Optical coherence tomography-guided decision-making for Descemet stripping automated endothelial keratoplasty in Ahmed glaucoma valve-related corneal decompensation.

Abstract

Objective: Ahmed glaucoma valve (AGV) implantation can lead to corneal decompensation in a significant proportion of patients. Anterior segment optical coherence tomography (ASOCT) evaluation may serve as a crucial tool for assessing AGV retention versus explantation and for planning Descemet stripping automated endothelial keratoplasty (DSAEK) in such cases. This study aims to evaluate the utility of ASOCT in guiding management decisions for AGV-related corneal decompensation.

Materials and methods: In this prospective interventional study, 11 eyes with AGV-related corneal decompensation were evaluated using anterior segment 5-line raster-mode OCT measurements. Parameters assessed included stromal scarring, corneal thickness, and tube tip to endothelium (TTE) distance. ASOCT findings guided management decisions: four patients with nonfunctional AGVs underwent staged procedures (AGV removal with augmented trabeculectomy, followed by DSAEK), while seven patients underwent DSAEK alone (six with functional AGVs with TTE distance > 150 μm; one patient with a non-functional AGV refused consent for AGV explantation).

Results: All patients demonstrated significant improvement in best-corrected visual acuity with well-controlled intraocular pressure. Graft attachment was successful in all cases except one patient who experienced detachment after one month. Based on our findings, we proposed a protocol for managing AGV-related corneal decompensation.

Discussion: Tube shunt implantation effectively reduces intraocular pressure in eyes with uncontrolled glaucoma but can lead to significant endothelial cell loss and corneal decompensation. In this series, two major challenges were addressed: the decision regarding AGV tube removal and its risks, and the determination of a safe tube-tip-to-endothelium (TTE) distance to prevent graft damage after DSAEK. We considered a preoperative TTE greater than 150 μm to be safe for single-stage DSAEK without AGV modification, accounting for lenticule thickness and the anticipated reduction in corneal edema. ASOCT-guided measurement of TTE distance proved invaluable for predicting complications and guiding surgical decision-making, with outcomes that support our proposed management protocol.

Conclusion: While performing DSAEK in patients with AGV-related corneal decompensation presents significant challenges, ASOCT is an essential modality for guiding surgical decision-making regarding AGV explantation versus retention and subsequent DSAEK.