Tube Shunt Revision With Excision of Fibrotic Capsule Using Mitomycin C With and Without Ologen—a Collagen Matrix Implant: A 3-Year Follow-up Study

Abstract

Tube revision with capsule excision in failed glaucoma drainage devices (GDDs) has good medium-term success effectively reducing the intraocular pressure (IOP) and medication burden. Implantation of Ologen may limit the complications, particularly erosion. To evaluate the 36-month outcomes of tube shunt revision with capsule excision using Mitomycin C (MMC) versus MMC with Ologen-a collagen matrix implant. Twenty-three eyes with failed GDD underwent tube revision with fibrotic capsule excision. 12 of them received a MMC application whereas the other 11 also received an Ologen implant. Qualified success, changes in IOP, medication burden, and complication rates were evaluated and compared. Three years post-revision, qualified success for the whole cohort was 58% with no significant difference between the MMC group (52%) and MMC+Ologen group (67%; P=0.606). Mean survival time for each group was 27.4 and 29.8 months, respectively. With no intergroup differences through 3 years, capsule excision leads to a significant decrease in IOP from 28.6±6.5 to 15.1±4.3 mm Hg (47% reduction) and in antiglaucoma medications, from 3.6±1.2 to 2.5±1.3 mm Hg (30% reduction; P<0.001). Complication rates were significantly lower in the MMC+Ologen group (27%) compared with the MMC group (75%; P=0.022). Plate erosion happened in 25% of the eyes in the MMC group which required excision of the tube and plate, but no such complication was observed in the MMC+Ologen group. Revision of a failed tube shunt by excision of the encapsulated bleb offers good medium-term outcomes by reducing the IOP and glaucoma medications. Although the addition of Ologen did not affect the medium-term success, IOP, or medication burden, its implantation yielded significantly lower complication rates.