Their study included 107 patients of which 51 patients comprised the group without a mucosal flap and 56 patients comprised the group with mucosal flap preservation. Does Mucosal Preservation in Endonasal Dacryocystorhinostomy Improve Long-Term Success? With the expansion of endonasal techniques, endoscopic dacryocystorhinostomy (eDCR) has gained popularity over conventional open approaches over the last decade.