●Causes – Conjunctivitis may be infectious (bacterial or viral) or noninfectious (allergic, toxic, dryness, and others). Most infectious conjunctivitis is probably viral; bacterial conjunctivitis is more common in children than in adults.
●Diagnosis – The diagnosis of conjunctivitis is made in a patient with a red eye and discharge only if the vision is normal and there is no evidence of keratitis, iritis, or angle-closure glaucoma. Warning signs for alternative conditions that should prompt evaluation by an ophthalmologist are discussed above.
●Distinguishing between types – Distinguishing between bacterial, viral and allergic conjunctivitis can be achieved on the basis of history and physical examination. All etiologies can cause symptoms of the eyes being stuck closed in the morning. Helpful distinguishing characteristics are presented in the table and graphic.
•Bacterial – Bacterial conjunctivitis should only be diagnosed in patients with thick purulent discharge that continues throughout the day and should be confirmed by a clinician examination. The discharge can generally be seen at the lid margins and at the corner of the eye. Bacterial conjunctivitis is usually unilateral but can be bilateral.
Hyperacute bacterial conjunctivitis may be due to Neisseria infection; this can be severe and sight-threatening. Such patients require urgent ophthalmology referral.
•Viral – Viral conjunctivitis typically presents as injection, mucoid or serous discharge, and a burning or gritty feeling in one eye. It may be an isolated manifestation or part of a systemic viral illness. The second eye usually becomes involved within 24 to 48 hours; unilateral viral infection may occur. Usually there is profuse tearing rather than discharge; the latter may be present on close examination. The symptoms generally worsen for three to five days and resolve over one to two weeks.
•Allergic – Allergic conjunctivitis typically presents as bilateral redness, watery discharge, and itching. Itching is the cardinal symptom of allergy, distinguishing it from a viral etiology. Patients with allergic conjunctivitis often have a history of atopy, seasonal allergy, or specific allergy.
●General measures – Infectious conjunctivitis is highly contagious. Contact limitation is advised. For bacterial conjunctivitis, 24 hours of treatment and resolution of drainage is advised before returning to school or work. Patients with viral conjunctivitis may remain infectious beyond that period; advice regarding return to school or work should be individualized.
