Effectiveness of Trabeculectomy in Primary Open-Angle Glaucoma with Low Preoperative Intraocular Pressure

The aim of this study was to evaluate the efficacy of trabeculectomy for primary open angle glaucoma (POAG) with low preoperative intraocular pressure (IOP).

This was a retrospective single facility, non-randomized study. We included POAG patients with preoperative IOP ≤12 mmHg who were taking maximally tolerance glaucoma medications. We enrolled 11 patients who underwent trabeculectomy and could be followed for ≥3 years. We used the value of inclination of the mean deviation (MD) slope (dB/year) as the speed of progression of visual field defects as an index of surgical efficacy. We compared the MD slope before and after trabeculectomy.

The mean preoperative IOP was 11.1±1.4 mmHg and the mean postoperative IOP was 6.5±2.5, 8.6±2.8 and 8.8±2.1 mmHg at 1, 2, and 3 years respectively. The inclination value of MD slope significantly improved from -1.19±0.35 to -0.13±0.37 dB/year (p<0.001). Trabeculectomy significantly decreased IOP and slowed the progression of visual field defects.

The results suggest that trabeculectomy might be effective even in patients with very low preoperative IOP.