Anterior Chamber Versus Ciliary Sulcus Ahmed Glaucoma Valve Tube Placement: Longitudinal Evaluation of Corneal Endothelial Cell Profiles

Precis: An Ahmed glaucoma valve (AGV) tube in the ciliary sulcus (CS) is safer for the endothelium. At 4 years of follow-up, there was a significant decrease in endothelial cell count only with anterior chamber (AC) placement. Purpose: Corneal endothelium (CE) damage is one of the most feared long-term complications that can result from glaucoma drainage devices. Nonetheless, there is a lack of studies evaluating longitudinal changes in CE cells. This study aims to compare CE changes after AGV implantation in eyes with AC or CS tube placement. Materials and Methods: This was a retrospective, nonrandomized, longitudinal study of pseudophakic eyes with open-angle glaucoma and medically uncontrolled intraocular pressure that received an AGV. Eyes with additional glaucoma surgeries performed during follow-up were excluded. The main outcome measure was endothelial cell density (ECD), which was evaluated 1 year +/- 2 months and 4 years +/- 2 months postoperatively. The average endothelial cell size (AS) and the distance from the tube tip to the cornea were also evaluated. Results: Twenty-six eyes from 26 patients, with a mean age of 73 +/- 10 years, were included. The tube was placed in the AC in 15 eyes and in the CS in 11 eyes. The eyes with tube placement in the AC showed a significant AS increase (P=0.007) and ECD decrease (P=0.034), whereas eyes with tube placement in the CS had no significant AS (P=0.575) or ECD (P=0.445) change. In the eyes with tube placement in the AC, there was no correlation between DTC and ECD (P=0.260) or AS (P=0.428) changes. Conclusions: Tube placement in the AC seems to lead to significant CE cell loss over time, compared with tube placement in the CS.