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Editors Selection IGR 22-3
Surgical Treatment: Scar prevention by Ologen implant?
Comment by Franz Grehn on:
25614 Trabeculectomy with OloGen versus trabeculectomy for the treatment of glaucoma: A pilot study, Papaconstantinou D; Georgalas I; Karmiris E et al., Acta Ophthalmologica, 2010; 88: 80-85
See also comment(s) by Sylvian Roy & André Mermoud •Control of wound healing following glaucoma filtration surgery is a pivotal contributor to long-term success or failure. The present routine of trabeculectomy uses a number of antiproliferative or vasoinhibitory drugs, such as Mitomycin C (MMC), 5-Fluorouracil (5-FU) or Bevacizumab for wound healing control. However, most antiproliferative agents can have considerable side effects. Therefore, better tolerated and more specific agents are urgently needed. Ologen™ is a biodegradable implant of scaffold Collagen-Glycosaminoglycan Matrix that is implanted into the surface of the sclera after trabeculectomy to inhibit scar formation. Ologen™ is advertised to degrade within approximately 90 days. The rationale of implanting this device is to inhibit fibroblast activity while aqueous can percolate in the spaces of the matrix (95% pores). The study of Papaconstantinou et al. (467) is a randomized prospective clinical pilot trial of trabeculectomy using Ologen™ versus a control group without Ologen™ in 40 eyes of 40 patients, 20 randomized to each group. No MMC or 5-FU during surgery was used in both groups. Follow-up was six months. Success was defined as IOP ≤21 mmHg and ≥6 mmHg without medication (complete success) or with additional medication (qualified success). Considering the height of the implant (four mm) a thorough wound closure of Tenon and conjunctiva seems mandatory. Two eyes of the study (Ologen™) group developed external fistulas resulting in flat anterior chamber which was repaired by additional conjunctival sutures. One eye of the study group developed endophthalmitis not related to the implant according to the report. Postoperative 5-FU injections to overcome encapsulation of the bleb were needed more often in the control group (five eyes) versus the study group (two eyes). No significant difference in resulting IOP between the study group and the control group could be found in the study at any follow-up time. The mean IOP was 15.3 mmHg in both groups after six months. Although this is somewhat higher than in trabeculectomy with MMC, one has to consider that the baseline IOP was higher in both groups (28.4 and 32.7 respectively) than in many other studies on trabeculectomy.
he use of a biodegradable collagen implant in filtering surgery has not proven superior to routine trabeculectomyHowever, the seemingly favourable result in the Kaplan-Meier graph with extremely low failure rate is biased by the selected success criterion of ≤21 mmHg, which is different from the recently published recommendatiosn of the Guidelines of the World Glaucoma Association suggesting an IOP reduction of ≥20-40% with an upper cut-off limit of 18 mmHg or less. There was no significant difference between the two groups regarding complications, number of medications and cataract surgery. One concern of the authors is the occurrence of one case of endophthalmitis and two cases of wound dehiscence in the Ologen™ group and the fact that in all cases the implant had only partly degraded at six-months follow-up different from the company's specifications. The authors conclude from their study that at present trabeculectomy with Ologen™ does not offer any significant advantages compared with trabeculectomy alone.
When analyzing the results of a novel surgical technique or an innovative medical device efficiency, safety and risk profile should be compared to the well established technique
In a recent poster presented at ARVO 2010 (607-A451) a randomised prospective comparison between phacotrabeculectomy Ologen™ versus MMC phacotrabeculectomy resulted in a considerably better IOP decrease in the MMC group (delta IOP 2.2 mmHg versus 8.0 mmHg in the Ologen™ and the MMC group, respectively). In the work-up of bleb structure, the Ologen™ material was retained in 40% of the cases and the blebs were more vascularized in the Ologen™ group according to the bleb grading system used. In summary, the use of a biodegradable collagen implant in filtering surgery has not proven superior to routine trabeculectomy at this time.
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