- Email: [email protected]
Intermediate-term clinical experience with the Ahmed Glaucoma Valve implant 1
Intermediate-term Clinical Experience With the Ahmed Glaucoma Valve Implant MORGAN C. HUANG, MD, PETER A. NETLAND, MD, PHD, ANNE L. COLEMAN, MD, PHD, SCOTT W. SIEGNER, MD, MARLENE R. MOSTER, MD, AND RICHARD A. HILL, MD
● PURPOSE:
We studied the intermediate-term clinical experience with the Ahmed Glaucoma Valve implant (New World Medical, Inc, Rancho Cucamonga, California). ● METHODS: In this multicenter, retrospective case series, we studied 159 eyes (144 patients) treated with the Ahmed Glaucoma Valve with a mean 6 SEM (standard error of mean) follow-up of 13.4 6 0.7 months (range, 4 to 44 months). The mean 6 SEM age was 60.9 6 1.9 years (range, 0.1 to 103 years). Surgical success was defined as intraocular pressure less than 22 mm See also pp. 34 – 42.
Hg and greater than 5 mm Hg without additional glaucoma surgery and without loss of light perception. Postoperative use of antiglaucoma medications was not a criterion for success or failure. The definition of hypotony was intraocular pressure of 5 mm Hg or less in two consecutive visits. ● RESULTS: Intraocular pressure was reduced from a mean of 32.7 6 0.8 mm Hg before surgery to 15.9 6 0.6 mm Hg (P < .0001) at the most recent follow-up after surgery. The number of antiglaucoma medications was decreased from 2.7 6 0.1 before surgery to 1.1 6 0.1 after surgery (P < .0001). The cumulative probability of success was 87% at 1 year and 75% at 2 years after surgery (Kaplan-Meier life-table analysis). PostoperaAccepted for publication Sept 24, 1998. From the University of Tennessee, Memphis, Tennessee (Drs Huang and Netland); Jules Stein Eye Institute, Los Angeles, California (Drs Coleman and Siegner); Wills Eye Hospital, Philadelphia, Pennsylvania (Dr Moster); and University of California, Irvine, California (Dr Hill). Supported in part by Research to Prevent Blindness, Inc, New York, New York. The authors have no proprietary interest in the Ahmed Glaucoma Valve implant. This study was presented in part at the annual meeting of the Association for Research in Vision and Ophthalmology in Fort Lauderdale, Florida, May 12, 1998. Correspondence to Peter A. Netland, MD, PhD, Department of Ophthalmology, University of Tennessee, Memphis, 956 Court Avenue, Memphis, TN 38163; fax: (901) 448-1299; e-mail: pnetland@mail. eye.utmem.edu 0002-9394/99/$20.00 PII S0002-9394(98)00394-8
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tively, 24 (15%) of 159 eyes had intraocular pressure greater than or equal to 22 mm Hg. The visual acuity was improved or within one Snellen line in 131 eyes (82%). Complications occurred in 75 eyes (47%), the majority of which did not affect surgical outcome. The most common complication was obstruction of the tube, which was observed in 17 eyes (11%). Transient postoperative hypotony was found in 13 eyes (8%). ● CONCLUSIONS: The Ahmed Glaucoma Valve implant is effective in lowering intraocular pressure, and postoperative hypotony is not commonly associated with this implant. (Am J Ophthalmol 1999;127:27–33. © 1999 by Elsevier Science Inc. All rights reserved.)
G
LAUCOMA DRAINAGE IMPLANTS ARE A USEFUL
alternative in treating glaucomas that are resistant to medical therapy and glaucoma filtration surgery.1,2 These implants have a small-caliber silicone tube that drains aqueous from the anterior or posterior chamber to an extrascleral device that maintains a fibrous pseudocyst through which filtration can occur. A variety of aqueous shunting devices have been developed, including open-tube and valved designs. Hypotony during the immediate postoperative period is a common complication associated with the open-tube implants.3,4 Although valved implants may not completely close after initial perfusion with fluid, they do function as flow-restricting devices.5 The Ahmed Glaucoma Valve implant (New World Medical, Inc, Rancho Cucamonga, California) directs aqueous flow through the silicone tube and between two thin silicone elastomer membranes in a tapered chamber. The initial clinical experience with this implant indicated that hypotony and its attendant complications during the immediate postoperative period were less common than reported with other glaucoma drainage devices.6 Our purpose in this study was to investigate the short- and long-term clinical effectiveness of the Ahmed Glaucoma Valve implant in a multicenter review of patients with glaucomas refractory to other treatments.
ELSEVIER SCIENCE INC. ALL
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Criteria for success and failure were defined before reviewing the data. Surgical success was defined as intraocular pressure less than 22 mm Hg and greater than 5 mm Hg without additional glaucoma surgery (excluding the injection of 5-fluorouracil) and without loss of light perception.3 Postoperative use of antiglaucoma medications was not a criterion of success or failure. Results of the most recent examination were used to record the final intraocular pressure and visual acuity for classification as a success or failure. Preoperative intraocular pressure and Snellen visual acuity were recorded on the most recent office visit prior to surgery. Intraocular pressure was measured with a Goldmann applanation tonometer, a Tono-pen (Mentor O & O, Norwell, Massachusetts), or a handheld applanation tonometer (Kowa; Kowa Optimet Inc, Torrance, California, or Perkins; Clement Clarke, Columbus, Ohio). Although formal motility testing was not performed in all patients, those with gross motility disturbances or symptoms were evaluated with ocular motility testing. The definition of hypotony in this study was intraocular pressure of 5 mm Hg or less in two consecutive visits. Paired t tests were used to assess differences in continuously scaled variables before and after surgery, and nonpaired t tests were used in comparisons of successes and failures. Chi-square test was used for noncontinuously scaled variables in comparisons of successes and failures. The cumulative probability of success was analyzed by Kaplan-Meier life-table analysis. P values less than .05 were considered statistically significant.
PATIENTS AND METHODS WE REVIEWED THE RECORDS OF PATIENTS WHO WERE
treated with the Ahmed Glaucoma Valve implant for increased intraocular pressure or glaucoma that was not responsive to medical treatment, laser treatment, or previous glaucoma surgery. A total of 144 patients (159 eyes) were included from four medical centers in the United States. Patients with less than 4 months of follow-up were excluded from the analysis. After informed written consent was obtained, the Ahmed Glaucoma Valve was implanted by one of four glaucoma subspecialty surgeons (P.A.N., A.L.C., M.R.M., and R.A.H.). Patients with neovascular glaucoma were treated with panretinal photocoagulation before the Ahmed Glaucoma Valve was implanted, when feasible. Seven eyes underwent additional surgical procedures at the same time as implant surgery: six eyes had penetrating keratoplasty, and one had cataract extraction with intraocular lens implantation. Although the Ahmed Glaucoma Valve is available in a smaller size, all implants in this study had a surface area of 185 mm2 (model S-2). The surgical procedure and postoperative management of this valve implantation have been described by Coleman and associates.6 Before implantation in our study, the tube of the Ahmed Glaucoma Valve was irrigated with balanced saline solution to open the valve mechanism. After conjunctival incision and separation of Tenon capsule from the sclera, the implant plate was secured 8 to 10 mm posterior to the corneal limbus with two interrupted 9-0 nylon or 6-0 polyglactin sutures. A majority of implants (80%) were inserted in the superotemporal quadrant, 19% were placed in the superonasal quadrant, and 1% were placed in the inferotemporal quadrant. The tube was trimmed to extend from 1 to 3 mm beyond the posterior surgical limbus. A 23-gauge needle was used to enter the anterior chamber at the surgical limbus parallel to the iris plane, and the tube was inserted into the anterior chamber through the needle track. The 23-gauge needle provided an adequate size track for tube insertion while minimizing leakage of aqueous around the tube postoperatively. The tube was loosely secured to the sclera posterior to the limbus and then covered with human donor sclera or pericardium, which was secured with interrupted 9-0 or 10-0 nylon or polyglactin sutures. The conjunctiva was closed with absorbable sutures, and subconjunctival injections of antibiotics and corticosteroids were administered before the eye was patched. Postoperative treatment consisted of topical corticosteroids and antibiotics. Two eyes (1%) were treated with three 5-mg subconjunctival injections of 5-fluorouracil— one eye at 2 months and the other at 20 months postoperatively. Four eyes that were classified as failures received 0.4 mg/ml mitomycin C in a sponge fragment in the area of the plate for a 3-minute intraoperative exposure period. No systemic antimetabolites or corticosteroids were given. 28
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RESULTS THE CHARACTERISTICS OF THE PATIENTS IN THE STUDY
are summarized in Table 1. A total of 159 eyes in 144 consecutive patients were included during the study period, from July 1992 to June 1996. The mean 6 SEM follow-up period was 13.4 6 0.7 months (range, 4 to 44 months). The mean 6 SEM age was 60.9 6 1.9 years (range, 0.1 to 103 years). The majority of eyes were pseudophakic (96 eyes, 61%) at the time of surgery. The most common diagnoses were open-angle glaucoma (55 eyes, 35%), glaucoma associated with penetrating keratoplasty (31 eyes, 19%), and neovascular glaucoma (28 eyes, 18%). Of the 28 eyes with neovascular glaucoma, 12 had proliferative diabetic retinopathy, 15 had central retinal vein occlusion, and one had chronic retinal detachment. Before Ahmed Glaucoma Valve implantation, eyes had been treated with an average of 2.7 ocular procedures, including cataract extraction (128 eyes, 81%), trabeculectomy (48 eyes, 30%), penetrating keratoplasty (31 eyes, 19%), cyclodestructive procedure (10 eyes, 6%), drainage implant (6 eyes, 4%), and other procedures (17 eyes, 11%). As shown in Table 2, the mean preoperative intraocular pressure was 32.7 6 0.8 mm Hg, with 2.7 6 0.1 antiglaucoma medications. Postoperatively, the mean intraocular OF
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TABLE 1. Characteristics of the Patients Number of patients Number of eyes Follow-up (months) Mean 6 SEM Range Age (years) Mean 6 SEM Range Gender (No. [%]) Male Female Race or ethnicity (No. [%]) Black White Hispanic Non-Hispanic Asian Lens status (No. [%]) Phakic Aphakic Pseudophakic Diagnosis (No. [%]) Neovascular glaucoma Congenital glaucoma Glaucoma associated with uveitis Open-angle glaucoma Chronic angle-closure glaucoma Glaucoma associated with penetrating keratoplasty Glaucoma associated with trauma Combined mechanisms glaucoma
TABLE 2. Preoperative and Postoperative Comparisons IOP (mean 6 SEM mm Hg)* Preoperative Postoperative Eyes with IOP . 21 mm Hg (No. [%]) Preoperative Postoperative Antiglaucoma medications (mean 6 SEM)* Preoperative Postoperative Postoperative visual acuity (No. [%]) Improved or within one Snellen line Worse by more than one Snellen line Outcome (No. [%]) Success Failure
144 159 13.4 6 0.7 4–44 60.9 6 1.9 0.1–103 68 (43) 91 (57) 22 (14) 131 (82) 32 (20) 99 (62) 6 (4) 31 (19) 32 (20) 96 (61)
2.7 6 0.1 1.1 6 0.1 131 (82) 28 (18) 134 (84) 25 (16)
had neovascular glaucoma with preoperative vision of finger counting and light perception. The remaining eye had preoperative vision of light perception, with postoperative vision loss due to blunt trauma and retinal detachment. The mean number of preoperative antiglaucoma medications decreased significantly postoperatively in the success (P , .0001) and the failure (P , .05) groups (Table 3). Although the mean number of preoperative medications was not significantly different in the successes and the failures, the number of postoperative medications was significantly higher (P , .001) in the failure group. The mean preoperative intraocular pressure was significantly reduced postoperatively in the successes (P , .0001) and the failures (P , .005). As expected, the mean postoperative intraocular pressure was significantly higher (P , .0001) in the failures; however, the preoperative intraocular pressure was also significantly higher (P , .05) in this group. The mean intraocular pressures at various times after implantation of the Ahmed Glaucoma Valve are shown in Figure 1. The mean preoperative intraocular pressure of 32.7 6 0.8 mm Hg was decreased to 11.7 6 0.8 mm Hg at 1 day, 14.8 6 0.7 mm Hg at 1 year, and 13.3 6 0.9 mm Hg at 2 years after surgery. After the initial reduction of intraocular pressure at postoperative day 1, the mean intraocular pressure gradually increased to a peak of 16.9 6 0.6 mm Hg at 2 months, then gradually decreased after that. The peak mean intraocular pressure at 2 months postoperatively was significantly higher than the intraocular pressure at 1 year (P , .02) and 2 years (P , .001) after surgery. Figure 2 shows the mean number of antiglaucoma medications after Ahmed Glaucoma Valve implantation.
28 (18) 11 (7) 14 (9) 55 (35) 10 (6) 31 (19) 7 (4) 3 (2)
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141 (89) 24 (15)
IOP 5 intraocular pressure. *P , .0001, paired t test.
pressure was 15.9 6 0.6 mm Hg at the most recent follow-up examination (P , .0001), with 1.1 6 0.1 antiglaucoma medications (P , .0001). At the most recent visit, the visual acuity was improved or within 1 Snellen line in the majority of eyes (131, 82%), and successful outcome was achieved in 134 eyes (84%). Of the 134 successful eyes, 101 (75%) required antiglaucoma medications, and 33 (25%) were not treated with antiglaucoma medications postoperatively. Of the 25 eyes considered failures, 14 (56%) had intraocular pressure greater than 21 mm Hg without additional glaucoma surgery, and 11 (44%) had loss of light perception or had elevated intraocular pressure with additional glaucoma surgery. Table 3 compares the characteristics of the successful Ahmed Glaucoma Valve implants with failed ones. In comparisons of follow-up period, mean age, gender, lens status, postoperative visual acuity, and postoperative complications, successes and failures were not significantly different. The number of failures was significantly higher in eyes with neovascular glaucoma compared with other diagnoses (P , .025). Three eyes were classified as failures because of loss of light perception. Of these three eyes, two VOL. 127, NO. 1
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TABLE 3. Characteristics of Successes and Failures
Number of eyes (%) Follow-up (mean 6 SEM months)* Age (mean 6 SEM years)* Gender (No. [%])† Male Female Diagnosis (No. [%])‡ Neovascular glaucoma Congenital glaucoma Glaucoma associated with uveitis Open-angle glaucoma Chronic angle-closure glaucoma Glaucoma associated with penetrating keratoplasty Glaucoma associated with trauma Combined mechanism glaucoma Lens status (No. [%])† Phakic Aphakic Pseudophakic Antiglaucoma medications (mean 6 SEM) Preoperative* Postoperative§ Intraocular pressure (mean 6 SEM mm Hg) Preoperative¶ Postoperative# Postoperative visual acuity (No. [%])† Improved or without 1 Snellen line Worse by more than 1 Snellen line Postoperative complications (No. [%])† Complications No complications
Success
Failure
134 (84) 13.9 6 0.9
25 (16) 10.9 6 1.6
61.0 6 2.1
60.7 6 4.6
59 (37) 75 (47)
9 (6) 16 (10)
19 (12) 10 (6) 12 (7)
9 (6) 1 (1) 2 (1)
50 (31) 7 (4) 25 (16)
5 (3) 3 (2) 6 (4)
6 (4)
1 (1)
3 (2)
0 (0)
22 (14) 28 (17) 84 (53)
9 (6) 4 (3) 12 (7)
2.6 6 0.1 0.9 6 0.1
2.8 6 0.2 1.8 6 0.3
31.9 6 0.9 14.3 6 0.4
36.6 6 2.1 24.8 6 2.1
114 (72)
17 (11)
20 (12)
8 (5)
58 (36) 76 (48)
17 (11) 8 (5)
FIGURE 1. Mean intraocular pressure after Ahmed Glaucoma Valve implantation. The preoperative intraocular pressure of 32.7 6 0.8 mm Hg (mean 6 SEM) decreased to 11.7 6 0.8 mm Hg at 1 day, 14.8 6 0.7 mm Hg at 1 year, and 13.3 1 0.9 mm Hg at 2 years after surgery.
FIGURE 2. Mean number of antiglaucoma medications after Ahmed Glaucoma Valve implantation. The number of preoperative medications (time 0) was 2.7 6 0.1 (mean 6 SEM). Eyes were treated, on average, with 1.3 6 0.2 medications at 1 year and 0.9 6 0.9 medications at 2 years after surgery.
analysis) following Ahmed Glaucoma Valve implantation, with 87% success at 1 year and 75% success at 2 years after surgery. Complications occurred in 75 (47%) of 159 eyes after Ahmed Glaucoma Valve implant surgery (Table 4). A common complication, obstruction of the tube, was encountered in 17 eyes (11%) and treated with tube irrigation in one eye. Although 33 eyes developed corneal edema or graft failure, tube-cornea touch was observed in only eight eyes (5%). The tube was repositioned surgically in two of the eight eyes with tube-cornea touch. Focal abnormalities caused by the tube were found in seven of 22 eyes with corneal edema, whereas the remaining 15 eyes had diffuse corneal edema. Graft failure in eyes with corneal transplants was observed in 11 (35%) of 31 eyes
*Not significant, success vs failure, t test. † Not significant, success vs failure, chi-square test. ‡ P 5 0.25, success vs failure, chi-square test. § P , .001, success vs failure, t test. ¶ P , .05, success vs failure, t test. # P , .0001, success vs failure, t test.
After the initial postoperative reduction in medications, the mean number of medications gradually increased during the first year after surgery. Eyes were treated with an average of 1.3 6 0.2 medications at 1 year and 0.9 6 0.9 medications at 2 years after surgery. Figure 3 shows the cumulative probablility of success (Kaplan-Meier life-table 30
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surgery. After valve implantation, two pseudophakic eyes developed malignant glaucoma, which was manifested by increased intraocular pressure and shallow anterior chamber and was successfully treated with Nd:YAG iridotomy and capsulotomy. In 10 eyes (6%) with Tenon cyst, six underwent needling of the bleb. Of the four eyes with motility disturbance after Ahmed Glaucoma Valve implantation, one had the implant removed and one required strabismus surgery. The three eyes (2%) with retinal detachment were repaired surgically. Two of the eyes with suprachoroidal hemorrhage required surgical drainage. Although 13 eyes (8%) had hypotony and 13 eyes (8%) had shallow anterior chamber, none of them required surgical anterior chamber reformation. A total of 35 complications required treatment in the operating room.
FIGURE 3. Cumulative probability of success following Ahmed Glaucoma Valve implantation was 87% at 1 year and 75% at 2 years (Kaplan-Meier life-table analysis).
DISCUSSION A VARIETY OF AQUEOUS DRAINAGE IMPLANTS HAVE BEEN
TABLE 4. Postoperative Complications* Complication
No. (%)
Number of eyes Number with complications Hypotony Shallow anterior chamber Choroidal effusion Suprachoroidal hemorrhage Corneal edema Diffuse Focal Graft failure Tube-cornea touch Obstruction of tube Erosion of tube Extrusion of implant Hyphema Motility disorder Retinal detachment Iritis† Tenon cyst Malignant glaucoma Phthisis bulbi
159 (100) 75 (47) 13 (8) 13 (8) 10 (6) 5 (3)
developed to treat recalcitrant glaucomas, including opentube and valved designs.1,2 The Ahmed Glaucoma Valve implant has a 185-mm2 polypropylene body, which is larger than the single-plate Molteno implant and smaller than the Baerveldt implant. Its tapered chamber valve is designed to provide resistance to aqueous flow. We found transient postoperative hypotony in only 13 (8%) of 159 eyes treated with the this implant, and none required anterior chamber reformation. We also found that the Ahmed Glaucoma Valve implant provides effective longterm control of intraocular pressure, with a cumulative probability of success of 87% at 1 year and 75% at 2 years after surgery. In our study, a successful outcome was achieved in the majority of eyes (131, 82%) at the most recent follow-up examination, although most eyes required approximately one antiglaucoma medication postoperatively. The overall success rate in this study compares favorably with the success rates of other glaucoma drainage devices. The Molteno implant has had success rates of 58% to 95%,7–13 and success rates of 64% and 80% were reported with the Krupin-Denver valve with disk.14,15 In a retrospective multicenter study of 103 eyes with follow-up comparable to our study, Siegner and associates3 reported an overall success rate of 72% with the Baerveldt implant. All of these glaucoma drainage implants divert aqueous from the eye to the Tenon space posterior to the limbus, which may explain similar success rates with different implants. Our success rate at the most recent follow-up examination of 68% in eyes with neovascular glaucoma was significantly lower compared with eyes that had other diagnoses. This decreased prognosis for successful outcome in eyes with neovascular glaucoma is comparable to results with other drainage implants.3,8,16 The eyes with failed Ahmed implants had a higher preoperative mean intraocular pressure than the eyes with successful implants. In our
15 (9) 7 (4) 11 (7) 8 (5) 17 (11) 4 (3) 4 (3) 10 (6) 4 (3) 3 (2) 9 (6) 10 (6) 2 (1) 2 (1)
*More than one complication may have occurred in an eye. Three eyes with iritis had a history of Vogt-Kayanagi-Harada disease. †
with grafts and was treated with repeat penetrating keratoplasty. Surgical treatment of four eyes (3%) with erosion of the tube and four eyes (3%) with extrusion of the implant was performed by covering the area with donor sclera or pericardium and the patient’s conjunctiva. Of the patients with hyphema and neovascular glaucoma, half had rubeosis iridis noted at the time of Ahmed Glaucoma Valve VOL. 127, NO. 1
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patients, very high preoperative intraocular pressure was a poor prognostic factor for success of the implant procedure, which may have simply represented an increased likelihood of neovascular glaucoma. The success rate of the implant in eyes with penetrating keratoplasties (81%) did not differ significantly from our overall success rate and was comparable to the results with the Ahmed Glaucoma Valve implant reported by Coleman and associates.17 In our 31 eyes with penetrating keratoplasty, we found graft failure in 11 eyes (35%). This finding is similar to the rate of graft failure in eyes with penetrating keratoplasty and Ahmed Glaucoma Valve implant (25%)17 or other glaucoma drainage devices (20% to 29%).3,18,19 In our patients with congenital or developmental glaucoma, the likelihood of success after Ahmed Glaucoma Valve implant did not differ significantly from the overall success rate. An advantage of the Ahmed Glaucoma Valve is the low rate of hypotony during the immediate postoperative period20 compared with the higher rate of such complications after nonvalved implants21 in pediatric patients. A period of transient elevation of intraocular pressure, termed the “hypertensive phase,” has been described after glaucoma drainage implant surgery, appearing approximately 4 weeks after surgery and lasting at least 12 to 16 weeks.8,11,14,22,23 In our study, the peak mean intraocular pressure 2 months postoperatively was significantly higher than the intraocular pressure at 1 and 2 years after surgery. This moderate hypertensive phase may be due to the intermediate-sized plate of the Ahmed Glaucoma Valve implant; the more prominent elevation of intraocular pressure after the single-plate Molteno implant may be due to the smaller surface area of this implant,8,11 and the absence of the hypertensive phase after the Baerveldt implant may be due to the larger plate surface area.3 The hypertensive phase may also have been minimized in our study because of the postoperative antiglaucoma medications used in these eyes. In our Kaplan-Meier life-table analysis, the cumulative probability of success following Ahmed Glaucoma Valve implant was 87% at 1 year and 75% at 2 years. These survival rates could be regarded as conservative estimates, because some patients considered failures by intraocular pressure greater than 21 mm Hg on one visit may have had successful control of intraocular pressure at a later visit. It is also likely that a higher proportion of failures would be followed by the glaucoma subspecialist and that successes would be followed by the primary ophthalmologists. Hypotony and complications of hypotony are common during the immediate postoperative period after nonvalved glaucoma drainage implants. The most common complications after the Baerveldt implant were hypotony (32% of eyes) and choroidal effusion (20% of eyes).3 Wilson and associates4 found a 20% incidence of hypotony-induced choroidal detachment and shallow anterior chamber after placement of the Molteno implant. By contrast, Coleman 32
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and associates6 reported eight of 60 eyes (13%) with intraocular pressure less than 5 mm Hg and two other eyes (3%) with shallow anterior chambers on the first postoperative day after Ahmed Glaucoma Valve implantation. In the current study, we also found complications associated with hypotony in the immediate postoperative period less frequently than would be expected with nonvalved glaucoma drainage implants. Although no eyes required surgical anterior chamber reformation, we identified 13 eyes (8%) with hypotony, 13 eyes (8%) with shallow anterior chambers, and 6 eyes (4%) with both shallow anterior chamber and hypotony. Suprachoroidal hemorrhage occurred in five eyes (3%), of which three had a significant reduction in vision. Several clinical studies have identified motility disturbances after implantation of glaucoma drainage devices.3,24 –28 These motility disorders may result from mechanical displacement (mass effect) by the implant and bleb, fat adherence syndrome, or posterior fixation suture (Faden) effect from scarring under the rectus muscle. We identified only four eyes (3%) with motility disorders after Ahmed Glaucoma Valve implantation, although formal motility testing was not performed in our study. One of these eyes underwent strabismus surgery and another had the implant removed. In our study, retinal detachment occurred in three eyes (2%) following Ahmed Glaucoma Valve implantation. One of these detachments was attributed to postoperative trauma unrelated to the Ahmed Glaucoma Valve surgery. This eye and an additional eye with retinal detachment were the two eyes that eventually developed phthisis bulbi in our study. Although the posterior aspect of the Ahmed Glaucoma Valve plate may extend to the region around the optic nerve, especially when implanted superonasally,29 we did not observe any eyes with clinical evidence of optic neuropathy. A common complication in our series was obstruction of the tube, which occurred in 17 eyes (11%). The obstruction was due to blood in six eyes (five had neovascular glaucoma), vitreous in one eye, and iris or cornea in four eyes. The remaining six eyes had presumed obstruction manifested by increased intraocular pressure during the first postoperative week, with an apparently patent tube on slit-lamp examination. The intraocular pressure returned to normal spontaneously or with digital pressure in five of the six eyes, and one eye was treated with irrigation of the tube in the operating room. We did not observe any instances of tube occlusion by the posterior capsule30 or irreversible valve membrane adhesion,31 which have been described in eyes with Ahmed Glaucoma Valve implants. In this study, we found a cumulative probability of success of 87% at 1 year and 75% at 2 years after implantation of the Ahmed Glaucoma Valve. The mean intraocular pressure was 14.8 6 0.7 mm Hg at 1 year and 13.3 6 0.9 at 2 years after surgery. We observed a mild hypertensive phase, which was likely attenuated by the use of approximately one antiglaucoma medication postoperOF
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atively. The mean intraocular pressure at the first postoperative day was 11.7 6 0.8 mm Hg, and transient postoperative hypotony was observed in 13 eyes (8%). We conclude that the Ahmed Glaucoma Valve implant causes effective and stable reduction of intraocular pressure and that postoperative hypotony is not commonly associated with this valved implant.
15. 16. 17.
REFERENCES 18. 1. Williams AS. Setons in glaucoma surgery. In: Albert DM, Jakobiec FA, editors. Principles and practice of ophthalmology: clinical practice. Philadelphia: WB Saunders, 1994: 1655–1667. 2. Rosenberg LF, Krupin T. Implants in glaucoma surgery. In: Ritch R, Shields MB, Krupin T, editors. The glaucomas, 2nd ed. Philadelphia: Mosby, 1996:1783–1807. 3. Siegner SW, Netland PA, Urban RC, et al. Clinical experience with the Baerveldt glaucoma drainage implant. Ophthalmology 1995;102:1298 –1307. 4. Wilson RP, Cantor L, Katz LJ, et al. Aqueous shunts. Molteno versus Schocket. Ophthalmology 1992;99:672– 678. 5. Francis BA, Cortes A, Chen J, Alvarado JA. Characteristics of glaucoma drainage implants during dynamic and steadystate flow conditions. Ophthalmology 1998;105:1708 –1714. 6. Coleman AL, Hill R, Wilson MR, et al. Initial clinical experience with the Ahmed Glaucoma Valve implant. Am J Ophthalmol 1995;120:23–31. 7. Melaned S, Cahane M, Gutman I, Blumenthal M. Postoperative complications after Molteno implant surgery. Am J Ophthalmol 1991;111:319 –322. 8. Minckler DS, Heuer DK, Hasty B, et al. Clinical experience with the single-plate Molteno implant in complicated glaucomas. Ophthalmology 1988;95:1181–1188. 9. Lloyd MA, Sedlak T, Heuer DK, et al. Clinical experience with the single-plate Molteno implant in complicated glaucomas: update of a pilot study. Ophthalmology 1992;95:679 – 687. 10. Nesher R, Sherwood MB, Kass MA, et al. Molteno implants in children. J Glaucoma 1992;1:228 –232. 11. Heuer DK, Lloyd MA, Abrams DA, et al. Which is better? One or two? A randomized clinical trial of single-plate versus double-plate Molteno implantation for glaucomas in aphakia and pseudophakia. Ophthalmology 1992;99:1512–1519. 12. Airaksinen PJ, Aisala P, Tuulonen A. Molteno implant surgery in uncontrolled glaucoma. Trans Ophthalmol Soc U K 1982;102:122–124. 13. Downes RN, Flanagan DW, Jordan K, Burton RL. The Molteno implant in intractable glaucoma. Eye 1988;2:250 – 259. 14. Fellenbaum PS, Almeida AR, Minckler DS, et al. Krupin
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disk implantation for complicated glaucoma. Ophthalmology 1994;101:1178 –1182. The Krupin Eye Valve Filtering Surgery Study Group. Krupin eye valve with disk for filtration surgery. Ophthalmology 1994;101:651– 658. Krupin T, Ritch R, Camras CB, et al. A long Krupin-Denver valve implant attached to a 180 degree scleral explant for glaucoma surgery. Ophthalmology 1988;95:1174 –1180. Coleman AL, Mondino BJ, Wilson MR, Casey R. Clinical experience with the Ahmed Glaucoma Valve implant in eyes with prior or concurrent penetrating keratoplasties. Am J Ophthalmol 1997;123:54 – 61. Kirkness CM, Ling Y, Rice NSC. The use of silicone drainage tubing to control postkeratoplasty glaucoma. Eye 1988;2:583–590. McDonnell PJ, Robin JB, Schanzlin DJ, et al. Molteno implant for control of glaucoma in eyes after penetrating keratoplasty. Ophthalmology 1988;95:364 –369. Coleman AL, Smyth RJ, Wilson MR, Tam M. Initial clinical experience with the Ahmed Glaucoma Valve implant in pediatric patients. Arch Ophthalmol 1997;115:186 –191. Netland PA, Walton DS. Glaucoma drainage implants in pediatric patients. Ophthalmic Surg 1993:24:723–729. Lieberman MF, Ewing RH. Drainage implant surgery for refractory glaucoma. Int Ophthalmol Clin 1990;30:198 –208. Smith MF, Sherwood MB, McGorray SP. Comparison of the double-plate Molteno drainage implant with the Schocket procedure. Arch Ophthalmol 1992;110:1246–1250. Smith SL, Starita RJ, Fellman RL, Lynn JR. Early clinical experience with the Baerveldt 350-mm2 glaucoma implant and associated extraocular muscle imbalance. Ophthalmology 1993;100:914 –918. Mun˜oz M, Parrish R. Strabismus following implantation of Baerveldt drainage devices. Arch Ophthalmol 1993;111: 1096 –1099. Ball SF, Ellis GS Jr, Herrington RG, Liang K. Brown’s superior oblique tendon syndrome after Baerveldt glaucoma implant [letter]. Arch Ophthalmol 1992;110:1368. Christmann LM, Wilson ME. Motility disturbances after Molteno implants. J Pediatr Ophthalmol Strabismus 1992; 29:44 – 48. Mun˜oz M, Parrish R. Hypertropia after implantation of a Molteno drainage device [letter]. Am J Ophthalmol 1992; 113:98 –100. Leen MM, Witkop GS, George DP. Anatomic considerations in the implantation of the Ahmed Glaucoma Valve. Arch Ophthalmol 1996;114:223–224. Tessler Z, Jluchoded S, Rosenthal G. Nd:YAG laser for Ahmed tube shunt occlusion by the posterior capsule. Ophthalmic Surg Lasers 1997;28:69 –70. Feldman RM, El-Harazi SM, Villanueva G. Valve membrane adhesion as a cause of Ahmed glaucoma valve failure. J Glaucoma 1997;6:10 –12.
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● PURPOSE:
We studied the intermediate-term clinical experience with the Ahmed Glaucoma Valve implant (New World Medical, Inc, Rancho Cucamonga, California). ● METHODS: In this multicenter, retrospective case series, we studied 159 eyes (144 patients) treated with the Ahmed Glaucoma Valve with a mean 6 SEM (standard error of mean) follow-up of 13.4 6 0.7 months (range, 4 to 44 months). The mean 6 SEM age was 60.9 6 1.9 years (range, 0.1 to 103 years). Surgical success was defined as intraocular pressure less than 22 mm See also pp. 34 – 42.
Hg and greater than 5 mm Hg without additional glaucoma surgery and without loss of light perception. Postoperative use of antiglaucoma medications was not a criterion for success or failure. The definition of hypotony was intraocular pressure of 5 mm Hg or less in two consecutive visits. ● RESULTS: Intraocular pressure was reduced from a mean of 32.7 6 0.8 mm Hg before surgery to 15.9 6 0.6 mm Hg (P < .0001) at the most recent follow-up after surgery. The number of antiglaucoma medications was decreased from 2.7 6 0.1 before surgery to 1.1 6 0.1 after surgery (P < .0001). The cumulative probability of success was 87% at 1 year and 75% at 2 years after surgery (Kaplan-Meier life-table analysis). PostoperaAccepted for publication Sept 24, 1998. From the University of Tennessee, Memphis, Tennessee (Drs Huang and Netland); Jules Stein Eye Institute, Los Angeles, California (Drs Coleman and Siegner); Wills Eye Hospital, Philadelphia, Pennsylvania (Dr Moster); and University of California, Irvine, California (Dr Hill). Supported in part by Research to Prevent Blindness, Inc, New York, New York. The authors have no proprietary interest in the Ahmed Glaucoma Valve implant. This study was presented in part at the annual meeting of the Association for Research in Vision and Ophthalmology in Fort Lauderdale, Florida, May 12, 1998. Correspondence to Peter A. Netland, MD, PhD, Department of Ophthalmology, University of Tennessee, Memphis, 956 Court Avenue, Memphis, TN 38163; fax: (901) 448-1299; e-mail: pnetland@mail. eye.utmem.edu 0002-9394/99/$20.00 PII S0002-9394(98)00394-8
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tively, 24 (15%) of 159 eyes had intraocular pressure greater than or equal to 22 mm Hg. The visual acuity was improved or within one Snellen line in 131 eyes (82%). Complications occurred in 75 eyes (47%), the majority of which did not affect surgical outcome. The most common complication was obstruction of the tube, which was observed in 17 eyes (11%). Transient postoperative hypotony was found in 13 eyes (8%). ● CONCLUSIONS: The Ahmed Glaucoma Valve implant is effective in lowering intraocular pressure, and postoperative hypotony is not commonly associated with this implant. (Am J Ophthalmol 1999;127:27–33. © 1999 by Elsevier Science Inc. All rights reserved.)
G
LAUCOMA DRAINAGE IMPLANTS ARE A USEFUL
alternative in treating glaucomas that are resistant to medical therapy and glaucoma filtration surgery.1,2 These implants have a small-caliber silicone tube that drains aqueous from the anterior or posterior chamber to an extrascleral device that maintains a fibrous pseudocyst through which filtration can occur. A variety of aqueous shunting devices have been developed, including open-tube and valved designs. Hypotony during the immediate postoperative period is a common complication associated with the open-tube implants.3,4 Although valved implants may not completely close after initial perfusion with fluid, they do function as flow-restricting devices.5 The Ahmed Glaucoma Valve implant (New World Medical, Inc, Rancho Cucamonga, California) directs aqueous flow through the silicone tube and between two thin silicone elastomer membranes in a tapered chamber. The initial clinical experience with this implant indicated that hypotony and its attendant complications during the immediate postoperative period were less common than reported with other glaucoma drainage devices.6 Our purpose in this study was to investigate the short- and long-term clinical effectiveness of the Ahmed Glaucoma Valve implant in a multicenter review of patients with glaucomas refractory to other treatments.
ELSEVIER SCIENCE INC. ALL
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Criteria for success and failure were defined before reviewing the data. Surgical success was defined as intraocular pressure less than 22 mm Hg and greater than 5 mm Hg without additional glaucoma surgery (excluding the injection of 5-fluorouracil) and without loss of light perception.3 Postoperative use of antiglaucoma medications was not a criterion of success or failure. Results of the most recent examination were used to record the final intraocular pressure and visual acuity for classification as a success or failure. Preoperative intraocular pressure and Snellen visual acuity were recorded on the most recent office visit prior to surgery. Intraocular pressure was measured with a Goldmann applanation tonometer, a Tono-pen (Mentor O & O, Norwell, Massachusetts), or a handheld applanation tonometer (Kowa; Kowa Optimet Inc, Torrance, California, or Perkins; Clement Clarke, Columbus, Ohio). Although formal motility testing was not performed in all patients, those with gross motility disturbances or symptoms were evaluated with ocular motility testing. The definition of hypotony in this study was intraocular pressure of 5 mm Hg or less in two consecutive visits. Paired t tests were used to assess differences in continuously scaled variables before and after surgery, and nonpaired t tests were used in comparisons of successes and failures. Chi-square test was used for noncontinuously scaled variables in comparisons of successes and failures. The cumulative probability of success was analyzed by Kaplan-Meier life-table analysis. P values less than .05 were considered statistically significant.
PATIENTS AND METHODS WE REVIEWED THE RECORDS OF PATIENTS WHO WERE
treated with the Ahmed Glaucoma Valve implant for increased intraocular pressure or glaucoma that was not responsive to medical treatment, laser treatment, or previous glaucoma surgery. A total of 144 patients (159 eyes) were included from four medical centers in the United States. Patients with less than 4 months of follow-up were excluded from the analysis. After informed written consent was obtained, the Ahmed Glaucoma Valve was implanted by one of four glaucoma subspecialty surgeons (P.A.N., A.L.C., M.R.M., and R.A.H.). Patients with neovascular glaucoma were treated with panretinal photocoagulation before the Ahmed Glaucoma Valve was implanted, when feasible. Seven eyes underwent additional surgical procedures at the same time as implant surgery: six eyes had penetrating keratoplasty, and one had cataract extraction with intraocular lens implantation. Although the Ahmed Glaucoma Valve is available in a smaller size, all implants in this study had a surface area of 185 mm2 (model S-2). The surgical procedure and postoperative management of this valve implantation have been described by Coleman and associates.6 Before implantation in our study, the tube of the Ahmed Glaucoma Valve was irrigated with balanced saline solution to open the valve mechanism. After conjunctival incision and separation of Tenon capsule from the sclera, the implant plate was secured 8 to 10 mm posterior to the corneal limbus with two interrupted 9-0 nylon or 6-0 polyglactin sutures. A majority of implants (80%) were inserted in the superotemporal quadrant, 19% were placed in the superonasal quadrant, and 1% were placed in the inferotemporal quadrant. The tube was trimmed to extend from 1 to 3 mm beyond the posterior surgical limbus. A 23-gauge needle was used to enter the anterior chamber at the surgical limbus parallel to the iris plane, and the tube was inserted into the anterior chamber through the needle track. The 23-gauge needle provided an adequate size track for tube insertion while minimizing leakage of aqueous around the tube postoperatively. The tube was loosely secured to the sclera posterior to the limbus and then covered with human donor sclera or pericardium, which was secured with interrupted 9-0 or 10-0 nylon or polyglactin sutures. The conjunctiva was closed with absorbable sutures, and subconjunctival injections of antibiotics and corticosteroids were administered before the eye was patched. Postoperative treatment consisted of topical corticosteroids and antibiotics. Two eyes (1%) were treated with three 5-mg subconjunctival injections of 5-fluorouracil— one eye at 2 months and the other at 20 months postoperatively. Four eyes that were classified as failures received 0.4 mg/ml mitomycin C in a sponge fragment in the area of the plate for a 3-minute intraoperative exposure period. No systemic antimetabolites or corticosteroids were given. 28
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RESULTS THE CHARACTERISTICS OF THE PATIENTS IN THE STUDY
are summarized in Table 1. A total of 159 eyes in 144 consecutive patients were included during the study period, from July 1992 to June 1996. The mean 6 SEM follow-up period was 13.4 6 0.7 months (range, 4 to 44 months). The mean 6 SEM age was 60.9 6 1.9 years (range, 0.1 to 103 years). The majority of eyes were pseudophakic (96 eyes, 61%) at the time of surgery. The most common diagnoses were open-angle glaucoma (55 eyes, 35%), glaucoma associated with penetrating keratoplasty (31 eyes, 19%), and neovascular glaucoma (28 eyes, 18%). Of the 28 eyes with neovascular glaucoma, 12 had proliferative diabetic retinopathy, 15 had central retinal vein occlusion, and one had chronic retinal detachment. Before Ahmed Glaucoma Valve implantation, eyes had been treated with an average of 2.7 ocular procedures, including cataract extraction (128 eyes, 81%), trabeculectomy (48 eyes, 30%), penetrating keratoplasty (31 eyes, 19%), cyclodestructive procedure (10 eyes, 6%), drainage implant (6 eyes, 4%), and other procedures (17 eyes, 11%). As shown in Table 2, the mean preoperative intraocular pressure was 32.7 6 0.8 mm Hg, with 2.7 6 0.1 antiglaucoma medications. Postoperatively, the mean intraocular OF
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TABLE 1. Characteristics of the Patients Number of patients Number of eyes Follow-up (months) Mean 6 SEM Range Age (years) Mean 6 SEM Range Gender (No. [%]) Male Female Race or ethnicity (No. [%]) Black White Hispanic Non-Hispanic Asian Lens status (No. [%]) Phakic Aphakic Pseudophakic Diagnosis (No. [%]) Neovascular glaucoma Congenital glaucoma Glaucoma associated with uveitis Open-angle glaucoma Chronic angle-closure glaucoma Glaucoma associated with penetrating keratoplasty Glaucoma associated with trauma Combined mechanisms glaucoma
TABLE 2. Preoperative and Postoperative Comparisons IOP (mean 6 SEM mm Hg)* Preoperative Postoperative Eyes with IOP . 21 mm Hg (No. [%]) Preoperative Postoperative Antiglaucoma medications (mean 6 SEM)* Preoperative Postoperative Postoperative visual acuity (No. [%]) Improved or within one Snellen line Worse by more than one Snellen line Outcome (No. [%]) Success Failure
144 159 13.4 6 0.7 4–44 60.9 6 1.9 0.1–103 68 (43) 91 (57) 22 (14) 131 (82) 32 (20) 99 (62) 6 (4) 31 (19) 32 (20) 96 (61)
2.7 6 0.1 1.1 6 0.1 131 (82) 28 (18) 134 (84) 25 (16)
had neovascular glaucoma with preoperative vision of finger counting and light perception. The remaining eye had preoperative vision of light perception, with postoperative vision loss due to blunt trauma and retinal detachment. The mean number of preoperative antiglaucoma medications decreased significantly postoperatively in the success (P , .0001) and the failure (P , .05) groups (Table 3). Although the mean number of preoperative medications was not significantly different in the successes and the failures, the number of postoperative medications was significantly higher (P , .001) in the failure group. The mean preoperative intraocular pressure was significantly reduced postoperatively in the successes (P , .0001) and the failures (P , .005). As expected, the mean postoperative intraocular pressure was significantly higher (P , .0001) in the failures; however, the preoperative intraocular pressure was also significantly higher (P , .05) in this group. The mean intraocular pressures at various times after implantation of the Ahmed Glaucoma Valve are shown in Figure 1. The mean preoperative intraocular pressure of 32.7 6 0.8 mm Hg was decreased to 11.7 6 0.8 mm Hg at 1 day, 14.8 6 0.7 mm Hg at 1 year, and 13.3 6 0.9 mm Hg at 2 years after surgery. After the initial reduction of intraocular pressure at postoperative day 1, the mean intraocular pressure gradually increased to a peak of 16.9 6 0.6 mm Hg at 2 months, then gradually decreased after that. The peak mean intraocular pressure at 2 months postoperatively was significantly higher than the intraocular pressure at 1 year (P , .02) and 2 years (P , .001) after surgery. Figure 2 shows the mean number of antiglaucoma medications after Ahmed Glaucoma Valve implantation.
28 (18) 11 (7) 14 (9) 55 (35) 10 (6) 31 (19) 7 (4) 3 (2)
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141 (89) 24 (15)
IOP 5 intraocular pressure. *P , .0001, paired t test.
pressure was 15.9 6 0.6 mm Hg at the most recent follow-up examination (P , .0001), with 1.1 6 0.1 antiglaucoma medications (P , .0001). At the most recent visit, the visual acuity was improved or within 1 Snellen line in the majority of eyes (131, 82%), and successful outcome was achieved in 134 eyes (84%). Of the 134 successful eyes, 101 (75%) required antiglaucoma medications, and 33 (25%) were not treated with antiglaucoma medications postoperatively. Of the 25 eyes considered failures, 14 (56%) had intraocular pressure greater than 21 mm Hg without additional glaucoma surgery, and 11 (44%) had loss of light perception or had elevated intraocular pressure with additional glaucoma surgery. Table 3 compares the characteristics of the successful Ahmed Glaucoma Valve implants with failed ones. In comparisons of follow-up period, mean age, gender, lens status, postoperative visual acuity, and postoperative complications, successes and failures were not significantly different. The number of failures was significantly higher in eyes with neovascular glaucoma compared with other diagnoses (P , .025). Three eyes were classified as failures because of loss of light perception. Of these three eyes, two VOL. 127, NO. 1
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TABLE 3. Characteristics of Successes and Failures
Number of eyes (%) Follow-up (mean 6 SEM months)* Age (mean 6 SEM years)* Gender (No. [%])† Male Female Diagnosis (No. [%])‡ Neovascular glaucoma Congenital glaucoma Glaucoma associated with uveitis Open-angle glaucoma Chronic angle-closure glaucoma Glaucoma associated with penetrating keratoplasty Glaucoma associated with trauma Combined mechanism glaucoma Lens status (No. [%])† Phakic Aphakic Pseudophakic Antiglaucoma medications (mean 6 SEM) Preoperative* Postoperative§ Intraocular pressure (mean 6 SEM mm Hg) Preoperative¶ Postoperative# Postoperative visual acuity (No. [%])† Improved or without 1 Snellen line Worse by more than 1 Snellen line Postoperative complications (No. [%])† Complications No complications
Success
Failure
134 (84) 13.9 6 0.9
25 (16) 10.9 6 1.6
61.0 6 2.1
60.7 6 4.6
59 (37) 75 (47)
9 (6) 16 (10)
19 (12) 10 (6) 12 (7)
9 (6) 1 (1) 2 (1)
50 (31) 7 (4) 25 (16)
5 (3) 3 (2) 6 (4)
6 (4)
1 (1)
3 (2)
0 (0)
22 (14) 28 (17) 84 (53)
9 (6) 4 (3) 12 (7)
2.6 6 0.1 0.9 6 0.1
2.8 6 0.2 1.8 6 0.3
31.9 6 0.9 14.3 6 0.4
36.6 6 2.1 24.8 6 2.1
114 (72)
17 (11)
20 (12)
8 (5)
58 (36) 76 (48)
17 (11) 8 (5)
FIGURE 1. Mean intraocular pressure after Ahmed Glaucoma Valve implantation. The preoperative intraocular pressure of 32.7 6 0.8 mm Hg (mean 6 SEM) decreased to 11.7 6 0.8 mm Hg at 1 day, 14.8 6 0.7 mm Hg at 1 year, and 13.3 1 0.9 mm Hg at 2 years after surgery.
FIGURE 2. Mean number of antiglaucoma medications after Ahmed Glaucoma Valve implantation. The number of preoperative medications (time 0) was 2.7 6 0.1 (mean 6 SEM). Eyes were treated, on average, with 1.3 6 0.2 medications at 1 year and 0.9 6 0.9 medications at 2 years after surgery.
analysis) following Ahmed Glaucoma Valve implantation, with 87% success at 1 year and 75% success at 2 years after surgery. Complications occurred in 75 (47%) of 159 eyes after Ahmed Glaucoma Valve implant surgery (Table 4). A common complication, obstruction of the tube, was encountered in 17 eyes (11%) and treated with tube irrigation in one eye. Although 33 eyes developed corneal edema or graft failure, tube-cornea touch was observed in only eight eyes (5%). The tube was repositioned surgically in two of the eight eyes with tube-cornea touch. Focal abnormalities caused by the tube were found in seven of 22 eyes with corneal edema, whereas the remaining 15 eyes had diffuse corneal edema. Graft failure in eyes with corneal transplants was observed in 11 (35%) of 31 eyes
*Not significant, success vs failure, t test. † Not significant, success vs failure, chi-square test. ‡ P 5 0.25, success vs failure, chi-square test. § P , .001, success vs failure, t test. ¶ P , .05, success vs failure, t test. # P , .0001, success vs failure, t test.
After the initial postoperative reduction in medications, the mean number of medications gradually increased during the first year after surgery. Eyes were treated with an average of 1.3 6 0.2 medications at 1 year and 0.9 6 0.9 medications at 2 years after surgery. Figure 3 shows the cumulative probablility of success (Kaplan-Meier life-table 30
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surgery. After valve implantation, two pseudophakic eyes developed malignant glaucoma, which was manifested by increased intraocular pressure and shallow anterior chamber and was successfully treated with Nd:YAG iridotomy and capsulotomy. In 10 eyes (6%) with Tenon cyst, six underwent needling of the bleb. Of the four eyes with motility disturbance after Ahmed Glaucoma Valve implantation, one had the implant removed and one required strabismus surgery. The three eyes (2%) with retinal detachment were repaired surgically. Two of the eyes with suprachoroidal hemorrhage required surgical drainage. Although 13 eyes (8%) had hypotony and 13 eyes (8%) had shallow anterior chamber, none of them required surgical anterior chamber reformation. A total of 35 complications required treatment in the operating room.
FIGURE 3. Cumulative probability of success following Ahmed Glaucoma Valve implantation was 87% at 1 year and 75% at 2 years (Kaplan-Meier life-table analysis).
DISCUSSION A VARIETY OF AQUEOUS DRAINAGE IMPLANTS HAVE BEEN
TABLE 4. Postoperative Complications* Complication
No. (%)
Number of eyes Number with complications Hypotony Shallow anterior chamber Choroidal effusion Suprachoroidal hemorrhage Corneal edema Diffuse Focal Graft failure Tube-cornea touch Obstruction of tube Erosion of tube Extrusion of implant Hyphema Motility disorder Retinal detachment Iritis† Tenon cyst Malignant glaucoma Phthisis bulbi
159 (100) 75 (47) 13 (8) 13 (8) 10 (6) 5 (3)
developed to treat recalcitrant glaucomas, including opentube and valved designs.1,2 The Ahmed Glaucoma Valve implant has a 185-mm2 polypropylene body, which is larger than the single-plate Molteno implant and smaller than the Baerveldt implant. Its tapered chamber valve is designed to provide resistance to aqueous flow. We found transient postoperative hypotony in only 13 (8%) of 159 eyes treated with the this implant, and none required anterior chamber reformation. We also found that the Ahmed Glaucoma Valve implant provides effective longterm control of intraocular pressure, with a cumulative probability of success of 87% at 1 year and 75% at 2 years after surgery. In our study, a successful outcome was achieved in the majority of eyes (131, 82%) at the most recent follow-up examination, although most eyes required approximately one antiglaucoma medication postoperatively. The overall success rate in this study compares favorably with the success rates of other glaucoma drainage devices. The Molteno implant has had success rates of 58% to 95%,7–13 and success rates of 64% and 80% were reported with the Krupin-Denver valve with disk.14,15 In a retrospective multicenter study of 103 eyes with follow-up comparable to our study, Siegner and associates3 reported an overall success rate of 72% with the Baerveldt implant. All of these glaucoma drainage implants divert aqueous from the eye to the Tenon space posterior to the limbus, which may explain similar success rates with different implants. Our success rate at the most recent follow-up examination of 68% in eyes with neovascular glaucoma was significantly lower compared with eyes that had other diagnoses. This decreased prognosis for successful outcome in eyes with neovascular glaucoma is comparable to results with other drainage implants.3,8,16 The eyes with failed Ahmed implants had a higher preoperative mean intraocular pressure than the eyes with successful implants. In our
15 (9) 7 (4) 11 (7) 8 (5) 17 (11) 4 (3) 4 (3) 10 (6) 4 (3) 3 (2) 9 (6) 10 (6) 2 (1) 2 (1)
*More than one complication may have occurred in an eye. Three eyes with iritis had a history of Vogt-Kayanagi-Harada disease. †
with grafts and was treated with repeat penetrating keratoplasty. Surgical treatment of four eyes (3%) with erosion of the tube and four eyes (3%) with extrusion of the implant was performed by covering the area with donor sclera or pericardium and the patient’s conjunctiva. Of the patients with hyphema and neovascular glaucoma, half had rubeosis iridis noted at the time of Ahmed Glaucoma Valve VOL. 127, NO. 1
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patients, very high preoperative intraocular pressure was a poor prognostic factor for success of the implant procedure, which may have simply represented an increased likelihood of neovascular glaucoma. The success rate of the implant in eyes with penetrating keratoplasties (81%) did not differ significantly from our overall success rate and was comparable to the results with the Ahmed Glaucoma Valve implant reported by Coleman and associates.17 In our 31 eyes with penetrating keratoplasty, we found graft failure in 11 eyes (35%). This finding is similar to the rate of graft failure in eyes with penetrating keratoplasty and Ahmed Glaucoma Valve implant (25%)17 or other glaucoma drainage devices (20% to 29%).3,18,19 In our patients with congenital or developmental glaucoma, the likelihood of success after Ahmed Glaucoma Valve implant did not differ significantly from the overall success rate. An advantage of the Ahmed Glaucoma Valve is the low rate of hypotony during the immediate postoperative period20 compared with the higher rate of such complications after nonvalved implants21 in pediatric patients. A period of transient elevation of intraocular pressure, termed the “hypertensive phase,” has been described after glaucoma drainage implant surgery, appearing approximately 4 weeks after surgery and lasting at least 12 to 16 weeks.8,11,14,22,23 In our study, the peak mean intraocular pressure 2 months postoperatively was significantly higher than the intraocular pressure at 1 and 2 years after surgery. This moderate hypertensive phase may be due to the intermediate-sized plate of the Ahmed Glaucoma Valve implant; the more prominent elevation of intraocular pressure after the single-plate Molteno implant may be due to the smaller surface area of this implant,8,11 and the absence of the hypertensive phase after the Baerveldt implant may be due to the larger plate surface area.3 The hypertensive phase may also have been minimized in our study because of the postoperative antiglaucoma medications used in these eyes. In our Kaplan-Meier life-table analysis, the cumulative probability of success following Ahmed Glaucoma Valve implant was 87% at 1 year and 75% at 2 years. These survival rates could be regarded as conservative estimates, because some patients considered failures by intraocular pressure greater than 21 mm Hg on one visit may have had successful control of intraocular pressure at a later visit. It is also likely that a higher proportion of failures would be followed by the glaucoma subspecialist and that successes would be followed by the primary ophthalmologists. Hypotony and complications of hypotony are common during the immediate postoperative period after nonvalved glaucoma drainage implants. The most common complications after the Baerveldt implant were hypotony (32% of eyes) and choroidal effusion (20% of eyes).3 Wilson and associates4 found a 20% incidence of hypotony-induced choroidal detachment and shallow anterior chamber after placement of the Molteno implant. By contrast, Coleman 32
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and associates6 reported eight of 60 eyes (13%) with intraocular pressure less than 5 mm Hg and two other eyes (3%) with shallow anterior chambers on the first postoperative day after Ahmed Glaucoma Valve implantation. In the current study, we also found complications associated with hypotony in the immediate postoperative period less frequently than would be expected with nonvalved glaucoma drainage implants. Although no eyes required surgical anterior chamber reformation, we identified 13 eyes (8%) with hypotony, 13 eyes (8%) with shallow anterior chambers, and 6 eyes (4%) with both shallow anterior chamber and hypotony. Suprachoroidal hemorrhage occurred in five eyes (3%), of which three had a significant reduction in vision. Several clinical studies have identified motility disturbances after implantation of glaucoma drainage devices.3,24 –28 These motility disorders may result from mechanical displacement (mass effect) by the implant and bleb, fat adherence syndrome, or posterior fixation suture (Faden) effect from scarring under the rectus muscle. We identified only four eyes (3%) with motility disorders after Ahmed Glaucoma Valve implantation, although formal motility testing was not performed in our study. One of these eyes underwent strabismus surgery and another had the implant removed. In our study, retinal detachment occurred in three eyes (2%) following Ahmed Glaucoma Valve implantation. One of these detachments was attributed to postoperative trauma unrelated to the Ahmed Glaucoma Valve surgery. This eye and an additional eye with retinal detachment were the two eyes that eventually developed phthisis bulbi in our study. Although the posterior aspect of the Ahmed Glaucoma Valve plate may extend to the region around the optic nerve, especially when implanted superonasally,29 we did not observe any eyes with clinical evidence of optic neuropathy. A common complication in our series was obstruction of the tube, which occurred in 17 eyes (11%). The obstruction was due to blood in six eyes (five had neovascular glaucoma), vitreous in one eye, and iris or cornea in four eyes. The remaining six eyes had presumed obstruction manifested by increased intraocular pressure during the first postoperative week, with an apparently patent tube on slit-lamp examination. The intraocular pressure returned to normal spontaneously or with digital pressure in five of the six eyes, and one eye was treated with irrigation of the tube in the operating room. We did not observe any instances of tube occlusion by the posterior capsule30 or irreversible valve membrane adhesion,31 which have been described in eyes with Ahmed Glaucoma Valve implants. In this study, we found a cumulative probability of success of 87% at 1 year and 75% at 2 years after implantation of the Ahmed Glaucoma Valve. The mean intraocular pressure was 14.8 6 0.7 mm Hg at 1 year and 13.3 6 0.9 at 2 years after surgery. We observed a mild hypertensive phase, which was likely attenuated by the use of approximately one antiglaucoma medication postoperOF
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atively. The mean intraocular pressure at the first postoperative day was 11.7 6 0.8 mm Hg, and transient postoperative hypotony was observed in 13 eyes (8%). We conclude that the Ahmed Glaucoma Valve implant causes effective and stable reduction of intraocular pressure and that postoperative hypotony is not commonly associated with this valved implant.
15. 16. 17.
REFERENCES 18. 1. Williams AS. Setons in glaucoma surgery. In: Albert DM, Jakobiec FA, editors. Principles and practice of ophthalmology: clinical practice. Philadelphia: WB Saunders, 1994: 1655–1667. 2. Rosenberg LF, Krupin T. Implants in glaucoma surgery. In: Ritch R, Shields MB, Krupin T, editors. The glaucomas, 2nd ed. Philadelphia: Mosby, 1996:1783–1807. 3. Siegner SW, Netland PA, Urban RC, et al. Clinical experience with the Baerveldt glaucoma drainage implant. Ophthalmology 1995;102:1298 –1307. 4. Wilson RP, Cantor L, Katz LJ, et al. Aqueous shunts. Molteno versus Schocket. Ophthalmology 1992;99:672– 678. 5. Francis BA, Cortes A, Chen J, Alvarado JA. Characteristics of glaucoma drainage implants during dynamic and steadystate flow conditions. Ophthalmology 1998;105:1708 –1714. 6. Coleman AL, Hill R, Wilson MR, et al. Initial clinical experience with the Ahmed Glaucoma Valve implant. Am J Ophthalmol 1995;120:23–31. 7. Melaned S, Cahane M, Gutman I, Blumenthal M. Postoperative complications after Molteno implant surgery. Am J Ophthalmol 1991;111:319 –322. 8. Minckler DS, Heuer DK, Hasty B, et al. Clinical experience with the single-plate Molteno implant in complicated glaucomas. Ophthalmology 1988;95:1181–1188. 9. Lloyd MA, Sedlak T, Heuer DK, et al. Clinical experience with the single-plate Molteno implant in complicated glaucomas: update of a pilot study. Ophthalmology 1992;95:679 – 687. 10. Nesher R, Sherwood MB, Kass MA, et al. Molteno implants in children. J Glaucoma 1992;1:228 –232. 11. Heuer DK, Lloyd MA, Abrams DA, et al. Which is better? One or two? A randomized clinical trial of single-plate versus double-plate Molteno implantation for glaucomas in aphakia and pseudophakia. Ophthalmology 1992;99:1512–1519. 12. Airaksinen PJ, Aisala P, Tuulonen A. Molteno implant surgery in uncontrolled glaucoma. Trans Ophthalmol Soc U K 1982;102:122–124. 13. Downes RN, Flanagan DW, Jordan K, Burton RL. The Molteno implant in intractable glaucoma. Eye 1988;2:250 – 259. 14. Fellenbaum PS, Almeida AR, Minckler DS, et al. Krupin
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disk implantation for complicated glaucoma. Ophthalmology 1994;101:1178 –1182. The Krupin Eye Valve Filtering Surgery Study Group. Krupin eye valve with disk for filtration surgery. Ophthalmology 1994;101:651– 658. Krupin T, Ritch R, Camras CB, et al. A long Krupin-Denver valve implant attached to a 180 degree scleral explant for glaucoma surgery. Ophthalmology 1988;95:1174 –1180. Coleman AL, Mondino BJ, Wilson MR, Casey R. Clinical experience with the Ahmed Glaucoma Valve implant in eyes with prior or concurrent penetrating keratoplasties. Am J Ophthalmol 1997;123:54 – 61. Kirkness CM, Ling Y, Rice NSC. The use of silicone drainage tubing to control postkeratoplasty glaucoma. Eye 1988;2:583–590. McDonnell PJ, Robin JB, Schanzlin DJ, et al. Molteno implant for control of glaucoma in eyes after penetrating keratoplasty. Ophthalmology 1988;95:364 –369. Coleman AL, Smyth RJ, Wilson MR, Tam M. Initial clinical experience with the Ahmed Glaucoma Valve implant in pediatric patients. Arch Ophthalmol 1997;115:186 –191. Netland PA, Walton DS. Glaucoma drainage implants in pediatric patients. Ophthalmic Surg 1993:24:723–729. Lieberman MF, Ewing RH. Drainage implant surgery for refractory glaucoma. Int Ophthalmol Clin 1990;30:198 –208. Smith MF, Sherwood MB, McGorray SP. Comparison of the double-plate Molteno drainage implant with the Schocket procedure. Arch Ophthalmol 1992;110:1246–1250. Smith SL, Starita RJ, Fellman RL, Lynn JR. Early clinical experience with the Baerveldt 350-mm2 glaucoma implant and associated extraocular muscle imbalance. Ophthalmology 1993;100:914 –918. Mun˜oz M, Parrish R. Strabismus following implantation of Baerveldt drainage devices. Arch Ophthalmol 1993;111: 1096 –1099. Ball SF, Ellis GS Jr, Herrington RG, Liang K. Brown’s superior oblique tendon syndrome after Baerveldt glaucoma implant [letter]. Arch Ophthalmol 1992;110:1368. Christmann LM, Wilson ME. Motility disturbances after Molteno implants. J Pediatr Ophthalmol Strabismus 1992; 29:44 – 48. Mun˜oz M, Parrish R. Hypertropia after implantation of a Molteno drainage device [letter]. Am J Ophthalmol 1992; 113:98 –100. Leen MM, Witkop GS, George DP. Anatomic considerations in the implantation of the Ahmed Glaucoma Valve. Arch Ophthalmol 1996;114:223–224. Tessler Z, Jluchoded S, Rosenthal G. Nd:YAG laser for Ahmed tube shunt occlusion by the posterior capsule. Ophthalmic Surg Lasers 1997;28:69 –70. Feldman RM, El-Harazi SM, Villanueva G. Valve membrane adhesion as a cause of Ahmed glaucoma valve failure. J Glaucoma 1997;6:10 –12.
Authors Interactivet We encourage questions and comments regarding this article via the Internet on Authors Interactivet at http://www.ajo.com/ Questions, comments, and author responses are posted.
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