Efficacy of a Novel Retrobulbar Extension Shunt to Rescue Eyes with Fibrotic Encapsulated Blebs and Uncontrolled Ocular Hypertension

  • William E. Sponsel
  • Sylvia Groth
  • Francesc March de Ribot
  • Hannia Ramos
  • Madeleine PuigEmail author



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.


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.


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).


Retrobulbar extension shunts can convert tube shunt failures, with high success rate, to eyes with IOP control comparable to successful primary filtration surgery.


Glaucoma Glaucoma tube shunt Encapsulated bleb Retrobulbar space Intraocular pressure 



No funding was received for this research.

Compliance with ethical standards

Conflict of interest

With the single exception listed below, all authors certify that they have no affiliations with or involvement in any organization or entity with any financial interest (such as honoraria; educational grants; participation in speakers’ bureaus; membership, employment, consultancies, stock ownership, or other equity interest; and expert testimony), or non-financial interest (such as personal or professional relationships, affiliations, knowledge, or beliefs) in the subject matter or materials discussed in this manuscript. William Sponsel is a co-patentee with Mateen Ahmed of New World Medical for the novel concept of shunting aqueous humor into the retrobulbar space. William Sponsel is also a co-patentee with AJL for the bleb-to-back (B2B) and anterior-to-back (A2B) tube shunts.

Ethical approval

All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards.

Informed consent

Informed consent was obtained from all individual participants included in the study.


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Copyright information

© Springer-Verlag GmbH Germany, part of Springer Nature 2019

Authors and Affiliations

  1. 1.Vision SciencesUniversity of Incarnate WordSan AntonioUSA
  2. 2.Biomedical Engineering University of Texas San AntonioSan AntonioUSA
  3. 3.Vanderbilt University Department of OphthalmologyNashvilleUSA
  4. 4.Barcelona University HospitalBarcelonaSpain
  5. 5.Universidad Autónoma de Guadalajara School of MedicineGuadalajaraMexico
  6. 6.University of Texas Health Science Center at San Antonio Long School of MedicineSan AntonioUSA

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