Conjunctivitis

Causes

Conjunctivitis can arise from various factors, including:

1. Infectious Causes:
   • Viral Conjunctivitis: Often caused by adenoviruses, this is the most common type and is highly contagious.
   • Bacterial Conjunctivitis: Caused by bacteria such as Staphylococcus aureus or Streptococcus pneumoniae, leading to purulent discharge.
   • Chlamydial Conjunctivitis: A sexually transmitted infection that can cause conjunctivitis, often associated with other genital infections.
2. Allergic Causes:
   • Allergic Conjunctivitis: Triggered by allergens such as pollen, pet dander, or dust mites, leading to itching, redness, and watery discharge.
3. Irritant Causes:
   • Chemical Conjunctivitis: Caused by exposure to irritants such as smoke, chlorine, or chemicals.
   • Foreign Bodies: The presence of foreign objects in the eye can lead to irritation and inflammation.

Differential Diagnoses

When evaluating conjunctivitis, it is important to consider other conditions that may present similarly. Differential diagnoses include:

1. Keratitis: Inflammation of the cornea, which can cause similar symptoms but may also lead to vision changes.
2. Uveitis: Inflammation of the uveal tract, which can cause redness and pain but is often associated with systemic diseases.
3. Blepharitis: Inflammation of the eyelid margins, leading to redness and crusting but primarily affecting the eyelids rather than the conjunctiva.
4. Dry Eye Syndrome: Can cause redness and irritation but is typically associated with a lack of tear production rather than inflammation.
5. Subconjunctival Hemorrhage: Bleeding under the conjunctiva can cause redness but does not typically involve discharge or irritation.