Lacrimal Syringing and Probing

This article will guide you in understanding the lacrimal punctal dilation, lacrimal probing, lacrimal syringing, and the nuanced art of interpreting their results.

Table of Contents

WHAT IS LACRIMAL SYRINGING?

Lacrimal syringing, a diagnostic procedure involving the infusion of saline into the nasolacrimal apparatus through the puncta, serves as a critical tool in assessing the patency of the tear drainage pathway.

INDICATIONS OF SYRINGING

The procedure finds its utility in a spectrum of scenarios:

Identification of Blockages: Lacrimal syringing helps rule out blockages in the lacrimal drainage system. It is instrumental in pinpointing the specific site of obstruction, whether it’s at the canaliculus, common canaliculus, or nasolacrimal duct.
Preoperative Assessment: Before intraocular surgeries like cataract or glaucoma procedures, lacrimal syringing becomes paramount. Clearing potential blockages is crucial as these could lead to complications such as dacryocystitis. A blocked lacrimal drainage system can cause a buildup of tear secretion, leading to infections within the apparatus. More ominously, it could result in endophthalmitis if a patient with dacryocystitis undergoes intraocular surgery.
Dacryocystography and Drug Administration: Lacrimal syringing is a versatile procedure. In dacryocystography, it can be employed to inject dye for imaging purposes. Additionally, it serves as a route for drug administration, showcasing its adaptability in diverse clinical scenarios.

Understanding the anatomical structures involved, such as the puncta, canaliculus, common canaliculus, lacrimal sac, nasolacrimal duct, and the opening guarded by the wall of Hasner, is crucial for the effective execution of lacrimal syringing. You can learn more about anatomy of lacrimal apparatus here.

CONTRAINDICATIONS TO SYRINGING

Lacrimal syringing is contraindicated in the following situations:

Acute Dacryocystitis:
- Avoid syringing during active lacrimal sac inflammation or infection to prevent the spread of infectious agents. Also it is extremely painful for the patient .
Lacrimal Abscess:
- Syringing is not recommended in the presence of a lacrimal abscess to avoid serious discomfort to the patient
Acute Conjunctivitis:
- Contraindicated in cases of acute conjunctivitis to prevent the spread of infection from the conjunctiva.
Lacrimal Sac Stones:
- Avoid syringing when lacrimal sac stones are present to prevent pushing stones into the nasolacrimal duct.
Allergic Reactions:
- Patients with known allergies to syringing substances should not undergo the procedure to prevent allergic reactions.
False Passages or Anomalies:
- Contraindicated in cases of suspected false passages or anomalies in the lacrimal drainage system.
Patient Discomfort or Anxiety:
- Consider alternative diagnostic methods if the patient experiences significant discomfort or anxiety during syringing.
- Patient counseling is a must

The Significance of Lacrimal Punctal Dilation: Nettleship vs. Castroviejo Dilators

Punctal dilation is often a precursor to syringing, especially in cases of smaller puncta or punctal stenosis. Two widely used dilators in this context are the Nettleship punctal dilator and the Castroviejo lacrimal dilator. Particularly useful in punctal dilation and, notably, in canalicular repair with a monoca stent.

Nettleship Punctal Dilator: Features a sharp, fine end on one side..
Castroviejo Lacrimal Dilator :Boasts a fine tip on both sides.

The technique for punctal dilation involves a series of precise steps:

Vertical Entry: Sterilize the dilator and insert it vertically into the puncta for about 2 mm, aligning with the vertical segment of the canaliculus.
Clockwise and Anticlockwise Rotation: Gently rotate the dilator in both clockwise and anticlockwise directions to navigate the vertical segment.
Horizontal Entry: Transition to the horizontal segment by providing lateral traction on the lower lid, straightening the ampulla.
Horizontal Rotation: Rotate the dilator horizontally, ensuring it enters the horizontal segment of the canaliculus.

This meticulous approach to punctal dilation optimally readies the lacrimal system for subsequent syringing.

Lacrimal Probing: Delving into Diagnosis

The process of passing a thin metal instrument ~probe into the lacrimal sac and down the duct to diagnose and if possible open the blockages .

Bowman’s lacrimal probes are instrumental in lacrimal probing, available in various sizes denoted by numbers (e.g., 4 zeros, 3 zeros, 2 zeros, single zero). The sizing corresponds to the age of the patient, ensuring optimal applicability:

Four zeros: 0.7 mm, suitable for a 3-month-old child.
Refer to the size-age table for precise selection.

We can classify obstructions based on the distance the probe travels from the puncta before it encounters resistance; this is as follows:-

PROXIMAL – distance from puncta is < 3 mm
MID LEVEL – 3-8 mm from puncta
DISTAL OBSTRUCTION – >8 mm from puncta

Hard Stop vs. Soft Stop: Decoding Sensations

Understanding the sensations of hard and soft stops during probing is pivotal for interpreting lacrimal probing results effectively.

Hard Stop: As the probe reaches the lacrimal bone, a hard stop is felt, indicating a patent common canalicular pathway. This sensation signifies that the probe has successfully traversed the punctum, canaliculus, and common canaliculus, reaching the lacrimal sac and encountering the resistance of the lacrimal bone. A hard stop is characteristic of an unobstructed common canalicular pathway.
Soft Stop: Conversely, a soft stop occurs when there’s an obstruction in the canalicular system. As the probe encounters this obstruction, the feel is less rigid compared to the hard stop. The probe may drag along, and the resistance encountered is softer. A soft stop indicates a potential canalicular blockage.

Understanding these sensations aids in determining the location of any obstruction within the lacrimal drainage system, providing crucial insights for further clinical decisions

If you would like to learn all this through a detailed video tutorial visit the video below :-

LACRIMAL SYRINGING : PROCEDURE

Materials Needed:

Normal saline solution
1 ml syringe
Sterile lacrimal canula (straight or curved)
Local anesthetic eye drops
Cotton wool or gauze
Towel and gloves

Procedure:

Wash hands and position the patient comfortably with good lighting.
Examine the punctum to determine if dilation is needed, ensuring the dilator tip is intact.
Draw up 1 ml of saline into the syringe and attach the lacrimal canula.
Flush the canula with a small amount of saline to ensure patency.
Instill local anesthetic eye drops and wait for 30 seconds.
Pull down the lower lid, give slight lateral traction, and inject saline slowly into the punctum.
Ask the patient to report any salty taste at the back of the throat or in the nose.
Observe for regurgitation of fluid through the opposite puncta.
Also note the Type of Regurgitate (Clear or Mucoid) and Hard/Soft Stop on Probing aids in further diagnosis.

BASIC INTERPRETATION OF SYRINGING

Positive Syringing: patients tastes the salty saline at the back of his throat / or feels fluid in the nose. This indicates an anatomically patent lacrimal system.
Negative Syringing: patient doesnot report any fluid in the throat or nose, this indicates a blockage or obstruction.

ADVANCED INTERPRETATION : Combining syringing and probing results

We can combine syringing results with probing and type of regurgitate seen to diagnose the lacrimal apparatus blockages more specifically.

EXAMPLE 1:

Findings:
- 100% regurgitation of fluid through the same puncta.
- Clear regurgitate.
- Soft stop on probing.
Interpretation:
- Indicates a canalicular block.

EXAMPLE 2:

Findings:
- 100% regurgitation of fluid through opposite puncta.
- Type of Regurgitate: Mucoid.
- Hard stop on probing.
Interpretation:
- Mucoid regurgitate with a hard stop indicates nasolacrimal duct obstruction.

EXAMPLE 3:

Findings:
- 100% regurgitation of fluid through opposite puncta.
- Type of Regurgitate: Clear.
- Hard stop on probing.
Interpretation:
- Nasolacrimal duct obstruction.
- Clear regurgitate with a hard stop indicates nasolacrimal duct obstruction with a fibrosed sac (fibrosed sac cannot produce mucoid secretions).

EXAMPLE 4:

Findings:
- 100% regurgitation of fluid through opposite puncta.
- Type of Regurgitate: Clear.
- Soft stop on probing.
Interpretation:
- Common canalicular obstruction.
- Clear fluid with a soft stop indicates common canalicular obstruction.

Lets take another set of examples showcasing scenarios where less than 100% regurgitation with specific responses during probing helps differentiate between common canalicular stenosis and partial NLD block, based on the type of regurgitate and the nature of the stop during probing.

EXAMPLE 5:

Findings:
- Less than 100% regurgitation of fluid through opposite puncta.
- Type of Regurgitate: Mucoid.
- Hard stop on probing.
Interpretation:
- Mucoid regurgitate with a hard stop indicates a partial NLD block.

EXAMPLE 6:

Findings:
- Less than 100% regurgitation of fluid through opposite puncta.
- Type of Regurgitate: Clear.
- Hard stop on probing.
Interpretation:
- Clear regurgitate with a hard stop indicates partial NLD block with a fibrosed sac (fibrosed sac cannot produce mucoid).

EXAMPLE 7:

Findings:
- Less than 100% regurgitation of fluid through opposite punctum
- Type of Regurgitate: Clear.
- Soft stop on probing.
Interpretation
- Clear fluid with a soft stop indicates common canalicular stenosis.