Impact of the restrictive technique on outcomes in Baerveldt-350 implant surgery.

Abstract

Background: Different aqueous restrictive manoeuvres in non-valved devices affect intraocular pressure (IOP) levels in the first postoperative month. This study compares tube ligature (TL) alone to TL plus rip cord stent (TLS) on the efficacy of the Baerveldt 350.

Methods: We conducted a retrospective consecutive case-series observational study to assess efficacy by measuring IOP, success rates and the reduction of antiglaucoma medication usage over 3 years.

Results: The study included 43 eyes in the TL group and 29 in the TLS group. Initial IOPs were 26.67 mm Hg for TL and 28.21 mm Hg for TLS. After 1 year, IOP decreased to 13.03 mm Hg and 12.11 mm Hg, respectively. Over 3 years, TLS consistently achieved greater reductions in IOP compared with TL, with significant differences of 3.56 mm Hg in the second year (p=0.01) and 3.34 mm Hg in the third year (p=0.01). Mean antiglaucoma medication use decreased from 3.03 (SD 1.29) to 0.72 (SD 0.47) over 3 years, representing a 76.24% reduction, with no differences between the TL and TLS groups. Failure rate at 1 year was significantly lower for TLS under the success criteria of IOP=(6-18) mm Hg (TL: 33.33%, TLS: 7.14%, p=0.02). Rates of transient hypotension and hypertensive phase were higher in the TL group: 93.02% vs 34.48% (p<0.001) and 58.14% vs 32.14% (χ²=4.59, p=0.03), respectively.

Conclusion: Adding the rip cord stent to the Baerveldt implant significantly enhances long-term IOP control and reduces failure rates compared with TL alone. The lower incidence of hypertensive phases could be due to sequential tube opening. Small sample size, lack of randomisation and follow-up discrepancies may introduce bias and limit statistical power, highlighting the need for further research to confirm these conclusions.