Mitomycin Versus 5-Fluorouracil Antimetabolite Therapy for Glaucoma Filtration Surgery

National survey of intraoperative mitomycin C use during trabeculectomy surgery in the UK

PURPOSE

Mitomycin C is a routinely used antimetabolite which effectively limits the scarring process. Conventionally, the intra-operative technique of MMC delivery during trabeculectomy is the direct application of the soaked sponges. The aim of this study is to evaluate the current practice of delivering MMC during trabeculectomy and to see the practices related to a retained MMC swab during trabeculectomy in the UK.

METHODS

An electronic questionnaire of 8 questions regarding the intraoperative use of MMC during trabeculectomy surgery was emailed to 69 ophthalmologist members of the UK and Eire glaucoma society (UKEGS) through email in July 2019.

RESULTS

97.2% of the surveyed glaucoma surgeons said they use MMC during trabeculectomy routinely, while 2.9% said they never use MMC for trabeculectomy. In reply to a question 'Have you ever had a retained MMC-soaked sponge/fragment of sponge', 11.76% replied 'yes', 88.24% said 'No'. In response to what technique was employed at the time of retained MMC sponges, all the respondents said they had employed the same technique of 'multiple individual sponges'. 47.1% surgeons said they use multiple individual sponges on being asked what technique they currently employ for delivering MMC during trabeculectomy surgery, while 14.7% surgeons use multiple sponges linked with a 'necklace suture' and 5.9% inject MMC.

CONCLUSION

Our survey suggests the intra-operative MMC use in the UK is high and that unintentional MMC-soaked swab retention does occur, albeit rarely. A preference of using the MMC-soaked swabs as a delivery method of MMC is seen in our survey.

Glaucoma Surgery with Soaked Sponges with Mitomycin C vs Sub-Tenon Injection: Short-term Outcomes

AIM

The aim of this study is to compare the outcomes, success rates, complications, and number of interventions of the trabeculectomy surgery with mitomycin C (MMC) in two different techniques: conventional soaked sponges and sub-Tenon injection.

MATERIALS AND METHODS

An observational retrospective study was performed with 79 eyes of 64 participants who underwent a glaucoma surgery with MMC. The conventional sponge soaked with MMC 0.03% for 3 minutes over the scleral flap (group I) and the subtenon injection of 0.1 mL of MMC 0.03% (group II) techniques were used to deliver the MMC. The data collected were patient demographics, preoperative intraocular pressure (IOP), central corneal thickness (CCT), number of pre- and postoperative ocular hypotensive drugs, postoperative complications, number of interventions, and need of further glaucoma surgery.

RESULTS

Seventy-nine eyes were divided into two: 39 eyes (49.37%) in group I and 40 eyes (50.63%) in group II. Trabeculectomy was performed in 53.17% and phacotrabeculectomy in 46.83%. The IOP decreased from 18.0 ± 11.0 mm Hg at the baseline to 10.0 ± 3.0 mm Hg at the last visit in group I and, in group II, from 16.0 ± 10.0-13.0 ± 6.0 mm Hg (median ± ID), p < 0.001. There were no significant differences between the groups regarding demographics, median follow-up, IOP in baseline, CCT, drugs reduction, success criteria adopted, postsurgical interventions, surgical complications, and need for new procedures (p > 0.05).

CONCLUSION

Sub-Tenon injection of MMC is a safe and as effective as the conventional soaked sponge method in trabeculectomies. This method reduces surgical time and sponge-related risks with equivalent surgical efficacy.

CLINICAL SIGNIFICANCE

As trabeculectomy is still the most common surgical procedure to reduce IOP and scar formation is one of the main causes of surgical failure, it is important to develop surgical techniques to improve its outcomes.

HOW TO CITE THIS ARTICLE

Guimarães MEV, de Pádua Soares Bezerra B, et al. Glaucoma Surgery with Soaked Sponges with Mitomycin C vs Sub-Tenon Injection: Short-term Outcomes. J Curr Glaucoma Pract 2019;13(2):50-54.

Wound Healing Modulation in Glaucoma Filtration Surgery-Conventional Practices and New Perspectives: The Role of Antifibrotic Agents (Part I)

Glaucoma filtration surgery is regularly performed for the treatment of glaucoma and trabeculectomy is often regarded as the ‘gold standard' glaucoma operation. The biggest risk of failure of the operation is bleb scarring. The advent of anti-fibrotic agents, such as mitomycin C (MMC) and 5-fluorouracil (5FU) has vastly prolonged the longevity of the bleb, but concerns remain regarding the potential increase in postoperative complications. More selective therapeutic targets have therefore been explored. One of these is vascular endothelial growth factor (VEGF) inhibition. Vascular endothelial growth factor inhi bition has a role not only in sub conjunctival angiogenesis inhi bition but also it has direct anti-fibrotic properties. Newer phar macological compounds and materials have also been developed in recent years in attempt to modulate the wound healing in different ways after glaucoma surgery. These include physical barriers to scarring and vehicles for sustained release of pharmacological agents, and early promising results have been demonstrated. This two-part review will provide a discussion of the application of anti-fibrotic agents in glaucoma filtration surgery and evaluate the newer agents that have been developed.

How to cite this article: Fan Gaskin JC, Nguyen DQ, Ang GS, O'Connor J, Crowston JG. Wound Healing Modulation in Glaucoma Filtration Surgery–Conventional Practices and New Pers pectives: The Role of Antifibrotic Agents (Part I). J Curr Glaucoma Pract 2014;8(2):37-45.

Peptide hydrogel as an intraocular drug delivery system for inhibition of postoperative scarring formation

A biocompatible hydrogel self-assembled from a peptide comprised of a peptide backbone containing Arg-Gly-Asp (RGD) sequence and a hydrophobic N-fluorenyl-9-methoxycarbonyl (FMOC) tail was designed and prepared to load antiproliferative model drug (5-fluorouracil, 5-Fu). After administering this 5-Fu-loaded peptide hydrogel in the filtering surgery of rabbit eyes, because of the sustained release of 5-Fu from the hydrogel to inhibit the scleral flap fibrosis efficiently, the pathology and immunohistochemistry demonstrate that the filtration fistula is patent without postoperative scarring formation, resulting in the significantly low intraocular pressure (IOP) of the rabbit eyes within postoperative 28 days. In a comparison with the conventional 5-Fu exposure, the strategy demonstrated here presents several advantages including providing convenience and preventing the toxicity of 5-Fu to the surrounding ocular tissues efficiently, suggesting a feasibility of this peptide hydrogel as a potential implanted drug delivery system for the inhibition of postoperative scarring formation.

Trabeculectomy surgery augmented with intra-Tenon injection of mitomycin C

PURPOSE

To describe a novel approach to mitomycin C (MC) application during trabeculectomy surgery and to report the 1-year results of surgery using this technique.

METHODS

One hundred and eight consecutive trabeculectomies and phaco-trabeculectomies using MC were performed by a single consultant surgeon, using a standardized technique. This technique involved injecting MC into the Tenon's layer during the procedure, rather than applying it directly to the under-surface of the conjunctiva.

RESULTS

Preoperative mean intraocular pressure (IOP) was 23.6 +/- 5.8 mmHg. Mean IOP 12 months following surgery was 12.2 +/- 3.9 mmHg. Seventy-six eyes (70.3%) had an IOP less than 2/3 listing IOP at 12 months without the need for anti-glaucoma medication. Ninety-three eyes (86%) had an IOP <21 mmHg, 79 (73%) had an IOP <16 mmHg and 62 (57%) had an IOP <14 mmHg without anti-glaucoma medication at 12 months. Transient complications included hyphaema, bleb leak and choroidal detachment in 14.8%, 5.6% and 15.7% of cases, respectively. Hypotony (defined as IOP <7 mmHg, excluding the first day postoperatively) was seen in 21.3% of cases. At 12 months, 21 eyes (19.4%) had cystic blebs and five (4.6%) had Tenon's cysts with an IOP greater than 20 mmHg.

CONCLUSION

A novel means of applying intraoperative MC is described. The 12-month outcome data show it to be an effective technique that compares favourably with others in the literature.

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.

Long-term effects of simultaneous subconjunctival and subscleral mitomycin C application in repeat trabeculectomy

PURPOSE

To assess the efficacy and safety of simultaneous mitomycin C application under conjunctival and scleral flaps in patients with repeat trabeculectomy.

METHODS

A total of 44 patients (44 eyes) with previous failed filtering surgery were randomized to one of two groups. The both-flaps group comprised 22 patients (22 eyes) with trabeculectomy and intraoperative mitomycin C application under conjunctival and scleral flaps, whereas the subconjunctival group comprised 22 patients (22 eyes) with subconjunctival application of mitomycin C. Particular attention was paid to intraocular pressure, postoperative medications, visual acuity, filtering bleb appearance, and complications. The mean follow-up time was 38.18 +/- 12.48 months.

RESULTS

The mean preoperative intraocular pressure decreased from 39.1 +/- 7.3 mm Hg to the postoperative level of 15.6 +/- 4.8 mm Hg in the both-flaps group (P = 0.014), and from 39.4 +/- 8.4 to 18.7 +/- 5.8 mm Hg in the subconjunctival group (P = 0.018). There was a statistically significant difference in intraocular pressure at all follow-up times, except at 1 week and 1 month postoperatively. Kaplan-Meier survival analysis showed there was no significant difference in total success rate (complete plus qualified success) between the two groups (P = 0.622, log-rank test). However, the two survival curves for the complete success subgroups (without additional medications) confirmed that mitomycin C applications under both flaps had a higher success rate than subconjunctival application (P = 0.043, log-rank test). No statistically significant difference in medications was present between the two groups, and no severe complications developed in either group.

CONCLUSIONS

Trabeculectomy augmented with mitomycin C application at both sites could produce a greater lowering of intraocular pressure with low incidence of postoperative complications, and could provide an increased chance of long-term success. The procedure is effective and safe in patients with repeat trabeculectomy.

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.

Simultaneous subconjunctival and subscleral mitomycin-C application in trabeculectomy

OBJECTIVE

To establish the efficacy and safety of simultaneous subconjunctival and subscleral application of mitomycin-C in trabeculectomy.

DESIGN

A prospective, randomized study.

PARTICIPANTS

Sixty-eight patients (68 eyes) with refractory glaucomas were included in the study.

INTERVENTION

Eyes were randomly assigned to receive intraoperative mitomycin-C (0.3 mg/ml) applied under the conjunctival flap (group 1), scleral flap (group 2), or under both flaps (group 3).

MAIN OUTCOME MEASURES

Mean intraocular pressure (IOP), postoperative medications, visual acuity, filtering bleb appearance, and complications.

RESULTS

There was a significant difference in IOP at 6, 9, and 12 months after surgery among the three groups (P = 0.021, 0.026, and 0.033, respectively ANOVA). At 12 months, the mean IOP in group 3 was 9.8+/-3.7 mm Hg compared with 13.4+/-5.5 mm Hg in group 2. (P = 0.015) and 12.4+/-4.4 mm Hg in group 1 (P = 0.039). Success rate (21 mm Hg or less), number of antiglaucoma medications, and complications showed no statistical significant difference between the three groups at each postoperative visit.

CONCLUSIONS

Mitomycin-C applied under the scleral flap may have an additional beneficial effect when combined with simultaneous subconjunctival exposure.

Nonpenetrating filtering procedures: viscocanalostomy and collagen wick

Unroofing of Schlemm's canal without entering the anterior chamber has been performed previously to lower intraocular pressure. Initial results were good, but long-term results were discouraging, and the techniques were abandoned. Recently, two variations have surfaced. Visco canalostomy is a technique devised by Robert Stegmann of South Africa. The glaucoma drainage device (Collagen Wick) was initially introduced by Koslov in Russia. These techniques are described in this article.

Nonpenetrating trabeculectomy with placement of a collagen drainage device

Since the advent of trabeculectomy with antimetabolite therapy, there have been few changes in the surgical management of glaucoma. This is the first report of a new technique, nonpenetrating trabeculectomy with placement of a collagen drainage device. The procedure facilitates aqueous drainage without entering the human eye. Meticulous surgical dissection of the trabecular meshwork is required with creation of an external filtration tract and subscleral positioning of a collagen device to facilitate aqueous drainage. With this procedure, the surgeon can avoid common complications of glaucoma surgery such as synechias, overfiltration, hypotony, intraocular infection, uveal prolapse, and failed surgical blebs. The procedure and device have been used extensively in Russia.

Mitomycin-C concentration in human aqueous humour following trabeculectomy

The aim of the study was to determine mitomycin-C (MMC) concentrations in human aqueous humour during trabeculectomy and to correlate anterior chamber concentrations with method of application. MMC was applied intra-operatively by saturating sponges, ranging in size from 2 x 2 x 5 mm to 2 x 4 x 10 mm on dry cut, with 0.5 mg/ml MMC during trabeculectomy for 3-5 minutes. Applications to episclera were made in 18 cases and to the scleral bed after scleral flap dissection in 9 cases. Aqueous samples were collected by paracentesis with a 30 gauge needle 2-7 minutes after removal of sponge and external irrigation. Aqueous MMC concentrations were determined by high-performance liquid chromatography. Aqueous MMC concentration in 27 samples ranged from below minimum detectable concentration (less than 5 ng/ml) to 120.8 ng/ml. Mean aqueous drug levels obtained when the applications were to the scleral bed were 35.65 +/- 39.17 ng/ml (range 5-120.8 ng/ml). Applications on episclera gave mean aqueous concentrations of 4.98 +/- 9.11 ng/ml (range 0-33.3 ng/ml). The difference was statistically significant (p = 0.004). There were no correlations between sponge size, time of MMC exposure and aqueous MMC level. In conclusion, MMC is detectable in aqueous humour within minutes of external application and the aqueous concentration level is higher if the application is in the scleral bed than on the episclera. Toxicity of the drug at this concentration range for corneal endothelial cells needs further investigation via in vitro and clinical studies.