Corneal patch grafts for exposure of glaucoma drainage devices

Glaucoma drainage devices (GDDs) can be associated with complications, including tube exposure. Tube exposure can lead to severe complications such as endophthalmitis due to microbial entry into the eye. Risk factors include prior ocular surgeries, chronic ocular inflammation, inferior GDD placement, and systemic conditions affecting wound healing. This chapter discusses the approach to diagnosing and managing tube exposure, emphasising the importance of early detection and prompt intervention. While some small conjunctival defects may heal spontaneously with antibiotic ointments, larger or persistent defects require surgical repair. Corneal patch grafting is an effective technique for covering exposed GDD tubes due to its availability, cost-effectiveness, high tensile strength, and optical transparency. The surgical technique involves meticulous preparation of a donor corneal graft using a lamellar ball technique, creating a customised scleral bed, securing the tube, and achieving optimal conjunctival closure. Special considerations include preoperative assessment for suitability of a corneal patch graft and intraoperative challenges such as tube transection. Corneal patch grafting has shown favourable outcomes, with lower re-exposure rates compared to other graft materials, such as scleral grafts. However, concomitant surgeries during GDD implantation and patient-specific factors such as diabetes and multiple prior glaucoma interventions may increase the risk of re-exposure.