Conjunctivitis

Conjunctivitis is an inflammation of the conjunctiva, the clear tissue covering the white part of the eye and inside of the eyelids. It is a very common condition seen in general practice, ophthalmology, and emergency settings. While usually mild, conjunctivitis can sometimes point towards more serious pathology, so accurate diagnosis and management following NICE and Royal College of Ophthalmologists guidance is essential.

Causes

Conjunctivitis can be caused by:

• Infections:
  1. Viral (most common, often adenovirus)
  2. Bacterial (such as Staphylococcus aureus, Streptococcus pneumoniae)
• Allergic reactions: To allergens like pollen, dust mites, or pet dander.
• Chemical irritants: Such as chlorine, smoke, or cleaning fluids.
• Foreign bodies: Like dust or debris entering the eye.
• Autoimmune conditions: Rarely, as part of diseases like Stevens-Johnson syndrome.

Pathophysiology

Infectious conjunctivitis occurs when viruses or bacteria infect the conjunctiva, causing local inflammation, vessel dilation, and discharge. Allergic conjunctivitis results from hypersensitivity reactions where allergens stimulate mast cells to release histamine, leading to swelling, redness, and itching. Chemical conjunctivitis is a result of direct irritation and damage to conjunctival tissues by toxic agents.

Signs and Symptoms

Patients typically present with:

• Redness of the eye, especially around the edges
• Watery or purulent (thick, sticky) discharge
• Gritty or burning sensation
• Itching (particularly in allergic conjunctivitis)
• Mild swelling of eyelids
• Sticky eyelids on waking (more common in bacterial conjunctivitis)
• Mild sensitivity to light
• Vision should remain normal; if vision is affected, serious causes like keratitis must be ruled out.

Risk Factors

• Recent upper respiratory tract infections (for viral conjunctivitis)
• Contact lens use, especially poor hygiene
• Exposure to allergens
• Crowded living conditions (increases transmission risk)
• Immunocompromised states (increased risk of severe infections)
• Direct contact with infected persons or contaminated surfaces

Investigation

Most cases are diagnosed clinically based on history and examination. However, investigations may be required in atypical or severe cases:

• Conjunctival swab and culture: If gonococcal or chlamydial infection is suspected or if standard treatment fails.
• Fluorescein staining and slit lamp exam: To rule out corneal involvement.
• PCR tests: In suspected viral outbreaks or neonatal infections.
• Allergy testing: In cases of persistent allergic conjunctivitis.
• Routine imaging is not usually necessary unless deeper eye structures are involved.

Management

1. Non-Pharmacological Management

• Good hygiene: Handwashing, avoiding eye touching, and using separate towels
• Cold compresses: For allergic and viral conjunctivitis to reduce discomfort
• Warm compresses: For bacterial conjunctivitis to loosen crusts
• Avoiding contact lenses: During active infection
• Environmental control: Avoiding allergens if identified

2. Pharmacological Management

• Bacterial conjunctivitis:
  1. First-line: Topical antibiotics like chloramphenicol eye drops/ointment for 5 days (NICE recommends treating only if severe or prolonged)
• Viral conjunctivitis:
  1. Supportive treatment only; antibiotics are ineffective
  2. Artificial tears can relieve irritation
• Allergic conjunctivitis:
  1. Antihistamine eye drops (e.g., olopatadine)
  2. Mast cell stabilisers (e.g., sodium cromoglicate)
  3. Oral antihistamines in severe cases

3. Surgical Management

Surgery is rarely required. However, urgent ophthalmology referral is necessary if there are complications like corneal ulceration, membrane formation, or severe vision-threatening infections.

Complications

If left untreated or if mismanaged, conjunctivitis can lead to:

• Corneal involvement (keratitis) leading to scarring and vision loss
• Chronic conjunctivitis
• Spread of infection to deeper eye structures (rare but serious)
• Psychosocial impact due to discomfort or cosmetic concerns
• Severe allergic reactions causing giant papillary conjunctivitis

References

• National Institute for Health and Care Excellence (NICE) – Clinical Knowledge Summary: Conjunctivitis
• Royal College of Ophthalmologists – Guidelines for Management of Red Eye
• Public Health England – Guidance on Management of Infectious Conjunctivitis
• British National Formulary (BNF) – Ophthalmology Section
• General Medical Council (GMC) – Standards of Good Medical Practice