Risk of Corneal Edema Increased With Use of Glaucoma Drainage Devices

Compared with trabeculectomy, glaucoma drainage devices (GDDs) were found to increase the risk of corneal edema in patients having surgery to address their glaucoma, according to a new study in Canadian Journal of Ophthalmology.¹ Minimally invasive glaucoma surgery (MIGS) and Xen stents were preferable alternatives to offer lower risk of complications.

Glaucoma is the second leading cause of blindness around the world,² affecting approximately 2.2% of the global population.¹ The number of people with glaucoma in the US is expected to increase to 111.8 million by 2040, making it an important area of concern when it comes to assessing best practices for treating the condition. Intraocular pressure (IOP) is the target for glaucoma treatment with all methods of surgical interventions aimed at lowering IOP.

This study aimed to assess the risk of developing corneal edema, a prominent complication of ocular surgery defined by an irreversible edema beginning 1 month after surgery, after a patient has had a GDD, Xen stents, or MIGS compared with trabeculectomy.

All patients who had undergone a glaucoma surgery by a single surgeon at the Kingston Health Sciences Center in Kingston, Canada, between January 2005 and August 2024 were eligible for the retrospective study. Any adult eyes with open angle glaucoma, at least 1 surgery for glaucoma, and more than 3 months of follow-up were included. Patients were excluded if they had corneal edema prior to their surgery or had preexisting corneal disease.

There were 333 eyes from 245 patients that were included in the study who had a mean (range) follow-up of 4.7 years (3 months to 19.3 years); the mean age at surgery was 73.9 (range, 33.7-97.0) years. It took 6.2 years (6 months to 13.0 years) on average for corneal edema onset in this group.

Eyes without corneal edema decreased from 94.2% at 5 years to 70.8% at 15 years. Patients who had received GDDs had the highest incidence of corneal edema at 27.7% compared with 13.5% for trabeculectomy, 0.98% for Xen stents, and 1.1% for MIGS.

GDDs significantly increased the risk of corneal edema compared with the trabeculectomy group (HR, 3.07; 95% CI, 1.02-9.17) in a univariate analysis and multivariate analysis. The MIGS and Xen groups had risks for corneal edema of 0.51 (95% CI, 0.06-24.60) and 0.24 (95% CI, 0.02-2.11), respectively. The number of glaucoma surgeries also increased the risk of corneal edema (HR, 2.40; 95% CI, 1.47-3.93).

There were some limitations to this study. Incomplete documentation and the retrospective design of the study could have led to potential misclassification of corneal edema, and survival estimates could have been biased due to more frequent follow-up for patients with corneal edema. The patients who had MIGS and Xen procedures had shorter follow-up times. Generalizability may be limited due to this study taking place in a single center, and statistical power may also be limited due to the small sample size. Patient attrition also was more likely in those with longer follow-up periods, which could have under- or overestimated survival.

“These findings underscore the importance of long-term monitoring for glaucoma patients, particular those undergoing multiple surgeries or GDD procedures, as they face increased risks of complications,” the authors concluded.

References

1. Pentland V, Martin RA, Campbell RJ, Johnson D. Risk of corneal edema following glaucoma filtering surgery: a retrospective cohort study. Can J Ophthalmol. Published online August 23, 2025. doi:10.1016/j.jcjo.2025.08.002

2. Glaucoma. Cleveland Clinic. Updated November 12, 2024. Accessed August 27, 2025. https://my.clevelandclinic.org/health/diseases/4212-glaucoma