Causes of Conjunctivitis
Causes of conjunctivitis can be grouped into infectious and non-infectious categories. Understanding the root cause of conjunctivitis is essential for selecting the right treatment and preventing future occurrences or complications. Each cause leads to inflammation of the conjunctiva, but the symptoms, duration, and level of contagion differ significantly.
Infectious Conjunctivitis
This form of conjunctivitis is caused by bacteria or viruses and is typically very contagious.
Viral conjunctivitis is the most common type, usually linked to adenoviruses. It often accompanies respiratory infections like the common cold or flu. It spreads through respiratory droplets, direct contact, or contaminated surfaces.
Bacterial conjunctivitis is caused by bacteria such as Staphylococcus aureus, Streptococcus pneumoniae, or Haemophilus influenzae. It often results in thick, yellow-green discharge and may affect both eyes. This type is common among children and spreads easily in group settings.
In both viral and bacterial cases, symptoms can last several days to two weeks and require isolation and hygiene precautions to avoid infecting others.
Allergic Conjunctivitis | Causes of Conjunctivitis
Non-contagious and triggered by allergens like pollen, pet dander, dust mites, or mould, this type causes itching, watery eyes, and eyelid swelling. It often occurs in people with hay fever or asthma and may be seasonal or chronic, depending on the allergen. Repeated exposure to the trigger can result in recurring symptoms.
Chemical and Irritant-Induced Conjunctivitis
Exposure to smoke, pollution, chlorine from swimming pools, or chemical sprays may lead to irritation. The reaction is not infectious but can cause significant redness, tearing, and discomfort. It usually resolves once the irritant is removed, though severe cases may require medical attention.
Neonatal Conjunctivitis | Causes of Conjunctivitis
Newborns may develop conjunctivitis due to blocked tear ducts, irritation from eye drops, or infections acquired during birth, especially if the mother has a sexually transmitted infection like chlamydia or gonorrhoea. Prompt treatment is critical to prevent eye damage.
To summarise, causes of conjunctivitis include viruses, bacteria, allergens, chemicals, and irritants. Correct identification of the cause enables effective treatment and helps prevent recurrence, complications, or further transmission in contagious cases.
[Next: Symptoms of Conjunctivitis →]
