Long-term outcomes of viscocanalostomy and phaco-viscocanalostomy in patients with narrow angle glaucoma

PURPOSE: To assess the outcomes of viscocanalostomy and phaco-viscocanalostomy in patients with narrow angle glaucoma at a single tertiary eye centre. METHOD: All patients undergoing viscocanalostomy for narrow angle glaucoma between June 2010 and June 2017 with a minimum follow-up of 12 months were included. Data was analysed from a prospectively maintained surgical outcome database. Primary outcome was a change in intraocular pressure (IOP). Secondary outcomes were changes in LogMAR visual acuity, number of eye drops, post-operative complications and further surgical interventions. Success was defined at two IOP cut-off points: IOP ≤ 21 mmHg and IOP ≤ 15 mmHg with (qualified success) or without (complete success) drops. Failure was any repeat glaucoma surgery or loss of light perception. RESULTS: Seventy eyes of 46 patients with a mean follow-up of 41.31 months (range 12–60 months) were included. Mean IOP changed from 25.7 ± 9.6 to 15.2, 15.6, 14.6, 13.8 and 14.0 mmHg at 1, 2, 3, 4 and 5 years post-operatively. Drops reduced from 3.2 ± 1.1 pre-operatively to 0.5 at 1 year and 1.1 at all time points thereafter. Qualified success for an IOP ≤ 21 mmHg was achieved in 94.2%, 88.1%, 92.5%, 91.1% and 92.0% and complete success in 63.8%, 37.3%, 30.2%, 22.2% and 24.0% in years 1 to 5, respectively. Qualified success for an IOP ≤ 15 mmHg was achieved in 53.6%, 60.9%, 69.8%, 68.9% and 64.0% and complete success in 39.1%, 26.9%, 22.6%, 20.0% and 8.0% in years 1 to 5, respectively. IOP was significantly lower at all examined post-operative time points (41.1%, 39.3%, 43.3%, 46.4% and 45.3% at years 1 to 5, respectively, p < 0.001 at all time points). Four eyes (5.7%) failed to meet any of the success criteria. Of these, 3 eyes (4.3%) required further glaucoma surgery and one eye (1.4%) progressed to no perception of light at 48 months. No patients had an IOP ≤ 5 mmHg on two consecutive occasions after 3 months. CONCLUSION: Viscocanalostomy and phaco-viscocanalostomy are a safe and effective surgical option in the management of chronic narrow angle glaucoma.