The conjunctiva is the clear layer of tissue that lines the inner eyelids (tarsal or palpebral conjunctiva) and the eyeball itself (bulbar conjunctiva). It extends from the eyelid margin to the edge of the cornea. Histologically, the conjunctiva is composed of an epithelial layer that contains goblet cells, a substantia propria layer that contains lymphatic vessels, and a lymphoid layer that is active in generating immune responses. The conjunctiva is normally clear, with a few visible blood vessels supplied by the anterior ciliary artery. The vessels become dilated when they are irritated (blood-shot eyes).

The conjunctiva is important in maintaining a normal tear film in the eye. The tears are composed of 3 layers (Figure 27–1). The bulk of the tear film is composed of the liquid aqueous layer, which is secreted by the lacrimal glands. The external surface of the tear film is composed of the lipid layer. This layer is formed by lipids secreted by the meibomian glands in the eyelids. The lipid layer maintains stability of the tear film and retards evaporation. The basal layer of the tear film is the mucin layer. This layer is secreted by the conjunctival goblet cells. Its primary function is to promote adhesion between the tear film and the eyeball and lubricate the eye. Abnormalities of any of these layers may cause dysfunction of the tears, with secondary ocular complications.

Inflammation of the conjunctiva due to allergies or infection (pink eye) is one of the most common ocular problems encountered by pediatricians.

The conjunctiva has a limited number of ways to respond to stimuli. The most common is dilation of the conjunctival blood vessels, which may occur as a reaction to external irritation (e.g., smoke), infection, trauma, or inflammation. These conditions may also cause edema of the conjunctiva, which produces a milky thickening of the conjunctival tissue (chemosis) (Figure 27–2). If the conjunctiva is diffusely damaged, the surfaces may scar. This can produce adhesion of the conjunctiva between the globe and the inner lining of the eyelid (symblepharon) (Figure 27–3). If a large area of the conjunctiva is injured, tear film dysfunction may develop due to loss of the mucin tear layer that is normally produced by the conjunctival goblet cells. In this condition the tear production is normal, but the tears do not function properly because they cannot adhere to the eye.

The tarsal conjunctiva has 2 common responses to inflammation. The first is papillae. This is a vascular reaction of the conjunctiva in which abnormal capillaries are surrounded by areas of inflammation. Because the conjunctiva is attached to the underlying tissue by fibrous septa, the follicles usually appear as multiple, small, elevated mounds with vessels in their centers (Figure 27–4A). These can vary from a fairly smooth, velvet-like appearance to multiple large nodules (giant papillary conjunctivitis) (Figure 27–4B).

The second type of conjunctival reaction is follicles. These are produced by clusters of lymphoid tissue within the conjunctiva, most readily visible on the inner surface of the lower eyelid. They may enlarge in response to certain infections or medication and are analogous to the swollen lymph glands in the neck that may develop in response to pharyngitis. They appear as pink, smooth, elevated nodules (Figure 27–5).

Most conjunctival disorders present with various degrees of conjunctival inflammation, edema, and dilation of the conjunctival blood vessels (commonly called injection of the blood vessels). The main etiologies are discussed below.

Follicular Conjunctivitis

One type of conjunctivitis that has a fairly specific differential diagnosis is follicular conjunctivitis, which presents with a follicular reaction of the conjunctiva lining the lower eyelid (Table 27–1 and Figure 27–5). The most common etiology of follicular conjunctivitis is infection, and several organisms are associated with this particular response. The most common is adenovirus, which is a frequent cause of infectious conjunctivitis (pink eye). Herpes simplex virus (HSV), if it involves the eye, may cause follicular conjunctivitis, and this finding may be helpful in establishing a diagnosis. Chlamydial conjunctivitis also may cause a follicular reaction. However, neonates do not produce follicles, and therefore they are not present in ophthalmia neonatorum secondary to chlamydial disease. Chlamydia is a common sexually transmitted disease in adolescents, and the presence of follicular conjunctivitis in this setting should prompt testing for this pathogen. Patients with Molluscum contagiosum that involve the eyelids and periocular structures may develop a secondary follicular conjunctivitis. This resolves with treatment of the eyelid lesions. Finally, follicular conjunctivitis may occur as a side effect of topical ocular medications, such as dipivefrin, brimonidine, and atropine.

Infectious conjunctivitis is one of the most common pediatric ophthalmology disorders encountered by pediatricians. Viral etiologies are most frequent, followed by bacterial and chlamydial.

Viral Conjunctivitis

Clinically, viral conjunctivitis usually produces symptoms of ocular irritation and discharge. Examination reveals injection of the conjunctival blood vessels, chemosis, and a mucoid discharge. A follicular reaction of the tarsal conjunctiva is often present. Most patients with viral conjunctivitis have other manifestations of viral infection, most commonly upper respiratory infection.

Most viral conjunctivitis is caused by adenoviruses. Certain serotypes may produce specific types of reactions, such as pharyngoconjunctival fever, hemorrhagic conjunctivitis, or follicular conjunctivitis. Epidemic keratoconjunctivitis(EKC) is a highly contagious form of viral conjunctivitis associated with adenovirus types 8, 19, and 37. It presents with a follicular conjunctivitis and is often accompanied by preauricular lymphadenopathy. Unlike most forms of viral conjunctivitis, EKC usually is associated with multiple fine corneal epithelial and subepithelial opacities, which are not visible without a slit lamp. The diagnosis can be made clinically. Confirmatory office testing with rapid immunochromatography is available (RPS Adenodetector, Rapid Pathogen Screening, Inc., South Williamsport, PA). Patients with EKC should be kept out of school because of the highly contagious nature of the disease. Treatment is usually supportive. Topical corticosteroids may be used in patients with marked symptoms due to corneal changes. These are effective in improving symptoms, but may prolong recovery.

Herpes Virus

HSV and herpes zoster virus may cause conjunctivitis. Primary HSV (usually HSV1) is most likely to present with symptoms of conjunctivitis, usually accompanied by vesicles on the eyelid and a follicular reaction of the tarsal conjunctiva (Figure 27–6). Recurrent HSV more commonly involves the cornea. Topical treatment of isolated HSV conjunctival disease is usually not necessary. Acyclovir is usually used if the cornea is involved.

Varicella may also cause conjunctivitis (Figure 27–7A), including small vesicles or ulcerations on the bulbar conjunctiva (Figure 27–7B). These almost always resolve without sequela, and treatment is not necessary, although topical antibiotics may be used to prevent secondary infection.

Bacterial Conjunctivitis

Bacterial conjunctivitis has symptoms that are similar to viral conjunctivitis, but it is usually associated with a mucopurulent ocular discharge. The most common organisms in children are Streptococcus pneumoniae and Moraxella. The use of vaccines has decreased the incidence of Haemophilus infections. The disorder is usually self-limited, but topical antibiotics are usually used to speed up the recovery. Many broad-spectrum antibiotics are available for treatment, including trimethoprim-polymixin B, aminoglycosides, and erythromycin. Newer medications, such as fourth-generation fluoroquinolones, are more rapidly effective, but are considerably more expensive than the alternatives. Cultures are typically not necessary unless the infection is severe or not improving with conventional therapy.

Neisseria gonorrhoea is a potentially severe form of bacterial conjunctivitis that may occur as a sexually transmitted disease in older children or acquired in neonates by exposure to an infected birth canal (ophthalmia neonatorum). This usually presents with hyperpurulent discharge and may progress rapidly to involve the cornea, potentially causing perforation. Erythromycin ointment is used in newborns as prophylaxis against N gonorrhoea and Chlamydia infections.

Neisseria meningiditis is another rare cause of bacterial conjunctivitis that presents with hyperpurulent discharge. N meningiditis has the potential for rapid systemic spread, leading to meningitis or septicemia. Affected patients require systemic treatment in addition to topical antibiotics, and individuals exposed to the patient require prophylactic treatment with rifampin to prevent disease.1

Chlamydial Conjunctivitis

Chlamydial conjunctivitis results from infection with Chlamydia trachomatis. It may occur as a form of ophthalmia neonatorum acquired through an infected birth canal (Figure 27–8), or as a sexually transmitted disease in older children. In older patients the conjunctivitis is usually accompanied by urethritis or cervicitis. Clinical symptoms include mild discharge. Corneal infiltrates are often present. The presence of a marked conjunctival follicular response is highly suggestive of chlamydial infections in adolescents.

Neonates with chlamydial infection acquired at birth usually present in the first week of life with conjunctival swelling and moderate discharge. Unlike older patients, the conjunctiva in neonates does not produce follicles, and therefore follicular changes are not seen in neonates with chlamydial conjunctivitis.

In both newborns and older patients, the diagnosis of Chlamydia may be established by culture, polymerase chain reaction, direct fluorescent antibody, or enzyme immunoassay tests. Erythromycin ointment is used prophylactically in newborns to prevent infection with N gonorrhoea and Chlamydia. If infants do become infected, systemic treatment with erythromycin is needed due to the risk of pneumonia. Older patients require systemic treatment and evaluation for other sexually transmitted diseases.

Molluscum Contagiosum

M contagiosum results from a DNA pox virus that is spread by direct contact. It produces elevated smooth nodules with umbilicated centers (Figure 27–9A). The lesions may develop anywhere on the body. Lesions on or near the eyes may shed viral particles into the tear film, causing follicular conjunctivitis (Figure 27–9B). Several treatment options are available. Removal of the core with a small needle is usually effective. Recurrences may occur if not all of the lesions are treated.