COMMENTARY

Amniotic Membrane or Mitomycin-C Trabeculectomy?

Shuchi B. Patel, MD

Disclosures

September 12, 2014

Viewpoint

Failure of trabeculectomy surgery as a result of fibrosis is one of the most common and frustrating complications of this gold standard procedure for the treatment of glaucoma. To reduce the amount of fibrosis, the use of an anti-fibrotic agent, such as MMC, has become widely accepted.[1] Unfortunately, although antifibrotic agents can reduce fibrosis and failure, the rates of bleb leaks and blebitis are higher when the surgical procedure is augmented with MMC.[2] Owing to the fact that MMC is an alkylating agent, over time the treated area may become completely avascular and thus more prone to these complications.

An agent that prevents fibrosis and achieves the same IOP reduction without causing the complications of MMC would be ideal. Alternatives that have been investigated include anti-vascular endothelial growth factor (VEGF) agents as well as space-occupying substances such as Ologen® (Aeon Astron; Leiden, The Netherlands). Some studies have found Ologen to have comparable success rates to MMC-augmented procedures,[3,4] whereas others have found Ologen to be suboptimal.[5] Similarly, success with using anti-VEGF agents has not provided the hoped-for optimistic results.[6] Therefore, there is still a need to investigate other alternatives to MMC.

Amniotic membrane may be an acceptable replacement to MMC; not only can it provide a space-occupying component, but it also may reduce fibrosis because it can suppress transforming growth factor.[7] The results of the study seem to support the use of amniotic membrane in lieu of MMC because the IOP-lowering results were comparable. Furthermore, assessment of bleb postoperatively demonstrated a more favorable morphology with AMT, with normal vascularity despite a diffusely elevated bleb. Although the study did not extend further than 24 months, the normal vasculature and conjunctival thickness should hopefully prevent later postoperative complications such as bleb leaks, blebitis, and endophthalmitis. On the other hand, it is possible that this could result in a higher rate of failure. Therefore, similar long-term studies should be carried out to determine whether amniotic membrane might be the future replacement for MMC.

The safety of amniotic membrane to the rest of the ocular structures is also a benefit that should not be overlooked. MMC can cause corneal toxicity as well as a potential for scleral melt or endothelial toxicity should it inadvertently enter the anterior chamber during the procedure. Use of amniotic membrane eliminates these potential risks. Amniotic membrane also does not pose any health risks to the surgical staff involved in the procedure and can be handled by or used in pregnant women. One drawback might be the cost of the membrane, which is significantly higher than the cost of MMC.

Once further long-term studies are done, the success rates should be balanced against the complications and cost restriction to determine whether amniotic membrane-augmented surgery will be the new gold standard.

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