A prospective comparison between trabeculectomy with mitomycin C and phacotrabeculectomy with mitomycin C

Editor, Combined phacoemulsification with intraocular lens implantation and trabeculectomy (phacotrabeculectomy) is a surgical option for elderly patients with glaucoma and coexisting cataracts (Friedman et al. 2002); however, whether or not phacotrabeculectomy lowers intraocular pressure (IOP) to the same extent as trabeculectomy remains controversial (Stewart et al. 1995; Guggenbach et al. 1999; Kleinmann et al. 2002; Lochhead et al. 2003). Therefore, the current prospective study compared the surgical outcomes of phacotrabeculectomy with mitomycin C (MMC) with those of trabeculectomy with MMC in patients with open-angle glaucoma (OAG) and coexisting cataracts. The protocol was registered with the University Hospital Medical Information Network Clinical Trials Registry of Japan (No. C000000437). Fifty-two patients (26 in the trabeculectomy group and 26 in the phacotrabeculectomy group) were recruited from Kumamoto University Hospital (Kumamoto City, Japan) between 1 July 2006 and 22 December 2009 using the following inclusion criteria: ≥40 years of age, primary OAG or exfoliation glaucoma with coexisting cataracts, IOP >21 mmHg and no history of ocular surgery. Trabeculectomy was performed by creating a fornix-based conjunctival flap and a 4-mm-wide half-layer scleral flap, followed by the application of MMC (0.4 mg/ml) for 4 min for phacoemulsification through a clear corneal temporal incision. The patient chose to receive either trabeculectomy or phacotrabeculectomy. We defined three criteria for IOP decrease at ≥3 months with or without anti-glaucoma medications: IOP ≥21 mmHg (criterion A), ≥18 mmHg (criterion B) and ≥15 mmHg (criterion C) or <20% decrease from baseline. IOP was measured again 1 month later, and surgical success or failure was decided on the basis of those values. However, if IOP was ≥26 mmHg at ≥3 months, despite completion of laser suture lysis and bleb needling, we immediately defined the patient as a surgical failure, irrespective of criteria. One patient from each group did not complete the 1-year follow-up examination. The baseline characteristics of patients who completed the study are shown in Table 1. Results of Kaplan–Meier survival curve analysis for both the groups with criteria A, B and C are shown in Fig. 1. The 1-year success rates were 96.2 versus 72.9% for criterion A (p = 0.024), 96.2 versus 61.1% for criterion B (p = 0.0024) and 80.4 versus 46.2% for criterion C (p = 0.0063) patients in the phakic and pseudophakic groups, respectively. No eye required repeat surgery or exhibited loss of light perception during the follow-up period. The number of anti-glaucoma medications at 12 months after surgery was 0.04 ± 0.20 and 0.44 ± 0.92 (p = 0.041), the number of postoperative laser suture lysis procedures was 1.6 ± 1.2 and 2.3 ± 1.0 (p = 0.032), and changes in the best-corrected visual acuity (LogMAR) at 12 months after surgery were 0.18 ± 0.37 and −0.07 ± 0.46 (p = 0.0045) in the trabeculectomy and phacotrabeculectomy groups, respectively. Cataract progressed in 3 eyes in the trabeculectomy group. Choroidal detachment occurred in 9 and 5 eyes, flat anterior chamber in 3 and 2, hyphema in 0 and 1, wound leak in 3 and 1, and late bleb leak in 1 eye each in the trabeculectomy and phacotrabeculectomy groups, respectively. No eyes exhibited chronic hypotony <5 mmHg, hypotony maculopathy or bleb infection. Guggenbach et al. (1999) prospectively compared trabeculectomy and phacotrabeculectomy outcomes, but the study excluded high-risk glaucoma patients administered adjunctive antifibrotic agents. The present prospective comparison of surgical outcomes between trabeculectomy with MMC and phacotrabeculectomy with MMC for medically uncontrolled OAG with coexisting cataract is unique to the literature. Phacotrabeculectomy with MMC resulted in inadequate IOP reduction at 1 year compared with trabeculectomy with MMC, despite greater postoperative visual improvement due to cataract extraction. Kaplan–Meier survival curves for surgical success in the trabeculectomy (solid line) and phacotrabeculectomy (dotted line) group patients with the following intraocular pressure (IOP) changes after surgery: IOP ≥21 mmHg or <20% decrease from baseline (A), IOP ≥18 mmHg or <20% decrease from baseline (B) and IOP ≥15 mmHg or <20% decrease from baseline (C). The cumulative probability of success was significantly lower in the phacotrabeculectomy group than in the trabeculectomy group (p = 0.024, p = 0.0024 and p = 0.0063 for patients with criteria A, B and C, respectively).