Abstract
Purpose :
To evaluate the impact of varying hypotony failure criteria on surgical success rates in a large cohort of patients undergoing glaucoma surgery.
Methods :
We identified fifty different hypotony criteria through a systematic literature review (Prospero protocol ID: CRD42017079778). We then applied the various hypotony definitions to a cohort of 1,765 eyes (1,385 patients) undergoing deep sclerectomy (DS) with or without cataract extraction between 2001 and 2020 in 2 UK centers and used them as failure criteria. Additional failure criteria were: IOP>21 mmHg or <20% IOP reduction from baseline in two consecutive postoperative visits >3 months after surgery, reoperation for glaucoma, and loss of light perception. We calculated Kaplan-Meier surgical success rates, and we tested differences in success rates as a function of the hypotony criteria with clustered Cox models. We conducted all analyses for each criterion and hypotony type (i.e., numerical [intraocular pressure threshold], clinical [clinical manifestations of hypotony], mixed [ combination of numerical and/or clinical criteria]).
Results :
Success rates greatly varied as a function of hypotony criteria used, ranging between 15.8-70.8%, 12.3-62.4%, and 11.3-57.5% at 3, 5, and 7 years, respectively (Fig 1). In comparison to no hypotony failure criteria (Fig 2A), numerical hypotony had the greatest impact on the calculated risk of failure (HR [95% confidence interval (CI): 1.75 [1.48-1.60], p<0.001), followed by mixed hypotony (HR [95%CI): 1.56 [1.43-1.69], p<0.001) and clinical hypotony (HR [95%CI): 1.15 [1.05-1.27], p=0.003). Differences among clinical, mixed, and numerical hypotony failure rates were significant between all pairs (p=0.02 or below). Every hypotony criterion had higher failure risk than no hypotony criterion, but the magnitude of the effect varied as a function of the specific criterion used, with hazard ratios (HRs) ranging between 1.02 and 13.30 (compared to not using any hypotony criterion).
Conclusions :
Glaucoma surgery success is greatly influenced by the hypotony criteria chosen. Numerical hypotony leads to higher failure rates than clinical hypotony. Its use as a failure criterion may underestimate glaucoma surgery success rates, especially those techniques more likely to reach low IOP values. Standardizing glaucoma surgery failure criteria with a focus on clinically relevant hypotony manifestations is needed.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.