Cutting Edge Glaucoma - Issue 2

14 • CUTTING EDGE - GLAUCOMA of these devices prohibits their regular use. Although the Ahmed glaucoma valve (AGV) (New World Medical, Rancho Cucamonga, CA, U.S.A.) has been available in India for the past 1–2 decades, the Baerveldt implant has never been made available. Since 2014, we have been using a prototype similar to the Baerveldt, the Aurolab aqueous drainage implant (AADI), developed by the Aravind Group (Madurai, Tamil Nadu, India). We use both flow-restricted, e.g., AGV, and non-flow-restricted, e.g., AADI, implants. The choice of device is dependent on the surgeon’s comfort and the availability of the GDD. Both types of GDD are equally effective in controlling IOP. However, studies in adults suggest that the need for medications is higher with flow-restricted GDDs, and hypotony-related problems are higher with non-flow-restricted GDDs [37]. One has to weigh the benefits and risks on an individual patient basis and choose the procedure that is safe and effective. Our indications for GDD surgery are failed CTT surgery in PCG as a primary pro- cedure or after failed trabeculectomy surgery in eyes with aniridia, Sturge–Weber syndrome, and other secondary childhood glaucomas and as primary surgery for secondary glaucomas following congenital cataract surgery, uveitis, trauma, steroid use, postkeratoplasty, and post-vitreoretinal surgery or in eyes with severely scarred conjunctiva. Proper planning, patient selection, and meticulous surgery are important for safe and suc- cessful surgery. With regard to technique, we prefer a superotemporal location and most often or always a limbal-based conjunctival flap (6 mm limbal-based conjunctival opening, 6 mm poste- rior to the limbus to reduce the size of the conjunctival opening). We prefer double ligature of the tube using 6/0 Vicryl. We use a 24G needle to perform 3–4 mm needle track, and the AC is entered parallel to the limbus. For eyes having a pars plana GDD, a 25G needle entry is preferred. We prefer to place the tube in the ciliary sulcus in pseudophakic eyes, leaving a long tube to allow visualization of the tube tip through the pupil and to avoid the tube blocking. In eyes with aniridia, a short tube with oblique entry into the AC oriented away from the crystalline lens can help prevent lenticular touch. We leave longer tubes in uveitic eyes to decrease the risk of occlu- sion from peripheral anterior synechiae. Pars plana tube insertion is preferred in vitrectomized eyes or eyes with shallow anterior chamber or those with penetrating keratoplasty. The conjunc- tiva is closed with 8/0 Vicryl in a continuous fashion with a mattress suture, ensuring traction- free closure. Continuous mattress conjunctival closure provides a posterior suture line, watertight closure, and with minimal discomfort. Refer to Videos 2 and 3 for the surgical technique of an AADI and AGV implant. We find the use of ICare tonometer (Icare Finland Oy, Vantaa, Finland) for IOP estimation and ultrasound biomicroscopy to evaluate the bleb dimensions and the fluid pocket very useful in decreasing the number of examinations under anesthesia in these children. Ultrasound also helps to identify posterior segment complications that may occur in the immediate or late postoperative period. A hypertensive phase occurs at 3–4 weeks after AGV implantation and the 9th–10th week following an AADI implant. Hypertensive phase is defined as elevated IOP >21 mmHg after initial low or normal IOP in the presence of cystic and tense bleb. Starting prophylactic glaucoma medi- cations post AGV implantation can decrease the rate of hypertensive phase. The high IOP during the hypertensive phase is managed with topical and oral glaucoma medications. In our experience