[CT dacryocystography: normal findings and pathology].

CT dacryocystography, performed under sterile technique and following local anesthesia, is well tolerated by patients. It is the imaging technique of choice in patients with persistent tearing following clinical examination with non-invasive procedures when patency of the lacrimal drainage system remains uncertain, when a dacryolith or tumor is suspected or following unsuccessful dacryocystorhinostomy. Two techniques are available: instillation or direct cannulation, either initially or after non-visualization of the nasolacrimal system after contrast instillation. Non-specific idiopathic stenosis at the mid portion of the nasolacrimal duct is the most frequent etiology in patients over 50 years old; dacryoliths are present in 5 to 20% of cases of nasolacrimal duct stenosis. CT dacryocystography also allows evaluation of surrounding structures (medicolegal) to identify variants and anomalies when surgery is contemplated to avoid potential complications.