Lacrimal drainage and epiphora testing

Anatomy of the Lacrimal Drainage Apparatus

The lacrimal drainage system is an active physiological pump and conduit that conveys tears from the ocular surface into the nasal cavity:

1. Lacrimal Puncta:
   • Small circular or oval apertures situated atop the lacrimal papillae at the junction of the ciliary and lacrimal portions of the eyelid margins. The inferior punctum lies approximately $6.5\text{ mm}$ lateral to the medial canthus; the superior punctum lies roughly $5.0\text{ mm}$ lateral. Both puncta are normally inverted and submerged within the tear lake (lacus lacrimalis).
2. Canaliculi:
   • Vertical Segment: Directs vertically from the punctum for $2.0\text{ mm}$, expanding slightly at its base to form the ampulla.
   • Horizontal Segment: Runs horizontally for $8.0\text{ mm}$ parallel to the eyelid margin.
   • Common Canaliculus (Sinus of Maier): In $90\%$ of individuals, the superior and inferior horizontal canaliculi unite to form a single common canaliculus before entering the lateral wall of the lacrimal sac; in the remaining $10\%$, they enter the sac independently through separate ostia.
3. Valve of Rosenmüller:
   • A mucosal fold located at the junction of the common canaliculus and the lacrimal sac. It functions as a physiological one-way flap valve, permitting the ingress of tears into the sac while preventing retrograde reflux of air, tears, or infected discharge back into the canalicular system during pressurized nose-blowing.
4. Lacrimal Sac:
   • Located within the bony lacrimal sac fossa on the medial orbital wall. The fossa is bounded anteriorly by the anterior lacrimal crest (maxilla) and posteriorly by the posterior lacrimal crest (lacrimal bone). The sac measures approximately $10-12\text{ mm}$ vertically, with its apex (fundus) extending $3-5\text{ mm}$ superior to the medial canthal tendon.
5. Nasolacrimal Duct (NLD):
   • Direct downward continuation of the lacrimal sac traversing the bony nasolacrimal canal within the maxilla. It travels downward, backward, and slightly laterally.
   • Consists of an intra-osseous segment ($~12\text{ mm}$) and an intra-meatal / mucosal segment ($~5\text{ mm}$), yielding a total ductal length of $15-18\text{ mm}$.
   • Opens into the inferior nasal meatus beneath the inferior nasal turbinate.
6. Valve of Hasner (Plica Lacrimalis):
   • A mucosal valve covering the inferior meatal opening of the NLD. Incomplete canalisation or persistent membranous imperforation of the Valve of Hasner is the characteristic cause of Congenital Nasolacrimal Duct Obstruction (CNLDO).

Clinical Evaluation of Epiphora

Clinical evaluation must differentiate epiphora (overflow of tears secondary to impaired lacrimal drainage) from hyperlacrimation (excessive reflex lacrimal secretion driven by ocular surface irritation, dry eye, or corneal pathology).

1. Biomicroscopic Assessment & Tear Meniscus

• Tear Meniscus Height (TMH): Normal is $0.2-0.4\text{ mm}$. A high, convex tear meniscus ($>0.5\text{ mm}$) indicates outflow insufficiency.
• Punctal Position & Patency: Look for punctal stenosis, punctal ectropion (eversion away from the tear lake), or secondary occlusion by lash follicles or conjunctival folds (conjunctivochalasis).

2. Dye Disappearance Test (DDT)

• A drop of 2% sodium fluorescein is instilled into both inferior conjunctival fornices without prior topical anesthesia.
• The tear meniscus is observed under cobalt blue illumination at 5 minutes:
  • Normal: Symmetrical, rapid clearance with complete disappearance of the dye ($<5\text{ min}$).
  • Abnormal: Persistent, asymmetric pooling of bright green fluorescein confirms physiological or anatomical outflow obstruction.

3. Diagnostic Probing & Irrigation (Syringing)

Following topical anesthesia, the punctum is gently dilated with a Nettleship dilator. A blunt lacrimal cannula mounted on a saline syringe is introduced vertically for $2\text{ mm}$, rotated $90^\circ$ horizontally, and advanced while maintaining lateral traction on the eyelid to avoid canalicular crimping:

• Hard Stop: The cannula tip traverses the canaliculi, passes through the common canaliculus into the sac, and strikes the rigid medial lacrimal bone. Confirms patency of the punctum, horizontal canaliculus, and common canaliculus.
  • Irrigation with Hard Stop: If saline passes easily into the patient's throat (tasted by patient), the system is patent. If saline fails to enter the throat and refluxes through the opposite punctum, there is complete nasolacrimal duct obstruction (NLDO).
• Soft Stop: A spongy, elastic resistance is encountered before reaching the lacrimal bone. Indicates canalicular obstruction (cannula cannot enter the sac; the resistance represents the lateral wall of the sac or a scarred common canaliculus).
  • Irrigation with Soft Stop: Saline immediately regurgitates through the same punctum (canalicular stenosis) or opposite punctum without entering the sac.

4. The Jones Dye Tests

Indicated in patients with persistent epiphora who have a normal, patent lacrimal syringing examination (to differentiate functional lacrimal pump failure from partial anatomical obstruction):

• Jones I Test (Primary):
  • Instill 2% fluorescein into the conjunctival fornix. After 5 minutes, insert a cotton-tipped wire applicator moistened with local anesthetic under the inferior turbinate in the inferior nasal meatus (or have the patient blow their nose into a white tissue):
    • Positive: Fluorescein recovered in the nose $\rightarrow$ confirms a physiologically patent drainage system. Tearing is due to hypersecretion or dry eye reflex.
    • Negative: Failure to recover dye is inconclusive by itself. Consider collection, pump function, obstruction and test technique, then select further assessment; it does not automatically prove a partial anatomical block.
• Jones II Test (Secondary):
  • Residual fluorescein is washed out of the conjunctival sac. Clear saline is irrigated through the inferior canaliculus with the cotton bud in the inferior meatus:
    • Dye-stained recovery: Dye reached the sac during the first test but did not drain normally. This supports partial distal obstruction or delayed drainage; it is not proof of isolated pump failure.
• Clear recovery on Jones II: This can indicate that dye did not reach the sac physiologically, including collection/pump or proximal drainage problems. Clear saline reaching the nose does not itself prove an anatomical complete block.