a greater likelihood of thinning than a rotational flap graft (P = 0.05). It is possible that the latter finding may be related to the structural characteristics of the patch material. Specifically, an autologous free-flap patch is harvested from a different quadrant in the same eye and lacks adequate blood supply, therefore making it prone to melt with progressive thinning after transplantation. The rotational flap is created from the sclera immediately adjacent to the tube, it has 1 portion that remains attached to the host sclera, and it maintains the vascular supply, thereby reducing the likelihood of patch melt. The preparation of the rotational flap is technically easy. The surgical maneuvers involved in these techniques are familiar to glaucoma surgeons and are similar to those performed in fashioning the trabeculectomy flap. This technique has been used successfully in the reconstruction of leaking trabeculectomy blebs,26 in the treatment of scleral melt after pterygium surgery,27 and in the repair of tube exposure after GDD implantation.28 Great care must Copyright
r
Autocleral Graft for Ahmed Valve
be taken when harvesting sclera to prevent iatrogenic staphylomas or choroidal injuries. We did not encounter any intraoperative or postoperative complications at the site where the flap was created. However, a choroidal “blue” show through the thin sclera at the harvesting site was observed in 9 patients in the free-flap graft group. This region was well covered by the lid and did not cause a cosmetic concern. We presume that the larger areas of sclera dissected for the free flap compared with the rotational flap might be the cause for sclera translucency. Although both incidences of tube exposure in our study occurred in the free-flap group, we did achieve successful results by repairing tube exposure with a new free-flap graft. Furthermore, we had favorable results with the use of an autoscleral patch in 2 pediatric patients who received a second AGV (they were not reported here as this study included adult patients with first AGV). We believe that the autoscleral rotational patch affords several advantages. First, the risks of an immunologic reaction are eliminated by using the patient’s own tissue. Second, the rotational flap allows the importation of blood supply, thereby reducing the likelihood of graft melting and tube exposure. Third, the color of the patch is similar to that of the recipient sclera, and the cosmetic result is excellent. Finally, the tissue is readily available, it eliminates the requirement for allografts, and it saves costs. The freeflap autograft is more prone to melting and tube exposure than the rotational flap, and thus has no advantage over other allografts except cost. However, when the sclera immediately adjacent to the tube is not available for harvesting (eg, due to scleral thinning or scarring), a free-flap graft is a viable option. The retrospective design of this study is a potential source of bias. The inclusion of consecutive cases, the longer term follow-up, and the absence of losses to followup, however, provide a clear picture of outcomes for the studied procedures. In conclusion, our experience demonstrates that the use of an autoscleral rotational flap is a valuable technique for primary tube patch grafting in routine AGV surgery. Its main advantages over donor graft options are availability and low cost. We recommend its usage as an alternative tissue option in GDD surgery.
REFERENCES 1. Krebs DB, Liebmann JM, Ritch R, et al. Late infectious endophthalmitis from exposed glaucoma setons. Arch Ophthalmol. 1992;110:174–175. 2. Zeppa L, Romano MR, Capasso L, et al. Sutureless human sclera donor patch graft for Ahmed glaucoma valve. Eur J Ophthalmol. 2010;20:546–551. 3. Raviv T, Greenfield DS, Liebmann JM, et al. Pericardial patch grafts in glaucoma implant surgery. J Glaucoma. 1998;7:27–32. 4. Lama PJ, Fechtner RD. Tube erosion following insertion of a glaucoma drainage device with a pericardial patch graft. Arch Ophthalmol. 1999;117:1243–1244. 5. Brandt JD. Patch grafts of dehydrated cadaveric dura mater for tube-shunt glaucoma surgery. Arch Ophthalmol. 1993;111: 1436–1439. 6. Tanji TM, Lundy DC, Minckler DS, et al. Fascia lata patch graft in glaucoma tube surgery. Ophthalmology. 1996;103: 1309–1312. 7. Rojanapongpun P, Ritch R. Clear corneal graft overlying the seton tube to facilitate laser suture lysis. Am J Ophthalmol. 1996;122:424–425.
2015 Wolters Kluwer Health, Inc. All rights reserved.
www.glaucomajournal.com |
Copyright r 2016 Wolters Kluwer Health, Inc. All rights reserved.
369
Wolf et al
8. Spierer O, Rachmiel R, Lazar M, et al. Double use of corneal graft for Descemet stripping automated endothelial keratoplasty and coverage of glaucoma drainage device tube. J Glaucoma. 2012;21:490–492. 9. Anand A, Sheha H, Teng CC, et al. Use of amniotic membrane graft in glaucoma shunt surgery. Ophthalmic Surg Lasers Imaging. 2011;42:184–189. 10. Nagi KS, Cumba RJ, Bell NP, et al. Short-term outcomes of KeraSys patch graft for glaucoma drainage devices: a case series. J Ophthalmol. 2013;2013:784709. 11. Smith MF, Doyle JW, Ticrney JW Jr. A comparison of glaucoma drainage implant tube coverage. J Glaucoma. 2002;11:143–147. 12. Mehta JS, Franks WA. The sclera, the prion, and the ophthalmologist. Br J Ophthalmol. 2002;86:587–592. 13. Aslanides IM, Spaeth GL, Schmidt CM, et al. Autologous patch graft in tube shunt surgery. J Glaucoma. 1999;8:306–309. 14. Stewart WC, Kristoffersen CJ, Demos CM, et al. Incidence of conjunctival exposure following drainage device implantation in patients with glaucoma. Eur J Ophthalmol. 2010;20:124–130. 15. Trubnik V, Zangalli C, Moster MR, et al. Evaluation of risk factors for glaucoma drainage device-related erosions: a retrospective case-control study. J Glaucoma. 2013. [Epub ahead of print]. 16. Pakravan M, Yazdani S, Shahabi C, et al. Superior versus inferior Ahmed glaucoma valve implantation. Ophthalmology. 2009;116:208–213. 17. Byun YS, Lee NY, Park CK. Risk factors of implant exposure outside the conjunctiva after Ahmed glaucoma valve implantation. Jpn J Ophthalmol. 2009;53:114–119. 18. Gedde SJ, Schiffman JC, Feuer WJ, et al. Tube Versus Trabeculectomy Study Group. The tube versus trabeculectomy study: design and baseline characteristics of study patients. Am J Ophthalmol. 2005;140:275–287.
J Glaucoma
Volume 25, Number 4, April 2016
19. Christakis PG, Tsai JC, Zurakowski D, et al. The Ahmed Versus Baerveldt Study: design, baseline patient characteristics, and intraoperative complications. Ophthalmology. 2011;118: 2172–2179. 20. Barton K, Gedde SJ, Budenz DL, et al. Ahmed Baerveldt Comparison Study Group. The Ahmed Baerveldt Comparison Study methodology, baseline patient characteristics, and intraoperative complications. Ophthalmology. 2011;118: 435–442. 21. Lankaranian D, Reis R, Henderer JD, et al. Comparison of single thickness and double thickness processed pericardium patch graft in glaucoma drainage device surgery: a single surgeon comparison of outcome. J Glaucoma. 2008;17:48–51. 22. Muir KW, Lim A, Stinnett S, et al. Risk factors for exposure of glaucoma drainage devices: a retrospective observational study. BMJ Open. 2014;4:e004560. 23. Wigton E, Swanner CJ, Joiner W, et al. Outcomes of shunt tube coverage with glycerol preserved cornea versus pericardium. J Glaucoma. 2014;23:258–261. 24. Geffen N, Buys YM, Smith M, et al. Conjunctival complications related to Ahmed glaucoma valve insertion. J Glaucoma. 2014;23:109–114. 25. Baudouin C, Pisella PJ, Fillacier K, et al. Ocular surface inflammatory changes induced by topical antiglaucoma drugs: human and animal studies. Ophthalmology. 1999;106:556–563. 26. Mandal AK. Management of the late leaking filtration blebs. A report of seven cases and a selective review of the literature. Indian J Ophthalmol. 2001;49:247–254. 27. Esquenazi S. Autogenous lamellar scleral graft in the treatment of scleral melt after pterygium surgery. Graefes Arch Clin Exp Ophthalmol. 2007;245:1869–1871. 28. Lee ES, Kang SY, Kim NR, et al. Split-thickness hinged scleral flap in the management of exposed tubing of a glaucoma drainage device. J Glaucoma. 2011;20:319–321.
370 | www.glaucomajournal.com Copyright r 2015 Wolters Kluwer Health, Inc. All rights reserved. Copyright r 2016 Wolters Kluwer Health, Inc. All rights reserved.
