Canaliculitis is a low-grade infection of the canaliculus, one of the tiny drainage channels that carry tears from the inner corner of your eye into the nose. It typically causes a red, swollen bump near the inner eyelid, a discharge that keeps coming back despite antibiotic drops, and a chronically watery or crusty eye on one side. The condition is uncommon enough that many eye-care providers rarely encounter it, and the symptoms overlap so heavily with more familiar problems like pink eye that it often goes unrecognized for months or even years before someone lands on the correct diagnosis.
What the Canaliculus Actually Is
Each eye has two canaliculi, one in the upper lid and one in the lower. They are narrow tubes, only about a millimeter wide, lined with a thin, non-mucus-producing lining. They begin at the puncta, the pinpoint openings visible at the inner edge of each eyelid, and merge into a common channel that empties into the lacrimal sac, which then drains into the nose. The lower canaliculus handles the majority of tear drainage. Because these channels are so small and tucked away, problems inside them are easy to miss on a standard eye exam unless the examiner is specifically looking for them.
How It Feels and What to Look For
The hallmark symptoms are a persistent sticky or pus-like discharge from the inner corner of one eye, redness and mild swelling at the inner angle of the lid, and tearing that won’t resolve. One study cataloguing the symptom profile found that all patients had increased eye discharge, about nine in ten had redness, roughly three-quarters had tearing, and over half had visible swelling near the inner corner of the eye. Pain and a foreign-body sensation were less common, reported by fewer than one in ten patients.1PubMed Central. Minimally invasive concretion-expulsion technique for primary canaliculitis: a prospective interventional study
A particularly telling sign is the “pouting punctum,” where the tiny opening of the canaliculus looks swollen, raised, and pouty rather than flat against the lid margin. Pressing gently on the area sometimes expresses a bead of thick, yellowish or gritty material from the punctum. That expressed material can contain concretions, which are small stone-like clumps of bacteria and calcium that form inside the channel. The combination of a unilateral (one-sided) discharge, a pouting punctum, and expressible material is considered classic for canaliculitis, but many patients never have all three signs at once, which is part of why the diagnosis gets missed.2PubMed. Primary and secondary lacrimal canaliculitis: a review of literature
Why It Gets Misdiagnosed So Often
Canaliculitis has a reputation among eye specialists as a “masquerading” disease, and the delay between symptom onset and correct diagnosis is striking. One clinical series found the average time to diagnosis was about 14 months, with some patients going four years before anyone identified the real problem.3PubMed. Canaliculitis: Too Often Underdiagnosed? Another study documented a similar average delay of about 16 months.4PubMed Central. Minimally invasive concretion-expulsion technique for primary canaliculitis: a prospective interventional study
The main reason is that the symptoms look a lot like chronic conjunctivitis. A patient walks in with a red, weepy eye on one side, and the reflexive move is to prescribe antibiotic or anti-inflammatory drops. The drops sometimes reduce the discharge temporarily because they suppress the surface inflammation, but they don’t reach the infection hiding inside the canaliculus. So the symptoms come back, the patient returns, and the cycle repeats. It’s not unusual for someone with canaliculitis to have been through multiple rounds of topical antibiotics for “pink eye” or “blepharitis” before the underlying cause is identified. If you’ve had a persistent one-sided eye discharge that responds only partially to drops and then returns, it’s worth specifically asking about canaliculitis.
What Organisms Are Involved
The classic teaching is that canaliculitis is caused by Actinomyces israelii, a slow-growing bacterium that thrives in low-oxygen environments and tends to form the gritty concretions (“sulfur granules”) that are a signature finding inside the infected canaliculus.5PubMed Central. Actinomycetes canaliculitis complicating congenital nasolacrimal duct obstruction in an infant That association is real, but newer microbiological work reveals a more complicated picture.
A study that carefully cultured discharge from canaliculitis patients found that while smear examination detected Actinomyces in the vast majority of cases (about 96%), actual culture growth of Actinomyces was far less common, at only about 6%. The cultures instead grew a wide mix of bacteria: roughly a third were aerobes (bacteria needing oxygen), about a third were anaerobes (bacteria preferring low-oxygen settings), and the remaining third were facultative organisms that can survive either way. The most commonly cultured species included Streptococcus, Capnocytophaga, and Propionibacterium. No fungal organisms grew in any of the cultures.6PubMed Central. Clinical diagnosis, treatment and microbiological profiles of primary canaliculitis
That disconnect between smear detection and culture growth probably reflects the fact that Actinomyces is notoriously difficult to culture. The organism grows slowly and is easily overshadowed by faster-growing bacteria on a culture plate. So smear staining (looking at the material under a microscope) catches what cultures miss. The practical takeaway is that canaliculitis is often a polymicrobial infection, with Actinomyces potentially providing the scaffolding for concretion formation while other bacteria contribute to the overall inflammation.
Viral canaliculitis is much rarer but does occur. Case reports have documented canaliculitis caused by herpes simplex virus and varicella-zoster virus, either alone or together.7PubMed. Multi-viral canaliculitis: case report and review of literature Viral cases tend to present a bit differently, often without the concretions and gritty discharge typical of bacterial canaliculitis, and they require antiviral rather than antibiotic treatment.
Who Gets It
Canaliculitis predominantly affects older adults, with peak occurrence somewhere between the mid-50s and mid-60s. One clinical series of 34 patients found a mean age of 64, with women outnumbering men by more than two to one.8PubMed. Clinical characteristics and factors associated the outcome of lacrimal canaliculitis A separate series of 22 patients with confirmed Actinomyces canaliculitis found a mean age of 54 and an even more skewed sex ratio, with 21 of 22 patients being women.9PubMed. Actinomycotic primary canaliculitis: Predisposing factors, clinical characteristics, and treatment outcomes
Why women are more affected isn’t entirely clear. One possibility is anatomical: women tend to have narrower lacrimal drainage passages, which could make stagnation and bacterial colonization easier. Hormonal changes after menopause that alter tear film composition or reduce drainage efficiency could also play a role, though this hasn’t been definitively established. The lower canaliculus is involved more often than the upper, likely because it handles the lion’s share of tear drainage and any organisms riding along with that flow.
Canaliculitis in Children
While the textbook description points to older adults, pediatric cases do exist and present a diagnostic challenge of their own. Case reports describe children as young as infancy developing canaliculitis, sometimes in association with congenital blockages of the nasolacrimal duct.10PubMed Central. Actinomycetes canaliculitis complicating congenital nasolacrimal duct obstruction in an infant When canaliculitis appears in a young child, the examining doctor should look carefully for underlying structural abnormalities of the tear drainage system that might be predisposing the child to infection.11PubMed Central. Pediatric Canaliculitis: A Case Report One published pediatric case involved a 12-year-old whose symptoms had started two years earlier, with no accompanying structural problem found. These cases are rare enough that they show up primarily as individual case reports rather than large series, but they’re a reminder that canaliculitis shouldn’t be dismissed out of hand in a younger patient with a stubborn unilateral discharge.
Punctal Plugs as a Trigger
There is a well-recognized secondary form of canaliculitis that occurs after insertion of punctal plugs. These tiny devices are placed into the punctum to block tear drainage and treat dry eye, essentially keeping more of the natural tear film on the eye’s surface. The plug itself, especially if it migrates deeper into the canaliculus, can act as a foreign body that promotes biofilm formation and bacterial colonization.12PubMed. Plug-related canaliculitis: a rare or underdiagnosed disease?
One case report describes a 73-year-old woman who developed canaliculitis in both eyes five months after permanent punctal plugs were placed in her lower lids for dry eye. Slit-lamp examination revealed pus draining from around the plugs, and cultures grew a mix of Enterobacter species. The infection resolved after the plugs were removed and appropriate antibiotics were given.13Annals of Optometry and Contact Lens. A Case of Mixed Enterobacter Infection in a Patient with Canaliculitis Caused by a Punctal Plug The microbiology in plug-related cases often differs from primary canaliculitis. Instead of Actinomyces-dominated infections, plug-related cases tend to involve a broader range of common bacteria, including gram-negative species that don’t usually cause primary canaliculitis.
If you have punctal plugs and notice new discharge, swelling, or tenderness at the inner corner of your eye, mention the plugs specifically when you see your eye-care provider. The treatment for plug-related canaliculitis almost always starts with removing the plug, and the sooner that happens, the better the outcome tends to be.
How It’s Diagnosed
The diagnosis of canaliculitis is primarily clinical, meaning it rests on recognizing the pattern of symptoms and physical signs rather than waiting for a lab test. The key maneuver during the exam is pressing on the canalicular area and watching for expressible material from the punctum. Any material that comes out can be sent for both smear (microscopic examination) and culture.
Getting a positive culture can be tricky, especially when Actinomyces is the suspected organism. One study found that culturing the expressed discharge identified the organism in only three out of six cases, while culturing the actual concretions (if retrieved during surgery) had a similar hit rate of three out of five. The most reliable method was directly staining the concretions, which was positive in all seven cases tested. Using specialized blood-culture media improved the yield compared to standard culture techniques.14Graefe’s Archive for Clinical and Experimental Ophthalmology. Actinomyces canaliculitis: Diagnosis of a masquerading disease
Imaging isn’t routinely needed but can be helpful in ambiguous cases. Ultrasound biomicroscopy or anterior-segment optical coherence tomography can sometimes reveal dilated, debris-filled canaliculi. In practice, though, most cases are diagnosed at the bedside or in the exam chair once the examiner thinks to look for the characteristic signs.
Treatment Options
Topical antibiotics alone rarely cure canaliculitis. The reason goes back to the anatomy: the infected material sits inside a narrow, partially enclosed tube. Antibiotic drops applied to the eye’s surface have poor penetration into the canalicular lumen, especially when concretions are present. Drops may temporarily reduce the surrounding inflammation and discharge, but the infection almost invariably returns. This is one reason the condition often bounces around for over a year without resolution.
The definitive treatment is surgical. Several techniques exist, and they all share the same basic goal: physically opening the canaliculus, removing the concretions and infected material, and irrigating the channel clean. The main approaches differ in how much tissue they disturb and whether the punctum is preserved.
- Canaliculotomy with curettage: The most established procedure. The canaliculus is incised along its length, the concretions and infected lining are scraped out, and the channel is irrigated. One series of 40 patients reported complete resolution of signs and symptoms in about 98% of cases after surgery, with good long-term outcomes in 85%.15Saudi Journal of Ophthalmology. Outcomes of canaliculotomy in recalcitrant canaliculitis Another study found that adding a silicone tube stent during canaliculotomy may further improve results by keeping the channel open during healing.16PubMed. Outcomes of Canaliculotomy with and without Silicone Tube Intubation in Management of Primary Canaliculitis
- Snip-punctoplasty with curettage: A slightly simpler technique where the punctum is widened with a snip incision and the concretions are curetted out through the enlarged opening. One study reported a 90% success rate with this approach.17PubMed Central. Primary canaliculitis: The incidence, clinical features, outcome and long-term epiphora after snip–punctoplasty and curettage
- One-snip punctoplasty with lateral canaliculotomy: A comparison study found this combined technique had a surgical failure rate of about 4%, compared to roughly 20% for punctum-sparing curettage alone, a statistically significant difference. The combined approach allows better visualization of the canalicular contents during surgery.18PubMed. Primary Lacrimal Canaliculitis with clinically detected concretions: One-snip punctoplasty with lateral canaliculotomy vs. punctum sparing canalicular curettage
- Punctum-sparing (mini-invasive) canaliculotomy: A newer approach that aims to preserve the anatomy of the punctum entirely. One prospective comparison found anatomical success rates above 90% for both the mini-invasive and conventional techniques, but functional success (meaning symptoms resolved and the drainage system worked normally) was higher in the mini-invasive group, at about 94% versus 82%.19Eye. A prospective study comparing mini-invasive and conventional canaliculotomy of punctum-sparing canaliculotomy for primary canaliculitis treatment
After any of these procedures, patients are typically prescribed a course of topical antibiotics (often fortified with irrigation during the procedure) and followed for several months to watch for recurrence. The period immediately after surgery is important because the canaliculus is healing and reforming its channel, and early signs of scarring or re-infection can be addressed before they become problems.
When Tearing Persists After Surgery
One concern patients have after surgical treatment is whether the procedure itself will cause chronic tearing by damaging the drainage system it was meant to clear. The short answer is that some degree of post-surgical epiphora (excess tearing) can occur, particularly with more aggressive techniques that widely open or alter the punctum. Techniques that preserve the punctal anatomy appear to have a lower rate of this complication, which is part of the rationale behind the newer punctum-sparing approaches.20Eye. A prospective study comparing mini-invasive and conventional canaliculotomy of punctum-sparing canaliculotomy for primary canaliculitis treatment Still, a canaliculus that was chronically infected and dilated before surgery may not return to its original caliber, and some patients continue to have mild tearing even after the infection is cleared. In most cases this is manageable and far preferable to the ongoing discharge and infection of untreated canaliculitis.
Concretions and Dacryoliths
The gritty particles that surgeons remove from an infected canaliculus are one of the more unusual features of this condition. These concretions, sometimes called dacryoliths when they grow large enough, form when bacterial colonies become mineralized with calcium and other salts. Mineral analysis of lacrimal system stones has shown them to be primarily composed of calcium carbonate.21PubMed. Canine dacryolithiasis: a case description and mineral analysis They can range from tiny granules barely visible to the naked eye to chunks several millimeters across that physically obstruct the canaliculus.
The concretions are both a product of the infection and a perpetuator of it. They provide a sheltered environment where bacteria, particularly slow-growing anaerobes like Actinomyces, can persist out of reach of topical antibiotics. This is a major reason why medical therapy alone fails: the antibiotics can’t penetrate the stone-like concretions to reach the bacteria embedded within them. Complete physical removal of this material is the cornerstone of successful treatment, and surgeons will sometimes irrigate with antibiotic solution during the procedure to try to sterilize any fragments left behind.
What to Tell Your Doctor
If you suspect canaliculitis, the single most useful thing you can do when seeking care is to describe the pattern clearly. Mention that the discharge is always on one side, that it keeps returning after antibiotic drops, and especially that you’ve noticed any swelling, tenderness, or expressible material at the inner corner of your lid. If you’ve had punctal plugs placed in the past, mention that too, even if it was years ago, because a migrated plug can cause symptoms long after insertion. General ophthalmologists can diagnose and treat straightforward cases, but complex or recurrent canaliculitis sometimes benefits from referral to an oculoplastics specialist who deals with the lacrimal drainage system regularly.