Ultrasound biomicroscopy images: long-term results after deep sclerectomy with collagen implant

Purpose The aim of this study was to understand the long-term outflow pathway mechanisms after deep sclerectomy - when collagen implant is resorbed - using ultrasound biomicroscopy (UBM). Methods: Forty-three eyes of 321 patients with medically uncontrolled open-angle glaucoma at least I year after deep sclerectomy were studied in an observational, non-randomised, consecutive case series. Postoperatively 15 eyes (35.7%) had gonio-puncture with the Nd:YAG laser. Four eyes (9.5%) had postoperative subconjunctival injections of mitomycin C and two eyes (4.7%) had an injection of 5-fluorouracil, because of intraocular pressure (IOP) increase. Complete examination and UBM of the filtering site were performed 1-6 years after surgery. The following parameters were assessed: (1) Presence of a subconjunctival filtering bleb, (2) presence and volume of an intrascleral cavity; (3) presence of a suprachoroidal hypoechoic area. Results: Intraocular pressure decreased significantly from 28.1 +/- 2.5 mmHg preoperatively to 12.4 +/- 3.8 (range 7-25) mmHg at the time of UBM (at least I year after surgery). Forty eyes showed clinically a diffuse filtering blob. UBM demonstrated a subconjunctival space in all eyes. In 39 eyes (92.8%) an intrascleral cavity was observed. The mean volume of this cavity was 1.8 (range 0.11-6.53) mm(3). In 19 eyes (45.2%) we observed a hypoechoic area in the suprachoroidal space. Conclusion: UBM examination demonstrated several aqueous humour drainage pathways. A low-reflective diffuse subconjunctival space meant persistent filtration in all eyes. More than I year after surgery 92.8% of eyes had a remaining intrascleral cavity. In almost half of the patients in additional suprachoroidal outflow was observed, significantly correlated with a lower IOP.