dacryocystography

Dacryocystography (DCG) is a radiographic imaging technique used to visualize the lacrimal drainage system, including the lacrimal sac and the nasolacrimal duct, after the introduction of radiopaque contrast into the tear drainage pathway. It is typically performed to assess suspected nasolacrimal duct obstruction (NLDO) and other causes of epiphora, as well as to plan or diagnose issues related to the lacrimal apparatus.

The procedure generally involves topical anesthesia and cannulation of the punctum with a lacrimal cannula. A nonionic iodinated contrast agent is slowly injected while fluoroscopic radiographs or cinefluoroscopy are obtained to outline the lacrimal sac and duct. Dynamic imaging during blinking can help evaluate drainage. In some settings, CT dacryocystography (CT-DCG) or MR dacryocystography (MR-DCG) may be performed, providing cross-sectional or multiplanar views and better assessment of surrounding structures and intranasal pathology.

Interpretation focuses on the patency of the lacrimal drainage system. Normal DCG shows filling of the lacrimal sac and the entire nasolacrimal duct. Obstruction is suggested by nonopacification distal to the suspected site, with possible reflux of contrast into the puncta or lacrimal sac. DCG can also identify strictures, diverticula, or redundant ducts and may help distinguish true NLDO from functional epiphora.

Risks are generally minor and include discomfort, allergic reaction to contrast, infection, and radiation exposure. DCG is increasingly complemented or replaced by CT- or MR-based dacryocystography in many centers for enhanced anatomic detail.