Posterior migration of an Ahmed glaucoma valve: A case report of a rare postoperative complication.

Purpose: Ahmed glaucoma valve (AGV) migration is a rare postoperative complication after AGV implantation. We report a single case of AGV posterior migration in the early postoperative period. A 67-year-old male patient with a history of primary open angle glaucoma, diabetes, and pseudophakia of both eyes presented two days after AGV placement in the right eye. Observations: He reported right eye pain, fever, and chills. On examination, he had broken sutures at the valve placement site, purulent discharge from the upper fornix, and an elevated intraocular pressure of 34 mmHg in the right eye. The patient was sent to the hospital due to concerns for orbital cellulitis. Computerized tomography (CT) showed superotemporal post-septal migration of the AGV plate and tube. The patient was admitted to the hospital and started on broad-spectrum intravenous (IV) antibiotics. Cultures of the right eye drainage grew Group A beta-hemolytic streptococci. Six days after the original AGV placement, the patient underwent orbital exploration with removal of the displaced AGV from the posterior third of the globe by an oculoplastics surgeon. The entire AGV plate and tube were removed intact. The wound was irrigated with vancomycin and the conjunctiva was closed. Two days after the AGV removal, the patient showed significant clinical improvement. Conclusions and importance: Upon further investigation, it was determined that the plate was not secured with fibrin glue or suture, only the patch graft was secured with suture. AGV posterior migration following AGV implantation is a rare but serious postoperative complication that must be recognized early and managed appropriately.