Impact of Different Literature-based High intraocular Pressure Failure Criteria on Success Rates of Glaucoma Surgery

Abstract

Purpose : To evaluate the impact of different intraocular pressure (IOP) criteria on glaucoma surgery success rates in two large patient cohorts.

Methods : From a systematic review (Prospero ID: CRD42023460048), we identified 150 different high IOP criteria, including 46 variations of the 21-mmHg criterion. Of these, 45 were replicable and tested in this study. We applied the identified IOP definitions as failure criteria in two geographically distinct cohorts undergoing trabeculectomy at a US institution and deep sclerectomy (DS) at two UK hospitals. Additional failure criteria were: further IOP lowering surgery or ciliodestructive procedure, reoperation for hypotony complications, and loss of light perception. We calculated Kaplan-Meier surgical success rates, and tested differences in success rates as a function of IOP criterion with clustered Cox models with IOP>21 mmHg at any visit (the most used criterion) as a reference.

Results : 934 eyes (766 patients) and 1,765 eyes (1,385 patients) were included in the trabeculectomy and DS cohorts, respectively, with a median (interquartile range) follow-up of 41.4 (19.3-74.8) and 45.4 (20.9-79.8) months. Compared to the DS cohort, the trabeculectomy cohort was slightly older (74.4 vs 73.1 years, p=0.009), had lower preoperative median IOP (17.0 vs 22.0 mmHg, p<0.001), higher median number of glaucoma medications (3 vs 2, p<0.001), higher prevalence of preoperative systemic acetazolamide (10.9% vs 2.5%, p<0.001), non-white ethnicities (44% vs 4%, p<0.001), secondary glaucoma (22.3% vs 11.4%, p<0.001), and previous cataract (54.2% vs 13.8%, p<0.001), glaucoma (22.4% vs 7.3%, p<0.001), and retinal surgery (4.8% vs 1.8% p<0.001). Success rates greatly varied according to the IOP criterion chosen to define failure (Figure 1), ranging, at 5 years, between 8.7% and 74.0% for trabeculectomy and between 22.1% and 89.9% for DS. In comparison to IOP>21 mmHg at any visit (Figure 2), various IOP criteria led to different risks of failure, with hazard ratios ranging from 0.35 to 4.42 for trabeculectomy and from 0.22 to 3.88 for DS.

Conclusions : Our findings highlight the significant impact of varying high IOP criteria on glaucoma surgery success rates, underscoring the need for standardized failure criteria to enable consistent interpretation and comparison across studies. Long-term visual field rates may provide a more consistent primary outcome measure.

This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.