In lacrimal-system probing, what is the primary use of a cannula?

The primary use of a cannula in lacrimal-system probing is to flush out a tear duct. This procedure involves the insertion of the cannula into the nasolacrimal duct to help clear any blockages that may be hindering the proper drainage of tears. By flushing the duct, the healthcare provider can help restore normal tear pathways and alleviate symptoms related to tear drainage issues, such as excessive tearing or dry eyes.

The design of a cannula allows for the introduction of saline or other solutions which can aid in washing out any obstructions and also ensure that the duct is patent (open). This is crucial in diagnosing conditions related to the lacrimal system and in providing effective treatment.

While removing a foreign body and administering anesthetics are important aspects of ophthalmic procedures, they are not the primary roles of a cannula in this context. Similarly, measuring intraocular pressure is a function associated with tonometry, not lacrimal system probing. Thus, the flushing capability of the cannula is vital for effectively managing and diagnosing tear duct obstructions.