Treatment outcomes in the Tube Versus Trabeculectomy (TVT) study after five years of follow-up

Ophthalmic viscoelastic device injection for the treatment of flat anterior chamber after trabeculectomy: a case series study

Purpose

Flat anterior chamber (FAC) in association with overfiltration is a complication after trabeculectomy. The aim of the current study was to investigate the efficacy of injection of an ophthalmic viscoelastic device (OVD) to treat FAC after trabeculectomy in a retrospective consecutive case series study.

Materials and methods

Twenty-five consecutive patients who underwent injection of OVD for the treatment of FAC after trabeculectomy were analyzed. The primary outcome variable was the qualified success of trabeculectomy, which was defined at three different levels by the achievement of one of three IOP-related criteria with or without glaucoma medication. Kaplan–Meier plots were generated to estimate survival functions for trabeculectomy with OVD injection.

Results

Twenty-one patients (21/25 = 84.0%) recovered from FAC by one OVD injection. The postoperative intraocular pressure (IOP) measured at 12 months, 24 months, 36 months, 48 months, and 60 months was 14.7 ± 3.6 mmHg, 15.6 ± 7.0 mmHg, 14.2 ± 2.8 mmHg, 14.2 ± 3.8 mmHg, and 14.6 ± 2.7 mmHg, respectively. All postoperative IOP measurements were significantly lower than the preoperative IOP (P < 0.001). The probabilities of qualified success for 5 years after trabeculectomy with OVD injection were as follows: 24.4% (IOP ≦ 21 mmHg and ≧20% reduction of preoperative IOP), 16.5% (IOP ≦ 16 mmHg and ≧20% reduction) and 6.3% (IOP ≦ 12 mmHg and ≧30% reduction). One patient, who had undergone deep lamellar keratoplasty, experienced a complication associated with the injection of the viscoelastic material, Descemet’s membrane detachment.

Conclusion

Injection of OVD may be effective for the treatment of FAC; however, the long-term success rate was relatively low.

[Tube versus trabeculectomy study]

Epibulbar glaucoma drainage devices have been only slightly modified since their introduction more than 40 years ago. Having been used primarily in only difficult cases with a poor prognosis (and therefore with poor clinical results) the recently published trabeculectomy versus tube study (TVT) led to a change in our understanding of these devices. In this study epibulbar glaucoma drainage devices (here the Baerveldt device) were employed for early implantation (in some cases as primary glaucoma surgery intervention). Being sceptically monitored the results over the first 5 year clearly showed an almost equal or even better outcome in comparison to trabeculectomy. Despite these good results a critical evaluation seems mandatory mainly because of the unsolved problems concerning late complications. Late tube erosion with subsequent blebitis and enophthalmitis as well as late base plate encapsulation need to be mentioned here. The latter leads to thick fibrous tissue around the base plate resulting in an increase of intraocular pressure (IOP). Late corneal decompensation is also a late complication the pathomechanism of which is only poorly understood. Solving and treating such late complications are often troublesome and time consuming. Future experiments should lead to development of new drainage implant designs and the bulk material should be enhanced and optimized to increase clinical surgical results.

[Clinical results of encapsulated bleb removal after Ahmed glaucoma valve implants]

In refractory glaucoma, surgical intervention is required which in most cases aims at artificially increasing the drainage of aqueous humor from the eye. One surgical option used with increasing frequency is the implantation of episcleral glaucoma drainage devices (GDD). The clinical success of such devices is often limited by excessive wound healing and scar formation around the base plate of the implant. In severe cases, which seem to occur most frequently in pediatric patients, the rapid formation of a thick, water-impervious fibrotic capsule within months after initial implantation leads to diminished aqueous resorption and an increase in intraocular pressure to presurgical values. Often additional surgical interventions become necessary. Excision of the fibrotic tissue around the implant may help to salvage function and might be an alternative to the more commonly practiced implantation of an additional GDD. In the case series presented here the surgical method of capsular revision is described and the clinical outcome in 11 eyes from 10 patients is reported.

[Pathophysiology of fibrotic encapsulation of episcleral glaucoma drainage implants: modification for improvement of clinical results]

Episcleral glaucoma drainage implants (GDI) are being used increasingly more as a surgical option for lowering intraocular pressure (IOP). One of the main reasons for failure to control IOP is the formation of water-impervious fibrotic tissue around the base plate of GDIs that prevents effective resorption of the drained aqueous humor and thus leads to an increase in IOP. Surgical removal of the fibrotic tissue can often rescue implant function; however, repeated encapsulation can often not be prevented and necessitates additional interventions up to the removal of the implant itself. The reasons for the fibrotic reaction are not fully understood. Apart from patient-dependent mechanisms that are also involved in bleb scarring after trabeculectomy, implant properties, such as size, shape, surface properties and biomaterial probably contribute to the encapsulation process. Based on the literature on this topic this article looks at possible ways of improving the design of currently used drainage implants including the potential use of GDIs as a carrier for antifibrotic medication released at low doses over an extended period of time.

A novel implantable glaucoma valve using ferrofluid

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.

The Ahmed versus Baerveldt study: three-year treatment outcomes

OBJECTIVE

To compare 2 commonly used aqueous drainage devices for the treatment of refractory glaucoma.

DESIGN

International, multicenter, randomized trial.

PARTICIPANTS

Patients aged 18 years or older with uncontrolled or high-risk glaucoma refractory to maximum medical therapy, many of whom had failed trabeculoplasty and trabeculectomy.

METHODS

Eligible patients were randomized to an Ahmed-FP7 valve implant (New World Medical, Inc., Rancho Cucamonga, CA) or a Baerveldt-350 implant (Abbott Medical Optics, Inc., Santa Ana, CA) using a standardized surgical technique.

MAIN OUTCOME MEASURES

The primary outcome was failure, defined as intraocular pressure (IOP) outside of the target range (5-18 mmHg, with ≥20% reduction from baseline) for 2 consecutive visits after 3 months, vision-threatening complications, de novo glaucoma procedures, or loss of light perception. Secondary outcome measures include IOP, medication use, visual acuity, complications, and interventions.

RESULTS

A total of 238 patients were enrolled and randomized; 124 received the Ahmed implant and 114 received the Baerveldt implant. Baseline characteristics were similar in both groups. Half the study group had secondary glaucoma, and 37% had previously failed trabeculectomy. The mean preoperative IOP was 31.4±10.8 mmHg on 3.1±1.0 glaucoma medications. Median baseline Snellen visual acuity was 20/100. At 3 years, the cumulative probability of failure was 51% in the Ahmed group and 34% in the Baerveldt group (P = 0.03). Mean IOP was 15.7±4.8 mmHg in the Ahmed group (49% reduction) and 14.4±5.1 mmHg in the Baerveldt group (55% reduction; P = 0.09). Mean number of glaucoma medications was 1.8±1.4 in the Ahmed group (42% reduction) and 1.1±1.3 in the Baerveldt group (65% reduction; P = 0.002). There was a moderate but similar decrease in visual acuity in both groups (P< 0.001). The 2 groups had similar complication rates (52% Ahmed, 62% Baerveldt; P = 0.12); however, the Baerveldt group had a higher rate of hypotony-related vision-threatening complications (0% Ahmed, 6% Baerveldt; P = 0.005). More interventions were required in the Baerveldt group, although the difference did not reach statistical significance (38% Ahmed, 50% Baerveldt; P = 0.07). Most complications were transient, and most interventions were slit-lamp procedures.

CONCLUSIONS

Both devices were effective in reducing IOP and glaucoma medications. The Baerveldt group had a lower failure rate and required fewer medications than the Ahmed group after 3 years, but it experienced more hypotony-related vision-threatening complications.

Previous cyclodestruction is a risk factor for late-onset hypotony and suprachoroidal haemorrhage after glaucoma drainage device surgery

AIM

To investigate whether previous cyclodestructive (eg, cyclophotocoagulation and cyclocryodestruction) procedures have any influence on the general outcome and pressure level after glaucoma drainage device (GDD) surgery.

METHODS

Retrospective analysis of 110 consecutive patients who had undergone GDD (Baerveldt 250 mm(2) and 350 mm(2) implant, AMO, USA) surgery with a minimum follow-up of 3 months. The patients were divided into patients with previous cyclodestructive surgery before GDD surgery (I; 47 patients) and patients without previous cyclodestructive surgery (II; 63 patients). Intraocular pressure (IOP), medication score, best-corrected visual acuity and surgical treatments were recorded before and after drainage device implantation.

RESULTS

Patients of group I had a mean preoperative IOP of 32.1 mm Hg and a mean medication score of 4.8; patients of group II had a mean preoperative IOP of 29.2 mm Hg (p=0.18) and a mean medication score of 4.9 (p=0.84). All patients who developed suprachoroidal haemorrhage (six cases) belonged to group I (6/47=12.8%), no patient of group II (0/63=0%) developed suprachoroidal haemorrhage (Fisher's test: p=0.01). Twelve patients developed late-onset (>6 weeks after GDD surgery) hypotony, nine of them belonging to group I (9/47=19.1%) and three of them to group II (3/63=4.8%) (Fisher's test: p=0.03).

CONCLUSIONS

While taking potential bias arising from the retrospective nature of the study into consideration, a history of previous cyclodestructive procedures before GDD surgery seems to be a major risk factor for suprachoroidal haemorrhage and for late-onset postoperative hypotony.

Outcomes of using a sutureless bovine pericardial patch graft for Ahmed glaucoma valve implantation

OBJECTIVE

To evaluate the long-term outcomes of a surgical technique using a sutureless bovine pericardial patch graft for the implantation of an Ahmed glaucoma valve (AGV). 


METHODS

This was a pilot study on patients with primary open-angle glaucoma refractory to repeated surgical filtering procedures. All patients underwent AGV implant technique using a sutureless bovine pericardial patch graft. The pericardial membrane was cut using an ordinary corneal trephine with a diameter of 9.0 or 10.0 mm. The anterior part of the tube was covered with the graft and kept in place with fibrin glue. Subsequently, the cap was stitched all around the tube and the dissected conjunctiva was laid over it. Intraocular pressure (IOP) and complications were evaluated 1 week and 1, 3, 6, 12, and 24 months after surgery.


RESULTS

The procedure was used to treat 20 eyes of 20 consecutive patients (12 men and 8 women: mean age [SD] 64.8 [7.8] years). Mean IOP was 28.1 mm Hg (SD 4.9) at baseline and decreased to 14.9 mm Hg (SD 1.5) 24 months after surgery (p<0.001). The overall mean number of topical medications was 3.1 (SD 0.5) at baseline and decreased to 1.4 (SD 0.8) after 24 months (p<0.001). During follow-up, there was no conjunctival erosion, thinning of pericardial patch graft over the tube, or tube exposure; no signs of endophthalmitis were recorded.


CONCLUSIONS

The results suggest that the sutureless technique using a bovine pericardial graft patch is a safe and rapid procedure for AGV implantation.

Tube Exposure Repair

All across the world, glaucomatologists are adopting broader use of glaucoma drainage implants even as a primary surgical modality. To avoid tube exposure, which may predispose the eye to endophthalmitis, the implanted tube must be covered by a patch graft. However, these patch grafts also carry a high rate of progressive thinning and erosion, which is believed to result from the lack of cellular infiltration from the surrounding host conjunctival stroma and poor integration of these patch grafts to the host tissue. An ideal patch graft should offer good tensile strength, be suitable for tectonic support, and have biological activities to promote cellular infiltration by the surrounding host conjunctival stroma, thus reducing progressive allogeneic patch graft thinning/erosion. This review talks about various materials and modalities used for an exposed tube repair.

How to cite this article: Oana S, Vila J. Tube Exposure Repair. J Current Glau Prac 2012;6(3):139-142.

Current status of epibulbar anti-glaucoma drainage devices in glaucoma surgery

BACKGROUND

The term "glaucoma" covers a heterogeneous group of progressive optic neuropathies that are accompanied by characteristic visual-field defects. Primary open-angle glaucoma, the most common type, progresses insidiously and causes blindness if untreated. All current forms of treatment aim at lowering the intraocular pressure (IOP) in patients whose IOP is elevated. The implantation of anti-glaucoma drainage systems is one of the available options for surgical treatment.

METHODS

This review is based on pertinent literature retrieved by a selective search, including glaucoma treatment guidelines from Germany and abroad.

RESULTS

A paradigm shift is currently underway regarding the indications for the implantation of anti-glaucoma drainage systems. Trabeculectomy (a "fistulating" operation in which the aqueous humor is led out of the eye under the conjunctiva) is still considered the surgical gold standard, but drainage systems have been implanted with increasing frequency in recent years. Studies have shown that these systems are more likely to be beneficial the earlier they are implanted in the course of the patient's disease. Five-year follow-up data from the randomized, multicenter Tube Versus Trabeculectomy (TVT) study have now revealed that anti-glaucoma drainage systems are equivalent to trabeculectomy with respect to long-term IOP reduction, complication rates, and absolute and relative clinical success rates.

CONCLUSION

Glaucoma is a major clinical and socio-economic problem whose surgical treatment increasingly involves the implantation of anti-glaucoma drainage systems.

Medical versus surgical interventions for open angle glaucoma

BACKGROUND

Open angle glaucoma (OAG) is a common cause of blindness.

OBJECTIVES

To assess the effects of medication compared with initial surgery in adults with OAG.

SEARCH METHODS

We searched CENTRAL (which contains the Cochrane Eyes and Vision Group Trials Register) (The Cochrane Library 2012, Issue 7), Ovid MEDLINE, Ovid MEDLINE In-Process and Other Non-Indexed Citations, Ovid MEDLINE Daily, Ovid OLDMEDLINE (January 1946 to August 2012), EMBASE (January 1980 to August 2012), Latin American and Caribbean Literature on Health Sciences (LILACS) (January 1982 to August 2012), Biosciences Information Service (BIOSIS) (January 1969 to August 2012), Cumulative Index to Nursing and Allied Health Literature (CINAHL) (January 1937 to August 2012), OpenGrey (System for Information on Grey Literature in Europe) (www.opengrey.eu/), Zetoc, the metaRegister of Controlled Trials (mRCT) (www.controlled-trials.com) and the WHO International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en). We did not use any date or language restrictions in the electronic searches for trials. We last searched the electronic databases on 1 August 2012. The National Research Register (NRR) was last searched in 2007 after which the database was archived. We also checked the reference lists of articles and contacted researchers in the field.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) comparing medications with surgery in adults with OAG.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed trial quality and extracted data. We contacted study authors for missing information.

MAIN RESULTS

Four trials involving 888 participants with previously untreated OAG were included. Surgery was Scheie's procedure in one trial and trabeculectomy in three trials. In three trials, primary medication was usually pilocarpine, in one trial it was a beta-blocker.The most recent trial included participants with on average mild OAG. At five years, the risk of progressive visual field loss, based on a three unit change of a composite visual field score, was not significantly different according to initial medication or initial trabeculectomy (odds ratio (OR) 0.74, 95% confidence interval (CI) 0.54 to 1.01). In an analysis based on mean difference (MD) as a single index of visual field loss, the between treatment group difference in MD was -0.20 decibel (dB) (95% CI -1.31 to 0.91). For a subgroup with more severe glaucoma (MD -10 dB), findings from an exploratory analysis suggest that initial trabeculectomy was associated with marginally less visual field loss at five years than initial medication, (mean difference 0.74 dB (95% CI -0.00 to 1.48). Initial trabeculectomy was associated with lower average intraocular pressure (IOP) (mean difference 2.20 mmHg (95% CI 1.63 to 2.77) but more eye symptoms than medication (P = 0.0053). Beyond five years, visual acuity did not differ according to initial treatment (OR 1.48, 95% CI 0.58 to 3.81).From three trials in more severe OAG, there is some evidence that medication was associated with more progressive visual field loss and 3 to 8 mmHg less IOP lowering than surgery. In the longer-term (two trials) the risk of failure of the randomised treatment was greater with medication than trabeculectomy (OR 3.90, 95% CI 1.60 to 9.53; hazard ratio (HR) 7.27, 95% CI 2.23 to 25.71). Medications and surgery have evolved since these trials were undertaken.In three trials the risk of developing cataract was higher with trabeculectomy (OR 2.69, 95% CI 1.64 to 4.42). Evidence from one trial suggests that, beyond five years, the risk of needing cataract surgery did not differ according to initial treatment policy (OR 0.63, 95% CI 0.15 to 2.62).Methodological weaknesses were identified in all the trials.

AUTHORS' CONCLUSIONS

Primary surgery lowers IOP more than primary medication but is associated with more eye discomfort. One trial suggests that visual field restriction at five years is not significantly different whether initial treatment is medication or trabeculectomy. There is some evidence from two small trials in more severe OAG, that initial medication (pilocarpine, now rarely used as first line medication) is associated with more glaucoma progression than surgery. Beyond five years, there is no evidence of a difference in the need for cataract surgery according to initial treatment.The clinical and cost-effectiveness of contemporary medication (prostaglandin analogues, alpha2-agonists and topical carbonic anhydrase inhibitors) compared with primary surgery is not known.Further RCTs of current medical treatments compared with surgery are required, particularly for people with severe glaucoma and in black ethnic groups. Outcomes should include those reported by patients. Economic evaluations are required to inform treatment policy.

Postoperative complications in the Tube Versus Trabeculectomy (TVT) study during five years of follow-up

PURPOSE

To describe postoperative complications encountered in the Tube Versus Trabeculectomy (TVT) Study during 5 years of follow-up.

DESIGN

Multicenter randomized clinical trial.

METHODS

SETTINGS

Seventeen clinical centers.

STUDY POPULATION

Patients 18 to 85 years of age who had previous trabeculectomy and/or cataract extraction with intraocular lens implantation and uncontrolled glaucoma with intraocular pressure (IOP) ≥18 mm Hg and ≤40 mm Hg on maximum tolerated medical therapy.

INTERVENTIONS

Tube shunt (350-mm(2) Baerveldt glaucoma implant) or trabeculectomy with mitomycin C (MMC 0.4 mg/mL for 4 minutes).

MAIN OUTCOME MEASURES

Surgical complications, reoperations for complications, visual acuity, and cataract progression.

RESULTS

Early postoperative complications occurred in 22 patients (21%) in the tube group and 39 patients (37%) in the trabeculectomy group (P = .012). Late postoperative complications developed in 36 patients (34%) in the tube group and 38 patients (36%) in the trabeculectomy group during 5 years of follow-up (P = .81). The rate of reoperation for complications was 22% in the tube group and 18% in the trabeculectomy group (P = .29). Cataract extraction was performed in 13 phakic eyes (54%) in the tube group and 9 phakic eyes (43%) in the trabeculectomy group (P = .43).

CONCLUSIONS

A large number of surgical complications were observed in the TVT Study, but most were transient and self-limited. The incidence of early postoperative complications was higher following trabeculectomy with MMC than tube shunt surgery. The rates of late postoperative complications, reoperation for complications, and cataract extraction were similar with both surgical procedures after 5 years of follow-up.