Background <p>Lacrimal canaliculus granuloma is an uncommon benign lesion of the lacrimal drainage system. This case is novel because it describes a lacrimal canaliculus granuloma caused by long-term retention of a suture that penetrated the canaliculus wall after double eyelid surgery—a complication not previously highlighted in the literature.</p> Case presentation <p>A 41-year-old female presented with a 7-day history of a growing mass in the medial canthal area of the right eye. Ophthalmic examination revealed a granulomatous mass protruding approximately 3&#xa0;mm from the right upper punctum. A clinical diagnosis of lacrimal canaliculus granuloma was made, and the patient underwent surgical treatment. Intraoperatively, a suture from prior double eyelid surgery was observed penetrating the canaliculus wall, with the pedicle of the granuloma tightly encasing the suture. The mass was excised, followed by canalicular reconstruction and lacrimal intubation. The patient recovered well postoperatively.</p> Conclusions <p>This case highlights that double eyelid surgery, if not performed according to strict operational standards, may cause injury to the lacrimal canaliculus and lead to complications. Clinicians should be aware of this rare but preventable condition.</p>