Abstract
Purpose: :
To determine the factors predicting the failure of bleb needling revision with mitomycin C following trabeculectomy.
Methods: :
Retrospective chart review was performed on 114 eyes of 99 glaucoma patients who had undergone bleb needling revision post-trabeculectomy, all by DY. Following sub-conjunctival injection of 0.02 ml mitomycin C (0.2 mg/ml), a 30G needle was used to puncture the cyst (for conjunctival or Tenon’s cystic blebs) or undermine the scleral flap (for fibrotic blebs). Patients were followed for at least 12 months post needling, with intraocular pressure (IOP) data collected immediately pre- and post-needling, as well as 1, 3, 6, 9, 12, 18 and 24 months post-needling. Success of the needling was defined as IOP ≤ 18 mmHg at follow up, ± glaucoma medications, without re-needling or repeat trabeculectomy. Failure was defined as IOP > 18 mmHg on maximal medical therapy, ± subsequent re-needling or another glaucoma surgery. The success and failure groups were compared for several pre- and peri-operative factors at 1, 6 and 12 months (Pearson Χ2 and Student t tests). Survival analysis was performed on the same factors (Kaplan Meier analysis and log rank test).
Results: :
IOP immediately pre- and post-needling was 24.1 ± 5.8 and 10.4 ± 5.6 mmHg respectively (p < 0.001). Success of needling at 1, 6 and 12 months was 63, 53, and 41% respectively. Factors correlating to needling failure included: non-Caucasian race (p = 0.003, RR = 1.8), re-op trabeculectomy (p = 0.05, RR = 1.6), history of previous needling (p < 0.001, RR = 2.1), pre-needling IOP > 25mmHg (p < 0.001, RR = 2.0), post-needling IOP > 12mmHg (p < 0.001, RR = 2.0), and resumption of glaucoma meds post-needling (p < 0.001, RR = 2.2). Factors not correlating to needling failure included (p > 0.05): gender, age > 65 years, pseudophakia, post-op time from surgery > 6 months, diabetes, post-op laser suture lysis and number of glaucoma meds (both pre- and post-operatively before needling).
Conclusions: :
Needling revision with mitomycin C is a highly efficacious procedure for salvaging a failing bleb post-trabeculectomy. Intervention with laser suture lysis or glaucoma meds post-operatively to manage a failing bleb is not correlated to subsequent bleb needling. Clinical predictors of needling failure may be helpful in determining if the procedure is likely to succeed, or whether further surgery should be considered.
Keywords: clinical (human) or epidemiologic studies: risk factor assessment • intraocular pressure • outflow: trabecular meshwork