A comparative study of a modified filtering trabeculotomy and conventional trabeculectomy

PURPOSE The objective of the study reported here was to evaluate the outcome of a modified filtering trabeculotomy (FTO) without iridectomy in open-angle glaucoma compared with that of conventional trabeculectomy (trab). PATIENTS AND METHODS Thirty eyes of 30 patients who underwent modified FTO were prospectively followed for 1 year and were compared with 87 conventional trab patients (87 eyes), matched for age and preoperative intraocular pressure (IOP). The FTO procedure consisted of a deep sclerectomy and trabeculotomy preserving the trabeculo-Descemet membrane, without iridectomy. Main outcome measures were complete success (IOP <18 mmHg and >/=30% IOP reduction, without medication), IOP, visual acuity, medication, complications, and subsequent surgeries. RESULTS In the conventional trab group, the median preoperative IOP was 23.0 mmHg (interquartile range 20.0-27.0) with 3.0 (2.0-3.0) medications, compared with 23.0 mmHg (20.0-27.0) and 3.0 (2.8-4.0) in the modified FTO group. Median postoperative IOP at 12 months was 12.0 mmHg (10.0-13.0) in the conventional trab and 11.0 mmHg (8.0-14.0) in the modified FTO group (P=0.3). The complete success rate at 1 year was 83.1% and 79.3% in the conventional trab group and modified FTO group, respectively (P=0.8). The complications hypotony (20.7%, 24.1%), choroidal detachment (2.3%, 10.3%), and bleb scarring (17.2%, 13.8%), were present in the conventional trab group and modified FTO group, respectively. CONCLUSION The outcomes of reduced IOP and medications in the FTO group were not different to those in the conventional trab group over 1 year, but some complications were more often seen with the modified FTO technique. The new filtration trabeculotomy, however, has the advantage of avoiding iridectomy, thus reducing the risk of cataract formation, and may result in the development of more favorable blebs by controlling the flow over two resistance levels.