title: Shunt revision versus additional tube shunt implantation after failed tube shunt surgery in refractory glaucoma.
abstract: OBJECTIVE
  To compare tube shunt revision with additional tube shunt after failed tube shunt surgery.
  
  
  METHODS
  We identified 281 patients who underwent a primary tube shunt procedure from 1985 to 1998 at Indiana University and reviewed 33 eyes of 33 patients that had failed and required further surgery. Shunt revision was performed in 12, whereas an additional shunt was placed in 21 eyes. Intraocular pressure, antiglaucoma medications, visual acuity, and complications were noted. Success was defined as at least a 25% reduction in intraocular pressure that was deemed clinically adequate. Qualified success was defined as a 25% intraocular pressure reduction but with additional medications or a significant reduction in medications with stable intraocular pressure for preoperative intraocular pressure less than 21 mm Hg.
  
  
  RESULTS
  Preoperative intraocular pressures (mean +/- 95% confidence interval) for the revision and additional tube groups were 28.8 +/- 5.8 mm Hg and 29.8 +/- 2.7 mm Hg (P =.73), with an average follow-up period of 25.2 months (range, 3 to 108 months) and 34.8 months (range, 6 to 84 months), respectively. Final mean intraocular pressure was 25.3 +/- 6.7 mm Hg for the revision group and 17.7 +/- 3.4 mm Hg for the additional tube group (P =.037). Forty-two percent in the revision group versus 62% in the additional tube group achieved at least a qualified success (P =.30, Fisher exact test). Corneal edema was a common complication, especially in the additional tube group. Limitations of this study include the small sample sizes and the uneven distribution of neovascular glaucoma between the two groups (six of 12 in the revision group vs two of 21 in the additional tube group; P =.015, Fisher exact test).
  
  
  CONCLUSIONS
  Our series showed that after failed tube shunt surgery, an additional tube shunt offers better intraocular pressure control than revision by excision of an encapsulated bleb.
authors.affiliation: Glaucoma Service, Department of Ophthalmology, Indiana University School of Medicine, Indianapolis, Indiana 46202, USA.
authors.forename: A A
authors.initials: AA
authors.lastname: Shah
authors.forename: D
authors.initials: D
authors.lastname: WuDunn
authors.forename: L B
authors.initials: LB
authors.lastname: Cantor
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D005901:Glaucoma / Q000601:surgery*; D020327:Glaucoma Drainage Implants; D006801:Humans; D007223:Infant; D007429:Intraocular Pressure; D008297:Male; D008875:Middle Aged; D011183:Postoperative Complications; D019919:Prosthesis Implantation; D012086:Reoperation; D012189:Retrospective Studies; D017211:Treatment Failure; D016896:Treatment Outcome; D014792:Visual Acuity