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Table of contents
Microbial Conjunctivitis

Inflammation of the conjunctiva is most commonly due to an acute, self-limiting bacterial infection. Be vigilant and escalate cases with corneal involvement (keratitis)


Overview

Follicles vs papillae

Conjunctivitis has 2 distinct clinical appearances which help you differentiate the potential causes.

Papillae

  • Papillae have a red (blood vessel) center and fat top
  • More common on the upper lid
  • Associated with: viral, chlamydial & toxic conjunctivitis

Follicles

  • Dome-shaped discrete transparent lesions
  • More common on the lower lid
  • Associated with: bacterial & allergic conjunctivitis

Broad Presentations

Bacterial

Acute/hyperacute red sticky eyes with purulent discharge

Viral

Acute red watery eyes with lymphadenopathy

Chlamydial

Subacute unilateral red eyes with persisting mucopurulent discharge and lymphadenopathy

Gonococcal

Hyperacute (<24hrs) red eyes, keratitis, and severe purulent discharge with STI risk factors

Allergic

Acute/recurrent red itchy eyes with watery discharge


General management

  • Conjunctival swabs for microbial investigations are reserved for severe/atypical cases and not routinely indicated in simple acute bacterial/viral conjunctivitis.
  • Specific treatment depends on the type of conjunctivitis (see sections below)

Bacterial Conjunctivitis

Bacterial infection of the conjunctiva is common, often self-limiting, and frequently encountered in primary care. It should be suspected in patients with red gritty sticky eyes and purulent discharge.


Pathology

Causes

  • Cool climates → Streptococcus Pneumoniae and Haemophilus influenzae
  • Warm climates → Haemophilus aegyptius
  • Children → Haemophilus influenzae

Chronic Pathology

  • Chronic and relapsing conjunctivitis typically indicates the presence of a nearby reservoir colony.
  • This should be suspected in the case of chronic dacryocystitis, staph blepharitis and giant fornix syndrome

Giant fornix syndrome is characterised by the sequestration of bacteria in the upper fornix of the conjunctiva and is typically seen in the elderly.


Diagnostics

A patient with bacterial conjunctivitis. The eye is red and there is a purulent green discharge. By Tanalai, CC BY 3.0.

Presentation

  • Acute/hyperacute red sticky eyes with purulent discharge
  • Typically bilateral but often starts unilaterally
  • Patients complain of their eyes being stuck together in the morning

Investigations

  • Diagnosis is clinical
  • Conjunctival swabs for microbiology are only required in unresolving cases or severe infections.

Any involvement of the cornea (keratitis) can be sight-threatening and warrants admission for further workup


Management

Initial

  • Practice good hand and eye hygiene
  • Advise the patient to return if the infection doesn't self-resolve within a week or gets worse
  • Switch to spectacles from contact lenses during the episode

Medications

  • Topical chloramphenicol drops
  • Systemic antibiotics are reserved for gonococcal conjunctivitis in adults or H.influenzae/Meningococcal conjunctivitis in children
    • H.influenzae → PO Co-amoxiclav

Chloramphenicol is associated with aplastic anaemia


Adult Inclusion Body Chlamydial Conjunctivitis

Chlamydia trachomatis can cause 2 different types of conjunctivitis and it’s important to be aware of both types: trachoma and inclusion body. This section will discuss inclusion body.


Pathology

  • Caused by Chlamydia trachomatis, a gram-negative intracellular obligate organism
  • Associated with serotypes D-K of Chlamydia trachomatis

Immunotypes L1, L2, L3 cause Lymphogranuloma Venereum


Diagnostics

A patient with Chlamydial conjunctivitis. Note the inferior follicular conjunctivitis. By Jonathan Trobe, M.D, CC BY 3.0.

Presentation

  • Subacute (2-3wks) unilateral conjunctivitis in young people
  • Associated with STI symptoms such as urethritis
  • Inferior follicular conjunctivitis with persisting mucopurulent discharge and lymphadenopathy

Investigations

  • Conjunctival swab for PCR provides prompt diagnosis

Giemsa stain shows basophilic intracytoplasmic inclusion bodies


Management

  • 1g oral azithromycin STAT or 100mg doxycycline BD for 14 days

Trachoma

Trachoma is a highly infectious epidemic conjunctivitis seen in developing countries. It is the leading cause of preventable blindness worldwide.


Pathology

  • Caused by Chlamydia trachomatis serotypes A-C
  • Acute conjunctivitis is caused by the pore-like infectious particle (elementary body) of chlamydia
  • A type 4 hypersensitivity reaction occurs after initial infection → scarring → trichiasis and entropion → corneal damage → blindness

The conjunctival scarring leads to entropion, where the lids roll inwards. This causes the lashes to rub against the cornea when blinking.


Presentation

  • Seen in poverty and crowded places
  • Chronic superior follicular conjunctivitis
  • Herbert pits (depressions of superior limbus)
  • Arlt’s line (a thick band of scar tissue in the conjunctiva)
  • Trichiasis and entropion

Management

WHO SAFE strategy:

  • Surgery for trichiasis (bilamellar rotation)
  • Azithromycin 1g PO
  • Facial hygiene
  • Environmental improvement

Adult Gonococcal Conjunctivitis

Gonococcal conjunctivitis is approached differently in children vs adults. This section will cover adult gonococcal conjunctivitis.


Pathology

  • Caused by infection with Neisseria gonorrhoeae, a gram -ve diplococcus.
  • These patients can be severely unwell.

Diagnostics

Presentation

  • Hyperacute and with severe pain, tearing and red-eye.
  • Conjunctival membranes and preauricular lymphadenopathy

Investigations

  • Conjunctival swab for microbiology and referral to GUM clinic for sexual health follow up

Management

  • Treat all with topical ofloxacin drops
  • Ceftriaxone IM 1g STAT to treat gonorrhoea
  • If keratitis → admit for IV ceftriaxone

Ophthalmia Neonatorum

Conjunctivitis within the first 30 days of life

Cause

Treatment

Notes

Chlamydia

PO erythromycin

Most common cause. Can progress to chlamydial pneumonitis

Gonococcal

IM ceftriaxone and IV penicillin

Typically presents within the first 3 days of birth

HSV

IV acyclovir

Presents with watery discharge and vesicular rash

Staphylococcus

Topical chloramphenicol


Gonococcal ophthalmia neonatorum.


Viral Conjunctivitis

Adenovirus is the most common microbial cause of conjunctivitis and is highly contagious. Definitive diagnosis can be achieved with PCR and management is conservative with cold compress and artificial tears. There are 3 clinical syndromes you should be aware of.


Viral conjunctivitis syndromes

Acute nonspecific follicular conjunctivitis (ANFC)

Pharyngoconjunctival fever

Epidemic Keratoconjunctivitis

  • Unilateral red itchy watery eye
  • Progressive involvement of the fellow eye
  • Lymphadenopathy

As for ANFC + pharyngitis/URTI + fever

Follicular conjunctivitis as ANFC followed by keratitis characterised by microcysts and punctate epithelial lesions

Adenovirus serovars 3,4,7

Adenovirus serovars 8, 19, 37


A patient with epidemic keratoconjunctivitis. Note the clear discharge and follicular conjunctivitis. By Marco Mayer, CC BY-SA 4.0.


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