Can antimetabolites in pediatric ages be used?

Fernando Trancoso Vaz, MD

Graduate Assistant/Consultant, Head of the Glaucoma Department of the Prof.Dr. Fernando Fonseca Hospital (Amadora-Lisbon), Amadora, Portugal.
Co-Autores: 
Susana Henriques, Ana Sofia Lopes, Diana Silva, Mafalda Mota, Maria Lisboa
Hospital Professor Doutor Fernando Fonseca, E.P.E.

Angle surgery (trabeculotomy or goniotomy) offers the best initial surgical option for most congenital glaucomas, with a success rate of 75% to 90%1,2. When this initial approach fails, filtration surgery/trabeculectomy, glaucoma drainage devices (GDD) or cyclodestruction can be used.

Trabeculectomy in children is particularly challenging due to the exuberant scarring response typical of these ages, bleb failure, and worst outcomes when compared to adults3. The use of antimetabolites as adjuvants in glaucoma surgery is important in modulating the natural healing process, thereby minimizing the risk of surgically induced drainage failure. Of all agents, mitomycin C (MMC) is the most widely used in children4. The MCC dose must take into account risk factors for surgical failure5. The benefit vs. risk profile6 should be assessed, as well as the long-term risk of developing bleb-related infections.

Despite their advantages, antimetabolites are also associated with a higher number of complications, both early, hypotony-related complications (anterior chamber collapse, hypotony maculopathy, choroid detachment, suprachoroidal hemorrhage), as well as late, bleb-related complications (leakage and infections). The Moorfields Safer Surgery (MSS) trabeculectomy7 introduces some modifications to the conventional technique, including a fornix-based conjunctival incision, adjustable/removable sutures and application of antimetabolites in a wider area, creating a more diffuse bleb. This increases procedural safety, thus reducing the potential for complications8,9. In a study10 in children under 2 years old, MMS trabeculectomy with MMC application resulted in 1-year and 7-year success rates of 78% and 60%, respectively, showing good long-term outcomes with low complication rates.

In addition to the use of MMC during surgery, subconjuntival injections of bevacizumab11 or Tenon's capsule excision12, which is thicker in children (with a potential increase in fibrosis associated with fibroblasts), can also increase surgery success, decrease filtering bleb encapsulation with better IOP control, and reduce the need for postoperative hypotensive drugs. Therefore, it is concluded that modified trabeculectomy (MSS)5,10,13, with fornix-based conjunctival incision, adjustable/removable sutures and antimetabolite application in a wider area, can be an effective and well-tolerated method for glaucoma surgical treatment in children.

 

4th Edition - June 2017