Influence of high myopia on outcomes of trabeculectomy with mitomycin C in patients with primary open-angle glaucoma

To determine the clinical characteristics and surgical outcomes of highly myopic (HM) eyes with an axial length (AL) of ≥26.0 mm that underwent trabeculectomy with mitomycin C (MMC). This was a retrospective study of 63 eyes of 54 patients with primary open-angle glaucoma that underwent trabeculectomy with MMC. The characteristics and surgical outcomes of 19 HM eyes were compared with those of 44 non-HM eyes. Surgical success was defined as an high intraocular pressure (IOP) of ≤21 mmHg (criterion A), ≤18 mmHg (criterion B), or ≤15 mmHg (criterion C), with a lower IOP cutoff of 6 mmHg and a >20 % reduction regardless of the use of antiglaucoma medication. Cox regression analyses were performed to evaluate the effect of each pretreatment and surgical factor on the success rate. Patients with HM eyes were significantly younger than those with non-HM eyes (mean age 64.1 ± 9.9 vs. 69.1 ± 9.5 years; P < 0.05). The 3-year qualified success rates for HM eyes and non-HM eyes did not differ significantly for the three criteria. Younger age [hazard ratio (HR) for a 1-year increase 0.93, P < 0.005], preoperative pseudophakia (HR 3.88, P < 0.005), and shorter AL (HR for a 1-mm increase 0.72, P < 0.05) were found to be significant risk factors for trabeculectomy failure based on an IOP of ≤15 mmHg (criterion C). Age and pseudophakia also had significant effects on trabeculectomy failure based on criteria A and B, and the AL had a significant influence based on criterion A. In our patient cohort a longer AL was not a risk factor for trabeculectomy failure, but it may be a success factor for trabeculectomy with MMC.