Canaliculitis: The Chronic Conjunctivitis That Won’t Clear

Canaliculitis is a chronic, often smoldering infection of the lacrimal canaliculus that is frequently misdiagnosed as ordinary chronic conjunctivitis. The two conditions can look deceptively similar for months before the correct diagnosis is finally made.

This is usually only after a course of standard conjunctivitis treatment has failed. omeone must specifically press on the canalicular region and produce the characteristic discharge that gives the diagnosis away.

Why It’s So Often Missed

The chronic mucopurulent discharge and mild conjunctival injection produced by canaliculitis closely resemble ordinary bacterial or chronic conjunctivitis.

Unless the examiner specifically looks at and palpates the canalicular region near the medial canthus, the source is easily overlooked.

It is easy to focus purely on the conjunctiva and lid margins more broadly. A history of a chronic, unilateral, treatment-resistant “conjunctivitis” is itself a clue. It should prompt specific examination of the punctum and canaliculus.

Microbiology

Actinomyces species (Actinomyces israelii), a filamentous, Gram-positive anaerobic bacterium, is the classic and most historically emphasized cause.

It is notable for forming characteristic sulfur granules within the canaliculus. These help confirm the diagnosis microscopically and explain why the condition can be so persistent.

These concretions can shelter the organism from antibiotics that would otherwise be expected to clear the infection.

Other bacteria, staphylococcal and streptococcal species, have also been implicated. So have fungal and, less commonly, viral (herpes simplex) causes.

A broader microbial spectrum should be kept in mind rather than assuming Actinomyces is responsible in every case.

Clinical Findings

• Chronic, often unilateral, mucopurulent discharge and mild conjunctival injection, easily mistaken for ordinary conjunctivitis
• Mild swelling and erythema localized specifically over the canalicular region, near the medial canthus — a subtle but genuinely useful localizing sign distinguishing this from more generalized conjunctivitis
• Expression of purulent material, sometimes containing visible small, yellowish “sulfur granules,” on gentle pressure over the affected canaliculus — a maneuver that, when performed and positive, is highly suggestive of the diagnosis
• A pouting, dilated, sometimes erythematous punctum on careful inspection
• Failure to respond to standard topical antibiotics used for presumed ordinary conjunctivitis, which is often what eventually prompts reconsideration of the diagnosis

Differential Diagnosis

• Chronic bacterial or viral conjunctivitis — the most common misdiagnosis, distinguished by the absence of localized canalicular swelling and expressible discharge on canalicular pressure
• Dacryocystitis — swelling and infection centered over the lacrimal sac, below the medial canthal tendon, rather than the canaliculus itself, discussed in its own dedicated article on this site; the two structures are anatomically adjacent but distinct, and the location of maximal swelling and tenderness usually distinguishes them
• Punctal or canalicular foreign body or plug complication — a retained punctal plug, sometimes placed for dry eye management, can become a nidus for chronic infection resembling primary canaliculitis, and a history of prior plug placement should be specifically asked about
• Allergic conjunctivitis — itchy, typically bilateral, without the localized canalicular findings or expressible discharge characteristic of canaliculitis

Diagnostic Evaluation

The diagnosis is largely clinical, based on the characteristic history of chronic, treatment-resistant “conjunctivitis.”

This is combined with the exam finding of expressible discharge on canalicular pressure. Expressed material can be sent for Gram stain and culture to confirm the causative organism and guide antimicrobial choice.

A specific request for anaerobic culture is important, given the possibility of Actinomyces. This needs particular culture conditions and enough incubation time that standard aerobic cultures alone can miss it.

Management

Canaliculotomy — surgical opening of the canaliculus with mechanical removal of any concretions or granules — is generally required.

This is combined with irrigation for durable resolution. This is because the concretions characteristic of actinomycotic canaliculitis can shelter the organism from antibiotics.

This holds even for antibiotics delivered by topical or systemic routes alone.

Topical or systemic antibiotics are used adjunctively, tailored to culture results when available. They are frequently insufficient as monotherapy, when concretions are present.

This is why the surgical component of treatment is so central to actually curing the condition.

It does more than just temporarily suppress symptoms. Warm compresses and gentle canalicular massage can help express material and provide some symptomatic relief while definitive treatment is arranged.

Recurrence after adequate canaliculotomy and concretion removal is uncommon. This is generally a curable condition once correctly diagnosed and properly treated.

References

• Freedman JR, Markert MS, Cohen AJ. Primary and secondary lacrimal canaliculitis: a review of literature. Survey of Ophthalmology.
• Vécsei VP, Huber-Spitzy V, Arocker-Mettinger E, Steinkogler FJ. Canaliculitis: difficulties in diagnosis, clinical features and treatment. Ophthalmologica.
• American Academy of Ophthalmology. Basic and Clinical Science Course, Section 7: Orbit, Eyelids, and Lacrimal System.