Corneal Perforation Following Ahmed Glaucoma Valve Implant: A Case Report

We report a rare case of non-traumatic corneal perforation as a complication of Ahmed glaucoma valve implantation (AGV) in a patient with neovascular glaucoma (NVG), in which a complex two-stage reconstruction of the anterior segment was required.

La Princesa University Hospital, Madrid (Spain). 

A 90-year-old woman presented to our emergency department with a 1-month history of unilateral painless vision loss in her left eye. Fundus examination revealed vitreous hemorrhage with no retinal view. Ultrasound showed multiple vitreous echoes with attached retina. Iridis rubeosis, a wide posterior chamber (PC), and elevated intraocular pressure (IOP) were detected during the slit-lamp examination and gonioscopy revealed a 360º closed iridocorneal angle. In this context, hypotensive and antiangiogenic treatment was initiated while awaiting combined retina surgery (vitrectomy with panretinal photocoagulation for central venous thrombosis) and glaucoma surgery (AGV implantation with the tube in the PC), without incidents. Two weeks later, she came back with corneal perforation and melting that allowed the tube to be visible through it, along with significant superior temporal and nasal thinning of the conjunctivo-scleral tissue, confirmed by anterior segment optical coherence tomography, as well as a positive Seidel test at the base of the bleb. Urgent closure of the defect was performed by applying an adhesive matrix patch over the perforated area and pericardium covering the bulbar conjunctiva. In a second time, a tectonic penetrating keratoplasty (PKP), new pericardium covering, conjunctival advancement, and amniotic membrane (AM) coverage of the reconstructed area were done. Eight months later, the patient had a functioning bleb, optimal IOP, and a clear corneal button.

The AGV is often a safe and effective method for reducing IOP in NVG. In contrast to the multiple cases of corneal decompensation secondary to tube contact reported to date, in our case, there was no history of trauma or malposition of the tube that could explain the corneal perforation. Therefore, we considered a mixed inflammatory condition with corneal melting, similar to the one observed at the conjunctivo-scleral level, as the cause of the hypotony that favored endothelial contact with the tube followed by corneal perforation. Reconstruction of the anterior segment, including PKP, as well as the use of AM, allowed for the maintenance of anatomical integrity and functionality in the long term.