The Measurement of Flow Resistance in Drainage Implants Using Various Tube Ligation Methods

PURPOSE: To evaluate the flow resistance though the tube in a glaucoma drainage implant using various tube ligation methods. METHODS: To measure the flow resistance, the following tube ligation methods were designed and tested: Type 1: no ligation of Ahmed valve tube. Type 2: ligation of Ahmed valve tube with 8-0 Vicryl. Type 3: ligation of Molteno tube and a 6-0 Vicryl as an intra-luminal stent with 8-0 Vicryl. Type 4: ligation of Ahmed valve tube and three strands of 8-0 nylon as extra-luminal stents with 8-0 Vicryl. Type 5: ligation of Ahmed valve tube and a 6-0 Prolene as an extra-luminal stent with 8-0 Vicryl followed by removal of the Prolene for partial ligation. RESULTS: The pressure was maintained under 0.143 mm Hg in type 1. In type 2, the pressure increased to 6.688 mm Hg and dropped to approximately 6.384 mm Hg. In type 3, the pressure was maintained at 5.396 mm Hg which decreased to 3.572 mm Hg after stent removal. In type 4, the pressure was maintained at 5.700 mm Hg which dropped to 5.472 mm Hg after the 1st stent removal, to 5.016 mm Hg after the 2nd stent removal and to 4.180 mm Hg after the 3rd stent removal. In type 5, the pressure increased to 6.384 mm Hg and decreased to 5.624 mm Hg. CONCLUSIONS: The tube ligation along with extra-luminal stents followed by staged removal may provide prevention of hypotony and staged control of intraocular pressure after a glaucoma implant operation.

The Comparison of Clinical Outcome after Ahmed Valve Implantation and Molteno Implantation

PURPOSE: To compare clinical outcome after Ahmed valve implantation and Molteno implantation with tube ligature and releasable internal stent insertion METHODS: The medical records of 56 eyes, which were followed up more than 6 months, after either Ahmed valve implantation (20 eyes, group A) or Molteno implantation (36 eyes, group M) were reviewed retrospectively. Preoperative and postoperative intraocular pressure (IOP) at 1 day, 1 week, and 1, 2 and 6 months and the number of glaucoma medication were measured. Comprehensive success was defined at IOP less than 22 mmHg or when there was a 30 % reduction of preoperative IOP regardless of glaucoma medication. Qualified success was defined at IOP less than 22 mmHg regardless of glaucoma medication. Complete success was defined at IOP less than 22 mmHg without glaucoma medication. RESULTS: There is no statistical significance in postoperative IOP at all the times between groups A and M (p>0.05). Comprehensive success rate between groups A (75.0 %) and M (91.7 %) was not statistically significant (p>0.05). Qualified success rate between groups A (65.0 %) and M (86.1 %) was not statistically significant (p>0.05). Complete success rate between groups A (10.0 %) and M (30.6 %) was not statistically significant (p>0.05). CONCLUSIONS: There was no statistically significant difference in the success rate at postoperative 6 months between Ahmed valve implantation and Molteno implantation with tube ligature and releasable internal stent insertion.

The Results of Molteno Implant Surgery

PURPOSE: The author evaluated the outcome of the Molteno implant drainage device in refractory glaucoma. METHODS: A retrospective study was performed on 17 eyes of 17 patients that had undergone Molteno implantation for glaucoma unresponsive to conventional treatment from May 1997 to February 2001 at our hospital. Complete success was defined as a postoperative intraocular pressure of less than 21 mmHg (but over 5 mmHg) at last visit without glaucoma medications, and qualified success was the same pressure as above with glaucoma medications and with no additional glaucoma surgery, phthisis, or removal of Molteno implant. RESULTS: The total success was 70.6% (41.2%, complete; 29.4%, qualified). There was a significant difference in number of antiglaucoma medications between preoperative and postoperative. Postoperative relief of ocular pain or headache was statistically significant. CONCLUSIONS: The Molteno implant surgery offers a reasonable outcome in eyes with intractable glaucoma. The proper management will result in less complications and a better control of intraocular pressure.

Strabismus with Ocualr Motility Disturbance after Molteno Implant

PURPOSE: We experienced a case of ocular motility disturbance with esotropia and hypotropia, following implantation of Molteno to the superotemporal quadrant. METHODS: The patient recovered to orthophoria after removal of implant and fibrotic scar tissue with recession and resection. RESULTS: Multiple complications have been reported in association with Molteno implantation, including hypotony, cataract, choroidal hemorrhage, retinal detachment, endophthalmitis, hyphema, phthisis. However ocular motility disturbances have been documented in only a few cases and never in Korea to our knowledge. Therefore, we report this case with the review of related literatures.

Histopathologic Findings of an Unsuccessful Molteno Implant

We documented the histopathologic findings of an eye with Molteno implant that was nonfunctional at 3 years after implantation.In 1995,a 62-year-old woman developed neovascular glaucoma in her right eye,and installation of a Molteno implant was performed.However,she was lost to follow-up until 1998,when she presented with a blind eye that have to be enucleated with molteno implant because of painful phthisis bulbi.On external examination the implant plate was located in the superotemporal equatorial region of the globe,8 mmposterior to the limbus and 9 mm anterior to the optic nerve.There were adhesions between the plate and surround-ing fibrous tissue.The drainage tube into the anterior chamber left in situ. On microscopic examination the adjacent bleb wall consisted of multilayer, degenerated collagenous connective tissue,maximal 0.7 mmin thickness.Its inner portion mainly consisted of paucicellular,hyalinized and sclerotic col-lagen fibers and outer portion was relatively fibrovascular tissues with a few vascular endothelial cells and fibroblasts.And,there were chronic lym-phocytic infiltrates around a silicone tube insertion site into the anterior chamber.

Molteno Implant Surgery in Refractory Glaucoma

The author evaluated the outcome of the Molteno implant drainage device. A retrospective chart review was performed on 26 eyes of 24 patients that had undergone Molteno implantation for uncontrolled glaucoma unresponsive to conventional treatment from February 1990 to December 1995 at the Pusan National Univeristy Hospital and had at least 6 months of follow-up data. Complete success was defined as a postoperative intraocular pressure of 22mmHg or lower without glaucoma medications, qualified success was same pressure as above with glaucoma medication and no additonal glaucoma surgery, or phthisis. The mean follow-up was 20.5 months(6-52 months). Indication for Molteno implantation were neovascular glaucoma(n=9), aphakia and pseudophakia(n=9), and other failed glaucoma filtering surgery(n=8). The total success was 65.4% (34.6% complete; 30.8% qualified). The aphakia/pseudophakia group had higher success rate than neovascular glaucoma and other failed operation groups. There was no significant statistical difference of the implant surgery adjunctive between with and without intraoperative Mitomycin_C. The Molteno implant surgery offers a reasonable outcome in eyes with intractable glaucomas. However, more effective device of method for modulation of wound healing for greater success is to be exepcted.

Molteno Implantation for Neovascular Glaucoma with a Laser-Releasable Intracameral Ligature to Limit Postoperative Pressure Fluctuations

We incorporated a 9-0 nylon ligature on the intracameral portion of the Molteno tube to limit postoperative hypotony in 15 eyes of 14 neovascular glaucoma patients. Postoperative hypotony, less than 5mmHg occured in 2 eyes at 1 week, and none thereafter. Argon laser release of the ligature, performed an average of 29 +/- 24 days after surgery, resulted in intraocular pressure reduction in all cases. After 7.3 +/- 3.3 months, the intraocular pressure was significantly lower(47.3 +/- 11.5 vs 18.7 +/- 7.7mmHg, p=0.0007) on less medications(2.2 +/- 1.0 vs 0.3 +/- 0.6, p=0.0008). Thirteen eyes(87%) achieved an intraocular pressure less than 21mmHg and twelve eyes(80%) maintained or improved their preoperative visual acuity. The releasable internal ligature is effective in limiting hypotony and intraocular pressure contral.

Molteno Implantation in Intractable Glaucoma

Fifteen patients, 15 eyes with medically uncontrollable glaucomas and poor surgical prognoses underwent one-stage, single plate Molteno implatation without postoperative adjunctive systemic antifibrosis therapy. The Molteno implant procedures were successful in 12 (80%) of the 15 eyes. The visual acuity was improved in 2 eyes (13%), but worsened in 2 eyes (13%). Complications included hyphema in 5 eyes (33%), choroidal detachment in 4 eyes (26%), shallow anterior chamber in 3 eyes (20%), tube-iris touch in one eye (6%).