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Retrobulbar Diversion of Aqueous Humor: Clinical Feasibility Studies

Sponsel, William, E.*; Groth, Sylvia, L.; Ayyala, Ramesh, S.

doi: 10.1097/IJG.0000000000000082
Original Studies

Introduction: The purpose of this study is to clinically evaluate a new form of glaucoma tube shunt drainage system. Tube shunts play an important role in management of advanced glaucoma, but eventually many blebs may become encapsulated and impervious to aqueous humor. This pilot study analyzed clinical efficacy of retrobulbar diversion of aqueous, either directly from anterior chamber (AC) or existing encapsulated blebs (EB), into the retrobulbar space (RS).

Methods: Nineteen patients with intractable glaucoma underwent retrobulbar fenestrated implant surgery (16 with EB-to-RS and 3 AC-to-RS). Intraocular pressure, glaucoma medications, and acuity were assessed relative to preoperative baseline values by paired t test preoperatively and bimonthly up to 2 years. Preoperative and postoperative values were compared by paired t test.

Results: Surgical patients (7 male, 12 female; mean, 62±3.3 y; progressive study entry; mean follow-up, 18.2 mo) maintained substantial intraocular pressure reduction, from preoperative mean 33.1±2.0 mm Hg to a sustained bimonthly mean of 14.6±1.6 mm Hg (14.6±1.1, 16.4±1.7, 13.9±1.2, 13.0±1.1, 13.3±2.0, 14.0±1.1, 12.2±2.2, 13.9±2.0, 15.1±1.4, 17.6±1.6, 15.6±2.0, and 16.0±1.6 at months 2 to 24, respectively; all P<0.00001). Acuity remained stable. Glaucoma medications were reduced from 2.8±0.3 to a bimonthly mean of 0.56±0.26 medications through 24 months (P<0.0001).

Conclusions: Retrobulbar shunts can divert aqueous from the AC into the RS, overcoming (through secondary EB-RS) and potentially obviating (through primary AC-RS) the ocular hypertension resulting from fibrotic plate encapsulation.

*UTSA Department of Biomedical Engineering, San Antonio, TX

University of Minnesota Medical School, Minneapolis, MN

Glaucoma Service, Department of Ophthalmology, Tulane University Medical Center, New Orleans, LA

Supported in part by the New World Medical, the Tulane Glaucoma Research Fund, and Right to Sight International.

W.E.S. and R.S.A. were responsible for the overall project and the study design and execution. S.L.G. was responsible for data collection and statistical analysis of clinical data. W.E.S., R.S.A., and S.L.G. wrote and edited the manuscript.

Disclosure: R.S.A. received research support from New World Medical (Rancho Cucamonga, CA). W.E.S. is a patentee for tube shunt concepts and designs and is a primary investigator with the Australian Research Council Centre of Excellence in Vision Science (ACEVS). S.L.G. declares no conflict of interest.

Reprints: Ramesh S. Ayyala, MD, FRCS, FRCOphth, Glaucoma Service, Department of Ophthalmology, Tulane University Medical Center, 1430 Tulane Avenue SL-69, New Orleans, LA 70112 (e-mail: rayyala@tulane.edu).

Received January 20, 2014

Accepted April 10, 2014

© 2014 by Lippincott Williams & Wilkins.