Ocular findings of multiple endocrine neoplasia type 2B (MEN 2B) include prominent corneal nerves, mucosal neuromas of the conjunctiva, glaucoma, and dry eyes. A 15-year-old girl with MEN 2B presents with advanced secondary open-angle glaucoma and bilateral perilimbal masses. High-resolution optical coherence tomography (HR-OCT) of the perilimbal lesions showed normal epithelial thickness and subepithelial lobular areas of mixed reflectivity, which correlates well with histopathologic findings of benign mucosal neuromas. The patient underwent bilateral gonioscopy-assisted transluminal trabeculotomy (GATT) in both eyes, which achieved adequate intraocular pressure control at short-term follow-up. To the authors' knowledge, this is the first report correlating HR-OCT and histopathologic findings in benign mucosal neuroma associated with MEN 2B, and the first description of secondary open-angle glaucoma associated with MEN 2B treated with GATT.