The diversity of etiologies for conjunctivitis makes a detailed patient history the most important step in the differential diagnosis of conjunctivitis. The patient history should include the chief complaint such as itching, burning, tearing, discharge, pain, foreign body sensation, and photophobia. It should also include questions about the onset and course of the disease, whether it is acute or chronic and progressive or stationary. The ocular history should include questions about previous episodes, prior exposure to infected individuals, history of trauma or contact lens wear, and the use of topical legend (i.e., prescription) or over-the-counter medications or cosmetics. The general health history should include descriptions of recent upper respiratory tract infections, autoimmune disorders, atopy, skin conditions, and sexually transmitted infections. Finally, the social history such as environmental exposure and the family history of ocular diseases may contribute to the diagnosis of “red eye.”
The signs and symptoms of conjunctivitis, including redness, tearing or discharge, and foreign body sensation, are similar regardless of the cause. Pain and photophobia are not symptoms of conjunctivitis; if present, they may indicate other entities, including corneal abrasion, keratitis, uveitis, or acute angle-closure glaucoma. Decreased vision is not typical in patients with conjunctivitis. Occasionally, extensive discharge may blur the visual axis intermittently, but, in general, a report of decreased acuity should prompt a search for more serious disorders.
The ocular examination in a patient with conjunctivitis should include examination of the skin of the lids and the face, looking for any associated skin conditions, edema, ecchymosis, and discoloration. Certain signs and symptoms are important to consider in differentiating among the various causes of conjunctivitis. The character of the discharge may provide some diagnostic help. Serous or watery discharge usually is associated with viral or allergic etiologies. Mucopurulent discharge suggests a viral or chlamydial infection, whereas purulent discharge suggests a bacterial etiology. Close inspection of the conjunctiva may reveal follicles, suggestive of viral or chlamydial infections, or papillae, suggestive of bacterial or allergic processes. Follicles are elevations encircled by blood vessels, whereas papillae have a central vascular core.
It is also important to look for clues on physical examination, which suggest other causes of a “red eye.” In general, the redness of conjunctivitis spares the limbus. If the limbus is involved, other diagnoses must be considered, including keratitis (inflammation of the cornea) and uveitis (intraocular inflammation). A comprehensive eye examination with dilation of the pupils should be performed in those patients with conjunctival hyperemia, accompanied by proptosis, optic nerve dysfunction, decreased visual acuity, diplopia, or evidence of anterior chamber inflammation.2
Manifestations of Common Causes of Conjunctivitis
The etiologies of conjunctivitis can be classified as infectious and noninfectious. Noninfectious causes may be primary in origin, e.g., allergic conjunctivitis, or secondary to other systemic diseases. Infectious conjunctivitis can be bacterial or viral in origin.
Bacterial conjunctivitis (Figure 21–1) can be classified as hyperacute, acute, or chronic. It occurs when an organism is able to overcome the host's resistance, or following trauma. Most common bacterial pathogens can cause conjunctivitis. These pathogens include Haemophilus species (nontypable H. influenzae), Streptococcus pneumoniae, and Moraxella species. S. pneumoniae and Haemophilus infections occur more frequently in children.3–5
Bacterial conjunctivitis. Note purulent discharge and conjunctival injection. (Shah BR, Lucchesi M. Atlas of Pediatric Emergency Medicine, McGraw-Hill.)
Symptoms of bacterial conjunctivitis typically include unilateral or bilateral conjunctival injection, purulent discharge, and matting of the eyelids. More severe forms of bacterial conjunctivitis, as indicated by copious purulent discharge, suggest infection by more virulent organisms. These include Neisseria gonorrhoeae, Neisseria meningitidis, or Pseudomonas aeruginosa.
Acute or mucopurulent bacterial conjunctivitis is caused by a number of microbial agents, primarily Staphylococcus aureus, S. pneumoniae, and Haemophilus species. It is a common infectious condition that can affect all ages and races and both genders. This condition is usually self-limiting and generally lasts for <3 weeks. Atypical unencapsulated strains of S.pneumoniae are responsible for large outbreak of conjunctivitis in college campuses.6
Hyperacute or purulent bacterial conjunctivitis is commonly caused by N. gonorrhoeae, microorganisms that can penetrate an intact corneal epithelium, or, less frequently, by N. meningitidis. Infection by N. gonorrhoeae is seen most often in neonates who acquire the disease via passage through an infected birth canal; this topic is discussed in Chapter 20.7 However, this infection can also be contracted through sexual activity and may indicate that a child has been sexually active or has been sexually abused. This organism is highly virulent and may lead to corneal ulceration and perforation. Hyperacute bacterial conjunctivitis is most commonly acquired by autoinoculation from infected genitalia and most often seen in neonates, adolescents, and young adults. It appears to be more common during warmer months of the year.8,9 A less common cause of bacterial conjunctivitis is P. aeruginosa, especially in hospitalized infants, which may lead to a rapidly progressive invasive infection with corneal perforation.10,11
When symptoms of bacterial conjunctivitis last longer than 4 weeks, it can be considered chronic. The most common cause of chronic bacterial conjunctivitis is S. aureus. Chronic bacterial conjunctivitis is frequently associated with continuous inoculation of bacteria associated with blepharitis (inflammation of the eyelids, particularly at the lid margins).12
An unusual cause of conjunctivitis is Lyme disease, which is caused by Borreliaburgdorferi. Conjunctivitis usually occurs early in the disease, is mild and transient, and may be followed by other ocular manifestations of Lyme disease including keratitis, vitritis, uveitis, neuroretinitis, optic atrophy, and Bell's palsy.13
Parinaud oculoglandular syndrome is an entity characterized by unilateral granulomatous conjunctivitis, ipsilateral tenderness, and enlargement of the preauricular lymph nodes. It is often caused by Bartonella henselae14 and less commonly by Francisella tularensis12,15 but may also be associated with other infections.
The conjunctivitis–otitis media syndrome, a distinctive clinical entity, is characterized by purulent conjunctivitis associated with acute otitis media. It was initially described by Coffey16 in 1966 and further characterized by Bodor17 in 1982. It begins with low-grade fevers and mild upper respiratory symptoms, followed several days later by eye discharge and pain, with the development of ear pain in some cases. Sometimes otitis media may be the initial presentation with subsequent development of purulent conjunctivitis. Nontypable strains of H. influenzae are responsible for more than 70% of cases of conjunctivitis–otitis syndrome.18,19 The remaining cases are usually caused by either S. pneumoniae or Moraxella species.
Adenoviruses, the most common viral cause of conjunctivitis, account for 20% of all cases of conjunctivitis.20 Other viral causes of conjunctivitis include herpes simplex virus (HSV), varicella zoster virus, and enteroviruses including coxsackievirus.
Adenoviral conjunctivitis is extremely contagious; transmission typically is by direct contact with infected persons or contaminated objects or instruments such as tonometers used widely in eye clinics.21 Adenovirus conjunctivitis (Figure 21–2) is characterized by acute onset of unilateral and then bilateral, bulbar, and palpebral conjunctival hyperemia and by the formation of follicles on the palpebral conjunctiva. Petechial hemorrhages are commonly present, particularly in the bulbar conjunctiva. Follicular conjunctivitis is the most common type of adenoviral conjunctivitis. Associated findings include watery discharge, rhinitis, and preauricular lymphadenopathy usually more prominent on the side of the initially affected eye.
Adenoviral conjunctivitis. Note intense bulbar and palpebral conjunctival injection and hemorrhages. (Shah BR, Lucchesi M. Atlas of Pediatric Emergency Medicine, McGraw-Hill.)
Depending on the stage of development, conjunctival pseudomembranes may be found on the superior or inferior tarsal conjunctiva. Lid edema may also be present.
Adenovirus infections tend to be more common in the fall and winter. Patients often have symptoms of an upper respiratory infection and may have had recent contact with another person with either a red eye or an upper respiratory tract infection.
Other less common forms of adenoviral conjunctivitis include epidemic keratoconjunctivitis and pharyngoconjunctival fever. Epidemic keratoconjunctivitis is caused by adenoviral serotypes 8, 19, and 37.22 Patients usually complain of severe discomfort, photophobia resulting from keratitis, and watery discharge. This form is very contagious and often occurs in epidemic outbreaks. Physical findings include injection, chemosis, follicular reaction, corneal superficial punctate defects, and eyelid edema. Corneal subepithelial infiltrates may begin to form after 2 weeks in the disease process and, if present, may last for as long as 2 years.
The third form of adenoviral conjunctivitis, the pharyngoconjunctival fever, is caused by adenoviral serotypes 3 and 7.22 In addition to the conjunctival injection and chemosis, patients usually present with fever, pharyngitis, and preauricular lymphadenopathy. Symptoms may last for 2 weeks or more. Summertime epidemics of pharyngoconjunctival fever, linked to swimming in infected pools, have been reported.5
Infection with a member of the Herpesvirus genus (e.g., herpes simplex, varicella zoster, or Epstein–Barr virus) can result in acute conjunctivitis. HSV conjunctivitis (Figure 21–3) may occur as either a primary or a secondary infection. Most ocular infections occur as result of HSV-1, except in neonates, in whom HSV-2 is more predominant. Transmission occurs by direct contact with another person who has an active lesion or by autoinoculation of the eye from skin lesions. Signs include a follicular conjunctival reaction, watery discharge, and preauricular lymphadenopathy. Other findings suggestive of herpes simplex infection include skin or lid vesicles, gingivostomatitis, and keratitis. Fifty percent of patients with herpes zoster ophthalmicus (involving the ophthalmic division of the trigeminal nerve) show involvement of the ocular structures, of which conjunctivitis is the most common manifestation.
HSV conjunctivitis. Note multiple vesicular lesions and ulcers around the eyelid margin and mucoid discharge. (Shah BR, Lucchesi M. Atlas of Pediatric Emergency Medicine, McGraw-Hill.)
Bulbar or palpebral conjunctivitis may occur during primary varicella zoster infection (chickenpox). The recurrence of varicella zoster infection in the distribution of the ophthalmic division of trigeminal nerve (cranial nerve V) is known as herpes zoster ophthalmicus. It involves the ocular structures, and conjunctivitis is a common manifestation of this disease. Signs and symptoms are similar to HSV infection and include conjunctival injection, follicular conjunctival reaction, vesicles, and watery discharge. Patients may also complain of pain in the cranial nerve V1 distribution.