Lacrimal canaliculus obstruction is a condition in which the lacrimal canaliculus (upper or lower canaliculus; vertical portion about 2 mm + horizontal portion about 8 mm = total about 10 mm) or the common canaliculus (from the junction of the upper and lower canaliculi to the entrance of the lacrimal sac) is blocked. Main causes include inflammatory scarring and postoperative adhesions.
Unilateral obstruction of one canaliculus often does not cause epiphora. In contrast, common canaliculus obstruction or bilateral canalicular obstruction prevents tear drainage into the nasolacrimal duct, resulting in significant epiphora. Prognosis depends largely on the extent of obstruction and the degree of scarring.
Anatomically, the upper and lower canaliculi run from the medial canthus nasally, bypass the Horner muscle, join at the common canaliculus, and open into the lacrimal sac. Understanding this anatomical pathway is crucial for diagnosis and treatment strategy.
It has been reported to occur after epidemic keratoconjunctivitis (EKC)1), and a multicenter study showed that about 60% of anticancer drug-related lacrimal duct obstructions involve punctum and canaliculus damage2).
The site of obstruction differs. In canalicular obstruction, resistance is felt when a probe is inserted less than 10 mm. In nasolacrimal duct obstruction, the probe can reach the lacrimal sac. Treatments also differ: canalicular obstruction is managed with dacryoendoscopic probing plus tube intubation or CDCR, while nasolacrimal duct obstruction is typically treated with DCR (dacryocystorhinostomy). Prognosis for canalicular obstruction is generally poorer than for nasolacrimal duct obstruction.
The main symptoms are as follows.
The Yabe-Suzuki classification1) is used for severity grading of canalicular obstruction.
| Grade | Bougie insertion length | Communication between upper and lower puncta | Clinical significance |
|---|---|---|---|
| Grade 1 | ≥11mm | Present | Equivalent to common canalicular obstruction. Endoscopic dacryoplasty is relatively easier to perform. |
| Grade 2 | ≥7–8 mm | None | Obstruction more proximal than Grade 1. Difficulty of probing increases. |
| Grade 3 | <7–8 mm | None | Obstruction more proximal. Many cases are difficult to probe. |
Grades 2 and 3 are significantly more difficult to treat than Grade 1, and may require skin incision or conversion to CDCR.
Inflammatory Scarring
Stevens-Johnson syndrome (SJS): Tends to cause severe cicatricial obstruction
Ocular cicatricial pemphigoid: Chronic inflammation leads to persistent epithelial damage
Chronic conjunctivitis / post-EKC: Post-inflammatory fibrosis obstructs the canaliculus
Post-surgical
After eyelid surgery: Scarring at the inner canthus compresses or obstructs the lacrimal canaliculus.
After lacrimal surgery: Adhesions may occur after surgical manipulation of the punctum or canaliculus.
Drug-induced
S-1 (tegafur preparation, TS-1®): The active metabolite 5-FU directly damages the lacrimal duct mucosa. It tends to become severe.
Long-term use of glaucoma eye drops: Chronic irritation from preservatives (e.g., BAK) is involved.
Post-traumatic/Post-infectious
Traumatic obstruction: Incomplete repair and scar formation after lacrimal canaliculus laceration.
After canaliculitis (Actinomyces infection): Luminal obstruction due to dacryolith formation and chronic inflammation.
Lacrimal duct obstruction caused by S-1 (tegafur, gimeracil, oteracil potassium combination) often becomes severe. Among anticancer drug-related lacrimal duct obstructions, punctum and canaliculus disorders account for approximately 60%2), and the longer the time from onset of tearing symptoms, the more refractory it becomes. Note that obstruction may progress even after discontinuation of the drug.
Since lacrimal duct obstruction due to S-1 tends to become severe, early ophthalmologic consultation and consideration of tube intubation are recommended when tearing occurs. During anticancer drug use, tube removal may lead to re-obstruction, so it is desirable to continue tube placement while the drug is being used. Collaboration between the primary physician (oncologist) and ophthalmologist is important.
Detailed prevalence data for lacrimal canalicular obstruction are limited, but associations with the following diseases and conditions have been reported.
Lacrimal duct disorders after SJS often involve canalicular obstruction, and severe cicatricial obstruction tends to be difficult to treat. Acquired lacrimal duct obstruction after EKC (epidemic keratoconjunctivitis) has been reported relatively frequently in East Asia1).
Multicenter studies have reported lacrimal duct disorders in patients using S-1 2). Additionally, lacrimal sac biopsies performed during DCR (dacryocystorhinostomy) for lacrimal duct obstruction revealed granulation/reactive lymphoid hyperplasia in 5.9% and tumors in 1.4% (of which 69% were malignant) 3). Therefore, it is important to rule out neoplastic lesions in the differential diagnosis of epiphora and lacrimal duct obstruction.
Check for patency of irrigation from each upper and lower punctum. Irrigation is the first step in estimating the site of obstruction, but its concordance rate with actual dacryoendoscopic findings is approximately 70% 1). The presence of reflux or resistance during irrigation provides diagnostic clues.
Considering the length of the lacrimal canaliculus (approximately 10 mm), estimate the extent of obstruction from the insertion length of the probe. In cases of common canalicular obstruction, inserting a metal probe yields a membranous resistance just before the lacrimal sac. Metal probes can easily create false passages, so they must be handled with particular care.
Dacryoendoscopy, which was covered by insurance in 2018 1), allows direct visualization of the obstruction site and is extremely useful for diagnosis. It can also assess the degree of fibrosis and mucosal inflammation at the obstruction site. It enables classification not only into common canalicular or nasolacrimal duct obstruction but also into detailed locations within the nasolacrimal duct 1).
The specifications of the scopes used are as follows:
Dacryocystography is useful for identifying the site of obstruction and assessing the condition of the lacrimal sac, but it can be difficult to determine whether the contrast agent has reached the obstruction site 1). CT/MRI is recommended to rule out extralacrimal pathology and confirm bony obstruction 1, 4).
| Disease | Probing Findings | Irrigation Findings | Characteristic Findings |
|---|---|---|---|
| Canalicular obstruction | Resistance within 10 mm | Regurgitation | Grade assessment by Yabe-Suzuki classification |
| Punctal obstruction | Cannot insert probe into punctum | Cannot perform | Confirm lacrimal papilla and closure findings |
| Nasolacrimal duct obstruction | Probe reaches lacrimal sac | Reflux | Reflux with lacrimal sac swelling/pressure |
| Canaliculitis | Resistance at canaliculus | Purulent reflux | Dacryoliths / Actinomyces infection |
Treatment of lacrimal canalicular obstruction is selected stepwise according to the Yabe-Suzuki classification Grade and the obstruction status.
Grade 1 (common canalicular obstruction)
Endoscopic perforation with DEP/SEP is first-line treatment
A silicone tube is placed and removed after 2–10 months. The Kaplan-Meier survival rate at a mean of 878.3 days postoperatively is 94%
Grades 2 and 3 (more proximal obstruction)
Attempt DEP/SEP. If perforation is difficult, switch to metal bougie dilation or skin incision method.
The longer the obstruction, the higher the difficulty. Surgery should be discontinued if eyelid edema occurs.
Both upper and lower canaliculi cannot be opened
CDCR (conjunctivodacryocystorhinostomy) is indicated
Choose the Jones tube method (87% of patients experience therapeutic effect) or the conjunctival pedicle flap method (success rate 75%)
Anesthesia
Perform intralacrimal anesthesia using 4% lidocaine hydrochloride solution. If the effect is insufficient, add infratrochlear nerve block (first branch of the trigeminal nerve) and intraorbital infiltration anesthesia with 2% lidocaine1).
Procedure
After sufficiently dilating the canaliculus with a punctum dilator, insert a nunchaku-type silicone tube or a catheter-type tube. During insertion, carefully check the sensation at the obstruction site and advance the tip little by little; do not force it. In some cases, the stenotic lacrimal passage may be dilated in advance with a bougie. Metal bougies are prone to creating false passages and must be handled with particular care.
The inserted tube is left in place for 1 to 2 months and then removed (for Grade 1, it may be longer, 2 to 10 months1)). If the tube is left in place for 9 months or longer, complications such as cheese-wiring (pressure erosion at the punctum) have been reported1), so caution is needed for long-term placement.
Probing using a lacrimal endoscope allows safe perforation of the obstruction under direct visualization1).
Treatment outcomes for Grade 1: The Kaplan-Meier survival rate at a mean of 878.3 days postoperatively is 94%1), indicating a favorable prognosis. The reocclusion rate for canalicular obstruction is reported to be approximately 0–18.2%1).
If perforation is possible with DEP/SEP, tube insertion is performed similarly. When the obstruction is long, the lacrimal endoscopic image may show a continuous white wall-like appearance. Do not push with excessive force; instead, leave the sheath in place and attempt perforation by probing with a thin bougie, using any depressions or pits as a guide.
If the lacrimal endoscopic view appears yellowish, it indicates that the sub-mucosal orbital fat is visible, posing a risk of eyelid edema. If eyelid edema occurs, surgery should be discontinued. If only one side can be opened, a unilateral lacrimal tube is placed.
In patients using anticancer agents, reocclusion is likely after tube removal, so it is advisable to maintain tube placement while the medication is continued2).
For common canalicular obstruction that cannot be perforated from the punctum, a skin incision approach is used.
CDCR is indicated for cases where both the upper and lower canaliculi cannot be opened.
Jones tube method
The Jones tube is a glass tube that completely bypasses the lacrimal canaliculi to drain tears from the conjunctival sac into the nasal cavity. A report indicates that 87% of patients experienced therapeutic benefit5). Lifelong placement is required, and repositioning due to displacement or replacement due to clogging may occur. As of 2023, the Jones tube is not approved in Japan, limiting its use1). The first use of the Jones tube in Japan was reported by Nakagawa et al. in 19695).
The Jones tube is a glass tube that completely bypasses the lacrimal canaliculi to drain tears from the conjunctival sac into the nasal cavity. It is used in cases where both the upper and lower lacrimal canaliculi are non-canalizable (CDCR-indicated cases). A report indicates that 87% of patients experienced therapeutic benefit. Lifelong placement is required, and repositioning or replacement due to displacement or clogging may be necessary. As of 2023, it is not approved in Japan, limiting its use.
Conjunctival pedicle flap method
The success rate is reported to be 75%5). This method involves temporary placement of a silicone sponge used in retinal detachment surgery, but the procedure is complex and may cause abduction limitation of the eye.
Endonasal CDCR
An endonasal method using a conjunctival pedicle flap has also been reported5). Similar to the external approach, there is a risk of abduction limitation.
This is a recently reported surgical technique that uses the lacrimal sac and nasolacrimal duct as a substitute for obstructed lacrimal canaliculi, directly anastomosing the lacrimal sac to the conjunctival sac6). Improvement of epiphora was confirmed in all 11 cases at one year postoperatively, with no complications reported6). It is expected as an alternative to CDCR, but long-term results are awaited.
| Treatment | Indication | Success rate | Remarks |
|---|---|---|---|
| DEP/SEP + tube (Grade 1) | Common canalicular obstruction | 94% (mean 878 days) | Placement period 2–10 months1) |
| Skin incision method | Common canalicular obstruction impassable from the punctum | No data | Procedure under direct microscopic visualization |
| CDCR (Jones tube) | Both upper and lower canaliculi cannot be opened | 87%5) | Requires lifelong placement. Not approved in Japan |
| CDCR (conjunctival pedicle flap) | Same as above | 75%5) | Risk of abduction deficit |
| Dacryocyst transposition | Same as above | 100% (11 cases)6) | Awaiting accumulation of long-term results |
The re-occlusion rate after surgery for lacrimal canalicular obstruction is reported to be approximately 0–18.2%. For Grade 1, the Kaplan-Meier survival rate is 94% (mean follow-up 878.3 days), which is favorable, but re-occlusion can occur even after initial patency is achieved. The risk is higher when the causative disease (e.g., SJS) remains active or when the obstruction is long. The survival rate at 3,000 days postoperatively is reported to be 64%, so long-term follow-up with consideration of recurrence risk is necessary.
The lumen of the lacrimal canaliculus is lined by non-keratinized stratified squamous epithelium, which functions in the passage of tear components and defense. The lacrimal canaliculus consists of a vertical portion (approximately 2 mm) and a horizontal portion (approximately 8 mm), with a total length of about 10 mm. The upper and lower canaliculi join via Horner’s muscle (posterior limb of the medial canthal tendon) to form the common canaliculus (approximately 2–5 mm long), which opens into the lacrimal sac.
When inflammation or trauma affects the lacrimal canaliculus, obstruction develops through the following processes:
When the scar is extensive or inflammation is severe, surgical reconstruction becomes difficult.
Tegafur (the main component of S-1) is metabolized in the body to 5-FU (fluorouracil). 5-FU is secreted into tears and directly damages the epithelial cells of the lacrimal duct mucosa, causing lacrimal canalicular obstruction. The risk increases with dose and duration of administration, and obstruction may progress even after the onset of epiphora symptoms.
The common canaliculus is located at the height of the medial canthal tendon and is approachable from the skin side. This anatomical relationship provides the theoretical basis for perforation via a skin incision. When the obstruction is long or scarring is severe, surgical reconstruction is extremely difficult, and bypass procedures such as CDCR or dacryocyst transposition become options.
Dacryocyst transposition is a recently reported surgical technique6) and is expected to be an alternative to CDCR. At one year postoperatively, all 11 cases showed improvement in epiphora, with no reported complications. Accumulation of long-term outcomes and comparison with CDCR remain future challenges.
Lacrimal endoscopy has been continuously improved from the early model (6,000 pixels) in 2002 to 2012 (10,000 pixels) and 2020 (improved depth of focus to 1.5–7 mm), enabling more detailed observation of the obstruction site. The spread of SGI and G-SGI has reduced the risk of submucosal misinsertion1), and standardization of the procedure is expected in the future.
Furthermore, establishing a method to determine the optimal timing for tube removal based on lacrimal endoscopic findings is thought to improve postoperative outcomes1).
The survival rate at 3,000 days after tube removal has been reported as 64%6). This suggests the need for long-term follow-up, and regular postoperative lacrimal irrigation tests are important for monitoring.
