Comparison of a second-generation trabecular bypass (iStent inject) to ab interno trabeculectomy (Trabectome) by exact matching

PurposeTo achieve a highly balanced comparison of trabecular bypass stenting (IS2, iStent inject)with ab interno trabeculectomy (T, Trabectome) by exact matching. In a similar study, IS1 (1st generation iStent) had shown a loss of effect at 6 months.Methods53 IS2 eyes were matched to 3446 T eyes. Patients were matched using exact matching by baseline IOP, the number of glaucoma medications, and glaucoma type and using nearest neighbor matching by age. Individuals without a close match were excluded. All surgeries were combined with phacoemulsification.ResultsA total of 78 eyes (39 in each group) could be matched as exact pairs with a baseline IOP of 18.3±5.1 mmHg and glaucoma medications of 2.7±1.2 in each. IOP in IS2 was reduced to 14.6±4.2 mmHg at 3 months and in T to a minimum of 13.1±3.2 mmHg at 1 month. In IS2, IOP began to rise again at 6 months, eventually exceeding baseline. At 24 months, IOP in IS2 was 18.8±9.0 mmHg and in T 14.2±3.5 mmHg. IS2 had a higher average IOP than T at all postoperative visits (pConclusionT resulted in a larger and sustained IOP reduction compared to IS2 where a rebound occurred after six months to slightly above preoperative values. This time course fits bioreactivity data of the IS1.