The effect of adjunctive mitomycin C in Molteno implant surgery

Wound Modulations in Glaucoma Surgery: A Systematic Review

Excessive fibrosis and resultant poor control of intraocular pressure (IOP) reduce the efficacy of glaucoma surgeries. Historically, corticosteroids and anti-fibrotic agents, such as mitomycin C (MMC) and 5-fluorouracil (5-FU), have been used to mitigate post-surgical fibrosis, but these have unpredictable outcomes. Therefore, there is a need to develop novel treatments which provide increased effectiveness and specificity. This review aims to provide insight into the pathophysiology behind wound healing in glaucoma surgery, as well as the current and promising future wound healing agents that are less toxic and may provide better IOP control.

Baerveldt Aqueous Shunt with or without Mitomycin C Augmentation: A Retrospective Comparison Study

OBJECTIVE

To evaluate if intraoperative mitomycin C (MMC) influences the success of Baerveldt aqueous shunts.

DESIGN

Retrospective comparative case series.

PARTICIPANTS

The study population consisted of 88 patients. Fifty-five received intraoperative MMC and 33 did not (controls).

METHODS

The medical records of consecutive patients who underwent standalone Baerveldt aqueous shunts at Birmingham Midland Eye Centre, United Kingdom, were retrospectively reviewed. Patients in the MMC group received 0.2 to 0.4 mg/mL of MMC intraoperatively whereas controls did not.

MAIN OUTCOME MEASURES

Primary outcome was survival, which was defined as an intraocular pressure (IOP) > 6 mmHg and ≤ 21 mmHg or ≤ 18 mmHg and > 20% IOP reduction from baseline. Further analysis of patients who required medications (qualified) or no medications (complete) was undertaken. Secondary outcomes were IOP, number of glaucoma medications, complications, intraluminal ripcord removal (IRR), and interventions.

RESULTS

Average follow-up was 4.7 ± 1.4 years. At year 5, complete success with the ≤ 21 mmHg threshold was significantly higher in MMC vs controls (39.3% vs 17.8%; log rank P = 0.016). Final complete success with the ≤ 18 mmHg threshold was higher in patients with MMC shunts vs controls (38% vs 15.6%; log rank P = 0.0042). Qualified success was not different between patients with MMC shunts and controls with ≤ 21 mmHg (82% vs 93%; log rank P = 0.29) and ≤ 18 mmHg thresholds (70.3% vs 79.3%; log rank P = 0.44). Uveitic patients were also more likely to achieve complete success at both 21 and 18 mmHg thresholds among the patients receiving MMC compared with controls. Mitomycin C was correlated with lower number of medications between month 3 and year 2 post operatively (P < 0.001) and with a lower rate of IRR at all timepoints (P < 0.001). There were no significant differences in the incidence of prolonged hypotony, although MMC cases had higher transient hypotony at year 1 (P = 0.049).

CONCLUSIONS

Mitomycin C provides a significant advantage in Baerveldt aqueous shunt survival when considering medication-free success but not in qualified success. Control patients required more medications to control IOP. This study suggests that intraoperative MMC augmentation of Baerveldt aqueous shunt surgery may be advantageous in achieving IOP control without the need for medication but that it may be associated with more transient hypotony episodes.

FINANCIAL DISCLOSURE(S)

The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Aqueous shunts with mitomycin C versus aqueous shunts alone for glaucoma

BACKGROUND

Glaucoma affects more than 70 million people worldwide, with about 10% being bilaterally blind, making it the leading cause of irreversible blindness globally. In patients with advanced glaucoma or those who have failed medical treatment without achieving adequate intraocular pressure (IOP) control, trabeculectomy (glaucoma filtration surgery where an ostium is created into the anterior chamber from underneath a partial thickness scleral flap to allow for aqueous flow out of the anterior chamber intointo the subconjunctival space forming a filtering bleb) and aqueous shunt surgery for more complex and refractory cases remain the mainstay therapies. Proliferation of fibrous tissue around an implanted aqueous shunt may block the diffusion of aqueous humour. Mitomycin C (MMC) is one of two commonly used adjunct antifibrotic agents used during aqueous shunt surgery to prevent proliferation of fibrous tissue. However, the effectiveness and safety of the use of intraoperative MMC during aqueous shunt surgery has not been established.

OBJECTIVES

To evaluate the effectiveness and safety of MMC versus no MMC used during aqueous shunt surgery for reducing IOP in primary and secondary glaucoma.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (which contains the Cochrane Eyes and Vision Trials Register) (2018, Issue 2); Ovid MEDLINE; Embase.com; PubMed; Latin American and Caribbean Health Sciences Literature Database (LILACS); ClinicalTrials.gov and the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP). We did not use any date or language restrictions in the electronic search for trials. We last searched the electronic databases on 13 February 2018.

SELECTION CRITERIA

We included randomized controlled trials (RCTs) in which one group of participants received MMC during aqueous shunt surgery and another group did not. We did not exclude studies based on outcomes.

DATA COLLECTION AND ANALYSIS

Two review authors independently reviewed titles and abstracts from the literature searches. We obtained full-text reports of potentially relevant studies and assessed them for inclusion. Two review authors independently extracted data related to study characteristics, risk of bias, and outcomes. We used standard methodological procedures expected by Cochrane.

MAIN RESULTS

We included five RCTs, with a total of 333 eyes with glaucoma randomized, and identified two ongoing trials. All included trials examined the effect of MMC versus no MMC when used during aqueous shunt surgery for glaucoma. The trials included participants with different types of uncontrolled glaucoma. One study was conducted in China, one in Saudi Arabia, two in the USA, and one study was a multicenter study conducted in Brazil, Canada, Scotland, and USA. We assessed all trials as having overall unclear risk of bias due to incomplete reporting of study methods and outcomes; two of the five trials were reported only as conference abstracts.None of the included trials reported mean decrease from baseline in IOP; however, all five trials reported mean IOP at 12 months post-surgery. At 12 months, the effect of MMC on mean IOP compared with no MMC was unclear based on a meta-analysis of trials (mean difference -0.12 mmHg, 95% CI -2.16 to 2.41; low-certainty evidence). Two trial did not report sufficient information to include in meta-analysis, but reported that mean IOP was lower in the MMC group compared with the no MMC group at 12 months.None of the included trials reported mean change from baseline in visual acuity; however, one trial reported lower mean LogMAR values (better vision) in the MMC group than in the no MMC group at 12 months post-surgery. None of the included studies reported the proportion of participants with stable best-corrected visual acuity. Three trials reported that loss of vision was not significantly different between groups (no data available for meta-analysis).None of the included studies reported the proportion of participants with a postoperative hypertensive phase, which is defined as IOP > 21 mmHg within 3 months after surgery. Two trials reported adverse events (choroidal effusion, corneal edema, flat anterior chamber, and retinal detachment); however, due to small numbers of events and sample sizes, no clear difference between MMC and placebo groups was observed.

AUTHORS' CONCLUSIONS

We found insufficient evidence in this review to suggest MMC provides any postoperative benefit for glaucoma patients who undergo aqueous shunt surgery. Data across all five included trials were sparse and the reporting of study methods required to assess bias was inadequate. Future RCTs of this intervention should report methods in sufficient detail to permit assessment of potential bias and estimate target sample sizes based on clinically meaningful effect sizes.

Incidence of Conjunctival Exposure following Drainage Device Implantation in Patients with Glaucoma

Purpose

To evaluate prior studies including a glaucoma drainage device and to describe the timing and incidence of conjunctival exposure. A meta-analysis of previously published articles.

Methods

Articles included were prospective, single cohort, or comparative parallel design, with a mean treatment period of at least 3 months and at least 30 patients per treatment arm. We limited our analysis to studies that evaluated the most common devices, including Ahmed, Baerveldt, and Molteno.

Results

We included 38 studies containing 45 treatment arms (16 Ahmed, 12 Baerveldt, and 17 Molteno). These studies included 3,105 patients and 3,255 eyes with an average follow-up of 26.1±3.3 months. The overall incidence of exposure was 2.0±2.6% (n=64) of eyes with an average exposure/month of 0.09±0.14%. There was no significant correlation between study length and incidence of exposure (p=0.11), although multivariate regression analysis identified length of follow-up as a risk factor for exposure (p=0.001). Among individual drainage devices, there was no significant difference in the incidence of exposure (p=0.22) or percent exposure per month (p=0.18). In addition, no difference existed in the incidence of exposure between sizes for the Baerveldt 250, 350 or 500 mm (p=0.7), number of plates for the Molteno Single or Double (p=0.3), nor between the composition of the Ahmed Silicone or Polypropylene (p=0.7).

Conclusions

This study suggests that tube exposure of glaucoma implants is unusual and the incidence does not differ between the Ahmed, Baerveldt, and Molteno implants. However, exposure appears to occur at any time within the first 5 years following implantation.

Adjunctive Mitomycin C or Amniotic Membrane Transplantation for Ahmed Glaucoma Valve Implantation: A Randomized Clinical Trial

PURPOSE

To determine whether adjunctive mitomycin C (MMC) or amniotic membrane transplantation (AMT) improve the outcomes of Ahmed glaucoma valve (AGV) implantation.

METHODS

This double-blind, stratified, 3-armed randomized clinical trial includes 75 eyes of 75 patients aged 7 to 75 years with refractory glaucoma. Eligible subjects underwent stratified block randomization; eyes were first stratified to surgery in the superior or inferior quadrants based on feasibility; in each subgroup, eyes were randomly assigned to the study arms using random blocks: conventional AGV implantation (group A, 25 eyes), AGV with MMC (group B, 25 eyes), and AGV with AMT (group C, 25 eyes).

RESULTS

The 3 study groups were comparable regarding baseline characteristics and mean follow-up (P=0.288). A total of 68 patients including 23 eyes in group A, 25 eyes in group B, and 20 eyes group C completed the follow-up period and were analyzed. Intraocular pressure was lower in the MMC group only 3 weeks postoperatively (P=0.04) but comparable at other time intervals. Overall success rate was comparable in the 3 groups at 12 months (P=0.217). The number of eyes requiring medications (P=0.30), time to initiation of medications (P=0.13), and number of medications (P=0.22) were comparable. Hypertensive phase was slightly but insignificantly more common with standard surgery (82%) as compared with MMC-augmented (60%) and AMT-augmented (70%) procedures (P=0.23). Complications were comparable over 1 year (P=0.28).

CONCLUSIONS

Although adjunctive MMC and AMT were safe during AGV implantation, they did not influence success rates or intraocular pressure outcomes. Complications, including hypertensive phase, were also comparable.

Pirfenidone inhibits fibrosis in foreign body reaction after glaucoma drainage device implantation

Background

The aim of this study was to investigate the antiscarring effects of pirfenidone on foreign body reaction in a rabbit model of glaucoma drainage implant surgery.

Methods

Adult New Zealand White rabbits had glaucoma drainage device implantation using Model FP8 Ahmed glaucoma valves. One eye was randomly assigned to receive postoperative intrableb injection of pirfenidone followed by topical treatment. The other eye underwent the same procedure but without the addition of pirfenidone. Histochemical staining and immunohistochemistry for blebs were performed.

Results

The degree of cellularity was smaller in the pirfenidone group than in the control group at 2 weeks post operation (P=0.005). A few foreign body giant cells were detected in the inner border of the capsule, and their numbers were similar in the control and pirfenidone groups (P>0.05). Using Masson’s trichrome stain, the inner collagen-rich layer was found to be thinner in the pirfenidone group than the control group at 4 weeks (P=0.031) and 8 weeks (P=0.022) post operation. The percentage of proliferating cell nuclear antigen-positive cells was lower in the pirfenidone group than in the control group at 2 weeks post operation (total bleb, P=0.022; inner bleb, P=0.036). Pirfenidone treatment decreased the immunoreactivity of connective tissue growth factor at 2 weeks post operation (total bleb, P=0.029; inner bleb, P=0.018). The height and area of α-smooth muscle actin expression were lower in the pirfenidone group than the control group at 2 weeks, 4 weeks, and 8 weeks post operation (all P<0.05).

Conclusion

Postoperative intrableb injection of pirfenidone followed by topical administration reduced fibrosis following glaucoma drainage device implantation. These findings suggest that pirfenidone may function as an antiscarring treatment in foreign body reaction after tube-shunt surgery.

A review of the efficacy of mitomycin C in glaucoma filtration surgery

The success of trabeculectomy, which is considered the gold standard in the surgical treatment of glaucoma, depends on the wound healing response. The introduction of antiproliferative agents such as mitomycin C (MMC) has increased the success rates of trabeculectomy. However, complications due to these agents can be challenging to manage. Hence, it is important to determine the most efficacious dose and duration of exposure. Multiple studies suggest that many factors, including but not limited to MMC preparation, different concentrations, different exposure times, and method of application may affect success rate, and these factors were reviewed in this article. We concluded that lower concentrations of MMC that are prepared and applied in a standardized fashion, such as that using the Mitosol(®) kit (for 2-3 minutes) during trabeculectomy, could potentially provide trabeculectomy success rates similar to that reported with off-label preparations, and that such a treatment regime could result in in lower complication rates than higher doses of MMC.

Uveitis and glaucoma: new insights in the pathogenesis and treatment

Glaucoma is a potentially blinding complication of uveitis, where intraocular inflammation, secondary corticosteroid response, and varying types and degrees of angle abnormalities contribute to its pathogenesis. Management of uveitic glaucoma remains challenging. Treatment is targeted at reducing the inflammation and lowering the intraocular pressure. Recent studies have highlighted the role of viruses, such as cytomegalovirus, herpes simplex virus, and more recently Ebola virus, in the pathogenesis of uveitic glaucoma. Antiviral therapy may be beneficial in eyes with detectable viral DNA. The success of glaucoma surgery is decreased in eyes with uveitic glaucoma, and surgical interventions are associated with a higher incidence of postoperative complications. Novel glaucoma surgical and laser treatments may improve the predictability of surgery for uveitic glaucoma, but these require further evaluation.

Pediatric Glaucoma: A Literature's Review and Analysis of Surgical Results

The purpose of this paper is to review the surgical options available for the management of pediatric glaucoma, to evaluate their advantages and disadvantages together with their long-term efficacy, all with the intent to give guidelines to physicians on which elements are to be considered when taking a surgical decision. Currently there is a range of surgical procedures that are being used for the management of pediatric glaucoma. Within these, some are completely new approaches, while others are improvements of the more traditional procedures. Throughout this vast range of surgical options, angle surgery remains the first choice in mild cases and both goniotomy and trabeculotomy have good success rates. Trabeculectomy with or without mitomycin C (MMC) is preferred in refractory cases, in aphakic eyes, and in older children. GDIs have a good success rate in aphakic eyes. Nonpenetrating deep sclerectomy is still rarely used; nevertheless the results of ongoing studies are encouraging. The different clinical situations should always be weighed against the risks associated with the procedures for the individual patients. Glaucomatous progression can occur many years after its stabilization and at any time during the follow-up period; for this reason life-long assessment is necessary.

Time Heals All Wounds: Obstacles in Glaucoma Surgery from an Asian Perspective

Glaucoma is the leading cause of irreversible blindness worldwide and is a particular burden on the Asian population. Glaucoma surgeries such as trabeculectomy and glaucoma drainage implants are routinely performed to lower intraocular pressure (IOP) to prevent disease progression. However, scarring of the filtering bleb limits their long-term success and Asian eyes are more at risk. Although this is so, many existing studies have been done on Caucasian patients, but few have focused solely on Asian patients. Intraoperative anti-metabolites such as Mitomycin-C (MMC) and 5-Fluorouracil (5-FU) are the current mainstay of adjunctive treatments to reduce scarring, and in this review, we evaluate the evolution, benefits and side effects of these agents. Recently, newer methods of wound modulation including anti-vascular endothelial growth factor (VEGF) agents and collagen implants are also being investigated as part of a multi-pronged approach to tackle this problem. Some opportunities exist to limit scarring post-operatively, but it is an ongoing battle.

Use of Mitomycin C to reduce the incidence of encapsulated cysts following ahmed glaucoma valve implantation in refractory glaucoma patients: a new technique

Background

To evaluate the surgical outcome of Ahmed glaucoma valve (AGV) implantation with a new technique of mitomycin C (MMC) application.

Methods

This is a retrospective study. All patients with refractory glaucoma underwent FP-7 AGV implantation. Two methods of MMC application were used. In the traditional technique, 6 × 4 mm cotton soaked with MMC (0.25–0.33 mg/ml) was placed in the implantation area for 2–5mins; in the new technique, the valve plate first was encompassed with a thin layer of cotton soaked with MMC, then inserted into the same area. A 200 ml balanced salt solution was applied for irrigation of MMC. The surgical success rate, intraocular pressure (IOP), number of anti-glaucoma medications used, and postoperative complications were analyzed between the groups.

Results

The surgical outcomes of two MMC applied techniques were compared. The new technique group had only one case (2.6%) of encapsulated cyst formation out of 38 eyes, while there were eight (19.5%) cases out of 41 eyes the in traditional group. The difference was statistically significant (P = 0.030). According to the definition of success rate, there was 89.5% in the new technique group and 70.7% in the traditional group at the follow-up end point. There was a significant difference between the two groups (P = 0.035). Mean IOP in the new technique group were significantly lower than those of the traditional group at 3 and 6 months (P < 0.05).

Conclusions

By using a thin layer of cotton soaked with MMC to encompass the valve plate, the new MMC application technique could greatly decrease the incidence of encapsulated cyst and increase the success rate following AGV implantation.

Glaucoma drainage devices: state of the art

Glaucoma drainage devices (GDDs) create an alternate aqueous pathway by channeling aqueous from the anterior chamber through a long tube to an equatorial plate, inserted under the conjunctiva, which promotes bleb formation. GDDs are being used more frequently in the treatment of glaucoma, both as the primary procedure of choice and following failure of trabeculectomy operations. This article outlines the current concepts involving different GDDs, surgical techniques and a review of the current literature. In addition, the importance of the biomaterial and its implications for the success of the operation are discussed.

Current surgical options for the management of pediatric glaucoma

Currently, there are numerous choices for the treatment of pediatric glaucoma depending on the type of glaucoma, the age of the patient, and other particularities of the condition discussed in this review. Traditionally, goniotomy and trabeculotomy ab externo have been the preferred choices of treatment for congenital glaucoma, and a variety of adult procedures adapted to children have been utilized for other types of pediatric glaucoma with variable results and complications. More recently, seton implantations of different types have become more popular to use in children, and newer techniques have become available including visualized cannulation and opening of Schlemm's canal, deep sclerectomy, trabectome, and milder more directed cyclodestructive procedures such as endolaser and transcleral diode laser cyclophotocoagulation. This paper reviews the different surgical techniques currently available, their indications, results, and most common complications to allow the surgeon treating these conditions to make a more informed choice in each particular case. Although the outcome of surgical treatment in pediatric glaucoma has improved significantly, its treatment remains challenging.

Expanded polytetrafluoroethylene membrane alters tissue response to implanted Ahmed glaucoma valve

PURPOSE

Long-term intraocular pressure control by glaucoma drainage implants is compromised by the formation of an avascular fibrous capsule that surrounds the glaucoma implant and increases aqueous outflow resistance. It is possible to alter this fibrotic tissue reaction and produce a more vascularized and potentially more permeable capsule around implanted devices by enclosing them in a porous membrane.

METHODS

Ahmed glaucoma implants modified with an outer 5-microm pore size membrane (termed porous retrofitted implant with modified enclosure or PRIME-Ahmed) and unmodified glaucoma implants were implanted into paired rabbit eyes. After 6 weeks, the devices were explanted and subject to histological analysis.

RESULTS

A tissue response containing minimal vascularization, negligible immune response, and a thick fibrous capsule surrounded the unmodified Ahmed glaucoma implant. In comparison, the tissue response around the PRIME-Ahmed demonstrated a thinner fibrous capsule (46.4 +/- 10.8 microm for PRIME-Ahmed versus 94.9 +/- 21.2 microm for control, p < 0.001) and was highly vascularized near the tissue-material interface. A prominent chronic inflammatory response was noted as well.

CONCLUSIONS

Encapsulating the aqueous outflow pathway with a porous membrane produces a more vascular tissue response and thinner fibrous capsule compared with a standard glaucoma implant plate. Enhanced vascularity and a thinner fibrous capsule may reduce aqueous outflow resistance and improve long-term glaucoma implant performance.

Ahmed valve implantation with adjunctive mitomycin C and 5-fluorouracil: long-term outcomes

PURPOSE

To evaluate long-term outcomes after Ahmed valve implantation in patients with glaucoma when using adjunctive intraoperative mitomycin C (MMC) and postoperative 5-fluorouracil (5-FU).

DESIGN

Retrospective, interventional, consecutive case series.

METHODS

A consecutive series of eyes undergoing Ahmed valve implantation, either alone (AHMED eyes) or in combination with cataract surgery (AHMED+PHACO), using both intraoperative MMC and postoperative 5-FU were evaluated. Failure was defined as the first occurrence of any of the following: 1) the first of three consecutive visits where intraocular pressure (IOP) was >18 mm Hg or <20% IOP reduction from baseline and the final number of topical medications was not reduced by at least two from baseline, 2) the need for additional surgery, or 3) the development of serious complications.

RESULTS

A total of 130 eyes underwent Ahmed valve implantation with intraoperative exposure to 0.5 mg/ml MMC (median time: eight minutes; range, four to 10) and postoperative subconjunctival injections of 5 mg of 5-FU (median: five injections; range, zero to nine). Kaplan-Meier estimates of the cumulative probability of valve success and confidence interval (CI) at the sixth follow-up year were 0.72 (95% CI, 0.59 to 0.82) for AHMED eyes (n = 88), 0.84 (95% CI, 0.65 to 0.93) for AHMED+PHACO eyes (n = 42). A median of two fewer medications were required relative to baseline for both AHMED and AHMED+PHACO eyes.

CONCLUSIONS

The adjunctive use of both intraoperative MMC and postoperative 5-FU with Ahmed valve implantation results in high success rates. IOP was well controlled in the majority of patients within the six-year postoperative period.

Mitomycin: clinical applications in ophthalmic practice

Mitomycin (mitomycin C; MMC) is an antibiotic isolated from Streptomyces caespitosus. The drug is a bioreductive alkylating agent that undergoes metabolic reductive activation, and has various oxygen tension-dependent cytotoxic effects on cells, including the cross-linking of DNA. It is widely used systemically for the treatment of malignancies, and has gained popularity as topical adjunctive therapy in ocular and adnexal surgery over the past 2 decades. In ophthalmic medicine, it is principally used to inhibit the wound healing response and reduce scarring of surgically fashioned ostia. Hence, it has been used as adjunctive therapy in various ocular surgeries, such as glaucoma filtering surgeries, dacryocystorhinostomy, corneal refractive surgery and surgeries for ocular cicatrisation. In addition, it has been used as an adjunct in the surgical management of pterygia, ocular surface squamous neoplasia, primary acquired melanosis with atypia and conjunctival melanoma. In many of these surgeries and ophthalmic pathologies, MMC showed a significant beneficial effect.

The last 11 years of Molteno implantation at the University of Cape Town. Refining our indications and surgical technique

AIMS

To analyse outcomes, factors influencing surgical success, and surgical technique of Molteno implantation over the past 11 years in order to identify ways of improving long-term control.

METHODS

Retrospective interventional review of case records of all consecutive patients undergoing Molteno implantation at Groote Schuur Hospital between 1/1/1991 and 31/12/2002. Data were recorded on an MSAccess database and processed using Kaplan-Meier survival curves and life table analysis.

RESULTS

We analysed 162 consecutive single-phase Molteno tube implantation procedures on 157 eyes of 148 patients with mean follow-up of 2.9 years. Intraocular pressure (IOP) dropped from a mean of 43.3 at booking to 19.1 at final follow-up. Overall 'complete success' was achieved in 30% and 'partial success' in 16%. A high preoperative IOP was a significant predictor of a high postoperative pressure. Pseudophakic patients had significantly better postoperative pressure control. Neovascular glaucoma was a risk factor for poor pressure control. Race, gender, previous surgery, uveitis, and trauma did not influence surgical outcome. Follow-up adjusted incidence of 2.4 cases of endophthalmitis per patient year was unexpectedly high. Tubes that migrated had been secured with absorbable sutures in 4/5 cases.

CONCLUSIONS

In this study, high preoperative IOPs were probably a significant contributing factor to relatively poor postoperative pressure control. Addressing this issue may aid in improving outcomes in future surgery. The high postoperative pressure outcomes suggest that single plate Molteno implantation is not an ideal way of achieving low target pressure in third world glaucoma patients.

Aqueous shunts for glaucoma

BACKGROUND

Aqueous shunts are employed for intraocular pressure (IOP) control in primary and secondary glaucomas that fail medical, laser, and other surgical therapies.

OBJECTIVES

This review compares aqueous shunts for IOP control and safety.

SEARCH STRATEGY

We searched CENTRAL, MEDLINE, PubMed, EMBASE, NRR all in January 2006, LILACS to February 2004 and reference lists of included trials.

SELECTION CRITERIA

We included all randomized and quasi-randomized trials in which one arm of the study involved shunts.

DATA COLLECTION AND ANALYSIS

Two authors independently extracted data for included studies and a third adjudicated discrepancies. We contacted investigators for missing information. We used fixed-effect models and summarized continuous outcomes using mean differences.

MAIN RESULTS

We included fifteen trials with a total of 1153 participants with mixed diagnoses. Five studies reported details sufficient to verify the method of randomization but only two had adequate allocation concealment. Data collection and follow-up times were variable.Meta-analysis of two trials comparing Ahmed implant with trabeculectomy found trabeculectomy resulted in lower mean IOPs 11 to 13 months later (mean difference 3.81 mm Hg, 95% CI 1.94 to 5.69 mm Hg). Meta-analysis of two trials comparing double-plate Molteno implant with the Schocket shunt was not done due to substantial heterogeneity. One study comparing ridged with standard double-plate Molteno implants found no clinically significant differences in outcome. Two trials investigating the effectiveness of adjunctive mitomycin (MMC) with the Molteno and Ahmed implants found no evidence of benefit with MMC. Two trials that investigated surgical technique variations with the Ahmed found no benefit with partial tube ligation or excision of Tenon's capsule. One study concluded there were outcome advantages with a double versus a single-plate Molteno implant and one trial comparing the 350 mm(2) and 500 mm(2) Baerveldt shunts found no clinically significant advantage of the larger device but neither of these trials included all patients randomized. One study suggested improved clinical outcome when MMC was employed with a newly described shunt including ultrasound supporting the conclusion. One small study did not demonstrate an outcome advantage to systemic steroid use postoperatively with single-plate Molteno shunts. One study comparing endocyclophotocoagulation (ECP) with Ahmed implant in complicated glaucomas found no evidence of better IOP control with Ahmed implant over ECP.

AUTHORS' CONCLUSIONS

Relatively few randomized trials have been published on aqueous shunts and methodology and data quality among them is poor. To date there is no evidence of superiority of one shunt over another.

Glaucoma drainage devices: a systematic literature review and current controversies

Glaucoma drainage devices create alternate aqueous pathways by channeling aqueous from the anterior chamber through a long tube to an equatorial plate that promotes bleb formation. Glaucoma drainage devices are being used more frequently in the treatment of glaucoma that does not respond to medications or trabeculectomy operations. In certain conditions, such as neovascular glaucoma, iridio-corneal syndrome, penetrating keratoplasty with glaucoma, glaucoma following retinal detachment surgery, and so on, it is becoming the primary operation. This review provides a systematic review of the literature and outlines the current controversies involving different glaucoma drainage devices and their design, overall surgical success, and complications following glaucoma drainage device insertion.

Update on antifibrotic use in glaucoma surgery, including use in trabeculectomy and glaucoma drainage implants and combined cataract and glaucoma surgery

PURPOSE OF REVIEW

This paper summarizes the use of antifibrotic agents adjunctive to glaucoma surgery, reviews recently published studies that address current use of these antifibrotics, and reviews new methods of wound modulation.

RECENT FINDINGS

The use of antifibrotic agents, namely, 5-fluorouracil and mitomycin C, in conjunction with glaucoma surgery has resulted in lower postoperative intraocular pressures after trabeculectomy or combined cataract and glaucoma surgery. Mixed results have been seen when these agents are used with glaucoma drainage device surgery. The use of antifibrotic agents has also created and increased complications. Therefore, methods of antifibrotic use have become more refined and modified for specific circumstances. Promising new wound modulation agents, such as CAT-152, are currently under study.

SUMMARY

Antifibrotics are potent adjuncts to glaucoma surgery, but along with their beneficial use are risks that need to be considered. While we continue to look for more efficacious agents and methods to treat glaucoma, we must continue to modify techniques with the individual patient's best interest in mind.

Aqueous shunt devices compared with trabeculectomy with Mitomycin-C for children in the first two years of life

PURPOSE

To compare the outcomes of children 24 months of age or younger treated with aqueous shunt devices or with mitomycin-C (MMC) trabeculectomy.

DESIGN

Retrospective, age-matched, comparative case series.

METHODS

Forty-six eyes of 32 patients with mean age of 7.0 +/- 5.1 month (range, 1 to 22 months) and uncontrolled glaucoma, which received an aqueous shunt device (Ahmed glaucoma valve or Baerveldt implant), compared with 24 eyes of 19 patients with mean age of 5.3 +/- 4.8 months (range, 0.5 to 24 months), which received an MMC trabeculectomy. Surgical success was defined as intraocular pressure < 23 mm Hg on maximal glaucoma medication, no further glaucoma surgery performed or recommended, no devastating complication, and stable ocular dimensions (axial length and corneal diameter).

RESULTS

Cumulative probabilities of success were 87% +/- 5.0% for the aqueous shunt group compared with 36% +/- 8.0% success in the trabeculectomy group at 12 months and 53% +/- 12% in the aqueous shunt group compared with 19% +/- 7% in the trabeculectomy group at 72 months (chi(2) of 23.5, P <.0001). Aqueous shunt implantation was associated with significantly more postoperative complications requiring a return to the operating room (21 of 46 eyes, 45.7%) compared with trabeculectomy with MMC (3 of 24 eyes, 12.5%, P =.0074). The most common postoperative procedure in the aqueous shunt group was tube repositioning, performed in 16 of 46 eyes (34.8%).

CONCLUSIONS

Aqueous shunt implantation offers a significantly greater chance of successful glaucoma control in the first 2 years of life, compared with trabeculectomy with MMC. However, the enhanced success with aqueous shunt devices is associated with a higher likelihood of postoperative complications requiring surgical revision, most commonly tube repositioning.

Partial Tenon's capsule resection with adjunctive mitomycin C in Ahmed glaucoma valve implant surgery

AIM

To verify if partial intraoperative Tenon's capsule resection (PTCR) with adjunctive mitomycin C is effective in developing thin, avascular blebs in eyes undergoing Ahmed glaucoma valve insertion, and to assess the efficacy and safety of this procedure.

METHODS

A multicentre, prospective, alternating case assignment, investigator unmasked, parallel group, comparative interventional study was conducted in four Latin American countries (Argentina, Brazil, Colombia, and Peru). Ahmed glaucoma valve implant insertion with PTCR (group A) and without PCTR (group B) was performed in neovascular glaucomatous eyes without previous surgery. Adjunctive mitomycin C (MMC) was used in both groups. Patients were examined 1 day, 10 days, 1 month, 2 months, 3 months, 6 months, and 1 year following the surgery. Intraocular pressure (IOP) and the appearance of the bleb were evaluated at each examination. Appearance of the bleb was classified at both the 1 month mark and last examinations into one of three groups: flat and vascularised; elevated avascular; or elevated and not avascular.

RESULTS

92 eyes from 92 patients were included in the study. The preoperative mean IOP was 50.0 (SD 10.5) mm Hg in group A and 48.4 (11.7) in group B (p>0.05). Statistically significant IOP reductions were observed at all periods of follow up. 12 months after surgery, the mean IOP was 17.2 (5.0) mm Hg in group A and 18.3 (8.7) mm Hg in group B (p>0.05). A hypertensive phase occurred in 40.0% in group A and in 46.8% in group B (p>0.05). At the 1 month and the final follow up, the blebs in all eyes were considered elevated and not avascular. The success rate (IOP</=21 mm Hg) at 1 year after surgery was 70.4% in group A and 77.7% in group B (p>0.05). Overall, 74.2% of the patients achieved an IOP </=21 mm Hg and 55.2% an IOP</=17 mm Hg, with or without additional medication administered to lower IOP. The incidence of complications was similar in both groups.

CONCLUSIONS

In eyes undergoing Ahmed valve implantation for neovascular glaucoma, PCTR with MMC augmentation showed no additional benefits or complications over MMC augmentation alone; no avascular bleb was obtained with this technique. The incidence of a hypertensive phase was lower than reported in previous studies.

Suprachoroidal seton implantation in refractory glaucoma: a novel surgical technique

PURPOSE

To describe a new surgical technique in which aqueous humor is diverted from the anterior chamber to the suprachoroidal space for the augmentation of uveoscleral outflow in the management of refractory glaucoma.

METHODS

Four painful-blind eyes of four consecutive patients were included in the study. Mean age of patients was 54.7+/- 9.2 years. Preoperative diagnosis was neovascular glaucoma complicating diabetic retinopathy in three cases and chronic angle-closure glaucoma in one case. Mean preoperative intraocular pressure of the patients receiving two medications was 58.5 +/- 9.2 mm Hg. A modified Krupin eye valve with disk was implanted into the suprachoroidal space. The anterior tube part of the Seton device was placed into the anterior chamber through the long scleral tunnel for draining the aqueous humor from the anterior chamber to the suprachoroidal space.

RESULTS

The placement of modified Krupin eye valve with disk to the suprachoroidal space was achieved in all cases. While mean preoperative intraocular pressure was 58.5 +/- 9.2 mm Hg, it was 14.2 +/- 4.7 mm Hg at postoperative one week. It was 13.5 +/- 4.6 mm Hg and 15 +/- 4.9 mm Hg at one and three months respectively. At the last follow-up visit, mean intraocular pressure was 17.25 +/- 5.37 mm Hg ranging from 12 to 24 mm Hg. Choroidal detachment was developed in one case and regressed in six weeks. Rubeosis irides regressed at third month in three cases. None of the eyes developed suprachoroidal hemorrhage, retinal detachment, or phthisis bulbi.

CONCLUSION

The drainage of aqueous humor from the anterior chamber to the suprachoroidal space with the implantation of the glaucoma Seton device is effective in lowering intraocular pressure in refractory glaucoma.

Mitomycin C eliminates the short-term intraocular pressure rise found following Molteno tube implantation

PURPOSE

Molteno implants remain popular for treating recalcitrant glaucomas. This study aimed to assess the effect of mitomycin C (MMC) use with Molteno tube implantation upon intraocular pressure (IOP) control and complication rates. In particular, the study aimed to assess any change that MMC might have upon the postoperative hypertensive phase.

METHODS

A retrospective case record study was conducted of all patients undergoing double plate Molteno implant surgery by one surgeon over 5 years. Eyes with recalcitrant glaucoma unresponsive to previous surgery, or deemed unlikely to succeed with trabeculectomy, underwent double plate Molteno tube implantation. Eyes that had MMC (0.3 mg/mL, 3 min) applied to Tenon's capsule over the secondary plate were compared with eyes that underwent surgery without adjunctive MMC application.

RESULTS

Twenty-seven eyes received MMC and were similar to 26 eyes not receiving MMC in terms of glaucoma subtype, age, sex, previous surgery, preoperative IOP and postoperative IOP lowering agents. Those not receiving MMC had raised IOP 31-90 days post implantation compared with MMC treated eyes (P < 0.01) and more often received oral antifibrosis medication (P < 0.05). Complications were no more common with MMC except for initial overdrainage. Significant systemic complications from the use of oral antifibrosis medication were common.

CONCLUSIONS

The findings suggest a useful role for MMC. Caution is advised in case selection for MMC use. Mitomycin C treatment over the secondary plate alone permits removal of this plate if MMC-related complications occur without requiring removal of the whole implant.

Intermediate-term outcome of Baerveldt glaucoma implants in Asian eyes

PURPOSE

To determine the intermediate-term efficacy and safety of Baerveldt glaucoma implants in Asian eyes with complicated glaucoma.

DESIGN

Retrospective, nonrandomized, comparative trial.

PARTICIPANTS

One hundred twenty-four Asian patients (124 eyes) with complicated glaucoma.

INTERVENTION

Implantation of 54 250-mm(2) and 70 350-mm(2) Baerveldt glaucoma drainage implants at Singapore National Eye Center from 1994 through 1999.

MAIN OUTCOME MEASURES

Intraocular pressure, number of glaucoma medications, and complications.

RESULTS

The mean follow-up period was 33.4 +/- 14.4 months (mean +/- SD; range, 12-72 months). Intraocular pressure (IOP) was reduced from a mean preoperative IOP of 36.5 +/- 10.7 mmHg (range, 21-80 mmHg) to 15.3 +/- 6.0 mmHg (range, 1-34 mmHg), and the number of glaucoma medications decreased from 2.6 +/- 0.6 (range, 1-5) before the time of surgery to 0.5 +/- 0.9 (range, 0-4) medications at last follow-up. Overall, there were 67 eyes (54%) that were classified as complete successes, 27 eyes (22%) that were qualified successes, and 30 eyes that failed (24%). Postoperative complications occurred in 43 eyes (34.7%), and 21 eyes (17%) required further surgical intervention and revision. There was no statistically significant difference between the 250-mm(2) and 350-mm(2) type of implants in terms of success rates, final IOP, number of medications, and rates of complications. After adjusting for gender, preoperative IOP, and length of follow-up, increasing age (odds ratio [OR], 1.05; 95% confidence interval [CI], 1.01-1.09; P = 0.02) and the number of previous operations performed before implant surgery (OR, 1.57; 95% CI, 1.07-2.31; P = 0.01) were found to be correlated positively with failure.

CONCLUSIONS

In Asian eyes with complicated glaucoma, Baerveldt glaucoma implants achieve stable and satisfactory IOP reduction with low incidence of complications in the intermediate term after surgery.

Antifibrotics and wound healing in glaucoma surgery

When medical and laser therapy fail to control intraocular pressure, glaucoma filtration surgery needs to be performed. Glaucoma surgery is unique in that its success is linked to interruption of the wound-healing response in order to maintain patency of the new filtration pathway. In this article we will review the wound-healing pathway and the pharmacologic interventions that have been employed clinically and experimentally to interrupt wound healing, particularly steroids and the antifibrotic agents 5-fluorouracil and mitomycin C. A review of the published literature looking at use of these agents to enhance success as well as the associated complications are presented, critiqued, and interpreted in order to put the studies in proper perspective. Future directions and recommendations regarding use of these agents are available and an introduction to newer wound modulating agents such as anti-transforming growth factor beta 2 is presented.

Tube fenestrations in Baerveldt Glaucoma Implant surgery: 1-year results compared with standard implant surgery

PURPOSE

To evaluate the efficacy and safety of tube fenestrations in eyes undergoing polyglactin suture-ligated Baerveldt Glaucoma Implant surgery.

PATIENTS AND METHODS

The authors performed a retrospective nonrandomized comparative interventional study of consecutive cases of 111 eyes of 111 patients with refractory glaucoma who received polyglactin (Vicryl) suture-ligated Baerveldt 350 implants as a single procedure. In 69 of these cases (group 1), fenestrations were placed anterior to the ligature using a suture needle. In 42 cases (group 2), no fenestrations were performed. Main outcome measures included intraocular pressure, visual acuity, and complications.

RESULTS

Mean (+/- SD) preoperative intraocular pressure was 36.7 +/- 10.2 mm Hg in group 1 and 28.3 +/- 10.3 mm Hg in group 2 (P <0.001). Postoperative mean intraocular pressure was lower in group 1 than in group 2 at day 1 (20.2 +/- 12.8 vs. 29.3 +/- 1.9 mm Hg, P <0.001) and week 1 (18.3 +/- 10.4 vs. 23.7 +/- 8.6 mm Hg, P = 0.006), but was virtually identical at 1 year (12.7 +/- 4.9 vs. 12.6 +/- 4.4 mm Hg, P = 0.95). Number of glaucoma medications used by group 1 patients was significantly lower up to 3 months (P </=0.05). Complication rates were similar in both groups. After tube opening at a mean of 36 +/- 4.7 days, there was an equal and sustained intraocular pressure reduction in both groups in patients taking a similar number of glaucoma medicines up to 12 months after surgery.

CONCLUSION

Tube fenestrations provide safe and effective short-term intraocular pressure control with fewer glaucoma medications in a ligated nonvalved glaucoma drainage implant, with comparable intraocular pressure control and medications required at 1 year. However, not all patients have sustained reduction of intraocular pressure in the immediate postoperative period with fenestrations, making the effect somewhat unpredictable.

Survival analysis for success of Molteno tube implants

AIM

To apply survival analysis in assessing the long term outcome of Molteno tube implantation and to identify risk factors for failure.

METHODS

A retrospective, 10 year, consecutive case series study of 119 eyes that underwent implantation of a Molteno tube. The main outcome measures considered were intraocular pressure (IOP), visual acuity, and complications.

RESULTS

A 30% or greater reduction in IOP was achieved in 68.9% of cases. However, the overall, "complete success" rate (IOP <22 mm Hg with no medications) after a mean (SD) follow up period of 43 (33) months (range 6-120) was only 33.6% despite a fall in mean (SD) IOP from 38.2 (8.2) mm Hg to 20.1 (11.0) mm Hg. The "qualified success" rate (IOP <22 mm Hg with or without medications) was 60.5%. Failure was most common in the first postoperative year but could occur after several years, the survival curve having an exponential shape. The only statistically significant risk factor for failure identified was pseudophakia, although eyes with neovascular glaucoma tended to fare poorly. Postoperative IOP tended to be lower after double plate than after single plate implantation. There was no significant difference in outcome based on age, sex, race, previous penetrating keratoplasty, or previous conjunctival surgery.

CONCLUSIONS

In eyes at high risk of trabeculectomy failure, implantation of an aqueous shunt device should be considered. Pseudophakia should be considered an additional risk factor for failure. Early failure appeared relatively more common but long term follow up of all cases is recommended to ensure adequate management of late failures.

Penetrating keratoplasty and glaucoma

Glaucoma remains the leading cause of blindness after penetrating keratoplasty. Post-keratoplasty glaucoma was originally described in 1969, and its management is still controversial. Recent developments in management include newer classes of drugs, surgical procedures, such as trabeculectomy with mitomycin-C, implantation of glaucoma drainage devices, and cyclodestructive procedures with Nd: YAG and diode lasers. However, the risk of graft failure continues to be high with all surgical procedures.

Follow-up of the original cohort with the Ahmed glaucoma valve implant

PURPOSE

To study the long-term results of the Ahmed glaucoma valve implant in patients with complicated glaucoma in whom short-term results have been reported.

METHODS

In this multicenter study, we analyzed the long-term outcome of a cohort of 60 eyes from 60 patients in whom the Ahmed glaucoma valve was implanted. Failure was characterized by at least one of the following: intraocular pressure greater than 21 mm Hg at both of the last two visits less than 6 mm Hg at both of the last two visits, loss of light perception, additional glaucoma surgery, devastating complications, and removal or replacement of the Ahmed glaucoma valve implant. Devastating complications included chronic hypotony, retinal detachment, malignant glaucoma, endophthalmitis, and phthisis bulbi; we also report results that add corneal complications (corneal decompensation or edema, corneal graft failure) as defining a devastating complication.

RESULTS

The mean follow-up time for the 60 eyes was 30.5 months (range, 2.1 to 63.5). When corneal complications were included in the definition of failure, 26 eyes (43%) were considered failures. Cumulative probabilities of success at 1, 2, 3, and 4 years were 76%, 68%, 54%, and 45%, respectively. When corneal complications were excluded from the definition of failure, 13 eyes (21.5%) were considered failures. Cumulative probabilities of success at 1, 2, 3, and 4 years were 87%, 82%, 76%, and 76%, respectively. Most of the failures after 12 months of postoperative follow-up were because of corneal complications.

CONCLUSIONS

The long-term performance of the Ahmed glaucoma valve implant is comparable to other drainage devices. More than 12 months after the implantation of the Ahmed glaucoma valve implant, the most frequent adverse outcome was corneal decompensation or corneal graft failure. These corneal problems may be secondary to the type of eyes that have drainage devices or to the drainage device itself. Further investigation is needed to identify the reasons that corneal problems follow drainage device implantation.

Glaucoma surgery: are there new perspectives in perioperative pharmacology?

The literature directed at perioperative pharmacologic advances in relation to glaucoma filtration surgery is reviewed. The successful use of subconjunctival anesthesia demonstrates a new alternative in preoperative glaucoma surgical anesthesia. The intraoperative use of the antimetabolites mitomycin C and 5-fluorouracil in both traditional filtration and glaucoma drainage implantation surgery has been expanded. The use of the antifibrinolytic agents urokinase and recombinant tissue plasminogen activator adds a new and controversial dimension to postoperative pharmacologic therapy.

Glaucoma drainage devices: pros and cons

Glaucoma drainage devices are an option in the management of complicated glaucomas that carry a high risk of failure from conventional filtering surgery. Examples include the glaucomas associated with aphakia or pseudophakia, neovascular glaucoma, and glaucomas associated with trauma, uveitis, epithelial downgrowth, iridocorneal endothelial syndrome, vitreoretinal disorders, and penetrating keratoplasty. Modifications in the various implant designs have been developed to limit the occurrence of postsurgical complications such as hypotony, serous and hemorrhagic choroidal detachment, tube and plate avulsion, tube exposure, and corneal endothelial damage.