Clinical outcomes of bio-interventional cyclodialysis with one or multiple allogeneic reinforcements: a multicenter real-world evidence study

Introduction: Bio-reinforced cyclodialysis uses an acellular scleral allograft spacer to maintain a surgically created cleft and enhance uveoscleral outflow. Surgeons may place one spacer or two, but whether the second adds IOP lowering has not been reported. We tested whether two spacers achieve greater 12-month IOP reduction than one, and whether any difference persists after adjustment for measured baseline differences. Methods: Observational analysis of 310 eyes in the prospective, multicenter CREST study undergoing combined phacoemulsification and bio-reinforced cyclodialysis with one spacer (n = 170) or two (n = 140). The primary endpoint was IOP change from baseline to month 12. Analyses comprised unadjusted comparison, baseline-adjusted regression, 1:1 propensity-score matching, doubly robust overlap weighting, and models accounting for enrolling site. IOP after a secondary IOP-lowering procedure was censored. Results: At baseline, IOP was 17.9 (4.4) versus 18.7 (5.8) mmHg and medications 1.19 (1.11) versus 1.46 (1.35), with one versus two spacers. The largest imbalance was enrolling site: one center contributed 43.6% of two-spacer eyes but 7.1% of one-spacer eyes. The unadjusted difference in IOP reduction was 2.52 mmHg (95% CI 1.20, 3.84; p<0.001), and persisted after propensity-score matching (2.36 mmHg; 0.94, 3.77; p=0.001) and overlap weighting (1.99 mmHg; 1.18, 2.79; p<0.001). After accounting for site it attenuated to 0.86 mmHg (−0.10 to 1.81; p=0.080), and to 0.42 mmHg (−0.61 to 1.45; p=0.42) within sites using both strategies. Medication reduction (−0.69 versus −0.62; p=0.64) and secondary IOP-lowering procedures (2.9% versus 2.9%; p=1.0) did not differ. Conclusion: Two-spacer treatment was associated with greater 12-month IOP reduction in unadjusted and patient-level adjusted analyses, but this association was substantially attenuated after accounting for enrolling site. These real-world data are compatible with, but do not establish, an independent incremental effect of a second spacer. A randomized comparison is required to determine whether spacer number independently influences IOP reduction.