When the tear duct block is higher up: the canaliculus, silicone tubes and the Jones tube

Most talk about a blocked tear duct is about the lower part of the channel, the one that a DCR operation bypasses. Sometimes the block sits higher, in the fine tubes that collect tears at the lid margin, and that changes the tests, the operations and the aftercare. This article sets out the drainage path in plain words, what a canalicular block is, how it is assessed, what the published options are from a silicone tube to a Jones tube, and what a Jones tube asks of the person who has one.

Where does a tear go, and where is the canaliculus in that path?

A tear leaves the eye through a tiny opening on each lid, the punctum, and passes along a fine tube, the canaliculus (plural canaliculi), into a shared channel called the common canaliculus. From there it enters the lacrimal sac, then the nasolacrimal duct, and finally the nose. That is why a runny nose and a watery eye so often arrive together.

EyeWiki, the American Academy of Ophthalmology's clinical wiki, divides the canaliculus by distance. The proximal part is the first 2 to 3 mm from the punctal opening, the mid part lies 3 to 8 mm from the punctum, and the distal part runs from a membrane at the opening of the common canaliculus to the lacrimal sac. Where a block sits along that length is one of the things that decides what can be done about it.

The opening itself can be too small without the tube behind it being blocked, which is a different problem and is covered in punctal stenosis, the small opening that causes a big watery eye. The wider question of whether the problem is too many tears or poor drainage is set out in watery eyes in adults.

How is a canalicular block different from the block that a DCR treats?

It sits upstream. The classic adult blockage lies in the nasolacrimal duct or at the sac, and a DCR (dacryocystorhinostomy, an operation that makes a new passage between the sac and the nose) works at that level. I explain the operation in what happens during DCR surgery and what recovery involves.

A DCR works from the sac downwards, so it cannot by itself reopen a canaliculus that is closed above it. EyeWiki lists the severe end of canalicular disease as a reason to move to a different operation, canaliculo-DCR or conjunctivodacryocystorhinostomy, in which tears are carried past the blocked canaliculus altogether. That is why a surgeon wants to know which level is blocked before choosing an operation, and why a general "blocked tear duct" label can hide quite different problems.

What can block the canaliculus?

EyeWiki groups the causes. Infection and inflammation include blepharitis, canaliculitis (an infection inside the canaliculus, described in one red, sticky eye that antibiotic drops do not clear), viral, bacterial and fungal infections, ocular cicatricial pemphigoid and Stevens-Johnson syndrome. Injury includes canalicular laceration and chemical or thermal burns. Other listed causes are involutional (age-related) change, malignancy, lichen planus and inflammatory bowel disease.

Some medicines are on the list too. EyeWiki names the taxane chemotherapy drugs docetaxel and paclitaxel and the chemotherapy drug fluorouracil, some glaucoma eye drops, some antiviral eye drops and the retinoid isotretinoin. Earlier treatment is also listed, including punctal plugs, cautery, previous surgery, prolonged intubation and radiotherapy.

A well-documented example is docetaxel. A prospective trial in patients with metastatic breast cancer, published in the Journal of Clinical Oncology in 2006, followed 28 patients on weekly docetaxel and 28 on a three-weekly schedule. Watering developed in 18 of 28 (64%) on the weekly schedule and 11 of 28 (39%) on the three-weekly one. On the weekly schedule nine had worsening canalicular stenosis and six needed surgery, against two in the three-weekly group. It is a small trial, and the dosing it studied may not match current regimens. What it supports is a single practical point: new watering during cancer treatment is a reason to tell the team prescribing it, because there are things to try, and the decision about the cancer drug belongs to them and not to the reader.

How is a canalicular block found?

By testing the path in stages. EyeWiki describes the dye disappearance test, in which a drop of dye is placed in the eye: if it has gone after five minutes the system is patent, and dye that remains points to an anatomical obstruction. Probing and irrigation then separate a narrowing from a complete block, and the depth at which the instrument stops can be measured to show where the obstruction lies. Canalicular endoscopy, a tiny camera passed along the tube, can show the blockage directly.

Probing is not a test to attempt at home, and not every watery eye is a drainage problem. Dryness, allergy and lid margin disease can all make eyes water, which is why the first question in any assessment is whether the drainage is actually the problem.

What treatments exist for a canalicular block, and how are they chosen?

The choice follows how severe the block is and where it sits. EyeWiki sets the options out roughly as follows.

• Mild to moderate narrowing: silicone stenting, a thin silicone tube threaded through the drainage path to hold it open while it heals. EyeWiki notes that canalicular stents may be left in place for several months.
• Proximal or mid blockage that can be reconstructed: reconstruction of the canaliculus over a stent.
• Distal blockage: trephination (opening the blocked segment) with stenting, and balloon canaliculoplasty.
• Severe blockage that cannot be rebuilt: canaliculo-DCR, or conjunctivodacryocystorhinostomy (CDCR), in which a tube carries tears from the corner of the eye straight into the nose.

The CDCR page on EyeWiki says silicone stenting can be tried first, and that an endoscopic CDCR is indicated if the result is unsatisfactory. Which of these a person is offered depends on an examination. The choice follows where the block is, not the name of an operation.

What is a Jones tube, and what does it ask of the person who has one?

A Jones tube is a small glass tube placed through the caruncle, the pink bump at the inner corner of the eye, into the nasal cavity, so that tears bypass the canaliculi altogether. The tube's position is checked with a nasal endoscope and it is secured with sutures. Newer designs include frosted tubes and flanged "stop loss" tubes made to reduce the chance of the tube slipping.

The honest summary from the sources is that it often works but needs lasting attention. EyeWiki says extrusion of the tube is the most frequent complication, with many people needing a revision within five years, and that malposition, infection and obstruction are lifelong possible risks. It adds that the tube may need routine irrigation in clinic to prevent or treat obstruction, and describes review visits at one week, six weeks and three to six months after surgery. Counselling points include avoiding nose blowing for the first week and placing a finger over the inner corner when sneezing, blowing the nose or coughing, to prevent dislocation.

A Korean review of endoscopic CDCR reoperations, published in the Journal of the Korean Ophthalmological Society in 2019, gives a feel for the problems. It covered 52 reoperations in 41 eyes of 40 patients. The causes were medial tube migration (53.8%), tube loss (17.3%), obstruction from conjunctival overgrowth or granulation tissue (13.46%) and lateral migration (11.53%), and the first reoperation came on average 52 months after the first operation. Reoperations succeeded in 78.04%. These are people who needed another operation, so the figures show the kinds of trouble that occur, not how many people with a Jones tube run into it. The sources cited here give no home cleaning routine, so what to do between visits is a question for the surgeon who placed the tube.

When should a problem near the tear drainage be seen soon?

A cut through the inner part of an eyelid, near the corner by the nose, can tear the canaliculus, and repair is time-sensitive. A 2007 report in Ophthalmology Times, quoting a Johns Hopkins surgeon, states that the timing of repair is critical to the outcome and may prevent persistent watering, and that the usual repair places a silicone tube through the channel while it heals, removed at three to six months. The reasons and the timings that other studies report are set out in a cut on the eyelid or near the inner corner of the eye. A watery eye with a hot, red, painful swelling at the inner corner is a separate urgent problem, because the sac may be infected.

If a Jones tube is already in place, a tube that has moved, fallen out, or a sudden return of watering with pain or discharge is a reason to contact the surgical team. Long-standing watering with none of these signs is not an emergency, but it is worth having the level of the block found, because the right treatment depends on it. The wider picture of tired, watery or sore-looking eyes is in what actually makes eyes look tired, and the rest of the series sits under watery eyes and blocked tear ducts.