Modified Schocket procedure can manage glaucoma after scleral buckling surgery

A surgeon explains how to control IOP after uncomplicated retinal detachment repair.

Issue: February 10, 2013

ByAhmad A. Aref, MD

Glaucoma associated with post-retinal detachment repair may be clinically challenging. Conventional strategies include medical treatment with topical anti-glaucoma drops; surgical intervention may be required for optimal control of IOP and preservation of vision.

Although scleral encircling bands are effective in retinal detachment repair, they reduce the available space for seton drainage devices and may not permit the use of some of the drainage devices that are currently available. In these cases, one has to consider a drainage device that can be effectively used in a limited amount of space. A seton device that can utilize the pre-existing scleral buckle band may be especially suited in the surgical management of glaucoma after retinal detachment surgery.

In this column, Dr. Aref describes a modified Schocket procedure for control of IOP after a scleral buckle.

Thomas John, MD
OSN Surgical Maneuvers Editor

Ahmad A. Aref

Uncontrolled glaucoma may develop after otherwise uncomplicated retinal detachment repair for a number of reasons. Open-angle glaucoma occurs with a higher frequency in eyes with a retinal detachment, possibly due to myopia as a common risk factor. Furthermore, glaucoma may develop after scleral buckling surgery due to increased episcleral venous pressure as a result of impaired venous drainage from the vortex veins by the scleral buckle. The surgical management of glaucoma in the setting of a pre-existing scleral buckle is often challenging because options are limited. Trabeculectomy surgery in this situation may be associated with a higher risk of conjunctival fibrosis and failure. Although conventional glaucoma drainage implant surgery may be successful, limited orbital space in an eye with a pre-existing scleral buckle may not always allow for insertion of a glaucoma drainage device.

Schocket et al originally described the use of an anterior chamber tube shunt connected to an encircling band in a series of adult eyes with neovascular glaucoma. The modified Schocket procedure, described herein, involves the connection of silicone tubing to a pre-existing scleral buckle in order to allow for aqueous drainage and long-term IOP control.

Surgical technique

Ocular anesthesia is achieved with a local retrobulbar block consisting of a 50:50 mixture of lidocaine 2% and bupivacaine 0.5% administered under monitored anesthesia care. A localized conjunctival peritomy is created in the superotemporal quadrant using blunt Westcott scissors. After carrying out blunt posterior dissection, the pre-existing scleral buckle is identified. Sharp Vannas scissors are used to incise the fibrous capsule surrounding the buckle (Figure 1). A blunt cyclodialysis spatula is inserted through this entry site and carried along the anterior aspect of the scleral buckle to create a tunnel within the capsule (Figure 2). Silicone tubing connected to a Crawford nasolacrimal stent (FCI Ophthalmics) is inserted through this entry tract (Figure 3).

Figure 1. After blunt posterior subconjunctival dissection, the pre-existing scleral buckle is identified and sharp Vannas scissors are used to incise the surrounding fibrous capsule.

Figure 2. A blunt cyclodialysis spatula is used to create a tunnel within the fibrous capsule surrounding the scleral buckle.

Images: Aref AA

Figure 3. Silicone tubing connected to a nasolacrimal stent is inserted into the previously created entry tract.

Figure 4. A sharp 23-gauge needle is used to enter the anterior chamber immediately posterior to the surgical limbus and parallel to the iris plane.

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The Vannas scissors are used to perform a cut-down over the distal end of the nasolacrimal stent, which is externalized from the fibrous capsule. The cyclodialysis spatula is used to make a tunnel within the adjacent portion of the scleral buckle, and the distal end of the tubing is inserted through this entry tract. The proximal and distal ends of the silicone tubing are cut from the stent using sharp Westcott scissors. An absorbable suture is used to ligate the tube for early flow restriction and prevention of immediate postoperative hypotony. Needle fenestrations placed across the silicone tubing using a 7-0 cutting needle allow for early flow prior to dissolution of the ligation suture.

A sharp 23-gauge needle is used to enter the anterior chamber immediately posterior to the surgical limbus and parallel to the iris plane (Figure 4). The tube is inserted into the anterior chamber through this needle tract (Figure 5). After ensuring that the tube is adequately positioned in the mid-anterior chamber, it may be fixated to the sclera using 9-0 sutures. To prevent erosion through the conjunctiva, the tube should be covered with a donor tissue patch graft (Figure 6). The conjunctiva is sutured closed in a watertight fashion (Figure 7), and subconjunctival injections of an antibiotic and corticosteroid are administered.

Figure 5. After ligation of the tube and creation of needle fenestrations, the proximal portion of the silicone tubing is trimmed with sharp Westcott scissors and inserted into the anterior chamber.

Figure 6. The proximal portion of the tube is covered with a donor tissue patch graft in order to prevent erosion through the conjunctiva.

Figure 7. The conjunctiva is sutured closed in a watertight fashion.

Figure 8. Postoperative slit-lamp photograph depicting the superonasal conjunctival quadrant and pre-existing scleral buckle in a 54-year-old man with uncontrolled glaucoma. The anterior ridge of the scleral buckling element is visualized under the conjunctival tissue.

Figure 9. Postoperative slit-lamp photograph demonstrating a filtering bleb overlying the portion of the scleral buckle in the superotemporal conjunctival quadrant in a 54-year-old man after the modified Schocket procedure was performed. The absence of visualization of the scleral buckle ridge (as seen in Figure 8) indicates adequate filtration.

Figure 10. Postoperative slit-lamp photograph demonstrating adequate tube positioning in the mid-anterior chamber after performance of the modified Schocket procedure for long-term IOP control.

Outcomes

Lee and colleagues reported on the outcomes of eight eyes of seven consecutive patients undergoing the modified Schocket procedure for IOP control after scleral buckling surgery. The group reported an overall success rate of 87.5%. Success was defined as an IOP of 8 mm Hg to 21 mm Hg and no requirement for an additional procedure. One eye in the series experienced tube exposure 10 months after surgery. All eyes had reduction in IOP and improvement in visual acuity by 1 year postoperatively.

The modified Schocket procedure is an effective method for IOP control after scleral buckling surgery (Figures 8-10).

References:

Gedde SJ. Curr Opin Ophthalmol. 2002;13(2):103-109.
Hayreh SS, et al. Br J Ophthalmol. 1973;doi:10.1136/bjo.57.4.217.
Lee KS, et al. J Glaucoma. 2011;doi:10.1097/IJG.0b013e318225b428.
Marcus MW, et al. Ophthalmology. 2011;doi:10.1016/j.ophtha.2011.03.012.
Schocket SS, et al. Ophthalmology. 1982;doi:10.1016/S0161-6420(82)34671-0.
Scott IU, et al. Am J Ophthalmol. 2000;129(3):334-341.
Scott IU, et al. Arch Ophthalmol. 2000;doi:10.1001/archopht.118.11.1509.
Sherwood MB, et al. Arch Ophthalmol. 1987;doi:10.1001/archopht.1987.01060040 132051.

For more information:

Ahmad A. Aref, MD, can be reached at Illinois Eye & Ear Infirmary, University of Illinois at Chicago School of Medicine, 1855 W. Taylor St., Suite #3.171, Chicago, IL 60612; 312-996-7030; fax: 312-413-8574; email: ahmadaref@gmail.com.
Thomas John, MD, is a clinical associate professor at Loyola University at Chicago and is in private practice in Oak Brook, Tinley Park and Oak Lawn, Ill. He can be reached at 708-429-2223; fax: 708-429-2226; email: tjcornea@gmail.com.
Disclosures: Aref and John have no relevant financial disclosures.