Conjunctivitis is typically caused by an infection of the conjunctiva but allergic and chemical conjunctivitis also occur. It is useful to consider infectious conjunctivitis according to the age of the patient, namely neonatal conjunctivitis (from birth to 4 weeks of age) and adult conjunctivitis (older children to older adults) separately as the mode of acquisition and the types of causative microbes differ.
Ophthalmia neonatorum is another name for neonatal conjunctivitis caused by either Neisseria gonorrhoeae or Chlamydia trachomatis. The original use of the term” ophthalmia neonatorum” referred to gonococcal conjunctivitis but current common usage includes chlamydial conjunctivitis as well.
Trachoma is the world’s leading cause of preventable blindness. It is a conjunctivitis caused by certain strains of C. trachomatis. Because of its importance, it is discussed separately in the next section.
In neonatal conjunctivitis, the bacteria or viruses are acquired during passage through the birth canal. The neonatal infection is acquired from a mother who either has a symptomatic infection or who is an asymptomatic shedder of the organism.
In adult conjunctivitis, the bacteria or viruses are acquired either by direct contact with infected individuals or by fomites (inanimate objects such as towels) that carry the microbe. A common mode of transmission is a finger that contacts infected secretions and transfers the organism to the eye. Other risk factors include contact lens use and swimming in under-chlorinated pools.
The most characteristic clinical manifestations are a red eye (hyperemia) and a discharge. When the red eye manifests as visibly enlarged blood vessels, the eye is said to be “injected.”) The discharge in bacterial conjunctivitis, such as gonococcal conjunctivitis, is typically copious and purulent (see Figures 80–1 and 80–2), whereas in chlamydial conjunctivitis it is less copious and watery (see Figure 80–3). Gonococcal conjunctivitis can be very severe and cause corneal ulceration, scarring, and blindness. Itching, lid edema, and light sensitivity are additional symptoms of conjunctivitis.
Gonococcal conjunctivitis in neonate (ophthalmia neonatorum). Note purulent exudate in medial aspect of child’s left eye. (Reproduced with permission from Knoop KJ, Stack LB, Storrow AB, et al. The Atlas of Emergency Medicine. 4th ed. New York, NY: McGraw-Hill Education; 2016. Photo contributor: David Effron, MD.)
Gonococcal conjunctivitis in neonate (ophthalmia neonatorum). Note copious exudate in both eyes. (Used with permission from Dr Pledger J. Public Health Image Library, Centers for Disease Control and Prevention.)
Chlamydial conjunctivitis. Note hyperemia and watery exudate. (Reproduced with permission from Knoop KJ, Stack LB, Storrow AB, et al. The Atlas of Emergency Medicine. 4th ed. New York, NY: McGraw-Hill Education; 2016. Photo contributor: Jeffrey Goshe, MD.)
In viral conjunctivitis, the discharge consists a small amount of watery, serous fluid that can cause matting of the eyelashes. Viral conjunctivitis, especially that is caused by adenovirus, is often called “pink eye.” (See Figure 80–4.) Epidemic keratoconjunctivitis is a severe infection caused by certain strains of adenovirus, typical serotypes 8 and 19. It is highly contagious, causes more severe symptoms, lasts longer, and has significant sequelae, such as scarring and chronic keratitis. Because it is highly contagious, concerns about patients returning to work or to school arise.
Viral conjunctivitis caused by adenovirus. Note hyperemia (redness) of both scleral and palpebral conjunctivae and matted eyelashes. (Reproduced with permission from Shah BR, Mahajan P, AModio J, et al. Atlas of Pediatric Emergency Medicine. 3rd ed. New York, NY: McGraw-Hill Education; 2019. Photo contributor: Binita R. Shah, MD.)
Chlamydial conjunctivitis is often called follicular conjunctivitis because follicles are seen on the mucosa of the palpebral conjunctivae. It is also called inclusion conjunctivitis because inclusion bodies are seen in the cytoplasm of infected cells.
Eye pain consists of mild irritation or is absent in conjunctivitis. Visual acuity may be mildly affected. Tearing and “matting” together” of the eyelashes are common. Constitutional symptoms such as fever do not occur.
Allergic conjunctivitis presents with many of the same symptoms, i.e. red eye, tearing, and a serous exudate but itching is more prominent in allergic conjunctivitis.
Neonatal conjunctivitis is commonly caused by two bacteria, N. gonorrhoeae and C. trachomatis, and by herpes simplex virus type-2 (HSV-2) (see Table 80–1). C. trachomatis is the most common cause in the United States.
TABLE 80–1Important Causes of Conjunctivitis ||Download (.pdf) TABLE 80–1 Important Causes of Conjunctivitis
|Age of Patient ||Bacterial Causes ||Viral Causes ||Comment |
|Neonate (Birth to 4 weeks of age) || |
Herpes simplex-2 virus
Asymptomatic shedding produces fewer organisms and therefore has reduced risk of causing disease in the neonate
Older Children and Adults
Herpes simplex-1 virus
Organisms typically acquired by contact with infected individuals
Adult conjunctivitis is commonly caused by Staphylococcus aureus, Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella species. Haemophilus aegypticus (Koch-Weeks bacillus) is a common cause in tropical areas. In sexually active adults, N. gonorrhoeae and C. trachomatis are also common causes. Neisseria meningitidis also causes conjunctivitis in adults.
Adenovirus is the most common viral cause of conjunctivitis but herpes simplex virus type-1 (HSV-1) and varicella–zoster virus (VZV) also are involved. Adenovirus types 8 and 19 are the most common cause of epidemic keratoconjunctivitis.
Conjunctivitis caused by fungi, protozoa, and helminths rarely occurs.
Most diagnoses are made based on clinical grounds. If serious bacterial conjunctivitis is suspected, microbiologic diagnosis of conjunctivitis can be made by Gram stain and culture of a specimen of the discharge. Polymerase-chain reaction (PCR) assay is the most sensitive and specific test for C. trachomatis. Conjunctival scrapings stained with Giemsa stain reveal cytoplasmic inclusion bodies in chlamydial conjunctivitis. Viral conjunctivitis caused by, for example, adenovirus, HSV-1, and HSV-2 can be diagnosed by using PCR assay.
Serious conjunctivitis, such as that caused by N. gonorrhoeae, should be treated with systemic ceftriaxone in both the neonate and adult. Neonatal chlamydial conjunctivitis should be treated with systemic erythromycin or azithromycin as that can prevent chlamydial pneumonitis as well.
Mild cases of conjunctivitis often resolve without treatment. In mild cases of bacterial conjunctivitis, topical ophthalmic antibiotics such as sulfacetamide, ciprofloxacin, or a polymyxin-trimethoprim combination can be used.
There is no treatment available for adenoviral conjunctivitis. Conjunctivitis caused by HSV-1 can be treated with oral acyclovir or topical ganciclovir. (There is no topical acyclovir available in the United States.) Neonatal conjunctivitis caused by HSV-2 should be treated with intravenous acyclovir.
Bacterial neonatal conjunctivitis can be prevented by the application of erythromycin ointment to the eyes of the neonate. Proper hand hygiene can limit spread to others.