Re-Trabeculectomy Versus Ahmed Glaucoma Valve Implantation in Secondary Surgical Management of Patients With Refractory Glaucoma

Re-Trabeculectomy Versus Ahmed Glaucoma Valve Implantation in Secondary Surgical Management of Patients With Refractory Primary Open Angle Glaucoma: a Three-year Comparative Study

The purpose of this study is to compare three-year outcomes of re-trabeculectomy with those of Ahmed glaucoma valve implantation in secondary surgical management of patients with primary open angle glaucoma (POAG) and a history of previous failed trabeculectomy.

Currently, lowering intraocular pressure (IOP) is the only treatment modality to prevent or slow progression of glaucomatous optic nerve damage. Incisional procedures are indicated when medical therapy and/or laser procedures cannot adequately reduce IOP. Trabeculectomy is the most common glaucoma incisional procedure globally. On the other hand, glaucoma drainage devices that have been historically reserved for cases of glaucoma deemed at high risk of failure have increasingly gained popularity particularly in eyes with previous history of glaucoma surgery.

There is still no agreement on the appropriate surgical procedure in those with prior glaucoma surgery. The five-year tube versus trabeculectomy (TVT) study, which evaluated the efficacy and safety of Baerveldt glaucoma implant versus trabeculectomy, showed that both surgical procedures had similar IOP reduction and use of anti-glaucoma medication; tube shunt surgery had a higher success rate than trabeculectomy with mitomycin C (MMC); the trabeculectomy/MMC had higher incidence of early postoperative complications compared to tube shunt surgery; and rates of late postoperative complications, reoperation for complications, and cataract extraction were comparable in both treatment groups.

In this study, the investigators compared three-year outcomes of re-trabeculectomy with those of Ahmed glaucoma valve implantation in secondary surgical management of patients with primary open angle glaucoma and a previous history of failed trabeculectomy.

Inclusion Criteria:

• Uncontrolled glaucoma defined as (1) IOP not achieving previously assigned target pressure despite prior trabeculectomy and use of maximally tolerated anti-glaucoma medication; and (2) recent progression of the disease based on glaucomatous changes in optic disc appearance and/or worsening of the visual field exam.
• In the case of two eligible eyes, only the first eye being operated on was enrolled

Exclusion Criteria:

• Younger than 40 years old
• Visual acuity of no light perception
• Lens opacity
• Elevated IOP associated with silicone oil
• Prior ocular surgeries other than one trabeculectomy with MMC
• Previous cyclodestructive treatment
• Increased risk of endophthalmitis
• Posterior segment disorders
• Pre-existing ocular comorbidities (e.g. pterygium,phacodonesis,corneal opacity, or corneal endothelial dystrophies)