[Glaucoma drainage system according to Molteno for therapy-resistant glaucoma--a two-stage surgical technique to avoid postoperative hypertension]

Abstract

Background: The treatment of therapy-resistant secondary glaucoma with cyclodestructive approaches may give rise to unsatisfactory intraocular pressure results, leading to phthisis. A final option may be the implantation of an external glaucoma drainage system (GDS). A consecutive positioning of the drainage system under the conjunctiva and implantation of the drainage tube into the anterior chamber, may result in an uncontrolled reduced of intraocular pressure leading to intraocular haemorrhages into the anterior chamber or vitreous cavity. In particular, expulsive haemorrhages are feared as deleterious complication.

Patients and methods: 15 patients (15 eyes) with secondary glaucoma received a GDS. All patients were previously unsuccessfully treated by numerous approaches (mean 2.7 times). The mean preoperative intraocular pressure was 37 mmHg (range: 22 to 55 mmHg). We performed a sequential approach: during the first operation we implanted and fixed the resorption site of a Molteno GDS onto the sclera close to the equator in the superotemporal quadrant. After an inflammation-free interval of 2 - 3 weeks we placed the drainage tube into the anterior chamber. The average postoperative follow-up period was 20.5 months (range: 3 to 62 months).

Results: The implantation of the GDS using a sequential approach was well tolerated by all patients. While 14 out of 15 eyes achieved an IOP of 15 mmHg (range: 12 to 18 mmHg), 2 of them still required additional topical glaucoma treatment. An unsatisfactory IOP regulation was observed in only one eye although a revision surgery was performed postoperatively. Four eyes developed a light anterior chamber haemorrhage that resorbed without serious complications within 3 weeks. A choroidal effusion in one eye was treated by an anterior chamber injection of a viscoelastic gel.

Conclusion: The potential disadvantage of the GDS can be almost completely avoided using a sequential approach. The implant heals well in the subtenon space during the first postoperative week, thus preventing an overfiltration of anterior chamber fluid. Our positive results show that the GDS is an important treatment option in selected patients.