|Year : 2015 | Volume
| Issue : 2 | Page : 70-76
Trabeculectomy augmentation in primary open-angle glaucoma: Mitomycin-C versus Ologen implant
Tamer I Salem1, Tarek N Attia1, Salah A Mady MD 1, Asaad A Ghanem2
1 Department of Ophthalmology, Faculty of Medicine, Banha University, Banha, Egypt
2 Mansoura Ophthalmic Center, Faculty of Medicine, Mansoura University, Mansoura, Egypt
|Date of Submission||21-Mar-2015|
|Date of Acceptance||13-Jun-2015|
|Date of Web Publication||28-Oct-2015|
Salah A Mady
Ophthalmology Department, Faculty of Medicine, Banha University, Banha 35516
Source of Support: None, Conflict of Interest: None
Trabeculectomy is the most commonly performed surgical intervention to reduce intraocular pressure (IOP) for medically uncontrolled glaucoma. Different augmentation procedures have been proposed to increase success rate and reduce postoperative complications.
The aim of this study was to evaluate the results of different augmentation procedures used with trabeculectomy in patients with primary open-angle glaucoma.
Patients and methods
The study included 60 patients. Patients were randomly divided into three groups: the first group underwent trabeculectomy with low-dose mitomycin-C (MMC) (0.1 mg/ml); the second group underwent trabeculectomy with collagen matrix implant (Ologen) TM; and the third group underwent trabeculectomy with both low-dose MMC and Ologen implant. IOP was the primary outcome measure and the target level was set at less than 18 mmHg. Secondary outcome measures included bleb evaluation, number of glaucoma medications, and frequency of postoperative adjunctive procedures and complications.
Postoperatively, there was a significant decrease in IOP in all studied groups when compared with their corresponding preoperative values, and there was no significant difference between the studied groups at any point of time except at 1 month, when there was a significant decrease in IOP in the MMC group compared with the Ologen or Ologen plus MMC groups. In addition, the Ologen plus low-dose MMC group had better bleb scoring. There was no significant difference between the groups as regards complications. The success was complete in 46 cases (76.7%), and qualified success was reported in 14 cases (23.3%). Complete success was equally reported in the MMC group and in the Ologen plus MMC group (85.0%), whereas it was 60.0% in the Ologen group.
Both MMC and Ologen appear to be safe, effective, and promising as augmentation procedures with trabeculectomy in patients with primary open-angle glaucoma.
Keywords: mitomycin-C, Ologen, primary open-angle glaucoma, trabeculectomy
|How to cite this article:|
Salem TI, Attia TN, Mady SA, Ghanem AA. Trabeculectomy augmentation in primary open-angle glaucoma: Mitomycin-C versus Ologen implant. Delta J Ophthalmol 2015;16:70-6
|How to cite this URL:|
Salem TI, Attia TN, Mady SA, Ghanem AA. Trabeculectomy augmentation in primary open-angle glaucoma: Mitomycin-C versus Ologen implant. Delta J Ophthalmol [serial online] 2015 [cited 2018 Oct 22];16:70-6. Available from: http://www.djo.eg.net/text.asp?2015/16/2/70/168534
| Introduction|| |
Glaucoma is one of the most common and dangerous eye disorders. It is defined as a multifactorial optic neuropathy with a characteristic acquired atrophy of the optic nerve and loss of the retinal ganglion cells and their axons, with subsequent characteristic visual field defects. Many hemodynamic factors (e.g. ocular blood flow and ocular perfusion pressure) have been reported to be associated with the development of glaucoma  . Intraocular pressure (IOP) remains the only modifiable factor that could be controlled by means of different treatment modalities, such as topical eye drops, laser procedures, and surgical intervention. Surgery is resorted to when maximum tolerated medications and laser therapy fail to control the progression of glaucomatous optic neuropathy  .
Trabeculectomy is the most commonly performed surgical intervention to reduce IOP for medically uncontrolled glaucoma since its introduction in 1968  . The most common cause of surgical failure in such cases is the scarring at the level of the conjunctiva-Tenon's-episcleral interface, the scleral flap, its overlying episclera, or the internal ostium  . The introduction of the antifibrotic mitomycin-C (MMC) and 5-fluorouracil - in the early 1990s - has improved the surgical outcome  . However, antifibrotics had significant complications (e.g. hypotony, cataract formation, avascular filtering blebs, thinning of the conjunctiva, subsequent blebitis, and endophthalmitis) ,, .
These adverse effects seen with antifibrotic agent application have been related to the dose and exposure time , . Different studies have shown that MMC-related complications, especially hypotony and cataract, are more common with increased concentration and longer exposure times , .
Different modifications of the surgical procedure to reduce the risk for such complications have been developed. These surgical modifications included the use of glaucoma drainage devices, deep sclerectomy, and viscocanalostomy ,,, . In addition, different medications were used to reduce bleb fibrosis; these included systemic anti-inflammatory fibrosis suppression agents (oral prednisone, colchicine, and NSAIDs) for 4-6 weeks during the postoperative period , .
As an alternative augmentation in trabeculectomy, with success rate comparable to MMC, a biodegradable implant has been developed. It includes a combination of a polymer scaffold with a population of stem, progenitor, or precursor cells with subsequent development of structures, which are similar to normal tissue  .
A porous collagen-glycosaminoglycan matrix (Ologen) has been tested in animal models and it had been reported to prevent the collapse of the subconjunctival space. Random collagen deposition and microcyst formation after trabeculectomy have been shown in the Ologen group , compared with negative controls. The most common advantage of the biodegradable implant is the decrease in early postoperative scarring  . Thus, it can maintain normal IOP for a long time after filtering surgery, provided it confers a comparable reduction in IOP. Another prospective preliminary study showed no significant difference in the postoperative IOP after trabeculectomy in the control group and trabeculectomy with Ologen in the study group  .
The aim of the present study was to evaluate the results of different augmentation procedures used with trabeculectomy in patients with primary open-angle glaucoma.
| Patients and methods|| |
The present study included 60 patients who presented with primary open-angle glaucoma. They were selected from the Ophthalmology Department, Banha Faculty of Medicine, during the period from January 2012 to June 2013. The study protocol was approved by the local Ethical Committee (Banha Faculty of Medicine), and all patients provided an informed written consent for participation in the study. Patient's confidentiality and their right to discontinue at any time of the study were ascertained.
Adult patients with primary open-angle glaucoma, patients 18 years or older, those with an IOP above 21 mmHg or progressive visual field deterioration on maximum-tolerated medical therapy, those with visual field defects, and those with glaucomatous optic disc with cupping were included in the present study.
Patients with closed-angle glaucoma, normal tension glaucoma, post-traumatic or any form of secondary glaucoma, the use of systemic or ocular medications that might affect vision, acute or chronic disease that could confound the outcomes of the study (e.g. immunodeficiency, connective tissue disease, and diabetes), clinically significant cataract for which combined surgery was indicated, patients with previously operated glaucoma, and those with previous vitroretinal surgery were excluded from the study.
For each patient, only one eye was operated and included in the present study. Patients were randomly assigned to one of the three equal groups: the first group included 20 participants (eyes) who underwent trabeculectomy with 0.2 mg/ml MMC solution for 4 min; the second group included 20 participants (eyes) who underwent trabeculectomy with Ologen (Aeon Astron Europe B.V., Leiden, the Netherlands) implant as an augmentation; and the third group included 20 participants who underwent trabeculectomy with both low-dose MMC and Ologen implant as an augmentation.
Randomization was carried out by means of allocation of the patient's number to one of the studied groups, and the allocation paper was enclosed in a closed envelope that was opened just before surgical intervention by a nurse (not included in the study).
The preoperative data were age, sex, medical history (presence of any ocular pathology and number of antiglaucoma medications), and measurement of IOP using applanation tonometry under maximum-tolerated topical therapy, slit-lamp, biomicroscopy, and computerized Humphrey visual field testing.
All procedures were performed under local peribulbar anesthesia by the same surgeon.
The technique started with a fornix-based conjunctival/Tenon's flap with a 9-mm limbal conjunctival incision using Westcott scissors. Cauterization of the episcleral vessels was carried out and then a rectangular 3.0 × 3.5 mm-wide, 300-μm-thick scleral flap was created at the 12-o'clock position using a bevel-up crescent knife. The scleral flap on 3.0 mm side incisions were not completed up to the limbus. This should encourage greater posterior aqueous flow and a more diffuse bleb, according to the 'Moorfields Safer Surgery System'  .
In the MMC-augmented group, a Weck-cell sponge was cut into two to three pieces, 4 × 2 × 0.5 mm, soaked with MMC at a concentration of 0.1 mg/ml and placed under the dissected conjunctiva surrounding the scleral flap and on the scleral bed. The sponges were left in position for 1 min to maintain contact with the Tenon's capsule side of the conjunctiva. Thereafter, the eye was irrigated with 15 ml of normal saline.
An ophthalmic viscoelastic was injected to increase the iris-cornea depth, and anterior chamber was entered at the base of the scleral flap with a 3.2 precalibrated knife. Two semicircular excisions of 1.5 mm in diameter were created along the same radial line to obtain an excision of corneoscleral tissue including the trabecular meshwork. A peripheral iridectomy was then performed, followed by reinjection of a viscoelastic into the anterior chamber. The scleral flap was closed with two 10-0 nylon sutures, one at each corner, applying minimal tension in MMC cases and with one loose stitch in Ologen cases , .
In the Ologen (OLO) group, a cylindrical implant with a diameter of 7 mm and a height of 4 mm [Figure 1] was centered on top of the scleral flap and under the conjunctiva. The conjunctival flap was secured to the limbus with two 10-0 nylon single-stitch tensioning sutures at the extremities of the limbal incision plus a tight 10-0 nylon running suture with buried knots. The filtration was assessed by injecting balanced salt solution into the paracentesis.
|Figure 1: Cylindrical implant with a diameter of 7 mm and a height of 4 mm|
Click here to view
In the combined group, after irrigation with normal saline, a 3.0 × 3.5 mm sclerectomy was performed, followed by a peripheral iridectomy. The scleral flap was repositioned and closed with one interrupted suture of 10-0 monofilament nylon. Ologen implant was positioned on top of the scleral flap without the use of any suture. Finally, the conjunctiva was closed with an 8-0 polyglactin vicryl suture.
Postoperative treatment included a topical tobramycin 0.3% five times daily for 14 days and topical dexamethasone drops 0.1% five times daily for 7 days, three times daily for 6 weeks, and twice a day for a final 1 week. If corkscrew bleb vessels were present, more frequent topical steroid administration was allowed, according to the 'intensified postoperative care' protocol  . In case of hypotony, 1% atropine drops were administered in the first week.
Postoperative evaluation was scheduled at the end of first week, first month, 3 months, 6 months, and 12 months. It included assessment of anterior chamber depth, need for ocular massage, and additional IOP-lowering medications.
IOP was the primary outcome measure and the target level was set at less than 18 mmHg. Complete success was defined as a target endpoint IOP without antiglaucoma drugs; qualified success was defined as a target endpoint IOP regardless of medications; and failure was defined as an IOP greater than 21 mmHg not responding to the medications.
Measures included bleb evaluation, number of glaucoma medications, and frequency of postoperative adjunctive procedures and complications. Bleb evaluation was carried out using the bleb classification score, which consisted of three parameters: avascularity, corkscrew vessels, and microcysts of the bleb  .
Complications were defined as follows: encapsulated filtering bleb (Tenon's cyst), shallow anterior chamber, hyphema, ablation of the choroidals (e.g. choroidal effusion), persistent leakage, hypotony (IOP <6 mmHg), macular edema, corneal complications, allergy, suprachoroidal hemorrhage, and blebitis/endophthalmitis.
| Results|| |
The results of the present study are presented in [Table 1] [Table 2] [Table 3]. The age ranged from 18 to 72 years. Of the studied cases, 38 cases (63.3%) were male and 22 cases (36.7%) were female. In addition, 34 cases (56.7%) were operated on the right side and 26 cases (43.3%) were operated on the left side. Preoperative IOP ranged from 24 to 35 mmHg, and preoperative medication number ranged from two to four drugs. Duration of preoperative therapy ranged from 2 to 5 years. There was no significant difference between the studied groups as regards these parameters [Table 1].
|Table 2 Postoperative intraocular pressure and bleb scoring in the studied cases (mmHg)|
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Postoperatively, there was a significant decrease in IOP in all studied groups when compared with their corresponding preoperative values. There was no significant difference between the studied groups at any point of time except at 1 month, when there was a significant decrease in IOP in the MMC group compared with the Ologen or the Ologen plus MMC group.
In addition, there was a significant decrease in avascularity bleb scoring and significant increase in corkscrew vessels and microcysts in the MMC group in the first 2 weeks postoperatively, and gradually faded in the following weeks to be nearly normal after 4 months [Figure 2]a-c) compared with the other two groups. Collectively, the Ologen plus low-dose MMC group had better bleb scoring [Table 2].
There was no significant difference between the groups as regards complications: hyphema was reported in three cases (two in the MMC group and one in the Ologen group); shallow anterior chamber was reported in five cases (one in the MMC group, two in the Ologen group, and two in the Ologen plus MMC group); leakage was reported in eight cases (two in the MMC group, four in the Ologen group, and two in the Ologen plus MMC group). Finally, Tenon's cyst was reported in one case (it was in the MMC group).
No case reported hypotony or needed revision surgery. The success was complete in 46 cases (76.7%), and qualified success was reported in 14 cases (23.3%). Complete success was equally reported in the MMC group and in the Ologen plus MMC (85.0%), whereas it was 60.0% in the Ologen group [Table 3].
| Discussion|| |
Achieving and maintaining good IOP control is the main aim of trabeculectomy in primary open-angle glaucoma. Several augmentation modifications (e.g. antimetabolites, amniotic membrane transplantation, and expanded polytetrafluoroethylene (Gore-Tex) implants have been tried ,,,,, .
The present study was designed as a trial to examine the better augmentation method with trabeculectomy operation in primary open-angle glaucoma. Findings of the present study revealed that MMC in the standard dose was the best one to reduce postoperative pressure at 1 month postoperatively. The effect was not continued for the next 11 months of follow-up, and the Ologen plus low-dose MMC group had better bleb scoring. No significant difference was found between the groups as regards postoperative complications or success rate. No cases reported hypotony or revision surgery.
In the published literature, only one method is compared with a control or to another method; no studies were found - according to the researchers' best knowledge - comparing more than two techniques.
The rationale behind antifibrotic substances (such as MMC) is that it has postoperative antiscarring effect. Hence, it increases the rate of surgical success  . However, the use of MMC in trabeculectomy had some side effects (e.g. cataract formation, avascular filtering blebs, conjunctival thinning, blebitis, and endophthalmitis) , . Thus, there is a need to search for the development of less-toxic agents and implants to inhibit cicatrisation without adverse effects. Biodegradable, tissue-engineered implants may form this substitute. These substances involve a combination of a polymer scaffold with a population of stem, progenitor, or precursor cells. Tissue growth is modeled to favor the development of a particular structure and, if the polymer scaffold used is biodegradable, can result in the formation of structures, which are similar to normal tissue  .
In one study, Ologen implant was used for augmentation in deep sclerectomy. It revealed that deep sclerectomy with Ologen implantation is an effective and well-tolerated method for reduction of IOP  . In addition, another pilot study revealed nonsignificant differences in postoperative IOP after trabeculectomy with Ologen and sole trabeculectomy  . These two studies reflected the effectiveness of Ologen implant in reducing postoperative IOP.
In a subsequent study, Rosentreter et al.  reported that trabeculectomy with an Ologen implant is a safe method for penetrating glaucoma surgery. They did not report any Ologen-specific side effects (e.g. translocation of the implant or erosion of the conjunctiva). No allergy was detected and corkscrew vessel scores were comparable in the MMC and Ologen groups. More recently, Cillino et al.  found no significant difference in the postoperative behavior between the MMC and Ologen groups, with a highly significant and stable IOP reduction and very few antiglaucoma medications throughout the 24-month follow-up, indicating that the efficacy of the Ologen implant is analogous to MMC.
Consistent with the results of the present study, Marey et al.  reported that both MMC and Ologen implant decreased IOP significantly than the preoperative levels. However, follow-up visits showed that MMC reduced IOP to lower levels compared with Ologen but the difference was statistically insignificant.
On comparing the bleb scoring, the Ologen plus low-dose MMC group had better bleb scoring compared with the MMC or Ologen groups. This is a very valuable effect that can support the use of both low-dose MMC with Ologen implants as an augmented procedure in trabeculectomy for primary open-angle glaucoma. However, the present study has the limitation of the small sample size. Thus, it is necessary to perform subsequent studies with a large number of eyes.
| Conclusion|| |
Ologen implant alone is less effective compared with MMC alone in reducing postoperative IOP and success rate. However, the difference is statistically insignificant. Combining both MMC and Ologen appears to be safe, effective, and promising as an augmentation procedure in trabeculectomy, but the results need to be confirmed in subsequent studies.
Ologen implant is a successful adjunct to glaucoma surgeries. Intraoperative and postoperative precautions should be taken to maintain proper aqueous drainage, functioning blebs, and better degree of success, reaching the target IOP and a stable visual field.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2]
[Table 1], [Table 2], [Table 3]