Purpose: Retrobulbar glaucoma shunts are large-bore fenestrated silicone stents that redirect aqueous humor into the retrobulbar space. They were designed to rescue failed standard tube shunts with fibrotic encapsulation in patients with intractable ocular hypertension. This article evaluates longer-term outcomes of a larger population undergoing retrobulbar aqueous redirection.
Methods: Outcomes of all retrobulbar shunts were placed among this progressive-entry surgical population over an 8-year interval. Implants were produced by New World Medical (NWM) in Rancho Cucamonga, California, and AJL in Bilbao, Spain. Mean and percentage IOP reduction and medications required were evaluated at annual intervals, along with pre-operative and final visual acuity. Significance of change was assessed by two-tailed paired t-test. Failure was designated as any eye requiring placement of another shunt or diode-cyclophotocoagulation. All data are included in this analysis regardless of outcome.
Results: Thirty-five retrobulbar shunts were implanted (18M, 17F; mean 54.3 years; mean follow-up 32.5 months). Short-term AJL shunt performance was comparable to that of the 26 NWM shunts, for which there was longer-term follow-up. Three shunts (9%) failed: Two eyes required diode at 6 months, one another standard shunt after > 2 years. Preoperative medications averaged 2.6, reduced to 0.4-0.75 medications at each annual assessment (P < 0.0001). IOP was substantially reduced (by 53-57% from mean baseline 29.9-32.5 mmHg to 16.4-18.4 mmHg; P < 0.0008) at every annual follow-up. Visual acuity remained stable (baseline mean VA 0.27, final VA 0.30; P = 0.68).
Conclusion: Retrobulbar extension shunts can convert tube shunt failures, with high success rate, to eyes with IOP control comparable to successful primary filtration surgery.
Keywords: Encapsulated bleb; Glaucoma; Glaucoma tube shunt; Intraocular pressure; Retrobulbar space.