Noncontact Conjunctiva: A Better Mitomycin C Application Site for Trabeculectomy

INTRODUCTION

Bleb scarring is the most important complication of trabeculectomy. Changing the application position of mitomycin C (MMC) during trabeculectomy might affect the surgery outcome. Our aim is to compare the effectiveness and safety of intraocular pressure (IOP) lowering in two different application sites of mitomycin in trabeculectomy.

METHODS

This retrospective trial compared the surgical outcomes of 177 eyes that underwent trabeculectomy with adjunctive mitomycin C. In 70 eyes, an MMC-soaked sponge was applied under the scleral flap without touching Tenon's capsule. In 107 eyes, an MMC-soaked sponge was applied under the scleral flap covered by Tenon's capsule. Outcome measures were the IOP, best-corrected visual acuity (BCVA), success rates, and incidence of complications.

RESULTS

Within both groups, a highly significant IOP reduction was seen during follow-up. The effectiveness in reducing IOP and the change in best-corrected visual acuity (BCVA) were similar between the two groups. Thin-walled blebs and postoperative hypotony were seen more often when MMC-soaked sponges were applied under the scleral flap covered by Tenon's capsule (P = 0.008 and P = 0.012, respectively). There was no significant difference in BCVA or other complications in either group.

CONCLUSION

Since the effectiveness of IOP reduction was similar between both groups and with a low incidence of thin-walled blebs and hypotony, the subscleral application without touching Tenon's capsule seems to be the safer application site of MMC during trabeculectomy.

Subconjunctival filtration in evolution: current evidence on MicroShunt implantation for treating patients with glaucoma

BACKGROUND

Although traditional surgical procedures for glaucoma (such as trabeculectomy and tube-shunt implantation) can significantly reduce intraocular pressure (IOP), they are associated with numerous complications, some of which are vision-threatening, or involve prolonged recovery or a highly intensive postoperative course. Micro-invasive glaucoma surgery (MIGS) procedures have shown better safety but reduced efficacy in achieving target IOP. Combinations of these methods have led to the development of subconjunctival micro-invasive procedures with safety comparable to traditional surgery and greater efficacy than minimally invasive methods. This review describes the use of one of these devices, the poly(styrene-block-isobutylene-block-styrene) (SIBS)-based PreserFlo MicroShunt (Santen, Emeryville, CA), in the surgical treatment of patients with glaucoma.

MAIN TEXT

The MicroShunt is an 8.5-mm tube made of an inert polymer with no endplate, an internal diameter of 70 μm, and fins intended to prevent peritubular flow and anchor the device within the sclera to prevent proximal migration into the eye. Following ab externo implantation, the tube provides a conduit for flow of aqueous humor from the anterior chamber into the subconjunctival/sub-Tenon space. Clinical trials to date have shown that, when paired with mitomycin C (MMC) treatment, MicroShunt implantation significantly reduced both IOP and the number of glaucoma medications. These IOP-lowering results were found both when surgery was performed alone and with phacoemulsification. The MicroShunt also showed a safety profile comparable to that of traditional filtering surgery.

CONCLUSIONS

The MicroShunt and other novel subconjunctival procedures have shown substantial IOP reductions while mitigating hypotony-related complications. MMC, which modulates fibrosis and scarring postoperatively, is essential to surgical success. Randomized, long-term clinical trials will further clarify the role of controlled micro-incisional device-assisted ab externo glaucoma filtering surgery in long-term glaucoma management.

Comparison of Ab Interno XEN Gelatin Stent vs Trabeculectomy with Mitomycin C: A Retrospective Study

Aim

To compare outcomes of ab interno XEN gelatin stent (Allergan, Dublin, Ireland) implantation vs trabeculectomy with mitomycin C (MMC).

Materials and methods

A retrospective review was conducted of eyes that underwent standalone XEN implantation or trabeculectomy with MMC at a single institution from 2014 to 2019. Intraocular pressure (IOP), visual acuity, glaucoma medications, complications, and postoperative interventions were evaluated. The primary endpoint was the reduction in IOP at 6 months postoperatively. Secondary endpoints included the incidence of postoperative intervention and complications.

Results

One hundred and seventy-nine eyes were included who underwent XEN (n = 90) or trabeculectomy (n = 89). The mean age was 74.5 ± 7.6 and 68.1 ± 8.2 years old for the XEN and trab groups, respectively (p < 0.001). Baseline IOP for XEN was 17.8 ± 6.0 vs 20.4 ± 9.0 mm Hg for the trab group (p = 0.03). At 6 months, mean IOP for XEN group was 13.5 ± 5.9 mm Hg, representing a 24.1% IOP reduction from baseline (p < 0.001) while mean for trab group was 10.8 ± 4.8 representing a 47% IOP reduction from baseline (p < 0.001). The mean IOP was 2.7 mm Hg lower in trab compared to the XEN group at 6 months (p < 0.003). The number of medications was reduced in both groups from 2.9 ± 1.1 and 3.1 ± 0.9 to 1.1 ± 2.3 and 0.8 ± 1.4 by 6 months postoperatively for XEN and trab groups, respectively (p < 0.001). Complication rates were low for both groups. The needling rate was 30% in XEN vs 7.9% in the trab group (p < 0.001), and 46.1% of eyes in the trab group underwent laser suture lysis. Additionally, IOP reduction and complication rates were similar following XEN in eyes receiving <40 or ≥40 μg of MMC.

Conclusion

XEN implantation produces a substantial reduction in IOP with a favorable safety profile comparable to trabeculectomy. Careful postoperative bleb management is critical to obtain optimum outcomes, and higher MMC doses appear safe and may reduce needling rates.

Clinical significance

This study confirms the safety and efficacy of XEN gelatin stent implantation in comparison to trabeculectomy with MMC.

How to cite this article

Sharpe R, Pham G, Chang P. Comparison of Ab Interno XEN Gelatin Stent vs Trabeculectomy with Mitomycin C: A Retrospective Study. J Curr Glaucoma Pract 2020;14(3):87–92.

First-in-human phase I study of ISTH0036, an antisense oligonucleotide selectively targeting transforming growth factor beta 2 (TGF-β2), in subjects with open-angle glaucoma undergoing glaucoma filtration surgery

Purpose

To evaluate the safety and tolerability of intravitreal ISTH0036, an antisense oligonucleotide selectively targeting transforming growth factor beta 2 (TGF-β2), in patients with primary open angle glaucoma (POAG) undergoing trabeculectomy (TE; glaucoma filtration surgery).

Methods

In this prospective phase I trial glaucoma patients scheduled for TE with mitomycin C (MMC) received a single intravitreal injection of ISTH0036 at the end of surgery in escalating total doses of 6.75 μg, 22.5 μg, 67.5 μg or 225 μg, resulting in calculated intraocular ISTH0036 concentrations in the vitreous humor of approximately 0.3 μM, 1 μM, 3 μM or 10 μM after injection, respectively. Outcomes assessed included: type and frequency of adverse events (AEs), intraocular pressure (IOP), numbers of interventions post trabeculectomy, bleb survival, visual acuity, visual field, electroretinogram (ERG), slit lamp biomicroscopy and optic disc assessment.

Results

In total, 12 patients were treated in the 4 dose groups. Main ocular AEs observed were corneal erosion, corneal epithelium defect, or too high or too low IOP, among others. No AE was reported to be related to ISTH0036. All other safety-related analyses did not reveal any toxicities of concern, either. The mean medicated preoperative IOP at decision time-point for surgery was 27.3 mmHg +/- 12.6 mmHg (SD). Mean IOP (±SD) for dose levels 1, 2, 3, and 4 were at Day 43 9.8 mmHg ± 1.0 mmHg, 11.3 mmHg ± 6.7 mmHg, 5.5 mmHg ± 3.0 mmHg and 7.5 mmHg ± 2.3 mmHg SD; and at Day 85 9.7 mmHg ± 3.3 mmHg, 14.2 mmHg ± 6.5 mmHg, 5.8 mmHg ± 1.8 mmHg and 7.8 mmHg ± 0.6 mmHg, respectively. In contrast to IOP values for dose levels 1 and 2, IOP values for dose levels 3 and 4 persistently remained below 10 mmHg throughout the observation period.

Conclusion

This first-in-human trial demonstrates that intravitreal injection of ISTH0036 at the end of TE is safe. Regarding IOP control, single-dose ISTH0036 administration of 67.5 μg or 225 μg at the time of TE resulted in IOP values persistently < 10 mmHg over the three month postoperative observation period.

A comparative study of trabeculectomy and the new clear-cornea filtering procedure, intrastromal diathermal keratostomy (IDK)

PURPOSE

For the first time to compare the 1-year success rates of trabeculectomy and the new clear-cornea filtering procedure, intrastromal diathermal keratostomy (IDK).

METHODS

Prospective clinical observational study including 99 consecutively operated eyes (69 patients) with well-established primary open-angle glaucoma referred for filtering operation. We compared the change in intraocular pressure (IOP), number of anti-glaucomatous medication, complications and reoperations after 1 year. Seventy-four eyes were operated with trabeculectomy, and 25 with IDK. Complete success was defined as IOP ≤ 18 mmHg, IOP lowered ≥ 30%, no medication and no reoperation. Qualified success was defined as IOP ≤ 18 mmHg, and IOP lowered ≥ 30% with or without medication or reoperation.

RESULTS

Intraocular pressure pre- and postoperatively in the trabeculectomy group was 25.3 and 14.1 mmHg versus 23.8 and 15.8 mmHg in the IDK group. The number of medications pre- and postoperatively in the trabeculectomy group was 3.1 and 0.5 versus 3.2 and 1.3 in the IDK group. Forty-four (59%) of the eyes in the trabeculectomy group met the complete success criteria compared with 5 (20%) in the IDK group (p < 0.01). Sixty-eight (92%) in the trabeculectomy group and 16 (64%) in the IDK fulfilled the qualified success criteria (p < 0.01).

CONCLUSION

Both the complete and qualified 1-year success rates of IDK are significantly lower compared with the success rates of trabeculectomy. The IDK does not reduce the IOP as much as the procedure of trabeculectomy, and it carries a higher frequency of reoperations and more medication postoperatively. Thus, our prospective data do not support the procedure of IDK as 'the gold standard' for filtering surgery in patients with open-angle glaucoma.

Interventions for late trabeculectomy bleb leak

BACKGROUND

Late trabeculectomy bleb leaks are a common complication after filtering glaucoma surgery. Although asymptomatic, late bleb leaks may lead to hypotony and are associated with bleb related infections.

OBJECTIVES

To assess the effects of interventions for late trabeculectomy bleb leak.

SEARCH METHODS

We searched CENTRAL (which contains the Cochrane Eyes and Vision Group Trials Register) (The Cochrane Library 2012, Issue 7), MEDLINE (January 1946 to July 2012), EMBASE (January 1980 to July 2012), the metaRegister of Controlled Trials (mRCT) (www.controlled-trials.com), ClinicalTrials.gov (www.clinicaltrials.gov) 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 18 July 2012.

SELECTION CRITERIA

We included randomised and quasi-randomised trials in which any treatments for eyes with late bleb leak (interventional and non-interventional) were compared with each other.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed trial quality and extracted data. We contacted study authors when additional information was needed.

MAIN RESULTS

The review included one multicentre trial based in the USA with 30 eyes of 30 participants. The trial compared two surgical procedures (conjunctival advancement and amniotic membrane transplant) to cover a filtering bleb leak. Conjunctival advancement has been shown to be more effective in sealing filtering bleb leaks.

AUTHORS' CONCLUSIONS

Although a variety of treatments have been proposed for bleb leaks, there is no evidence of their comparative effectiveness.The evidence in this review was provided by a single trial that compared two surgical procedures (conjunctival advancement and amniotic membrane transplant). The trial did show a superiority of conjunctival advancement, which was regarded as standard treatment, to amniotic membrane transplantation. There is a need for more randomised trials to validate the findings of this single trial and provide more information on the different types of interventions, especially non-surgical treatments compared to surgical procedures. We recommend that any intervention should be compared to a standard procedure, which is to date conjunctival advancement.

Outcomes and bleb-related complications of trabeculectomy

PURPOSE

To determine rates of success and complications of trabeculectomy surgery.

DESIGN

Case series.

PARTICIPANTS

Consecutive patients undergoing trabeculectomy by 2 surgeons between May 2000 and October 2008.

INTERVENTION

By using the Wilmer Institute's billing database, we identified all patients at least 12 years of age coded as having undergone trabeculectomy between May 2000 and October 2008 by 1 of 2 glaucoma surgeons and whose surgery was not combined with another operation. From the chart, we abstracted demographic information on the patients and clinical characteristics of the eyes. The Kaplan-Meier product-limit method and Cox proportional hazard models were used to look at success rates and characteristics associated with inadequate intraocular pressure (IOP) reduction. Complications were tabulated.

MAIN OUTCOME MEASURES

(1) Success rate of trabeculectomy, as determined by the achievement of each of 4 different IOP goals, with or without IOP-lowering medications; and (2) incidence of surgical complications.

RESULTS

During the study period, 797 eyes of 634 persons underwent trabeculectomy without concurrent surgery. The success rates 4 years after surgery, with or without the use of IOP-lowering eye drops, were 70%, 72%, 60%, and 44%, for achievement of target IOP, ≤18 mmHg and ≥20% IOP reduction, ≤15 mmHg and ≥25% reduction, and ≤12 mmHg and ≥30% reduction, respectively. Increased chance of success was associated with European-derived race; use of mitomycin C (MMC); higher concentrations of MMC, when used; and higher preoperative IOP. Age and previous intraocular surgery were not associated with surgical success. Complications included worsening lens opacity in 242 of 443 phakic eyes (55%), loss of ≥3 lines of acuity (Snellen) in 161 eyes (21%), surgery for bleb-related problems in 70 eyes (8.8%), and infection occurring >6 weeks after surgery in 27 eyes (3.4%). A total of 101 eyes of 94 patients had at least 1 subsequent operation for inadequate IOP control.

CONCLUSIONS

Trabeculectomy surgery performed by 2 experienced glaucoma specialists achieved target IOP at 4 years in 70% of those operated and was associated with progressive cataract and small risks of bleb-related complications. These results are comparable to those reported in smaller series.

Outcome of repeat trabeculectomies

BACKGROUND

To determine the success of repeat trabeculectomy augmented with mitomycin C in a cohort of patients who had undergone previously failed trabeculectomy surgery.

DESIGN

A consecutive cohort series of patients.

PARTICIPANTS

Fifty patients undergoing augmented trabeculectomy surgery following a previously failed trabeculectomy and at least 12 months' follow up.

METHODS

All patients had demographic and clinical data collected at the time of surgery and at all subsequent follow-up visits.

MAIN OUTCOME MEASURES

Visual field progression, loss of visual acuity, intraocular pressure (IOP) control.

RESULTS

The mean follow up was 36.7 months. Forty-one patients (82%) achieved an IOP ≤21 mmHg (with ≥20% reduction of preoperative IOP) and ≥6 mmHg on no additional glaucoma treatment at 12 months' follow up. Forty-four patients (88%) achieved a qualified success with the same criteria at 1 year. The median logMAR acuity preoperative was unchanged after surgery; however, 11 patients (22%) lost ≥2 Snellen lines during follow up. There was no significant change in mean deviation during the follow-up period.

CONCLUSIONS

  Repeating trabeculectomy augmented with mitomycin C is an effective method of controlling IOP and preventing further visual deterioration in the majority of patients treated. However, visual loss was seen in a significant proportion of patients.

Use of pimecrolimus to prevent epidural fibrosis in a postlaminectomy rat model

OBJECT

Epidural fibrosis is the scar tissue formed over the dura mater after a laminectomy. Extensive epidural fibrosis may be an important underlying cause of failed back syndrome. Pimecrolimus, an ascomycin derivative, is one of the new classes of immunomodulating macrolactams and was specifically developed for the treatment of inflammatory diseases. This study examined the preventive effects of the local application of pimecrolimus in minimizing spinal epidural fibrosis in a rat laminectomy model.

METHODS

Thirty Wistar rats were divided into 3 equal groups: control, mitomycin C (MMC), and pimecrolimus groups. Each rat underwent a laminectomy at the L-3 lumbar level. In the experimental groups, a cotton pad soaked with MMC (0.5 mg/ml) or 5 mg pimecrolimus was placed on the exposed dura mater. No treatment was performed in the control group rats. Thirty days after surgery, the rats were killed and the dura mater thickness, epidural fibrosis, and arachnoidal involvement were quantified.

RESULTS

The mean dura thickness was measured at 9.28 +/- 3.39 microm in the MMC group and at 8.69 +/- 2.32 microm in the pimecrolimus group, compared with 14.70 +/- 4.14 microm in the control group. In addition, the epidural fibrosis and arachnoidal involvement were reduced significantly in the treatment groups compared with the control group.

CONCLUSIONS

In this animal model, it was shown that locally applied pimecrolimus effectively reduces epidural fibrosis and dural adherence in rats that underwent lumbar laminectomy. Mitomycin C was equally effective as pimecrolimus in reducing epidural fibrosis and dural adherence in this study.

Mitomycin protection of peridural fibrosis in lumbar disc surgery

Object

In this prospective, randomized clinical study the authors sought to evaluate the effects of locally applied mitomycin C on peridural fibrosis during lumbar microdiscectomy.

Methods

Patients undergoing lumbar disc surgery were randomly divided into 2 groups. Thirty patients had 1 mg/ml mitomycin C applied at the site of discectomy for 5 minutes, and 30 age- and sex-matched patients underwent lumbar microdiscectomy without mitomycin C application as the control group. The groups were compared for degree of postoperative neurological function, radicular/back pain, and degree of peridural fibrosis on MR imaging 6 months after the operation.

Results

The median follow-up was 18 months. No serious drug adverse effects and no clinically significant laboratory adverse effects were reported in patients in the mitomycin C group. Patients in both groups showed similar clinical recoveries postoperatively. On postoperative evaluation of the MR images, pain scores, and neurological function, patients given mitomycin C have shown no reduction of peridural fibrosis either clinically or radiographically.

Conclusions

Mitomycin C is easy to use and safe in patients undergoing lumbar microdiscectomy. However, no benefit was observed either clinically or radiographically in this study.

Non-penetrating glaucoma surgery augmented with mitomycin C or 5-fluorouracil in eyes at high risk of failure of filtration surgery: long-term results

PURPOSE

To investigate the long-term efficacy and safety of non-penetrating glaucoma surgery (NPGS) augmented with mitomycin C (MMC) or 5-fluorouracil (5FU) in eyes at high risk of failure of glaucoma filtration surgery.

METHODS

Prospective study of all eyes, undergoing NPGS with 0.04% MMC (1 to 2 min topical or 0.04 mL subconjunctival injection into the superior fornix) or 5FU (25 mg/mL topically for 5 min). Complete success was an intraocular pressure (IOP)<or=21 mmHg on no medication and qualified success an IOP<or=21 mmHg with topical medication. An additional criterion for success was a >or=20% drop in IOP or a reduction of at least two medications.

RESULTS

Twenty-three eyes of 22 patients with a mean follow up of 41.4 months were reviewed. Fifteen eyes had failed trabeculectomy and seven had uveitic glaucoma. Mean preoperative IOP reduced from 25.8+/-7.8 to 15.4+/-4.9 mmHg at final visit, a mean change of 41%. Median number of preoperative medications decreased from 3 to 0 postoperatively. Cumulative probability of success was 100% at 2 years, 94% at 3 years and 85% at 4 years. No patient developed any long-term complications. Complete success was achieved in 11 eyes and qualified success in 10 eyes. Two eyes failed and required further surgery.

CONCLUSION

NPGS augmented with small-volume MMC/5FU provides good long-term IOP control in eyes at high risk of failure with a lower incidence of complications compared with augmented trabeculectomy and eliminates the need for postoperative bleb or suture manipulation.

Mitomycin C, 5-fluorouracil, and cyclosporin A prevent epidural fibrosis in an experimental laminectomy model

This study examined the preventive effects of the local application of mitomycin C (MMC), 5-fluorouracil (5-FU), and cyclosporine A (CsA) in minimizing spinal epidural fibrosis in a rat laminectomy model. Thirty-two 2-year-old male Wistar albino rats, each weighing 400 +/- 50 g, were divided into four equal groups: sham, MMC, 5-FU, and CsA. Each rat underwent laminectomy at the L5-L6 lumbar level. Cotton pads (4 x 4 mm2) soaked with MMC (0.5 mg/ml), 5-FU (5 ml/mg), or CsA (5 mg/ml) were placed on the exposed dura for 5 min. Thirty days after surgery, the rats were killed and the epidural fibrosis, fibroblast density, inflammatory cell density, and arachnoid fibrosis were quantified. The epidural and arachnoid fibroses were reduced significantly in the treatment groups compared to the sham group. Fibroblast cell density and inflammatory cell density were decreased significantly in the MMC and 5-FU groups, but were similar in the sham and CsA groups. The decreased rate of epidural fibrosis was promising. Further studies in humans are needed to determine the short- and long-term complications of the agents used here.

Uses and complications of mitomycin C in ophthalmology

Mitomycin C is a chemotherapeutic agent that acts by inhibiting DNA synthesis. Its use and application in ophthalmology has been increasing in recent years because of its modulatory effects on wound healing. Current applications include pterygium surgery, glaucoma surgery, corneal refractive surgery, cicatricial eye disease, conjunctival neoplasia and allergic eye disease. Although it has been used successfully in these conditions, it has also been associated with significant complications. This article reviews the current trends and uses of mitomycin C in the eye and its reported complications.

The effect of mitomycin C in reducing epidural fibrosis after lumbar laminectomy in rats

Object

xtensive epidural fibrosis after lumbar spine surgery might be an important underlying cause of failed-back syndrome. Based on previously obtained data, the effect of mitomycin C (MMC) in a concentration of 0.1 mg/ml on spinal epidural fibrosis in a rat laminectomy model was investigated in a large series.

Methods

ighty adult Wistar rats underwent lumbar laminectomy. In 40 rats, MMC in a concentration of 0.1 mg/ml was locally applied to the laminectomy sites. No similar treatment was performed in the other 40 rats. At intervals from one to 12 weeks after laminectomy, both macroscopic and histological evaluations were performed. For radiological investigation, 10 rats underwent magnetic resonance (MR) imaging at 6 weeks postoperatively. Furthermore, the concentration of MMC in cerebrospinal fluid (CSF) and serum was determined 12 hours postoperatively in seven rats.

Due to ease of absorption, high levels of MMC were rapidly detectable in serum, whereas the values obtained from the CSF were markedly lower. In the majority of MMC-treated laminectomy sites, epidural scarring was significantly reduced and dural adhesions were absent, in comparison with control sites (p < 0.001), as confirmed by MR images. Accordingly, the macroscopic dissection of epidural fibrous tissue to reexpose the dura mater was performed more easily and without severe bleeding in these rats. The healing of skin and the lumbar fascia was not affected, and dural leakage was not observed. All control sites showed dense epidural fibrosis with marked dural adherence.

Conclusions

n this experimental model, it was shown that locally applied MMC in a concentration of 0.1 mg/ml effectively reduces epidural fibrosis and dural adherence without side effects in rats that underwent lumbar laminectomy.

Determinants of Bleb Morphology in Minimally Invasive, Clear-Cornea Micropenetrating Glaucoma Surgery with Mitomycin C

PURPOSE

Antimetabolites, especially mitomycin C (MMC), increase the incidence of late bleb-related endophthalmitis in trabeculectomy. This is related to a higher incidence of avascular, thin, cystic, translucent blebs, which may be caused by a toxic effect on conjunctival tissue. An MMC dose-response study was carried out focusing on bleb morphology and function.

PATIENTS AND METHODS

In a retrospective, comparative case series study, 2 successive groups of patients with complicated glaucoma were compared 2 years after a special, minimally invasive, filtering procedure (intrastromal holmium laser keratostomy). Preoperative local subconjunctival injections of a fixed MMC dose (4 microg) were used in group A, and lower MMC doses, calculated individually (1 or 2 microg), were used in group B. Bleb vascularity and morphology were evaluated by masked grading of photomicrographs. Bleb function was evaluated by intraocular pressure (IOP).

RESULTS

Total bleb avascularity occurred in 63% of the blebs in group A and 0% in group B (P < 0.01). In eyes with IOP < or = 20 mmHg without medical treatment, the mean IOP was significantly lower in group 1 (8 vs 15 mm Hg, P < 0.002). A translucent cystic bleb without conjunctival stroma was observed in only 1 eye in group A. An optimal spongy stromal bleb was observed in all other eyes (96%) despite the different MMC doses. The numbers of complications in the 2 groups were nearly equal.

CONCLUSIONS

Bleb avascularity after 4 microg MMC could be avoided by the use of 1 or 2 microg MMC on the basis of preoperative prognosticators for failure, but at the expense of some of the IOP-lowering effect. This indicates that the therapeutic index (clinical safety margin) of MMC seems to be narrow. An MMC dose-response relation was not observed for the thin, cystic, and translucent bleb. The low incidence of this bleb (4%) indicates that the operative technique, apart from the vascularity, may be the most essential determinant of bleb morphology.

Protocol for mitomycin C use in glaucoma surgery

PURPOSE

To evaluate the results of a protocol described for mitomycin C (MMC) use in trabeculectomy or combined surgery (phacoemulsification and trabeculectomy).

METHODS

A total of 143 eyes (60 trabeculectomies and 83 combined surgeries) of 124 patients were divided into four groups: group 1 (without MMC); group 2 (with 0.1 mg/ml MMC); group 3 (with 0.2 mg/ml MMC), and group 4 (with 0.4 mg/ml MMC). Two-minute MMC was used in every case in groups 2, 3 and 4. The results were analysed after 1 year of follow-up. Intraocular pressure (IOP) and complications were evaluated. Successful IOP control was defined when IOP was <21 mmHg and <16 mmHg if advanced glaucoma was present, always without additional medical treatment.

RESULTS

Mean preoperative IOP decreased from 24.60 mmHg (SD 1.40 mmHg) to 13.47 mmHg (SD 0.37 mmHg) (p < 0.00001), 12 months postoperatively. Control in IOP was achieved in 79.02% of eyes. No significant differences were found in final mean IOP values (p > 0.196) or in postoperative complications (p > 0.120) in groups 2, 3 and 4.

CONCLUSION

With the protocol described, a selection of concentration of MMC has been made in different clinical forms of glaucoma. No significant differences in IOP control and postoperative complications were noticed among the groups.

Mitomycin C in preventing spinal epidural fibrosis in a laminectomy model in rats

Object. Extensive epidural fibrosis after lumbar surgery may be the underlying cause in most cases of failed—back surgery syndrome. Various materials have been used to prevent epidural fibrosis, but only moderate success has been shown.

Mitomycin C, an alkylosing antibiotic substance isolated from Streptomyces caespitosus, potentially supresses fibroblast proliferation after surgery. In this study, the authors investigated the effect of mitomycin C by local application on spinal epidural fibrosis in a rat laminectomy model.

Methods. Five Wistar rats underwent laminectomy at cervical, thoracic, and lumbar levels. Based on data obtained from ophthalmological studies, mitomycin C was applied to the laminectomy sites in various concentrations (0.01, 0.05, and 0.1 mg/ml). One laminectomy site in each rat was left untreated and thus served as a control. Evoked potentials were measured pre- and postoperatively, and all rats underwent clinical evaluation. Mobility status and evidence of neurological deficit were recorded. Twelve weeks later, the rats were killed, and the spinal column, including surrounding muscle tissue, was removed en bloc, decalcified, and fixed in formaldehyde. Epidural fibrosis was evaluated histologically.

In all mitomycin C—treated laminectomy sites, epidural scarring was significantly reduced compared with control sites. Remarkably, dural adhesions were absent in laminectomy defects treated with mitomycin C concentrations of 0.05 and 0.1 mg/ml. Moderate to marked epidural fibrosis with adhesion to the dura mater was noted at sites receiving 0.01 mg/ml of mitomycin C. All control sites showed dense epidural fibrosis with marked dura adherence.

Conclusions. In this experimental model, mitomycin C applied locally at a concentration of 0.1 mg/ml effectively reduced epidural fibrosis, completely avoided dural adherence, and induced no side effects.

Long-term follow-up of initially successful trabeculectomy with 5-fluorouracil injections

PURPOSE

To study the long-term results (1-14 years) of trabeculectomies with 5-fluorouracil injections that were successful at 1 year.

DESIGN

A retrospective noncomparative case series. INTERVENTION/PARTICIPANTS: We identified 87 patients (87 eyes) who had trabeculectomies with 5-fluorouracil injections from 1984 to 1989 that were successful at 1 year and had a follow-up range of 1.0 to 14.7 years (mean, 8.1, standard deviation of 4.4 years). All patients had previously failed glaucoma surgery (66.7%), cataract surgery (47.1%), or other diagnoses making them at high risk for failure.

MAIN OUTCOME MEASURES

Successful control of intraocular pressure (IOP) was defined as IOP less than 21 mmHg or a reduction of 33% if preoperative pressure was less than 21 mmHg. Statistical analysis was performed using Kaplan-Meier life table analysis.

RESULTS

If an eye is considered successful by IOP at 1 year, the probability of successful control is 61% at 5 years, 44% at 10 years, and 41% at 14 years.

CONCLUSIONS

Despite successful IOP control at 1 year, trabeculectomies with 5-fluorouracil injections show a continual loss of IOP control over time.

Efficacy and safety of mitomycin-C in primary trabeculectomy: five-year follow-up

PURPOSE

To examine the 5-year complications and results of primary trabeculectomy with mitomycin-C (MMC).

DESIGN

Retrospective, noncomparative interventional case series.

PARTICIPANTS

One hundred twenty-three eyes that underwent primary trabeculectomy with MMC between December 1991 and March 1995.

METHODS

All patients received standard trabeculectomy performed by one of two surgeons, using a Weck cell-soaked pledget of MMC, 0.25, 0.33, or 0.5 mg/ml, for 0.5 to 5 minutes. Laser suture lysis was performed postoperatively for intraocular pressure control.

MAIN OUTCOME MEASURES

The incidence of complications, including hypotony with or without maculopathy, bleb leak or blebitis, pressure control, and medication reduction at yearly intervals.

RESULTS

Mean preoperative and year 5 postoperative intraocular pressures (IOP) were 25.79 and 9.91 mmHg (P < 0.05, paired t test). Hypotony (IOP < 6) occurred in 42.2% of eyes after a mean follow-up of 26.1 months. Hypotony maculopathy occurred in 8.9% of eyes at mean follow-up of 33.7 months. Bleb leak occurred in 14.6% of eyes at a mean follow-up of 27.9 months. Blebitis occurred in 5.7% of eyes at a mean follow-up of 35.4 months, and endophthalmitis occurred in 0.8% of eyes at 15 months; 14.9% of eyes lost 4 lines of visual acuity. The single predictor for the development of late-term hypotony was IOP 1 month after operation (P < 0.05).

CONCLUSIONS

Primary mitomycin trabeculectomy significantly lowers IOP at 5 years but is associated with a high incidence of delayed hypotony.

Intraoperative episcleral versus postoperative topical application of mitomycin-C for trabeculectomies

OBJECTIVE

To assess the efficacy of a new application technique of mitomycin-C to enhance the outcome of filtering surgery in cases of complicated glaucoma.

DESIGN

Randomized clinical trial.

PARTICIPANTS

Fifty consecutive patients scheduled for glaucoma surgery in one large surgical center.

INTERVENTION

Patients underwent routine trabeculectomy. In group 1, mitomycin-C (0.05 mg/ml) was applied topically to the filtering bleb on days 1, 2, and 3 after surgery (postoperative application). In group 2, mitomycin-C (0.2 mg/ml) was applied by means of to a sponge during surgery (intraoperative application).

MAIN OUTCOME MEASURES

Preoperative and postoperative intraocular pressure (IOP) values, visual acuity, the need for antiglaucoma medication, previous surgical procedures, and the need for further surgical interventions were monitored.

RESULTS

Sufficient follow-up data were available from 24 of 25 patients in each of the two groups. The follow-up ranged from 12 to 28 months and was evaluated at 12 months for all patients. The mean IOP decreased from 27.3 to 15.5 mmHg in group 1 and from 29.0 to 17.5 mmHg in group 2. The average number of medications decreased from 2.3 and 2.4 to 0.9 and 0.8 (P = 0.68; t test) in groups 1 and 2, respectively, at the 12-month visit. Hypotony was more frequent in group 2, in which the only case of hypotony maculopathy occurred. There was a tendency of more eyes with lower IOP values in this group. The rate of loss of visual acuity of more than 2 lines was higher in group 2. Failures were more frequent in group 2 (7 of 24) compared with group 1 (1 of 24) (P = 0.04, chi-square test).

CONCLUSIONS

To our knowledge, this is the first prospective, randomized clinical study to evaluate the efficacy of this different technique of mitomycin-C application. The postoperative application of mitomycin-C was effective, having few failures. This application of mitomycin-C may be associated with a lower rate of complications when used in eyes with complicated forms of glaucoma.

Impact of Mitomycin-C application time on the scleral Mitomycin-C concentration

The aim of this study was to determine the effect of varying the application time of Mitomycin-C (MMC) on the scleral concentration of MMC. The sclerae of 14 human donor eyes were used for this study. The episcleral sides of the 4 scleral quadrants of each donor eye were exposed for 0.5, 1, 3 and 5 min to round, 8 mm-diameter sponges soaked with 50 microl of 0.2 mg/ml MMC. After 40-ml irrigation with saline, a central 8-mm diameter scleral disk was punched out, homogenized and analyzed with high performance liquid chromatography (HPLC). The scleral MMC concentrations (microg/g) after 0.5, 1, 3 and 5 min application times were 6.40 (+/-3.38), 9.02 (+/-2.40), 12.31 (+/-3.37), and 13.97 (+/-3.83). The differences of scleral MMC concentration in paired t-tests were statistically significant comparing 0.5 with 1 and 1 with 5 min application. However the effect was relatively small within the range of usual application times (1 to 5 min), and 64% of the MMC was delivered to the sclera within the first min.

Combined cataract and glaucoma surgery

The management of cataract in glaucoma patients has been continuously changing over the past decade. Extracapsular cataract extraction has been replaced by small-incision phacoemulsification with foldable lenses, and in glaucoma surgery, adjunctive antifibrotic therapy based on risk factors for failure has become standard. Furthermore, new techniques in filtering and nonfiltering surgery have been suggested. The techniques, however, change so fast that well-controlled studies with a follow-up of more than 12 months are increasingly seldom. The purpose of this paper is to review the current literature and to point out some new ideas for the future investigation.

Low-dose 5-fluorouracil trabeculectomy as initial surgery in uncomplicated glaucoma: long-term followup

OBJECTIVE

To compare the effectiveness of trabeculectomy with adjunctive, low-dose, subconjunctival 5-fluorouracil (5-FU) to trabeculectomy alone in patients with uncomplicated glaucoma undergoing their first incisional surgical procedure.

DESIGN

Retrospective, nonrandomized comparative trial.

PARTICIPANTS

Consecutive series of 52 patients and 74 control subjects.

INTERVENTION

Trabeculectomy was performed in all patients. Study patients received adjunctive, subconjunctival injections of 5-FU up to 14 days from the date of surgery.

MAIN OUTCOME MEASURES

Intraocular pressure, number of postoperative antiglaucoma medications, interventions, and complications were evaluated.

RESULTS

Mean followup for all patients was 58.1 +/- 44.1 months (range, 1.1-159.9 months). Mean followup for successful eyes was 55.9 +/- 47.1 months (range, 7.6-159.9 months). The cumulative 5-year success (intraocular pressure [IOP] < or = 21 mmHg) was 77.8% in the 5-FU group and 62.2% in the control group (P = 0.02, Wilcoxon test. Complete success (IOP < or = 21 mmHg without medications) at 5 years was lower in both the 5-FU group (72.3%) and the control group (51.3%). Postoperative mean IOP at 5 years for all successful patients was lower in eyes receiving 5-FU (10.7 +/- 3.6 mmHg vs. 16.0 +/- 6.1 mmHg [P = 0.02, t-test]). For those patients considered to be complete successes, there was no difference in IOP between the two groups of patients at any evaluated time interval. Patients in the 5-FU group were using 0.7 +/- 1.1 medications at final followup compared with 1.8 +/- 1.4 medications in the control group (P = < 0.0001, t test). Bleb-related ocular infection occurred in 6.3% of patients and was more common in patients receiving 5-FU than controls (6 of 52 vs 2 of 74, respectively; P = 0.05, Fischer's exact test).

CONCLUSIONS

Adjunctive, low-dose 5-FU at the time of initial surgery in uncomplicated glaucoma improves long-term IOP control and reduces the need for postoperative, antiglaucoma therapy. Eyes receiving 5-FU are at greater risk of developing late bleb-related ocular infection.