The almond shaped pair of glands located in the outer section of the orbit of each eye are known as lacrimal glands. They are responsible for producing tears that flow into the lacrimal sacs. These sacs have ducts connected to them that, release the tears into the surface of the eyes when a person cries. These tears enter the nose via nasolacrimal duct, due to allergic reaction or watery eyes. So, the lacrimal drainage system begins at the small orifices known as puncta that are found in the margins of the upper and lower eye lids. These minuscule openings lead into their own lacrimal ducts that join into the lacrimal sacs. So, whenever there is a blockage in the lacrimal drainage system, the duct is filled with fluid and this, leads to swollen and infected eyes. This condition is caused when the lacrimal duct that allows tears to drain the tears is obstructed. If medical attention is not sought, infection can set in. This condition is more commonly found in new born babies, for whom the tear ducts do not have an opening in the membrane that covers the former. In adults, the cause is attributed to a nose injury or sinusitis. Lacrimal probing is a procedure that is engage to evaluate the functioning of the lacrimal glands and to investigate blockage in the lacrimal drainage system.
Lacrimal probing is a procedure that involves usage of lacrimal probes, punctal dilator and an irrigating cannula. The surgical probe is inserted into the punctum of the lacrimal duct to clear the blockage. In the next step, a small tube containing water with a tracer chemical – fluorescein, is inserted into the duct. Ousting of the dye from the nasal cavity indicates that the probing is complete and successful.
Blockages in lacrimal drainage system is common in new borns. In some cases, the issues are self resolved by the time the child completes 12 months. However, if the blockage does not go away on its own, lacrimal probing is performed on the child, wherein the canaliculi and the nasolacrimal ducts are thoroughly investigated. General anesthesia is administered before the probing procedure is initiated. However, in case of dacryocystitis and acute canaliculitis, the probing procedure is not advised.
The other probing procedures include Diagnostic and Therapeutic probing. In diagnostic probing, the lower punctum is dilated using a punctal dilator. This allows the insertion of the lacrimal probe, which in the initial phase of the procedure, is small. The size of the probe is increased progressively to evaluate the size and the severity of the blockage. During the probing procedure, the probe intercepts lacrimal bone, clumping of tissues that could happen because of a canalicular obstruction or because of the traction of the tip of the probe. If an obstruction is intercepted at any point in the procedure, the probe tip is clamped at the punctum. Now, the probe is removed and the distance from the probe to the clamp is measured, before the treatment is commenced with.
Therapeutic probing involves usage of a vasoconstrictor – oxymetazoline hydrochloride to mitigate bleeding when the probe is inserted nasally. Once, the probe reaches into the lacrimal sac, the probe is rotated gently towards the superior orbital rim. From there, the probe is further pushed down into the nasolacrimal duct. On interception of any obstruction, the probe is withdrawn gently. This procedure is repeated until the probe has reached the inferior meatus of the nasal system. Now, a second instrument is inserted under the inferior turbinate of the nose gently. Once the instrument has made contact with the probe, irrigation procedure is lined up.
The patient is administered anaesthesia before the irrigation procedure. The punctum of the lower eye lid is dilated with the help of a punctal dilator. A lacrimal cannula with an attachment of a 3mL syringe filled with saline, is placed at the orifice of the canaliculus. The saline is further injected into the opening. For a patient who has no blockage in the lacrimal drainage system, can taste the saline in his or her nasopharynx. However, if there is a total canalicular blockage, the fluid is bound to reflux back through the punctum. But, if the saline refluxes back through the canalicular system, there is an indication of a nasolacrimal duct obstruction.
Lacrimal probing is very useful in assessing anomalies in the lacrimal drainage system such as, internal laceration, lacrimal tearing, congenital nasolacrimal duct obstruction and canalicular injuries. The causes of such blockage in the lacrimal drainage system could be caused by an external trauma. In case of obstruction in the nasolacrimal duct, the probing procedure aids in identifying the location of the blockage and its degree.
Every probing procedure contains risk of incurring damage to the lacrimal drainage system. Usually, the procedures are carried out after administering patients general or topical anaesthesia such as proparacaine.
Dr. Debraj Shome has been accredited with accolades for having operated on various aspects of Oculoplastic eyelid orbit surgery.