RESUMEN
A 69-year-old female presented with complaints of persistent watering in the left eye for the past 8 years. She underwent a left external dacryocystorhinostomy (DCR) 8 years ago. On examination, left lacrimal passage irrigation showed regurgitation of fluid from opposite punctum. She underwent a revision external DCR with bicanalicular intubation and a portion of fibrosed sac was sent for histopathological examination (HPE). HPE showed a Microfilarial worm with surrounding granulomatous inflammation. Polymerase chain reaction (PCR) on the DNA extracted from the specimen identified the species to be Dirofilaria repens. Dirofilariasis is an accidental zoonotic infection in humans. Due to its migration, the worm can affect ocular and periocular structures. There are two case reports of perilacrimal dirofilariasis. This is the first case to report a filarial worm in the lacrimal sac causing chronic inflammation which probably led to failure of DCR. Treatment of choice is the complete eradication of the worm. PCR aids in the identification of species.