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This study reviews current concepts in the goals of glaucoma therapy, interventional sequence, and options for the management of glaucoma in light of recent clinical trials.Recent randomized prospective trials of ocular hypertension and glaucoma have provided evidence for more specific treatment goals in glaucoma therapy. In addition, the advent of the prostaglandin analogs, advances in laser technology, and innovative techniques for filtering surgery have expanded the armamentarium that ophthalmologists use in the treatment of glaucoma.Despite continued advances in laser and incisional surgery, medical therapy still appears to be the primary means by which intraocular pressure is controlled. Initial medical therapy has changed with the introduction of prostaglandin analogs, which are replacing beta-antagonists as the drug of first choice. Laser trabeculoplasty, using either photocoagulative (argon and diode) or photodisruptive (frequency doubled Nd:YAG) lasers, is still reserved for patients who do not improve with medical therapy, although there is good evidence that initial laser trabeculoplasty is just as effective as initial medical therapy. Trabeculectomy with antifibrotic agents (5-fluorouracil or mitomycin C) is still the next step in intraocular pressure control, and glaucoma drainage implants are reserved for refractory cases. Cyclophotocoagulation is a last resort procedure because of poor visual outcomes and is reserved for patients with intractable pain and vision thought not to be useful.

Purpose: To report a case of endophthalmitis due to Nocardia brasiliensis in an eye with an exposed, infected Ahmed glaucoma drainage implant (GDI).Design: Retrospective case report.Methods: A patient with an exposed GDI experienced recurrent episodes of endophthalmitis despite repeated intravitreal injections of antibiotics and steroids. The tube was initially repositioned and finally removed.Results: Whereas repeated cultures from the anterior chamber and vitreous were negative, cultures from the removed tube grew Nocardia brasiliensis. Despite oral trimethoprim-sulfamethoxazole and intravitreal amikacin the eye became phthisical and lost light perception.Conclusions: An exposed GDI may lead to endophthalmitis due to Nocardia brasiliensis and may require explantation to establish a diagnosis.

To investigate the postoperative hypertensive phase (HP) in patients undergoing glaucoma drainage implant surgery.Interventional case series.A retrospective chart review of 156 consecutive eyes (139 patients) who underwent placement of an Ahmed Glaucoma Valve (AGV) with a follow-up ofor=3 months was performed. Main outcome measures were occurrence and resolution of the HP and intraocular pressure (IOP) control. The HP was defined as IOP21 mm Hg during the first 3 months after surgery. Resolution of the HP was defined as an IOP22 mm Hg and an IOP reduction of 3 mm Hg with the same or fewer number of glaucoma medications.An HP was observed in 88 eyes (56%). It occurred after a mean of 5.0 weeks (median, 4 weeks; range, 1-13 weeks) with an average (+/- standard deviation) peak IOP of 30.1 (+/- 7.5) mm Hg. Resolution of the HP occurred in 19 of 68 eyes (28%) with available data. Eyes with an HP had a higher mean IOP and needed more medications 6 to 12 months after surgery than eyes without an HP (17.2 +/- 5.6 vs 14.3 +/- 5.8 mm Hg; P =.012 and 1.7 +/- 1.2 vs 0.3 +/- 0.6 medications; P.001, respectively).A hypertensive phase occurs frequently after implantation of the AGV. However, it resolves in only a minority of eyes. The majority of eyes with an HP have no significant improvement of IOP control and continue to require the same number of glaucoma medications as they did during the HP.

Purpose: Based on lessons learned from earlier attempts, a novel miniature glaucoma implant, Ex-PRESS, was developed in 1998. The current study summarizes the histopathologic evaluation of this device implanted in the eyes of rabbits. Methods: The device was implanted into the anterior chamber at the corneoscleral junction in 1 eye each of 8 white New Zealand rabbits, while the contralateral eye served as control. Three and 6 months after implantation, the rabbits were killed and their eyes were enucleated and processed histologically, leaving the device in situ when sectioning. Results: Three and 6 months postoperatively, the local tissue reaction typically consisted of an enveloping, thin, mature, fibrotic capsule (thickness

Congenital anterior staphyloma entails grave visual prognosis. The majority of reported patients have undergone enucleation. We report a promising result of staphylectomy with implantation of a keratoprosthesis and a glaucoma drainage device in a seven-month-old child with a large, congenital anterior staphyloma.

Surgeons may use various materials, including donor sclera, dura, or pericardium grafts to cover glaucoma drainage implant tubes, prior to repositioning conjunctiva. We reviewed our experience with these materials.Sixty-four eyes with at least 24 months follow-up status post glaucoma drainage implant surgery were evaluated for signs of tube erosion, as well as patch graft thinning, after initial placement of donor sclera (23), dura (18), or pericardium (23) patch grafts.Sixty-two eyes required no intervention for conjunctival and patch graft melting with subsequent tube erosion. Three cases (two eyes) of erosion requiring reoperation (1-dura at 6 months, 1-sclera at 15 months, and in the same eye 21 months later, 1-pericardium) were noted. Significant thinning of the donor patch graft such that the tube was visible beneath intact conjunctiva ocurred in 6 out of 23 donor sclera eyes, 4 out of 18 donor dura eyes, and 6 out of 23 donor pericardium eyes.No material was more prone to melting than another. Donor sclera may be slightly more cost-efficient, but gamma-irradiated pericardium has sterility advantages.

Tubal obstruction is a recognized complication of glaucoma drainage implants. In correcting a blocked tube, the surgeon may be uncertain about shunt competence even after removing the suspected cause of obstruction. We report the use of trypan blue dye to show tubal patency directly after the repair of a blocked Baerveldt tube.

Purpose: To evaluate the results and extrusion rates of the Ahmed glaucoma valve (AGV) implantation through a needle-generated scleral tunnel, without a tube-covering patch, in children. Materials and Methods: A retrospective review of the charts of 106 Mexican children implanted with 128 AGVs operated between 1994 and 2002, with the needle track technique, at our institution, with at least six months follow up was done. Main outcome measures were intraocular pressure (IOP) control, tube extrusions or exposure and other complications. Results: Kaplan-Meier analysis demonstrated a 96.9% survival rate at six months, 82.4% at one year, 78.7% at two years, 70% at three years and 41.6% at four years. Total success at the last follow-up (IOP between 6 and 21 mm Hg without medications) was achieved in 30 eyes (23.5%), 58 eyes (45.3%) had qualified success (only topical hypotensive drugs) and 40 eyes (31.3%) were failures. The mean pre- and post-operative IOP at the last follow up was 28.4 mmHg (SD 9.3) and 14.5 mmHg (SD 6.3), respectively. No tube extrusions or exposures were observed. Tube-related complications included five retractions, a lens touch and a transitory endothelial touch. The risk of failure increased if the eye had any complication or previous glaucoma surgeries. Conclusion: Medium-term IOP control in Mexican children with glaucoma can be achieved with AGV implantation using a needle-generated tunnel, without constructing a scleral flap or using a patch to cover the tube. There were no tube extrusions, nor any tube exposures with this technique.

RE: Long-term outcomes and risk factors for failure with the EX-press glaucoma drainage device

In the recently published article, Saheb et al 1 evaluated changes to the anatomy of the supraciliary space with anterior segment optical coherence tomography imaging after CyPass Micro-Stent implantation. …

Epithelial ingrowth of the bleb cavity, a true Tenon cyst, is a rare complication of a glaucoma drainage implant. Previous cases have been associated with persistent bleb leak, and most have occurred in eyes with prior extraocular surgery. We describe a case of a true Tenon cyst causing strabismus and an elevated intraocular pressure that was successfully treated by surgical revision.

We read with interest the comparison by Tran et al of success rates of Ahmed valve implantation versus trabeculectomy in open-angle glaucoma.1 As the authors know, the retrospective nature of the study may result in selection bias. The validity of the comparison depends critically on the two groups of patients being similar preoperatively, and we feel this may not have been adequately shown. The mean baseline visual acuities (table 1) of the …

Refractory glaucoma remains a challenging problem for the ophthalmologist. Drainage implant surgery is a valuable and effective option for its treatment. Recent developments in implant design and surgical technique have decreased the incidence and severity of postoperative complications while increasing the efficacy of glaucoma drainage implant devices.

Increased intraocular pressure after glaucoma drainage implant surgery may be caused by obstruction of the tube. A case of obstruction of an Ahmed glaucoma valve tube after pars plana insertion due to kinking of the tube was treated with a Pars Plana Clip (New World Medical, Rancho Cucamonga, CA). [Ophthalmic Surg Lasers Imaging 2005;36:167-168.]

PURPOSE: To present a novel design of an implantable glaucoma valve based on ferrofluidic nanoparticles and to compare it with a well-established FDA approved valve. SETTING: Massachusetts Eye & Ear Infirmary, Boston, USA. METHODS: A glaucoma valve was designed using soft lithography techniques utilizing a water-immiscible magnetic fluid (ferrofluid) as a pressure-sensitive barrier to aqueous flow. Two rare earth micro magnets were used to calibrate the opening and closing pressure. In-vitro flow measurements were performed to characterize the valve and to compare it to Ahmed™ glaucoma valve. The reliability and predictability of the new valve was verified by pressure/flow measurements over a period of three months and X-ray diffraction (XRD) analysis over a period of eight weeks. In vivo assessment was performed in three rabbits. RESULTS: In the in vitro experiments, the opening and closing pressures of the valve were 10 and 7 mmHg, respectively. The measured flow/pressure response was linearly proportional and reproducible over a period of three months (1.8 µl/min at 12 mmHg; 4.3 µl/min at 16 mmHg; 7.6 µl/min at 21 mmHg). X-ray diffraction analysis did not show oxidization of the ferrofluid when exposed to water or air. Preliminary in vivo results suggest that the valve is biocompatible and can control the intraocular pressure in rabbits. CONCLUSIONS: The proposed valve utilizes ferrofluid as passive, tunable constriction element to provide highly predictable opening and closing pressures while maintaining ocular tone. The ferrofluid maintained its magnetic properties in the aqueous environment and provided linear flow to pressure response. Our in-vitro tests showed reliable and reproducible results over a study period of three months. Preliminary in-vivo results were very promising and currently more thorough investigation of this device is underway.

Glaucoma represents a leading cause of preventable vision loss in Sub-Saharan Africa. Recent studies evaluating outcomes of glaucoma drainage implant (GDI) surgery suggest an important role for this approach in the African patient population. The Tube Versus Trabeculectomy study demonstrated a higher success rate with non-valved GDI surgery compared to trabeculectomy with mitomycin C after five years. The Ahmed Baerveldt Comparison study showed no difference in surgical failure rates between the Ahmed Glaucoma Valve and the Baerveldt Glaucoma Implant (BGI) but better intraocular pressure outcomes with the BGI at one year. The Ahmed Versus Baerveldt study demonstrated a lower failure rate for the BGI, but also a requirement for more post-operative interventions. Further study of GDI surgery in the Sub-Saharan Africa is necessary to determine its optimal place in the treatment paradigm for glaucoma patients in the region.

Glaucoma drainage devices (GDD) occupy an important place in the surgical management of glaucoma that is not responding to medications and trabeculectomy operations. In certain conditions, such as neovascular glaucoma, pediatric glaucoma, iridocorneal endothelial syndrome, penetrating keratoplasty with glaucoma, glaucoma following retinal detachment surgery, it has become the preferred operation. GDD create an alternate aqueous pathway from anterior chamber by channeling aqueous out of the eye through a tube to subconjunctival space. Glaucoma drainage implants that have been used extensively include the non-restrictive and restrictive drainage devices. This article outlines history of implants, types of implant, surgical technique of implantation, various complications following GDD insertion and their management.

To assess clinical outcomes in patients who were treated with the Baerveldt glaucoma drainage implant.The authors performed a retrospective multicenter study of 100 patients (103 eyes) with medically uncontrollable glaucomas who underwent a one-stage implantation with either the 200-, 250-, 350-, or 500-mm2 Baerveldt implant. The authors defined surgical success as 5 mmHg less than intraocular pressure less than 22 mmHg without additional glaucoma surgery and without loss of light perception.With a mean follow-up of 13.6 +/- 0.9 months (range, 4-37 months), 74 eyes (71.8%) had successful outcomes. Cumulative life-table success rates were 90.3% at 3 months (n = 103), 72.6% at 6 months (n = 84), and 60.3% at 24 months (n = 34). Intraocular pressure (IOP) was reduced from a mean of 38.5 +/- 1.4 mmHg with 2.2 +/- 0.1 antiglaucoma medications to 15.1 +/- 0.8 mmHg (P0.0005) with 0.5 +/- 0.1 antiglaucoma medications (P0.0005). Visual acuity was improved or remained within one line of the preoperative visual acuity in 90 eyes (87.4%). Complications occurred in 74 eyes (71.8%). A significant portion of these complications (45%) was transient, resolving without any intervention. Only 8% were serious sight-threatening complications. The most common complications included shallow anterior chamber or hypotony (32%), choroidal effusion or hemorrhage (20.4%), corneal decompensation or edema (17.5%), hyphema (14.1%), and tube obstruction (12.6%).The Baerveldt implant is effective in lowering the IOP in patients with intractable glaucomas. Hypotony and other complications are common, which also have been reported in other nonvalved glaucoma drainage implants. However, the majority of these complications did not affect surgical outcome.

Purpose: To determine pressure-flow characteristics at physiologic flow rates in vitro and in vivo in rabbits for Ahmed, Baerveldt, Krupin disk, and OptiMed glaucoma implants. The Molteno dual-chamber implant also was evaluated in vivo only. Methods: Five samples of each glaucoma implant were studied. Baerveldt implants were ligated partially for in vitro testing. Opening and closing pressures in air or after immersion in balanced salt solution or plasma were evaluated for the valued devices (Ahmed and Krupin). Pressures were measured in vitro and in vivo in normal rabbits at flow rates preset at between 2 and 25 μl/minute after the tubes were connected to a closed manometric system. In vivo measurements were made 24 hours after implantation. Resistance to flow was calculated using Poiseuille's equation after at least three separate flow rate readings. Results: In air, the Ahmed and Krupin valves had opening pressures of 9.2 ± 3.4 and 7.2 ± 0.6 mmHg and closing pressures of 5.2 ± 0.9 and 3.9 ± 1 mmHg, respectively. Neither opening nor closing pressures could be determined when Ahmed and Krupin valves were immersed. In vitro, the Ahmed and OptiMed devices had higher pressures than did other devices at a 2-μl/minute flow rate of balanced salt solution. During perfusion with plasma, only the OptiMed device maintained higher pressures than with balanced salt. With all devices, pressures fell rapidly to zero after flow was stopped. The OptiMed device demonstrated the highest resistance values. In vivo, the Ahmed device provided pressures of 7.5 ± 0.8 mmHg and the OptiMed device gave pressures of 19.6 ± 5.6 mmHg at a 2,ul ~mnnute flow rate. After 15 minutes of flow shutdown, the OptiMed implant maintained pressures of 7.1 ± 1.1 mmHg. The Baerveldt (nonligatured), Krupin, and Molteno dualchamber implants had similar resistances and pressures in vivo. Pressures with all devices in vivo fell rapidly to zero after conjunctival wound disruption. Conclusion: Neither the Ahmed nor Krupin devices had demonstrable opening or closing pressures when tested in vitro immersed in balanced salt solution or plasma. With all devices, pressures were higher in vivo than in vitro due to tissue-induced resistance around the explant. Both Ahmed and Krupin valves functioned as flow-restricting devices at the flow rates studied, but did not close after initial perfusion with fluid.

Optical coherence tomography (OCT) has transformed macular disease practices. This report describes the use of conventional OCT systems for peripheral retinal imaging. Thirty-six eyes with peripheral retinal pathology underwent imaging with conventional OCT systems. In vivo sectional imaging of lattice degeneration, snail-track degeneration, and paving-stone degeneration was performed. Differences were noted between phenotypes of lattice degeneration. Several findings previously unreported in histopathology studies were encountered. Certain anatomic features were seen that could conceivably explain clinical and intraoperative behavior of peripheral lesions. Peripheral OCT imaging helped elucidate clinically ambiguous situations such as retinal breaks, subclinical retinal detachment, retinoschisis, choroidal nevus, and metastasis. Limitations of such scanning included end-gaze nystagmus and far peripheral lesions. This first of its kind study demonstrates the feasibility of peripheral retinal OCT imaging and expands the spectrum of indications for which OCT scanning may be clinically useful.

We report on the significant improvement of central macular thickness in a case of clinically significant macular edema after dexamethasone 0.7 mg sustained-release intravitreal implant (Ozurdex®; Allergan, Inc, Irvine, CA, USA). Patient presented to us with persistent clinically significant macular edema (CSME) in both eyes. Right eye received dexamethasone implant and left eye received two intravitreal bevacizumab injections 1.25 mg/0.05 mL (Avastin®; Genentech Inc., South San Francisco, CA, USA) with an interval of four weeks. After six weeks of follow-up, dexamethasone implant in the right eye showed normal macular thickness whereas persistent macular edema (ME) was found even after second intravitreal bevacizumab injection in the left eye.

Glaucoma drainage implants provide a useful option in the management of complicated glaucomas for which the risk of failure of conventional filtering surgery is high. The basic design of these devices is similar; a silicone tube shunts aqueous humor from the anterior chamber to a fibrous capsule surrounding a synthetic plate or band positioned at the equatorial region of the globe. The capsule serves as a reservoir for aqueous drainage. Drainage implants have been used in the treatment of various refractory glaucomas, including those associated with aphakia and pseudophakia, prior unsuccessful filtering surgery, anterior segment neovascularization, trauma, youth, uveitis, epithelial downgrowth, iridocorneal endothelial syndrome, vitreoretinal disorders, and penetrating keratoplasty. Modifications in implant design and surgical technique have been developed to limit the occurrence of postoperative complications such as hypotony and its related sequelae, and strabismus.