|Year : 2015 | Volume
| Issue : 2 | Page : 65-69
Comparison between trabeculectomy with Ologen implant and trabeculectomy alone in open-angle glaucoma
Tharwat H Mokbel1, Mohamed A El-Malah2, Hossam T Al-Sharkawy MD 1
1 Ophthalmology Center, Faculty of Medicine, Mansoura University, Mansoura, Egypt
2 Ophthalmology Department, Faculty of Medicine, Al-Azhar University, Cairo, Egypt
|Date of Submission||04-Apr-2015|
|Date of Acceptance||06-May-2015|
|Date of Web Publication||28-Oct-2015|
Hossam T Al-Sharkawy
Ophthalmology Center, Faculty of Medicine, Mansoura University, Elgomhoria Street, Mansoura 35516
Source of Support: None, Conflict of Interest: None
The aim of this study was to compare surgical outcomes of trabeculectomy with Ologen implant to trabeculectomy alone in terms of intraocular pressure (IOP), postoperative medications, bleb function, and postoperative complications in open-angle glaucoma.
Patients and methods
Setting : Mansoura Ophthalmic Centre and Al-Azhar University Hospital, Egypt. Design: Prospective study. Forty-two eyes of 30 patients with primary open-angle glaucoma (34 eyes, 80.95%) or pseudoexfoliation glaucoma (eight eyes, 19.05%) were included in this study. Twenty-one eyes were treated by subscleral trabeculectomy with a subconjuctival implant of Ologen over the closed scleral flap (Ologen or study group) and the other 21 eyes were treated by subscleral trabeculectomy alone (control group). One-year follow-up was completed for all eyes.
Preoperatively, the mean IOP was 29.51 ± 2.85 mmHg in the Ologen group and 30.64 ± 2.36 mmHg in the control group. Postoperative mean IOP was13.26 ± 2.45 mmHg in the Ologen group and 16.85 ± 3.56 mmHg in the control group (P = 0.031). The mean number of postoperative antiglaucoma medications in the Ologen group was 0.43 ± 0.59 compared with 1.06 ± 0.85 drugs in the control group (P = 0.005).
The new degradable collagen implant (Ologen) improves and normalizes filtering surgical wound healing with more loosely organized and healthy bleb tissue and better IOP control than blebs formed with trabeculectomy alone in primary open-angle and pseudoexfoliation glaucomas.
Keywords: intraocular pressure, Ologen, trabeculectomy
|How to cite this article:|
Mokbel TH, El-Malah MA, Al-Sharkawy HT. Comparison between trabeculectomy with Ologen implant and trabeculectomy alone in open-angle glaucoma. Delta J Ophthalmol 2015;16:65-9
|How to cite this URL:|
Mokbel TH, El-Malah MA, Al-Sharkawy HT. Comparison between trabeculectomy with Ologen implant and trabeculectomy alone in open-angle glaucoma. Delta J Ophthalmol [serial online] 2015 [cited 2017 Jun 27];16:65-9. Available from: http://www.djo.eg.net/text.asp?2015/16/2/65/168532
| Introduction|| |
Trabeculectomy operation was introduced by Cairns in 1968  . Nowadays, it is the most common operation for the treatment of glaucoma worldwide  . Mitomycin-C (MMC) and 5-fluorouracil were introduced more than 20 years ago to reduce wound healing and improve the surgical success of the trabeculectomy operation , .
The role of these antifibrotic agents is to inhibit fibroblast proliferation in the wound-healing process, thus preventing scar formation and bleb failure ,, . However, the use of antimetabolites increases the risks of bleb leakage, hypotonous maculopathy, endophthalmitis, and other many dangerous ophthalmic complications ,, .
Recent studies in animals reported that the use of a biodegradable collagen-glycosaminoglycan matrix (Ologen) implant in the subconjunctival space offers an alternative method for wound-healing modulation after glaucoma surgery. This material (Ologen implant) is composed of a three-dimensional disk-shaped porous structure that is implanted over the scleral flap before closure of the conjunctiva during a trabeculectomy operation , .
This implant aims at regulating aqueous flow by maintaining pressure on top of the scleral flap and by acting as a reservoir as aqueous becomes absorbed into its porous structure  . This implant should also prevent the collapse of the subconjunctival space and allows the creation of microcysts with collagen deposition  .
The aim of this study was to compare the surgical outcomes of trabeculectomy with an Ologen implant to trabeculectomy alone in terms of intraocular pressure (IOP), postoperative medications, bleb function, and postoperative complications in open-angle glaucoma.
| Patients and methods|| |
A prospective randomized clinical study was carried out. The study included 42 eyes of 30 patients (34 eyes, 80.95%, with primary open-angle glaucoma and 8 eyes, 19.05%, with pseudoexfoliation glaucoma) who were not controlled medically and required subscleral trabeculectomy at Mansoura Ophthalmic Centre and Al-Azhar University Hospital, Egypt between July 2012 and June 2013. Twenty-one eyes were treated by trabeculectomy with a subconjuctival implant of Ologen over the closed scleral flap (Ologen or study group) and the other 21 eyes were treated by trabeculectomy alone (control group). Ologen is a collagen matrix of 1% collagen/C-6-S copolymer (OculusGen Biomedical Inc., Taipei, Taiwan). The selected size is the recommended size by the manufacturer, which is round and disk shaped with a diameter of 7 mm and a height of 4 mm for all cases [Figure 1].
|Figure 1: Collagen– glycosaminoglycan matrix used in the study, 7.0 ± 0.5 mm (diameter), 4 ± 0.3 mm (h eight)|
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The preoperative assessment included measurement of best-corrected visual acuity, slit-lamp examination, anterior chamber angle evaluation, fundus biomicroscopy, visual field testing, and optical coherence tomography. IOP was measured using a calibrated Goldmann applanation tonometer (Haag-Streit, Koeniz, Switzerland), and numbers of antiglaucoma medications were recorded. Exclusion criteria were a history of previous ocular surgery or uveitis, pregnancy, normal tension, closed angle, and other secondary glaucomas.
All surgeries were performed by two surgeons using identical techniques. After local (peribulbar anesthesia) and betadine preparation, a superior rectus bridle suture using 6-0 silk was taken and then a limbal-based conjunctival flap 8 mm from the limbus was fashioned. Good dissection of the Tenon's capsule was performed with mild episcleral cauterization. Half-thickness scleral flap dissection 4 × 3.5 mm, paracentesis, trabecular meshwork block removal 2 × 1.5 mm, peripheral iridectomy, and closure of the scleral flap using 10-0 silk sutures were performed.
Ologen implant was applied over the scleral flap before closure of Tenon's capsule and conjunctiva in 21 eyes of the study (Ologen or study group). Closure of Tenon's capsule and conjunctiva was performed in two separate layers using 8-0 virgin silk sutures. Postoperative treatment in the form of topical antibiotics, corticosteroids, and mydriatic eye drops was administered for all eyes. One-year follow-up was performed for all eyes as follows: first postoperative day, 1 week, 2 weeks, 1 month, 3, 6, and 12 months. At each postoperative visit, the examination included measurement of best-corrected visual acuity, IOP measurement using the same calibrated applanation tonometer, slit-lamp biomicroscopy assessment of cell and flare, bleb evaluation, and funduscopy. Any complication was recorded at the end of each examination. Statistical analysis was carried out using the SPSS program (version 15.0; SPSS Inc., Chicago, Illinois, USA) for demographic data; preoperative and postoperative data which were analyzed using Student's t-test.
| Results|| |
All patients included in this study completed the period of follow-up (1 year). There was no statistically significant difference between the two groups in demographic data, preoperative IOP, or the number of preoperative antiglaucoma medications as shown in [Table 1]. No intraoperative complication was recorded in either group.
[Table 2] shows the postoperative IOP in both groups at all postoperative visits. There was no statistically significant difference in the mean IOP between the two groups at 1 day, 1 week, and 12 months, whereas it was significantly less in the Ologen group at 2 weeks, 1 month, 3 months, and 6 months.
The mean IOP in all postoperative visits was calculated in each group, and as reported in [Table 3], the mean IOP in the Ologen group was 13.26 ± 2.45 mmHg, whereas in the control group, the mean IOP was 16.85 ± 3.56 mmHg (P = 0.031). The mean of last visit IOP for the Ologen group was 14.06 ± 1.91 mmHg and that for the control group was 18.69 ± 3.05 mmHg. In terms of the number of postoperative antiglaucoma medications, in the Ologen group, the mean was 0.43 ± 0.59 compared with 1.06 ± 0.85 drugs in the control group (P = 0.005).
The rate of success was 20/21 eyes (95.24%) in the Ologen group as the Ologen matrix was removed in one eye that had a complication of severe hypotony, despite interventions in the form of a viscoelastic injection in the anterior chamber twice and tightening of the sutures of the scleral flap. In the control group, the rate of success was 17/21 eyes (80.96%) as there were 3/21 eyes (14.29%) with encapsulated bleb with high IOP and flat bleb in 1/21 eye (4.76%) with high IOP at the 6-month follow-up visit, despite different methods of interference.
Postoperative complications in both groups are reported in [Table 3]. In the Ologen group, two eyes 2/21 (9.52%) developed a complication of severe hypotony with a flat anterior chamber; an intervention in the form of a viscoelastic injection was performed for both. One eye responded and the other eye did not respond even with repeated injections of viscoelastic, until Ologen was removed with multiple sutures of the scleral flap. Transient shallowing of the anterior chamber was observed in 5/21 eyes (23.81%), which improved within a few days postoperatively. Hyphema was recorded only in 3/21 eyes (14.29%) and resolved within 2-3 days postoperatively. Cataract progression was reported in 2/21 eyes (9.52%), but as it was low grade, no intervention was performed. No other major complications such as endophthalmitis, bleb leakage, or encapsulated bleb were encountered.
Postoperative complications in the control group included hypotony in 2/21 (9.52%) with a shallow anterior chamber; one eye showed improvement with conservative treatment, whereas the other eye required aviscoelastic injection in the anterior chamber. Hyphema was reported in 3/21 eyes (14.29%); it was transient and disappeared gradually within a few days postoperatively. Bleb encapsulation was reported in 3/21 eyes (14.29%), which led to increased IOP that failed to return to normal levels despite multiple 5-fluorouracil injections. Flat bleb with high IOP was reported in 1/21 (4.76%) eye at the 6-month follow-up visit. Cataract progressed in 2/21 (9.52%) and these were planned for phaco at the end of follow-up. No endophthalmitis or bleb leakage was reported in the group.
[Figure 2] shows serial photos of the conjunctival bleb with Ologen postoperatively after 1 week [Figure 2]a), 3 weeks [Figure 2]b), 6 months [Figure 2]c), and 12 months [Figure 2]d). The bleb appears elevated, diffuse, polycystic, and relatively avascular.
|Figure 2: Bleb with Ologen; (a) after 1 week, (b) after 3 weeks, (c) after 6 months, and (d) after 12 months. Note the elevated diffuse polycystic relatively avascular bleb|
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| Discussion|| |
It is known that postoperative scarring is a major problem compromising postoperative surgery success in a trabeculectomy operation  . Wound healing and scar formation could cause fibrosis and obstruction of aqueous outflow, which is one of the most common reasons for the failure of glaucoma surgery ,, .
Since the introduction of MMC in 1990, there has been significant improvement in the rate of success, but adverse effects such as cataract formation, avascular filtering blebs, thinning of the conjunctiva, blebitis, and endophthalmitis have increased [14, 18, 19]. Other antiscar agents such as growth-factor inhibition and amniotic membrane have been used to enhance the rate of success of glaucoma surgery, with limited results , .
The Ologen implant is a possible alternative to antimetabolite use in trabeculectomy surgery because of its modulatory effect on wound healing. The aim of this porous collagen polymer is to enable random proliferation of fibroblasts through the collagen matrix, hence decreasing collagen deposition and scarring. Hisu et al.  suggested that Ologen degradation time was about 30-60 days, but Boey et al.  found that the Ologen implant residue was still present in up to 40% of patients at 90 days.
The clinical applications of Ologen have been presented at conferences (European Congress of Ophthalmology, Vienna, June 2007 and world glaucoma congress, Singapore, July 2007)  . Dimitris et al.  concluded that there were no statistically significant differences between trabeculectomy and trabeculectomy with Ologen in terms of the mean postoperative IOP, the mean number of antiglaucoma drugs, and postoperative complications. The present study found that the mean postoperative IOP was more controlled by trabeculectomy with Ologen than the control group. At the same time, the mean postoperative antiglaucoma drugs and complications were lower in the Ologen group than in the control group.
Recent experimental studies , have shown that the use of antiscar materials such as a solid hyaluronic acid-carboxymethyl cellulose film (Seprafilm) significantly reduced postoperative conjunctival-scleral adhesion. In this study, Ologen implant was used to get the same principle of antiscarring effect.
Although more studies with large sample designs are necessary to evaluate the effectiveness of Ologen matrix with a trabeculectomy operation, this study has reported a high success rate in comparison with trabeculectomy alone at the 1-year follow-up. Rosentreter et al.  , in a recent study, has reported that Ologen was effective and enabled scarring regression. Another study  reported a nonsignificant difference in postoperative IOP after trabeculectomy with Ologen and sole trabeculectomy. In the current study, no postoperative infection, and no implant extrusion or conjunctival erosion was reported, which is the same as reported in a previous study  .
In comparison with trabeculectomy with MMC, it was found that MMC was more effective on conjunctival healing, resulting in marked reduction of fibrosis and transparent polycystic blebs, but with a high incidence of complications  . In this study, no case of endophthalmitis was reported with Ologen whereas in another study  , the authors reported one case of endophthalmitis, but after culture, it was found that it was not because of Ologen. The limitations of this study are the small sample size of the patients included and the short duration of follow-up.
| Conclusion|| |
This new degradable collagen implant (Ologen) improves and normalizes filtering surgical wound healing with more loosely organized and healthy bleb tissue and better IOP control than blebs formed with trabeculectomy alone in primary open-angle and pseudoexfoliation glaucomas.
| Acknowledgements|| |
Conflicts of interest
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[Figure 1], [Figure 2]
[Table 1], [Table 2], [Table 3]