Predictability of success for combined iStent inject trabecular bypass implantation with phacoemulsification in the subsequent eye

BackgroundTo investigate in combined iStent inject implantation with phacoemulsification carried out bilaterally, whether intraocular pressure (IOP)-lowering effectiveness in the first eye has a predictive potential for the outcome of the second eye in primary open-angle glaucoma (POAG). MethodsThis retrospective study included 72 eyes from 36 participants, who underwent trabecular bypass implantation in combination with cataract surgery at two study centres (Dusseldorf, Cologne). Surgery was classified as either 'success' or 'failure' based on three scores: IOP at follow-up <21 mmHg (Score A) or IOP < 18 mmHg (Score B), with an IOP reduction >20% respectively, without re-surgery and IOP <= 15 mmHg with an IOP reduction >= 40%, without re-surgery (Score C). ResultsThe IOP lowering outcomes of first and second eyes did not differ significantly. There was a significantly higher chance of success in the second eye after effective surgery in the first eye compared with cases after a preceding failure. Within our cohort, a 76% probability of success for the subsequent eye was determined following prior success for Score A. This probability was reduced to 13% if surgery in the first eye failed. The respective probabilities were 75% and 13% for Score B and 40% and 7% for Score C. ConclusionsIn bilateral trabecular bypass implantation combined with cataract surgery, there is a high predictive potential for subsequent eyes based on the extent of IOP-lowering in the initial eye, which should be considered by the surgeon for second eye surgeries.