Early Ahmed Glaucoma Valve Exposure Repaired With Corneal Patch Graft: A Case Report

Glaucoma drainage devices are effective treatment options, particularly in refractory and high-risk glaucoma patients; however, they may be associated with vision-threatening complications such as tube exposure. Tube exposure carries a significant risk for endophthalmitis and requires immediate surgical intervention. The purpose of this case report is to present the surgical management of an early-onset tube exposure following Ahmed glaucoma valve (AGV) implantation using a corneal patch graft combined with the conjunctival advancement technique.

Ankara Bilkent City Hospital 

A 23-year-old female patient with a history of diabetes mellitus and hypertension presented with medically uncontrolled glaucoma. She was pseudophakic in both eyes, and a peripheral iridectomy was present in the right eye. The baseline best-corrected visual acuity was counting fingers at 2 meters in the right eye and 1.3 logMAR in the left eye. An AGV was implanted in the superotemporal quadrant of the left eye. Postoperative follow-ups were unexceptional until the two month follow-up visit, where tube exposure was detected 1 mm posterior to the limbus. A revision surgery was planned under general anesthesia. A 4 × 3 mm partial-thickness corneal patch graft was manually prepared from donor tissue. After debridement of the exposed area, the graft was secured to the underlying sclera with 10-0 nylon sutures. The surrounding conjunctiva was then mobilized and repositioned over the graft using a conjunctival advancement technique, achieving tension-free closure and restoration of anatomical integrity.

Tube exposure following AGV implantation is a rare but significant complication that may lead to ocular inflammation, hypotony, decreased vision, phthisis bulbi, and endophthalmitis. Risk factors such as young age, female sex, and diabetes mellitus may contribute to the development of exposure. In high-risk cases, primary conjunctival closure may be insufficient. A partial-thickness corneal patch graft provides reliable coverage with favorable long-term structural stability. Prompt surgical intervention and appropriate graft selection are critical to prevent endophthalmitis and preserve filtration function.