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Editors Selection IGR 23-4

Surgical Treatment: Mitomycin C vs. Collagen Matrix: 2-year outcomes

Comment by Tanuj Dada on:

70854 Collagen matrix vs mitomycin-C in trabeculectomy and combined phacoemulsification and trabeculectomy: a randomized controlled trial, Tanna AP; Rademaker AW; De Moraes CG et al., BMC Ophthalmology, 2016; 16: 217

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The Ologen CM (Aeon Astron Europe) is a collagen-glycosaminoglycan co-polymer. Its biodegradable matrix is used to modulate wound healing in trabeculectomy by maintaining the subconjunctival space and guiding fibroblast proliferation through its porous structure to form a loosely organized scar.

Tanna et al. report two-year results of an RCT comparing outcomes of trabeculectomy using Ologen vs Mitomycin C. The study was sponsored by Aeon Aestron Europe and four of the authors declared competing interests . Both groups had similar success rates with higher rates of persistent hypotony in the MMC group. These results are in sharp contrast with previous publications where trabeculectomy with Ologen was associated with significantly poorer IOP outcomes.^1,2

The present study has several limitations. A very high dose of MMC (0.4 mg/ml) was used and the duration of exposure was not uniform. This could well be reason for higher hypotony rates in this group. Using a lower dose of MMC C (0.1-0.2 mg/ml) should have been adequate for eyes undergoing a primary trabeculectomy.³ The second variable is the suture tension, as the Ologen group had sutures adjusted to have a lower tension as compared to the Mitomycin C group, and would have resulted in lower IOPs. The third variable, attributed to be the main reason for higher success rates compared to other studies, is the size of the collagen matrix. The authors have used a 12 mm x 1 mm disc, and propose that this lowers the rate of fibrosis as compared to the 6 mm x 2 mm disc used in earlier studies. However, there is no evidence from literature to support this hypothesis and the present study was not designed to answer this question. Finally, the study did not define a target IOP based on the severity of glaucoma and it is unlikely that IOP in the low teens, as required for advanced glaucoma cases could be achieved with use of Ologen alone.

Evidence for the use of Ologen as an adjunct to trabeculectomy is still evolving

Trabeculectomy augmented by Ologen alone, may be a useful adjunct in eyes with a thin conjunctiva, early/moderate glaucoma where a low target IOP is not required and patients with previous history of Mitomycin C induced complications (bleb leak, hypotony, etc.), when the other eye is being operated. In eyes with a higher risk for filtration failure or eyes with advanced glaucoma , it may be prudent to use Ologen along with low dose Mitomycin C⁴ and/or use a dual approach with a small piece of implant under the scleral flap to maintain an aqueous lake.⁵ In summary, the evidence for the use of Ologen as an adjunct to trabeculectomy is still evolving and requires further well-designed RCTs before it can be placed as a universal alternative to Mitomycin C in trabeculectomy.

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