What is the recommended treatment for a patient with a history of glaucoma who has undergone tube (glaucoma drainage device) implant surgery and is experiencing complications such as tube exposure or conjunctival erosion?

Management of Tube Exposure Following Glaucoma Drainage Device Implantation

For tube exposure or conjunctival erosion after glaucoma drainage device surgery, immediate surgical revision with patch graft coverage (using sclera, cornea, or pericardium) and conjunctival advancement is the definitive treatment to prevent endophthalmitis and preserve device function. 1

Immediate Management

• Initiate topical antibiotics immediately upon discovery of tube exposure to reduce infection risk until surgical repair can be performed 1
• Recognize that tube erosion typically develops a few millimeters behind the limbus following anterior chamber insertion 1
• The reported incidence ranges from 1-5% in major clinical trials (5% in TVT Study, 1% in ABC Study) 1

Surgical Revision Technique

The standard approach involves:

• Adequately open the area of eroded conjunctiva with complete exposure of the defect 1
• Thoroughly release any areas of traction that may have contributed to the erosion 1
• Debride or cauterize areas of epithelialization to prevent inclusion cyst formation—this is critical as retained epithelial tissue can lead to devastating complications including endophthalmitis 2
• Cover the exposed tube with patch graft material (processed pericardium, donor sclera, or corneal graft) 1
• Advance and secure conjunctiva over the patch graft with careful attention to wound closure 1

Patch Graft Material Selection

The American Academy of Ophthalmology guidelines note that patch allografts of sclera, cornea, or pericardium are commonly used to prevent tube erosion, though no single material has proven superior for long-term tectonic durability 1, 3. Recent evidence suggests:

• Traditional materials (sclera, cornea, pericardium) remain the standard of care 1
• Newer synthetic materials like keraSys patch grafts show concerning early exposure rates (10% in one series), limiting their effectiveness 4

Critical Technical Considerations

To prevent recurrent erosion:

• Ensure Tenon's membrane closure prior to conjunctival closure for additional tissue layers 1
• Use nylon suture rather than braided polyester (Mersilene), as braided sutures may contribute to erosion 1
• Rotate knots posteriorly underneath any suture tabs and leave tails long to create a lower profile 1
• In pediatric cases, place additional sutures to secure the patch graft during initial implantation to prevent displacement 2

Alternative Approach for Recurrent Erosion

For cases with repeated conjunctival erosion despite standard repair, lateral tube repositioning (changing the insertion site into the anterior chamber without disturbing the plate) represents a viable alternative, though this requires adequate tube length 5. This technique avoids repeated conjunctival manipulation in scarred tissue.

Monitoring for Complications

Tube exposure represents a significant risk factor for endophthalmitis 3, 2. The risk of postoperative infection appears lower with aqueous shunts than after trabeculectomy with antifibrotic agents, but vigilance remains essential 1.

Key warning signs requiring urgent intervention:

• Progressive conjunctival thinning over the tube 1
• Any signs of infection or inflammation 3, 2
• Development of inclusion cysts under patch grafts (particularly in pediatric patients) 2

Common Pitfall

Never assume small amounts of wound leakage will resolve spontaneously—meticulous wound inspection and complete closure at the time of revision is mandatory 1. Inadequate initial repair leads to recurrent erosion and increased infection risk.