Differentiating Types of Conjunctivitis

Conjunctivitis—or pink eye—is an inflammatory but nontraumatic eye complaint, and many people head to the emergency department for treatment even though they don't need to. It occurs when infectious agents adhere to the conjunctiva and overwhelm normal defense mechanisms. What follows is a constellation of redness, discharge, irritation, and, sometimes, photophobia.

Conjunctivitis can be allergic, bacterial, chemical, chlamydial, contact lens—related, fungal, parasitic, toxic, or viral in origin. Viral infection is responsible for more cases than the common staphylococcal and streptococcal bacterial infections, and is more likely to develop in the summer. Bacterial conjunctivitis occurs more often in winter and spring.

Conjunctivitistends to be a benign, self-limited process unless the patient's immune status is compromised; in these patients, conjunctivitis can progress and may threaten the patient's sight.

Most retail health clinicians often see just a few types of conjunctivitis:

• Allergic conjunctivitis is usually acute or subacute in onset and painless. When patients are asked if they currently know anyone else with pink eye symptoms, they usually say no. Patients almost always indicate they have allergies. This type of conjunctivitis causes considerable pruritus. Clear, watery discharge may be accompanied by moderate mucus production.
• Bacterial conjunctivitis is an acute condition that is occasionally painful and very contagious, especially in children's daycare facilities. It occurs more often in children than adults. They often have purulent or mucopurulent discharge, which can be bilateral or unilateral.
• Chlamydial conjunctivitis is a chronic, usually painless condition that is sometimes itchy. Patients have histories of sexually transmitted disease. This condition requires systemic treatment with doxycycline or erythromycin.
• Viral conjunctivitis often comes on quickly, causes little pain, and is very contagious. Patients may have been exposed at daycare, at school, or in communal living situations. This type of conjunctivitis is often itchy, and both of the patients' eyes may weep with clear fluid. Sometimes, patients shy from the light or indicate it feels like something is in the affected eye (foreign-body sensation).

Differentiating between viral and bacterial conjunctivitis is difficult. Researchers who have looked for differentiating signs report that patients who awaken with 1 or both eyes “glued” shut are 3 times more likely to have a bacterial infection than a viral infection if 1 eye is affected, and 15 times more likely if both eyes are affected.

Note that keratoconjunctivitis, an adenoviral infection, mimics the symptoms of bacterial infection and may cause the lids to stick together. Patients with keratoconjunctivitis will report foreign body sensation and photophobia, whereas patients with bacterial infection usually do not.

Supportive care includes the use of artificial tears to ameliorate keratitis and photophobia, as well as the application of cold, damp compresses to relieve swelling and lid discomfort. Patients with pruritus may respond to decongestants.

Bacterial conjunctivitis can be a secondary complication of a primary viral infection; therefore, many prescribers treat it with antibiotics. Broad-spectrum antibiotic drops (besifloxacin, ciprofloxacin, or ofloxacin) can help to prevent secondary bacterial infections from occurring. Sulfacetamide and trimethoprim/sulfamethoxazole have been used for years and still work well. Avoid aminoglycosides, as they are toxic to epithelia and retard healing. Many experts recommend a wait-and-watch approach before treatment.

Prescribers should avoid topical corticosteroids and refer patients with significant inflammation to an ophthalmologist.

Teach patients good hand hygiene and eye care, and remind them to clean their contact lenses well or wear glasses for a few days. Advise patients to return for assessment and follow-up in 3 days if the condition fails to improve.