- Email: [email protected]
Needling revision of glaucoma drainage device filtering blebs: Authors’ reply
Letters eyes with Fuchs endothelial states may not fair so well.
dystrophy
to the Editor
or other disease
ANISHA J. JUDGE, MD KATAYOUN NAJAFI, MD DAVID A. LEE, MD KEVIN M. MILLER, MD
Los Angeles, California
Needling Revision of Glaucoma Device Filtering Blebs
Drainage
Dear Editor: The results of the study on needling revision of glaucoma drainage devices (GDD) filtering blebs by Chen and Palmberg’ are encouraging. Needling revision could be a useful option for managing failing GDDs with overfibrosis or encapsulation. However, we are a little bit surprised that no association was found between successful needling and adjunctive use of 5fluorouracil (5-FU). This may have resulted from the small sample size and the nonrandomized sampling method of the cases in the study, as 5-FU was used in casesthat appeared to be at higher risk for failure. The successof the needling revision dependson the ability to maintain the patency of the newly created needle tracks. Inhibition of wound healing, fibrosis, and scarring of the newly created channels with antimetabolites would conceptually help to increase the chance of success,especially when more fibrous reaction is expected in the presenceof the GDD, which is a foreign body to the eye. We recently treated two eyes with failed GDDs becauseof overfibrosis using simple needling revision with two sequential needlings each. The newly created channels closed within 48 hours after each needling procedure. We then gave subconjunctival mitomycin C (MMC) (0.05 ml of MMC at a concentration of 0.4 mg/ ml) as an adjunct 1 day before the third needling revision. The mean intraocular pressure(IOP) of the two casesfell from 32 mmHg preoperatively to 15 mmHg at 3 months postoperatively. No antiglaucomatous medications were required after the third revision in either case. Ewing et al2 were the first to report on the use of 5FU with needling revision for failed trabeculetomy, but their results did not show that 5-FU was useful. On the other hand, Mardelli et al3 and Apostolov et al4 reported the successful use of MMC as adjunctive treatment for needling revision of failed filtering blebs. No major complications were encountered in their series, and no evidence of intraocular toxicity related to MMC was noted, perhaps because the dosage used was very small. With the presence of the GDD as protection, GDD needling is technically easier and safer when compared with that of needling for failed trabeculectomy. The risk of globe perforation, intraocular tissue damage, and hemorrhage should be lower, depending on the hardnessof the explant material. We have not recognized any such complications in our cases. Single intraoperative use of MMC has been shown by many authors to increase the surgical successrate of trabeculectomy and to yield lower IOP when compared
with repeated postoperative 5-FU injections. The combination of intraoperative MMC and GDD has been performed in rabbits with encouraging short-term results.5 The single use of subconjunctival MMC as an adjunct for GDD needling revision appearsto be promising. Studies on the safety, efficacy, and minimal effective dosage of MMC for this purpose seem indicated. DENNIS S. C. LAM, FRCS, FRCOphth JIMMY S. M. LAI, FRCS, FRCOphth JOHN K. H. CHUA, FRCS DOROTHY S. P. FAN, BM, MCh Shatin, Hong Kong
References 1. Chen PP, PalmbergPF. Needling revision of glaucoma drainage device filtering blebs. Ophthalmology 1997;104:1004-10. 2. Ewing RH, StamperRL. Needlerevision with andwithout 5fluorouracil for the treatmentof failed filtering blebs.Am J Ophthalmol 1990;110:254-9. 3. Mardelli PC, LedererCM Jr., Murray PL, et al. Slit-lamp needlerevisionof failed filtering blebsusingmitomycin C. Ophthalmology 1996;103:1946-55. 4. Apostolov VI, Siarov NP. Subconjunctivalinjectionof lowdosemitomycin-C for treatmentof failing humantrabeculectomies.Int Ophthalmol 1996;20:101-5. 5. Prata JA, Jr., Minckler DS, Mermoud A, Baerveldt G. Effects of intraoperative mitomycin-C on the function of Baerveldt glaucomadrainageimplantsin rabbits. J Glaucoma 1996;5:29-38. Authors’
reply
Dear Editor: We found that adjunctive 5-fluorouracil (5FU) injections were not significantly associatedwith successfulneedling revision of glaucoma drainage device (GDD) blebs.’ This did not surprise us, given the small number of eyes (6 of 21) that received postneedling injections in our retrospective study and the probable bias in selection of those patients. We could not find any references in the literature in which a significant difference in successwas revealed on comparison of filtering bleb needling with or without adjunctive antifibrosis agents. A prospective randomized trial would best settle this issue. Drs. Lam et al present two casesin which adjunctive mitomycin C (MMC) was administered 1 day prior to GDD bleb needling, with successful intraocular pressure (IOP) control after follow-up of 3 months; no details are given of the needling technique or the type and surface area of each implant. Subconjunctival injection of 1 mg MMC (50 times more than the amount used by Drs. Lam et al) hasbeen shown to significantly reduce IOP.* Perkins et al3 showed use of MMC with double-plate Molten0 implant surgery provided significantly better IOP control without medications compared with a historical control, and in animal studies, MMC use with Baerveldt implant surgery was associatedwith a thinner capsule around the implant, although this did not always result in significantly different IOP.4*5Mardelli et aI6 used MMC in needling revision of trabeculectomy blebs and achieved suc-
1127
Ophthalmology
Volume 10.5, Number 7, July I998
cess (IOP 5 18 mmHg) without medications in 76% of 62 patients, which may lend support to its adjunctive use with GDD bleb needling. Although the report by Drs. Lam et al is interesting, particularly for their efforts to prevent entry of MMC into the eye, further study with more patients and longer follow-up are needed, as the potential for toxicity exists. In rabbit eyes, intraocular doses of MMC as small as .015 mg resulted in severe cornea1 edema.’ PHILIP P. CHEN, MD Seattle, Washington PAUL F. PALMBERG, Miami, Florida
MD, PhD
References
1. Chen PP, PalmbergPF. Needling revision of glaucoma drainagedevice filtering blebs. Ophthalmology 1997;104: 1004-10. 2. Gandolfi SA, Vecchi M, Braccio L. Decrease of intraocular pressureafter subconjunctivalinjection of mitomycin in humanglaucoma.Arch Ophthalmol1995;113582-5. 3. PerkinsTW, CardakliUF, EiseleJR, et al. Adjunctive mitomycin C in Molten0 implant surgery. Ophthalmology 1995;102:91-7. 4. Glover TL, NasisseMP, DavidsonMG. Effects of topically applied mitomycin-C on intraocular pressure,facility of outflow, and fibrosis after glaucomafiltration surgery in clinically normal dogs.Am J Vet Res 1995;56:936-40. 5. PrataJA, Jr., Minckler DS, Mermoud A, Baerveldt G. Effects of intraoperative mitomycin-C on the function of Baerveldt glaucomadrainageimplantsin rabbits. J Glaucoma 1996;5:29-38. 6. Mardelli PG, LedererCM Jr., Murray PL, et al, Slit-lamp needlerevisionof failed filtering blebsusingmitomycinC. Ophthalmology 1996;103:1946-55. 7. Morrow GL, Stein RM, HeathcoteJG, et al. Ocular toxicity of mitomycin C and 5-fluorouracil in the rabbit. Can J Ophthalmol 1994;29:268-73. Complications Hydroxyapatite
of Motility Implants
Peg Placement
in
Dear Editor: I am writing to you about a recent paper entitled, “Complications of Motility Peg Placement for the Hydroxyapatite Orbital Implant” (Ophthalmology 1997; 104:lO: 1616-21). In the authors’ second introductory paragraph, they state “To our knowledge, there are no reports that assess the complications of motility peg placement in hydroxyapatite implants.’ ’ I found this rather misleading. Reference 3 of their report (Kolberg GI. The hydroxyapatite (Bio-Eye@) implant: a historical perspective. J Ophthal Prosth 1996; 1:29-36) clearly states various problems (complications) associatedwith the peg system (granulation tissueformation in the baseof the drilled hole causing peg extrusion, collapse of the peg hole when the peg was removed, threaded sleeve sitting above conjunctival layer, threaded sleeve inserted at an off angle). Reference 4 of their report (Dutton JJ. Coralline hydroxyapatite as an ocular implant. Ophthalmology 1991; 98:870-7) also
1128
states several problems associated with pegs, namely, granulation tissue within the central peg hole (2 patients), conjunctival overgrowth of peg hole (1 patient), peg falling out (1 patient), peg hole drilled obliquely (2 patients). In two of the authors’ former articles (references#5,7), they mention various peg complications: audible click, tissue overgrowth of peg, and granulation tissue in the peg hole in a limited number of patients. In another article entitled, “The popping peg phenomenon” (Jordan DR. Arch Ophthalmol 1994; 112:300- l), several of the above complications of pegs are mentioned, plus an additional complication-the popping peg phenomenon in one patient. Clearly, complications of pegs have been reported in the literature previously but unfortunately not cited in this article. In the first paragraph of the discussion, the authors state, “The majority of patients will not require or request peg placement due to cosmetically adequatemotility with the hydroxyapatite implant alone. In a report of 250 cases of hydroxyapatite orbital implants, only 12% (31 of 250) of patients had a peg placed.” I find this statement misleading as well and disagree with it. The fact that only 3 1 of 250 patients (12%) had a peg, is low, and I suspect representsthe nature of the authors practice rather than most practices. I have personally performed over 300 hydroxyapatite implants, with 65% being pegged. I am not overly impressedwith the motility of the hydroxyapatite on its own and do not feel the readership should be given the impression that most will not require pegs. I feel it would have been more accurate if the authors stated that most of the patients in their practice were not pegged rather than “the majority of patients will not require or request peg placement. ” The main advantage of the hydroxyapatite implant comes with pegging. If it is not pegged, the physician should consider a less expensive porous implant like Med-pore (Porex Surgical, Inc., College Park, GA) or even the Universal Implant (Oculoplastik, Montreal, Canada). In the Discussion section, the authors state that “the main problem with this system (referring to the original ball and socket motility peg) was the formation of granulation tissuein the baseof the drilled vestibule that housed the peg. This occasionally led to extrusion of the peg [3,7].” This statement unfortunately is inaccurate. Reference 3 by Kolberg, in his discussionabout patients receiving the original peg, states: “some had a tendency to form granulation tissue in the base of the drilled hole. Over a period of time, this tissue would begin to expel the peg and prosthesis” Reference 7 by Shield et al, a report on 250 patients (31 of whom had pegs) reports 2 patients who had granulation tissue pushing the peg out as a complication and 3 who had audible clicking. I fail to see how the authors can state that the main problem with the original peg was formation of granulation tissue at the baseof the drilled vestibule. There are insufficient patient data in either article to substantiate this statement. In the authors current paper, the data they present do show that peg extrusion due to granulation tissue pushing the peg out was the most common complication, unfortunately this was not previously proven in the literature.
dystrophy
to the Editor
or other disease
ANISHA J. JUDGE, MD KATAYOUN NAJAFI, MD DAVID A. LEE, MD KEVIN M. MILLER, MD
Los Angeles, California
Needling Revision of Glaucoma Device Filtering Blebs
Drainage
Dear Editor: The results of the study on needling revision of glaucoma drainage devices (GDD) filtering blebs by Chen and Palmberg’ are encouraging. Needling revision could be a useful option for managing failing GDDs with overfibrosis or encapsulation. However, we are a little bit surprised that no association was found between successful needling and adjunctive use of 5fluorouracil (5-FU). This may have resulted from the small sample size and the nonrandomized sampling method of the cases in the study, as 5-FU was used in casesthat appeared to be at higher risk for failure. The successof the needling revision dependson the ability to maintain the patency of the newly created needle tracks. Inhibition of wound healing, fibrosis, and scarring of the newly created channels with antimetabolites would conceptually help to increase the chance of success,especially when more fibrous reaction is expected in the presenceof the GDD, which is a foreign body to the eye. We recently treated two eyes with failed GDDs becauseof overfibrosis using simple needling revision with two sequential needlings each. The newly created channels closed within 48 hours after each needling procedure. We then gave subconjunctival mitomycin C (MMC) (0.05 ml of MMC at a concentration of 0.4 mg/ ml) as an adjunct 1 day before the third needling revision. The mean intraocular pressure(IOP) of the two casesfell from 32 mmHg preoperatively to 15 mmHg at 3 months postoperatively. No antiglaucomatous medications were required after the third revision in either case. Ewing et al2 were the first to report on the use of 5FU with needling revision for failed trabeculetomy, but their results did not show that 5-FU was useful. On the other hand, Mardelli et al3 and Apostolov et al4 reported the successful use of MMC as adjunctive treatment for needling revision of failed filtering blebs. No major complications were encountered in their series, and no evidence of intraocular toxicity related to MMC was noted, perhaps because the dosage used was very small. With the presence of the GDD as protection, GDD needling is technically easier and safer when compared with that of needling for failed trabeculectomy. The risk of globe perforation, intraocular tissue damage, and hemorrhage should be lower, depending on the hardnessof the explant material. We have not recognized any such complications in our cases. Single intraoperative use of MMC has been shown by many authors to increase the surgical successrate of trabeculectomy and to yield lower IOP when compared
with repeated postoperative 5-FU injections. The combination of intraoperative MMC and GDD has been performed in rabbits with encouraging short-term results.5 The single use of subconjunctival MMC as an adjunct for GDD needling revision appearsto be promising. Studies on the safety, efficacy, and minimal effective dosage of MMC for this purpose seem indicated. DENNIS S. C. LAM, FRCS, FRCOphth JIMMY S. M. LAI, FRCS, FRCOphth JOHN K. H. CHUA, FRCS DOROTHY S. P. FAN, BM, MCh Shatin, Hong Kong
References 1. Chen PP, PalmbergPF. Needling revision of glaucoma drainage device filtering blebs. Ophthalmology 1997;104:1004-10. 2. Ewing RH, StamperRL. Needlerevision with andwithout 5fluorouracil for the treatmentof failed filtering blebs.Am J Ophthalmol 1990;110:254-9. 3. Mardelli PC, LedererCM Jr., Murray PL, et al. Slit-lamp needlerevisionof failed filtering blebsusingmitomycin C. Ophthalmology 1996;103:1946-55. 4. Apostolov VI, Siarov NP. Subconjunctivalinjectionof lowdosemitomycin-C for treatmentof failing humantrabeculectomies.Int Ophthalmol 1996;20:101-5. 5. Prata JA, Jr., Minckler DS, Mermoud A, Baerveldt G. Effects of intraoperative mitomycin-C on the function of Baerveldt glaucomadrainageimplantsin rabbits. J Glaucoma 1996;5:29-38. Authors’
reply
Dear Editor: We found that adjunctive 5-fluorouracil (5FU) injections were not significantly associatedwith successfulneedling revision of glaucoma drainage device (GDD) blebs.’ This did not surprise us, given the small number of eyes (6 of 21) that received postneedling injections in our retrospective study and the probable bias in selection of those patients. We could not find any references in the literature in which a significant difference in successwas revealed on comparison of filtering bleb needling with or without adjunctive antifibrosis agents. A prospective randomized trial would best settle this issue. Drs. Lam et al present two casesin which adjunctive mitomycin C (MMC) was administered 1 day prior to GDD bleb needling, with successful intraocular pressure (IOP) control after follow-up of 3 months; no details are given of the needling technique or the type and surface area of each implant. Subconjunctival injection of 1 mg MMC (50 times more than the amount used by Drs. Lam et al) hasbeen shown to significantly reduce IOP.* Perkins et al3 showed use of MMC with double-plate Molten0 implant surgery provided significantly better IOP control without medications compared with a historical control, and in animal studies, MMC use with Baerveldt implant surgery was associatedwith a thinner capsule around the implant, although this did not always result in significantly different IOP.4*5Mardelli et aI6 used MMC in needling revision of trabeculectomy blebs and achieved suc-
1127
Ophthalmology
Volume 10.5, Number 7, July I998
cess (IOP 5 18 mmHg) without medications in 76% of 62 patients, which may lend support to its adjunctive use with GDD bleb needling. Although the report by Drs. Lam et al is interesting, particularly for their efforts to prevent entry of MMC into the eye, further study with more patients and longer follow-up are needed, as the potential for toxicity exists. In rabbit eyes, intraocular doses of MMC as small as .015 mg resulted in severe cornea1 edema.’ PHILIP P. CHEN, MD Seattle, Washington PAUL F. PALMBERG, Miami, Florida
MD, PhD
References
1. Chen PP, PalmbergPF. Needling revision of glaucoma drainagedevice filtering blebs. Ophthalmology 1997;104: 1004-10. 2. Gandolfi SA, Vecchi M, Braccio L. Decrease of intraocular pressureafter subconjunctivalinjection of mitomycin in humanglaucoma.Arch Ophthalmol1995;113582-5. 3. PerkinsTW, CardakliUF, EiseleJR, et al. Adjunctive mitomycin C in Molten0 implant surgery. Ophthalmology 1995;102:91-7. 4. Glover TL, NasisseMP, DavidsonMG. Effects of topically applied mitomycin-C on intraocular pressure,facility of outflow, and fibrosis after glaucomafiltration surgery in clinically normal dogs.Am J Vet Res 1995;56:936-40. 5. PrataJA, Jr., Minckler DS, Mermoud A, Baerveldt G. Effects of intraoperative mitomycin-C on the function of Baerveldt glaucomadrainageimplantsin rabbits. J Glaucoma 1996;5:29-38. 6. Mardelli PG, LedererCM Jr., Murray PL, et al, Slit-lamp needlerevisionof failed filtering blebsusingmitomycinC. Ophthalmology 1996;103:1946-55. 7. Morrow GL, Stein RM, HeathcoteJG, et al. Ocular toxicity of mitomycin C and 5-fluorouracil in the rabbit. Can J Ophthalmol 1994;29:268-73. Complications Hydroxyapatite
of Motility Implants
Peg Placement
in
Dear Editor: I am writing to you about a recent paper entitled, “Complications of Motility Peg Placement for the Hydroxyapatite Orbital Implant” (Ophthalmology 1997; 104:lO: 1616-21). In the authors’ second introductory paragraph, they state “To our knowledge, there are no reports that assess the complications of motility peg placement in hydroxyapatite implants.’ ’ I found this rather misleading. Reference 3 of their report (Kolberg GI. The hydroxyapatite (Bio-Eye@) implant: a historical perspective. J Ophthal Prosth 1996; 1:29-36) clearly states various problems (complications) associatedwith the peg system (granulation tissueformation in the baseof the drilled hole causing peg extrusion, collapse of the peg hole when the peg was removed, threaded sleeve sitting above conjunctival layer, threaded sleeve inserted at an off angle). Reference 4 of their report (Dutton JJ. Coralline hydroxyapatite as an ocular implant. Ophthalmology 1991; 98:870-7) also
1128
states several problems associated with pegs, namely, granulation tissue within the central peg hole (2 patients), conjunctival overgrowth of peg hole (1 patient), peg falling out (1 patient), peg hole drilled obliquely (2 patients). In two of the authors’ former articles (references#5,7), they mention various peg complications: audible click, tissue overgrowth of peg, and granulation tissue in the peg hole in a limited number of patients. In another article entitled, “The popping peg phenomenon” (Jordan DR. Arch Ophthalmol 1994; 112:300- l), several of the above complications of pegs are mentioned, plus an additional complication-the popping peg phenomenon in one patient. Clearly, complications of pegs have been reported in the literature previously but unfortunately not cited in this article. In the first paragraph of the discussion, the authors state, “The majority of patients will not require or request peg placement due to cosmetically adequatemotility with the hydroxyapatite implant alone. In a report of 250 cases of hydroxyapatite orbital implants, only 12% (31 of 250) of patients had a peg placed.” I find this statement misleading as well and disagree with it. The fact that only 3 1 of 250 patients (12%) had a peg, is low, and I suspect representsthe nature of the authors practice rather than most practices. I have personally performed over 300 hydroxyapatite implants, with 65% being pegged. I am not overly impressedwith the motility of the hydroxyapatite on its own and do not feel the readership should be given the impression that most will not require pegs. I feel it would have been more accurate if the authors stated that most of the patients in their practice were not pegged rather than “the majority of patients will not require or request peg placement. ” The main advantage of the hydroxyapatite implant comes with pegging. If it is not pegged, the physician should consider a less expensive porous implant like Med-pore (Porex Surgical, Inc., College Park, GA) or even the Universal Implant (Oculoplastik, Montreal, Canada). In the Discussion section, the authors state that “the main problem with this system (referring to the original ball and socket motility peg) was the formation of granulation tissuein the baseof the drilled vestibule that housed the peg. This occasionally led to extrusion of the peg [3,7].” This statement unfortunately is inaccurate. Reference 3 by Kolberg, in his discussionabout patients receiving the original peg, states: “some had a tendency to form granulation tissue in the base of the drilled hole. Over a period of time, this tissue would begin to expel the peg and prosthesis” Reference 7 by Shield et al, a report on 250 patients (31 of whom had pegs) reports 2 patients who had granulation tissue pushing the peg out as a complication and 3 who had audible clicking. I fail to see how the authors can state that the main problem with the original peg was formation of granulation tissue at the baseof the drilled vestibule. There are insufficient patient data in either article to substantiate this statement. In the authors current paper, the data they present do show that peg extrusion due to granulation tissue pushing the peg out was the most common complication, unfortunately this was not previously proven in the literature.