CHAPTER 92

Infections of the Eye

Teresa O. Rosales, MD

Infections of the eye and surrounding structures are commonly seen by pediatricians. Such infections range in severity from common problems, such as blepharitis and conjunctivitis, which lack serious sequelae, to severe and less common infections, such as periorbital and orbital cellulitis. The presenting concern in many children with eye infection is a red-appearing eye. Familiarity with the common causes of a red eye makes prompt diagnosis and treatment possible.

Epidemiology

Conjunctivitis, which affects children of all ages, is perhaps the most common eye infection of childhood. The rate of conjunctivitis in the newborn period is estimated to range from 1.6% to 12%. The prevalence of chlamydial conjunctivitis is approximately 8 in 1,000 live births. Approximately two-thirds of acute childhood conjunctivitis has a bacterial etiology, and one-third is viral. Haemophilus influenzae and Streptococcus pneumoniae are the most common bacterial agents and account for approximately 40% and 10% of culture-proven cases, respectively. The incidence of H influenzae is decreasing with the advent of the H influenzae type b vaccine. The incidence of community-acquired methicillin-resistant Staphylococcus aureus (MRSA) is increasing. Staphylococcus aureus is isolated from the conjunctivas of children with acute conjunctivitis, but it is found with approximately the same frequency in the eyes of children without conjunctivitis. Adenovirus is the most common viral isolate. Most cases of acute conjunctivitis in young adults have a viral etiology. Serious eye infections, such as periorbital and orbital cellulitis, occur far less often.

Clinical Presentation

Red eyes and discharge are the common presenting signs of infection of the eyelids and conjunctivas. Eyelid edema and erythema surrounding the eye characterize periorbital and orbital cellulitis. Proptosis, abnormal extraocular movement, or loss of visual acuity may signal spread of the infection beyond the orbital septum, as in orbital cellulitis (Box 92.1).

Pathophysiology

Eye infections may be divided into 2 types: those affecting the structures surrounding the orbit and those involving the orbital contents themselves (Figure 92.1). Although all structures surrounding the eye may potentially become inflamed or infected, the eyelids; nasolacrimal drainage system, as in dacryocystitis (see Chapter 93); conjunctiva; and cornea are most commonly involved. Orbital cellulitis is defined as an infection of the orbital structures posterior to the orbital septum. The orbital septum, an extension of the periosteum of the bones of the orbit, extends to the margins of the upper and lower eyelids and provides an anatomic barrier to the spread of most infectious and inflammatory processes. Preseptal or periorbital cellulitis is localized to structures superficial to the orbital septum, whereas postseptal or orbital cellulitis implies that the disease process involves orbital structures extending beyond the septum.

Differential Diagnosis

Infections of the eye are included in the differential diagnosis of conditions presenting with red eye (Box 92.2). Also included in the differential diagnosis are congenital, inflammatory, traumatic, and systemic processes. Although infection and irritation are by far the most common causes of an acute onset of red eye, other possibilities, including trauma, glaucoma, or underlying systemic disease, must be considered.

Figure 92.1. The eye and surrounding structures.

Eyelid Infections

Common conditions affecting the eyelid and its related structures are blepharitis, hordeolum, and chalazion.

Blepharitis is an inflammation of the lid margins. This condition, which is often bilateral, may be chronic or recurrent. The 2 most common causes of blepharitis are staphylococcal infection and seborrheic dermatitis. The child with staphylococcal blepharitis often presents with scales at the base of the lashes, ulceration of the lid margin, and loss of lashes. The infection may spread to the conjunctiva or cornea, producing conjunctivitis or keratitis. In contrast, seborrheic blepharitis is characterized by greasy, yellow scales attached to the base of the lashes. Additionally, associated seborrhea of the scalp or eyebrows may be present. Mixed staphylococcal-seborrheic infections, which occur as staphylococcal superinfection, may complicate seborrheic blepharitis. Less commonly seen forms of blepharitis are parasitic blepharitis, which results from infestation of the lids by the head louse, Pediculus humanus capitis, or crab louse, Phthirus pubis, and primary or recurrent human herpesvirus 1 infections that may manifest as clusters of vesicles on the eyelids. Rosacea may rarely occur in childhood and can present very similarly to chronic blepharitis.

The glands of the eyelid can also be infected. Staphylococcus aureus is the most common organism. A hordeolum, or common stye, results from an infection of the meibomian glands located along the lid margins. The glands become obstructed and an abscess can form. The affected child presents with a well-circumscribed, painful swelling that may be at the lid margin or deeper in the lid tissue. These generally rupture or resolve without complications when managed aggressively with hot compresses.

A chalazion is a hordeolum that has not resolved over weeks to months. It is no longer an infectious process but has become a chronic granulomatous inflammation of the meibomian glands. The resulting firm, nontender, slow-growing mass within the upper or lower eyelid may be painful if secondary infection is present.

Infections of the Conjunctiva

Conjunctivitis refers to any inflammation of the conjunctiva. The condition may be allergic, chemical, viral, or bacterial in etiology. Additionally, it may be a sign of systemic disease, such as Kawasaki disease or Stevens-Johnson syndrome.

Acute conjunctivitis, or pinkeye, is common during childhood and can be extremely contagious. The usual signs are conjunctival injection, tearing, discharge, crusting of the lashes, and conjunctival edema (ie, chemosis). Pain and decreased vision are uncommon symptoms and may signal corneal involvement.

Generally, it is difficult to distinguish bacterial conjunctivitis from viral conjunctivitis on clinical features alone. Certain clinical characteristics may guide the diagnosis. The average age of children affected with bacterial conjunctivitis tends to be younger than the age of those with viral conjunctivitis, which occurs more frequently in adolescents; however, considerable overlap occurs. The child with bacterial conjunctivitis typically presents with an acute onset of unilateral or bilateral injection and edema of the palpebral and bulbar conjunctiva, minimal to copious purulent discharge, and crusting of the eyelashes. The child may have difficulty opening the eyes on awaking in the morning because of the exudate. An association between conjunctivitis and concomitant otitis media has been well described. Haemophilus influenzae, which is often resistant to ampicillin, is the pathogen most commonly isolated from affected children.

The diagnosis of viral conjunctivitis is considered if signs of viral upper respiratory infection (eg, low-grade fever, cough, rhinorrhea) are evident. Viral infection is associated with conjunctival injection, watery or thin mucoid discharge, and only mild lid edema and erythema. Adenoviral infection is usually bilateral, with significant conjunctival injection and chemosis of the conjunctiva, and is often accompanied by a tender preauricular lymph node. Epidemic keratoconjunctivitis is a highly contagious form of adenoviral conjunctivitis. Affected children often report foreign body sensation beneath the lids or photophobia resulting from corneal involvement. Pharyngeal conjunctival fever, another presentation of adenoviral conjunctivitis, usually manifests as conjunctivitis in association with pharyngitis and fever.

The infant with chronic or recurrent conjunctival discharge may have an obstruction of the nasolacrimal duct, whereas the older child with chronic conjunctivitis may have allergic disease, recurrent blepharitis, or chlamydial infection. Blepharitis is the most common cause of chronic conjunctivitis in older children. Staphylococcus aureus is frequently implicated in these infections.

Itching, tearing, and conjunctival edema are the hallmarks of allergic conjunctivitis, a noninfectious form of conjunctival inflammation often occurring in children with other allergic disorders, such as asthma or hay fever. Conjunctival injection tends to be mild, bilateral, and seasonal. The etiology is most often a hypersensitivity to pollens, dust, or animal dander. Vernal conjunctivitis is a bilateral, severe form of allergic conjunctivitis seen primarily during childhood. Most cases occur during the spring and summer. Severe itching and tearing are the most frequent complaints. The palpebral conjunctiva may have a cobblestone appearance resulting from the accumulation of inflammatory cells, or there may be small, elevated lesions of the bulbar conjunctiva at the corneal lim-bus. The pathogenesis is unclear, but atopy seems to play a role.

Chlamydial conjunctivitis frequently affects neonates and adolescents. Inclusion conjunctivitis is an acute infection of the eyes caused by sexually transmitted Chlamydia trachomatis (usually serotypes D–K). This condition may be seen in the neonate or sexually active adolescent. Trachoma, the most common cause of impaired vision and preventable blindness worldwide, is a chronic conjunctivitis usually caused by C trachomatis serotypes A, B, and C. Although this disease is rarely seen in North America, it is endemic among certain populations, especially Native Americans. Inclusion conjunctivitis and endemic trachoma are characterized initially by conjunctivitis with small lymphoid follicles in the conjunctiva.

Neonatal conjunctivitis, or ophthalmia neonatorum, occurs during the first month after birth. In decreasing order of frequency, the major causes of neonatal conjunctivitis are chemical, chlamydial, and bacterial. Ophthalmia neonatorum may be produced by the same bacteria that cause childhood conjunctivitis but also results from organisms such as C trachomatis and Neisseria gonorrhoeae. The newborn may acquire these latter pathogens following premature rupture of membranes or passage through an infected or colonized birth canal. Chlamydia trachomatis is the organism most commonly identified. It has been isolated from 17% to 40% of neonates with conjunctivitis. The neonate born to a mother with active cervical chlamydial infection has a 20% to 50% chance of developing chlamydial conjunctivitis. Viruses are uncommon causes of neonatal ocular infections. Human herpesvirus is the primary viral agent involved in neonatal conjunctivitis. The presence of characteristic vesicular skin lesions or corneal dendritic lesions helps in the diagnosis.

Time of onset of symptoms is related to the etiologic agent. Inflammation secondary to the silver nitrate drops instilled at birth to prevent gonococcal infection presents as mild conjunctivitis 12 to 24 hours after birth in 10% to 100% of treated newborns. This condition usually resolves spontaneously in 24 to 48 hours. This is more of historic interest because erythromycin ointment 0.5% has replaced silver nitrate in most hospitals. (Silver nitrate was ineffective against C trachomatis.) Conjunctivitis resulting from N gonorrhoeae appears 2 to 5 days after birth and is associated with copious purulent discharge. Conjunctivitis caused by C trachomatis occurs at 5 to 14 days, a result of a longer incubation period. Time of onset and severity of symptoms of these 2 conditions may overlap, however. The presentation of gonococcal infection may be delayed for 5 days or more because of the partial suppression of the infection by the prophylactic drops instilled at birth. Chlamydial infection can vary in severity from mild erythema of the eyelids to severe inflammation and copious purulent discharge. Chlamydial infection is primarily localized to the palpebral conjunctiva and only rarely affects the cornea. Gonococcal conjunctivitis is considered a medical emergency because the gonococcus can penetrate the cornea, resulting in corneal ulceration and perforation of the globe within 24 hours if untreated.

Concomitant nasopharyngeal chlamydial infection is common. Spread of the organism from the nasopharynx to the lungs is a sequela of colonization. Ten percent to 20% of newborns and infants with conjunctivitis have chlamydial pneumonia. It may occur simultaneously with the conjunctivitis or up to 4 to 6 weeks later. The affected newborn or infant usually is afebrile and presents with symptoms of increasing tachypnea and cough.

Anterior uveitis may be confused with conjunctivitis. The uvea consists of the iris, ciliary body, retina, and choroid. Inflammation of the iris or ciliary body may produce conjunctival injection, which may be associated with decreased visual acuity, pain, headache, and photophobia. Systemic conditions associated with uveitis include Kawasaki disease, juvenile idiopathic arthritis, Lyme disease, tuberculosis, sarcoidosis, Toxocara infection, toxoplasmosis, and spondyloarthropathies.

Infections of the Eye and Surrounding Tissues

Preseptal cellulitis and orbital cellulitis are 2 serious infections of the eyelids and surrounding structures. Although these infections are not as frequent as those that are limited to the eye, they have serious sequelae. The preseptal space is defined by the skin of the eyelid on one side and the orbital septum on the other. The child with preseptal cellulitis, or periorbital cellulitis, usually presents with acute onset, unilateral upper and lower eyelid edema, erythema, and pain. The condition is often associated with systemic signs and symptoms, such as ill appearance, fever, and leukocytosis. The eye itself usually appears normal. Infection may follow hematogenous seeding of the preseptal space, most often with H influenzae type b or S pneumoniae, or after traumatic breaks in the skin that usually result in S aureus infection.

Orbital cellulitis is an infection of the contents of the orbit posterior to the orbital septum. Usually an insidious onset of eyelid edema, proptosis, decreased extraocular movements, and loss of visual acuity occur. As with periorbital cellulitis, the affected child is often febrile and ill-appearing. Contiguous spread of infection from adjacent sinusitis (most often ethmoid) is the most common cause. The organisms most often involved are the same as those in acute sinusitis (ie, S aureus, S pneumoniae, non-typeable H influenzae). Untreated, the infection may progress to orbital abscess formation or progress posteriorly in the orbit to the cavernous sinus and brain.

Primary human herpesvirus infection can affect the skin surrounding the eyes as well as the eye itself. Most of these infections are caused by human herpesvirus 1, although human herpesvirus 2 infections may occur in the newborn. The child with herpetic infection of the eye usually presents with unilateral skin vesicles and a mild conjunctivitis or keratitis. Herpetic keratoconjunctivitis can recur after fever, exposure to sunlight, or mild trauma. The characteristic corneal lesion of herpetic keratitis is the dendritic corneal ulcer, which appears as a tree branch pattern on fluorescein staining of the cornea. Although this lesion may occur with primary infection, it is more common in recurrent infections. Skin vesicles may not appear with a recurrence, which makes it difficult to distinguish herpetic infection from other causes of conjunctivitis. Steroids may cause progression of the herpetic infection and permanent corneal scarring as well as cataracts and glaucoma. Empiric topical steroid treatment for presumed viral conjunctivitis should be avoided for this reason. Neonatal herpetic infections of the eye primarily result from human herpesvirus 2. Infections may be isolated to the eye, or the eye may be infected secondarily resulting from central nervous system or disseminated disease. Proper diagnosis is important because disseminated herpetic disease has a mortality rate of approximately 85%, and central nervous system disease has a mortality rate of 50%. Isolated herpetic eye disease is quite rare in neonates.

Evaluation

History

A careful history taken from the parent or primary caregiver as well as the child can guide the diagnosis (Box 92.3). It is important to exclude the possibility of ocular trauma or exposure to noxious chemicals when evaluating the child with red, irritated eyes.

Physical Examination

A thorough examination of the eyes should be performed. The eyelids, conjunctiva, and cornea should be inspected for evidence of inflammation or foreign bodies. The presence of any discharge or crusting of the eyelids as well as light sensitivity or pain should be noted. Extraocular movements should be checked, and their symmetry should be noted. Visual acuity should be determined, and an ophthalmoscopic examination of the retina should be performed whenever possible. A slit-lamp examination of the eye is indicated if uveitis is suspected. Additionally, it is important to perform a thorough head and neck examination, noting the presence of associated sinusitis, otitis media, pharyngitis, or preauricular nodes.

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