Likelihood of Corneal Transplantation after Tube versus Trabeculectomy: An IRIS® Registry Study

Utilization of glaucoma drainage devices (tube shunts) has increased. In this analysis we evaluate long-term likelihood and time-to-event for corneal transplantation after trabeculectomy versus tube shunt glaucoma surgeries.

Retrospective cohort study.

American Academy of Ophthalmology IRIS® Registry (Intelligent Research In Sight) patients who underwent glaucoma surgery between 2001 and 2021.

Patients with glaucoma who underwent isolated trabeculectomy, isolated tube shunt, or both surgeries in a given eye were identified by procedure codes. Subsequent corneal transplantation procedures performed in the same eye were similarly identified. Multivariable Cox proportional hazard regression models were used to evaluate the likelihood of corneal transplantation and time from first glaucoma surgery to corneal transplantation.

Hazard ratios and 95% confidence intervals (CIs) for corneal transplantation.

We identified 246 521 eyes among 197 910 patients with glaucoma surgery meeting study inclusion criteria. Corneal transplantation was most frequently observed among patients who previously underwent both trabeculectomy and tube shunt (5.00%, n = 672), followed by isolated tube shunt (2.97%, n = 3473) and isolated trabeculectomy (0.80%, n = 929). Eyes that only underwent tube shunts had a mean time to corneal transplantation of 2.49 years (standard deviation [SD], 2.4), compared with 3.75 years (SD, 3.3) for isolated trabeculectomy eyes and 3.21 years (SD, 2.6) for eyes that received both trabeculectomy and tube shunt. Adjusted likelihood of corneal transplantation was highest with both trabeculectomy and tube shunt (hazard ratio [HR], 5.88; 95% CI, 5.34-6.48), and isolated tube shunt (HR, 3.97; 95% CI, 3.69-4.26), compared with isolated trabeculectomy.

The likelihood of corneal transplantation is over 4 times higher after tube shunts compared with trabeculectomies. This may reflect factors such as chronic, cumulative corneal endothelial mechanical trauma from the tube shunt, changes to aqueous humor fluid circulation, altered aqueous humor composition and associated signaling pathways, differences in use of antimetabolites as adjunctive therapy, tube material, and tube movement or migration over time. Further research is needed to understand causes of corneal compromise, and consideration of corneal health is warranted in glaucoma surgical decision-making.

Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.