Conjunctivitis
Conjunctivitis: Excerpt from Professional Guide to Diseases (Eighth Edition)
Conjunctivitis is characterized by hyperemia of the conjunctiva due to infection, allergy, or chemical reactions. (See Recognizing conjunctivitis.) This disorder usually occurs as benign, self-limiting pinkeye; it may also be chronic, possibly indicating degenerative changes or damage from repeated acute attacks.
Causes and incidence
The most common causative organisms include:
❑ bacterial — Staphylococcus aureus, Streptococcus pneumoniae, Neisseria gonorrhoeae, Neisseria meningitidis
❑ chlamydial — Chlamydia trachomatis (inclusion conjunctivitis)
❑ viral — adenovirus types 3, 7, and 8; herpes simplex virus, type 1.
Other causes include allergic reactions to pollen, grass, topical medications, air pollutants, smoke, or unknown seasonal allergens (vernal conjunctivitis); environmental (wind, dust, and smoke) and occupational irritants (acids and alkalies); and a hypersensitivity to contact lenses or solutions.
Vernal conjunctivitis (so-called because symptoms tend to be worse in the spring) is a severe form of immunoglobulin E-mediated mast cell hypersensitivity reaction. This form of conjunctivitis is bilateral. It usually begins at age 3 to 5 years and persists for about 10 years. It’s sometimes associated with other signs of allergy commonly related to pollens, asthma, and allergic rhinitis.
Epidemic keratoconjunctivitis is an acute, highly contagious viral conjunctivitis caused by adenovirus types 8 and 19. It’s commonly complicated by visual loss due to corneal subepithelial infiltrates. Health care providers must be careful to wash their hands and sterilize equipment to prevent the spread of this disease.
In the Western hemisphere, conjunctivitis is probably the most common eye disorder.
Signs and symptoms
Conjunctivitis commonly produces hyperemia of the conjunctiva, sometimes accompanied by discharge, tearing and, with corneal involvement, pain and photophobia. It generally doesn’t affect vision. Conjunctivitis usually begins in one eye and rapidly spreads to the other by contamination of towels, washcloths, or the patient’s own hand.
Acute bacterial conjunctivitis (pinkeye) usually lasts only 2 weeks. The patient typically complains of itching, burning, and the sensation of a foreign body in his eye. The eyelids show a crust of sticky, mucopurulent discharge. If the disorder is due to N. gonorrhoeae, however, the patient exhibits a profuse, purulent discharge.
Viral conjunctivitis produces copious tearing with minimal exudate, and enlargement of the preauricular lymph node. Some viruses follow a chronic course and produce severe disabling disease; others last 2 to 3 weeks and are self-limiting.
Diagnosis
Physical examination reveals peripheral injection of the bulbar conjunctival vessels. In children, possible systemic symptoms include sore throat or fever, if the conjunctivitis is suspected of being of adenoviral origin.
Lymphocytes are predominant in stained smears of conjunctival scrapings if conjunctivitis is caused by a virus. Polymorphonuclear cells (neutrophils) predominate if conjunctivitis is due to bacteria; eosinophils, if it’s allergy-related. Culture and sensitivity tests identify the causative bacterial organism and indicate appropriate antibiotic therapy.
Treatment
Treatment for conjunctivitis varies with the cause. Bacterial conjunctivitis requires topical application of the appropriate broad-spectrum antibiotic. Although viral conjunctivitis resists treatment, a sulfonamide or broad-spectrum antibiotic eyedrops may prevent a secondary infection. Patients may be contagious for several weeks after onset. The most important aspect of treatment is preventing transmission. Herpes simplex infection generally responds to treatment with trifluridine drops or vidarabine ointment or oral acyclovir, but the infection may persist for 2 to 3 weeks. Treatment for vernal (allergic) conjunctivitis includes administration of corticosteroid drops followed by cromolyn sodium, cold compresses to relieve itching and, occasionally, oral antihistamines.
Instillation of a one-time dose of erythromycin or 1% silver nitrate solution (Credé’s procedure) into the eyes of neonates prevents gonococcal conjunctivitis.
Special considerations
❑ Teach proper hand-washing technique because bacterial and viral conjunctivitis are highly contagious. Stress the risk of spreading infection to family members by sharing washcloths, towels, and pillows. Warn against rubbing the infected eye, which can spread the infection to the other eye and to other people.
❑ Caution the patient who wears contact lenses to stop wearing the lenses while his eyes are infected.
❑ Apply compresses and therapeutic ointment or drops, as ordered. Don’t irrigate the eye, as this will spread the infection. Have the patient wash his hands before he uses the medication. Tell him to use clean washcloths or towels frequently so he doesn’t infect his other eye.
❑ Teach the patient to instill eyedrops and ointments correctly — without touching the bottle tip to his eye or lashes.
❑ Remind the patient that the ointment will blur his vision.
❑ Stress the importance of safety glasses for the patient who works near chemical irritants.
❑ Notify public health authorities if cultures show N. gonorrhoeae.
Pictures
Book Source Details
- Book Title: Professional Guide to Diseases (Eighth Edition)
- Author(s): Springhouse
- Year of Publication: 2005
- Copyright Details: Professional Guide to Diseases (Eighth Edition), Copyright © 2005 Lippincott Williams & Wilkins.
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Copyright notice for book excerpts: Copyright © 2008 Lippincott Williams & Wilkins. All rights reserved.
» Next page: Inclusion conjunctivitis (Professional Guide to Diseases (Eighth Edition))
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