Standalone versus combined preserflo MicroShunt surgery: A two-year controlled cohort study

To compare efficacy, safety, and surgical success of standalone Preserflo MicroShunt (PMS) implantation versus PMS combined with phacoemulsification in open-angle glaucoma (OAG).

A retrospective cohort study included consecutive OAG patients who underwent standalone or combined PMS surgery with 0.04% mitomycin C at a tertiary centre. Primary outcomes were intraocular pressure (IOP), glaucoma medications, and surgical success at 2 years. Success was defined as ≥20% IOP reduction with IOP <18 mmHg (criterion 1) or ≥30% reduction with IOP <18 mmHg (criterion 2).

A total of 173 eyes (113 standalone, 60 combined) were analysed. Mean IOP decreased from 22.1 ± 5.8 mmHg to 12.5 ± 3.1 mmHg ( - 39.4%) in the standalone group and from 20.6 ± 6.7 mmHg to 14.2 ± 4.0 mmHg ( - 33.0%) in the combined group (p = 0.023; 95% CI -3.16 to -0.25), with similar medication use in both groups. Success rates were 76.1% versus 61.7% for criterion 1 (p = 0.084) and 70.0% versus 41.7% for criterion 2 (p = 0.001). Kaplan-Meier analysis showed higher cumulative success in standalone surgery (criterion 1: HR 1.77, p = 0.044; criterion 2: HR 2.40, p = 0.0003). Complications occurred in 38.2% of eyes (36.3% standalone, 41.7% combined), with only 6.4% requiring surgical intervention.

Both standalone and combined PMS implantation achieved significant IOP and medication reductions with acceptable safety. However, standalone PMS appears to offer superior mid-term IOP control and higher surgical success, supporting its use in advanced glaucoma cases requiring maximal pressure reduction.