Impact of Different Intraocular Pressure and Medication Endpoint Criteria on Success Rates in Subconjunctival Minimally Invasive Glaucoma Surgery.

Abstract

Precis: Applying different combinations of intraocular pressure and medication endpoint criteria recommended by the World Glaucoma Association can have a significant influence on the risk of failure following glaucoma surgery, which hinders the comparison of outcomes.

Purpose: The definition of success in glaucoma surgical trials lacks standardization, leading to difficulty comparing outcomes across studies. This study evaluates how different intraocular pressure (IOP) and medication criteria affect success in a representative subconjunctival Minimally invasive glaucoma surgery (MIGS) dataset.

Methods: A literature review identified the range of criteria used to define surgical success in studies of Xen gel stent, which were summarized into four definitions: (A) final IOP within upper and lower thresholds only, (B) criteria A plus ≥20% decrease in IOP vs baseline, (C) ≥20% IOP decrease plus no increase in medications vs baseline, (D) all three criteria combined. These definitions were then applied to a cohort of 308 eyes that underwent Xen surgery to compare the apparent risks of failure.

Results: Success rates at 12 months across studies reviewed ranged from 18.5% to 33.4% for complete and 22.4% to 64.6% for qualified success. In our cohort, the hazard ratios of failure ranged from 0.27 to 5.87 (95% confidence intervals 0.21 to 7.63, P<0.001) across the four definitions. The greatest degree of difference in apparent failure rates was observed at the upper IOP threshold of 21 mmHg , and when evaluating qualified success.

Conclusion: Using different IOP and medication criteria to define success can have a significant influence on the apparent risk of failure, particularly at the 21 mmHg threshold and when incorporating a minimum 20% IOP reduction from baseline. Reporting success using guidelines-recommended criteria and at multiple upper IOP thresholds may enable better comparison of outcomes between studies.