Comparison of Efficacy Between Silicone Ahmed Glaucoma Valves and Second Trabeculectomy in Glaucoma Patients

Comparison of Efficacy Between Silicone Ahmed Glaucoma Valves and Second Trabeculectomy in Glaucoma Patients

In the management of open angle glaucoma, frequently more then one procedure is necessary to control the intra ocular pressure. There is still no consensus whether this second intervention should be a second trabeculectomy or a shunt device. In the present study we compare a second trabeculectomy versus Ahmed silicone shunt device in open angle glaucoma patients with previous trabeculectomy without proper IOP control.

In the management of open angle glaucoma, frequently more then one procedure is necessary to control the intra ocular pressure. There is still no consensus whether this second intervention should be a second trabeculectomy or a shunt device. In the present study we compare a second trabeculectomy versus Ahmed silicone shunt device in open angle glaucoma patients with previous trabeculectomy without proper IOP control.

40 Patients with clinically uncontrolled open angle glaucoma with previous trabeculectomy surgery were selected from the glaucoma sector of Federal university of Sao Paulo. Patients were randomized to one of two groups:

1. Silicone Ahmed Implant
2. Second trabeculectomy

Surgery description:

Ahmed silicone tube implant: A fornix-based conjunctival flap was created between two adjacent recti muscles. Before placement of the tube implant body to the sclera, tube was irrigated with saline solution to open the valve mechanism. The implant's polypropylene body was sutured to sclera with 6.0 silk suture. The tube then trimmed and the anterior chamber was entered from 1mm posterior to corneoscleral limbus with 23-gauge needle. A human donor scleral flap was placed over the tube and sutured to the sclera with 10.0 nylon suture. The conjunctiva was sutured to the limbus.

Second Trabeculectomy: A fornix-based conjunctival flap was created in the opposite superior quadrant of the previous trabeculectomy. Mitomycin-C was used under the conjunctival flap for up to 4 minutes (0,3mg/mL) and rinsed with 30mL saline solution. Scleral flap with crescent bevel and sclerectomy with a punch. Iridectomy and flap suture with nylon 10-0. Conjunctival suture with nylon 10-0.

Follow up after surgery was in the 1st, 4th, 7th, 15th, 30th days and after that monthly or whenever needed for clinical reasons.

Inclusion Criteria:

• Patients with open angle glaucoma and uncontrolled IOP despite the use of maximum tolerated glaucoma medication.
• Patients over 18 years old.
• Patients who can understand and sign the inform consent form.

Exclusion Criteria:

• Other forms of glaucoma other than open angle glaucoma; previous psiquiatric condition ;
• Patients who can understand and sign the inform consent form;
• visual acuity worse than hand motion;
• previous retina surgery with buckle implant