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    Understanding drainage in glaucoma surgery

    Procedures and practices for postoperative care

    Glaucoma drainage devices are increasingly flowing in many glaucoma practices. You may be familiar with laser glaucoma procedures, including argon laser trabeculoplasty, selective laser trabeculoplasty, and micropulse  laser trabeculoplasty. Trabeculectomy is a commonly performed filtering surgery as well.

    But, you may not know the differences among Baerveldt Glaucoma Implant (Abbott Medical Optics), Ahmed Glaucoma Valve (New World Medical, Inc), iStent (Glaukos), and ExPress Glaucoma Filtration Device (Alcon). It is important for optometrists to be familiar with these devices and the rationale behind the device chosen. This article describes what each device is, how they work, complications, and postoperative care.

    More glaucoma: How patients perceive their glaucoma matters

    iStent

    The iStent trabecular micro-bypass is a micro invasive glaucoma surgery (MIGS) tool.1 It is essentially a small snorkel comprised of Heparin (heparin sodium, Hospitra)-coated titanium. The iStent is usually implanted nasally into Schlemm’s canal during cataract surgery and is designed to improve the aqueous outflow and decrease intraocular pressure (IOP) by creating a permanent opening in the trabecular meshwork.

    The procedure involves inserting the iStent through the phacoemulsification incision site past the pupillary margin. The angle is viewed with a gonioscopy lens, and an approach is made to the upper one third of the trabecular meshwork at an angle of 15 degrees. The trabecular meshwork is engaged, and the iStent is gently inserted into Schlemm’s canal. The bottom of the inserter is pushed to release the iStent. The button is released, and the side of the snorkel is gently tapped to ensure the device is properly seated. The inserter and viscoelastic are then removed.1

    Because the procedure is minimally invasive, it spares tissue damage caused by traditional glaucoma surgery. It is the smallest FDA-approved device for mild to moderate glaucoma. The iStent Inject is being developed with multiple iStents in a preloaded injector system if the surgeon deems it necessary to use more than one.2

    More glaucoma: Drance hemorrhages and quarterly optic disc evaluation

    Contraindications for iStent use include primary- or secondary-angle closure glaucoma, neovascular glaucoma, thyroid eye disease, Sturge-Weber syndrome, or any other condition that may cause elevated episcleral venous pressure. Gonioscopy should be performed before surgery to rule out peripheral anterior synechiae, rubeosis, and any angle abnormalities or conditions that would occlude sufficient visualization of the angle that could lead to improper placement of the stent.1 Complications can include corneal edema, posterior capsular haze, stent obstruction, early postoperative cells in the anterior chamber (AC), and early postoperative corneal abrasion.1

    Postoperative care generally includes the usual cataract recovery drop schedule as well as the patient’s currently prescribed glaucoma medications. Commonly used postoperative drops include Besivance (besifloxacin, Bausch + Lomb) tid for one week; prednisolone tid for one week, then bid for one week, then qd for two weeks, and Ilevro (nepafenac ophthalmic suspension, Alcon) qd for four weeks. If the IOP remains the same as it was preoperatively, then usually the patient will continue with his glaucoma drop regimen. A trial discontinuation of the glaucoma drops may be used to see how well the IOP is maintained.3

    Next: Baerveldt Glaucoma Implant

    Barbara J. Fluder, OD
    Dr. Fluder has been in practice for 22 years and currently practice at Williams Eye Institute in Merrillville, IN. She is a member of ...

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