-IBIS-1.5.0-
tx
eyes/ears/nose/throat
conjunctivitis
diagnoses

definition and etiology

definition: An acute infection of the conjunctiva, which may be viral, bacterial or allergic.

etiology: Only 25% of cases are caused by bacteria. Allergies and viruses (esp. adenoviruses) are responsible for most of the rest, along with other irritations to the eye and cornea, such as smoke, dust, wind, sunlamps, reflection of the snow, the common cold and exanthems. In neonates, the most common causes of conjunctivitis are chemical (silver nitrate), chlamydia, gonorrhea and other bacteria (Strep pneumoniae, Staph aureus, Hemophilus influenza), and viruses (esp. Herpes simplex I and II). Bacterial infections may superimpose viral or allergic conditions.

signs and symptoms

viral: Clear discharge; minimal or absent lid swelling; no itching; often, lymphadenopathy of periauricular node is present.

allergic: Clear, mucoid discharge; high eosinophils; mild to marked lid swelling; severe itching with increased lacrimation; no nodal involvement.

bacterial: Purulent, green discharge; high polymorphonuclear leukocytes; moderate lid swelling; no itching; no nodal involvement; possible fever.

In any of the three, but more typically in bacterial cases, the patient may wake up in the morning with eyelids agglutinated shut. Children may find this very traumatic the first time it happens.

neonatal conjunctivitis:
gonorrhea: usually occurs within 3-5 days of birth

chlamydia: usually occurs within 5-14 days of birth

• chemical irritation from silver nitrate (now becoming rare as most hospitals have switched to erythromycin): occurs 6-8 hours after instillation into the eyes

lab findings:
• discharge should be cultured, and stained with Gram's and Wright's
• examination of conjunctival scrapings
• flourescein stain to rule-out foreign body presence

course and prognosis

• Allergic conjunctivitis is likely to persist until the season is over (e.g. from hay fever in spring), until the allergen is identified and removed from the patient's exposure, or the symptoms are suppressed with antihistamines.

• Viral conjunctivitis is usually self-limiting in 1-2 weeks, but is highly contagious and care should be taken to not spread the infection from one eye to the other or to another person. For example, the infected person should use separate towels.

• In bacterial conjunctivitis, treatment should be initiated promptly to avoid eye damage.

If the irritating factor is not removed a chronic conjunctivitis may develop with symptoms less severe than that of the acute disease but still quite noticeable (redness, itching, smarting, feeling of foreign body).

differential diagnosis

• inclusion conjunctivitis
• trachoma
• vernal conjunctivitis
• iritis
• glaucoma
• corneal ulceration


footnotes