Fiberoptic microcatheter-assisted 360-degree trabeculotomy ab externo is a recent technique. Retrospective studies have proved the effectiveness as a first-angle surgery in eyes with primary congenital glaucoma. However, there are no reports in which it is performed after another unsuccessful surgical procedure. We present our case of a monolateral congenital glaucoma. We first performed an ab externo trabeculotomy with poor control of intraocular pressure (IOP). Then, a microcatheter-assisted 360-degree trabeculotomy was performed with IOP lowering. Microcatheter-assisted 360-degree trabeculotomy supplies successful IOP lowering after another angle surgery procedure.