Eye Infection: Cures for a Common Ailment, Part 2
ABSTRACT: Bacterial keratitis warrants use of topical antibiotics. Referral to an ophthalmologist is indicated for both bacterial and viral keratitis. Treatment of superficial keratitis should be directed at the underlying cause.
For both scleritis and episcleritis, treatment involves managing the underlying condition and use of NSAIDs, cycloplegics, and topical corticosteroids. The mainstay of treatment of uveitis is topical corticosteroids, such as 1% prednisolone acetate. NSAIDs may also be added to the regimen.
Cycloplegic-mydriatic agents, such as 1% atropine, help reduce the development of synechiae. Outpatient management with oral antibiotics may be appropriate for the afebrile, nontoxic child with preseptal cellulitis. However, if the child looks toxic or the diagnosis is unclear or orbital cellulitis or abscess is suspected, then hospitalization, imaging, and parenteral antibiotics are warranted. For orbital cellulitis, parenteral antibiotic therapy should be empirically chosen and includes cefuroxime and ampicillin/sulbactam. Clindamycin or metronidazole may be added for suspected anaerobic organisms.
Presentations of infections of the eye to the pediatrician are a common occurrence. It is imperative that a thorough history be obtained and a systematic physical examination be performed. Once a diagnosis is made and a vision-threatening etiology has been ruled out, immediate treatment followed by close follow-up ensures healing and good prognosis. Although most cases are benign and can be followed by the primary care physician, early referral to an ophthalmologist must be considered in certain cases to prevent severe complications.
This article is the second in a 2-part series on eye infections commonly managed by primary care practitioners. Here we discuss infections of the cornea, sclera, uveal tract, and orbit. In Part 1, we reviewed infections of the eyelid, lacrimal system, and conjunctiva.
INFECTIONS OF THE CORNEA
Keratitis in children may be caused by various factors. Inflammation or infection of the cornea often causes concurrent inflammation of the conjunctiva leading to the appearance of a red eye. Infectious keratitis can be bacterial, viral, fungal, or parasitic.
Bacterial keratitis is usually caused by Staphylococcus aureus, coagulase-negative Staphylococcus, Pseudomonas, diphtheroids, and Streptococcus pneumoniae. Although bacterial keratitis is more common in children who wear contact lenses overnight, it can develop in children who do not wear contact lenses. It can also occur with dry eyes, topical corticosteroid use, and immunocompromised states. Diagnostic findings include corneal opacity or infiltrates with a red eye, photophobia, and foreign-body sensation. Patients may have mucopurulent discharge. In fulminant cases, a hypopyon (layer of white cells in the anterior chamber) may be present.
Treatment. This should include an urgent ophthalmologic referral and use of topical antibiotics. Oral or parenteral antibiotics may be indicated in severe cases.
Viral keratitis that involves the cornea may be caused by strains of adenovirus that cause epidemic keratoconjunctivitis, by herpes simplex type 1, and occasionally by herpes zoster infections that involve the forehead. After the initial period of symptoms of conjunctivitis, patients with viral keratitis have foreign-body sensation and photophobia. Fluorescein staining reveals multiple punctate lesions in the cornea.
Treatment. Referral to an ophthalmologist is indicated for close monitoring.
Superficial keratitis is usually caused by dry eyes, contact lens use, viral conjunctivitis, blepharitis, chemicals, or ultraviolet light. Symptoms include eye discomfort, redness, pain, sensitivity to bright light, watering, and decreased vision. There may be a history of foreign-body sensation in the eye. Characteristic clinical findings include superficial corneal epithelial defects, conjunctival inflammation, and hyperemia. Preauricular lymphadenitis may occur. Punctate lesions may be seen with fluorescein eye staining, but a slit lamp examination may be necessary.
Treatment. Treatment of superficial keratitis should be directed at the underlying cause. An eye patch may provide symptomatic relief.
INFECTIONS OF THE SCLERA
The sclera is made up of thick collagen and connective tissue, the thin membrane between the sclera and conjunctiva—the episclera.
Scleritis, although uncommon in children, can occur in association with juvenile rheumatoid arthritis or infection (eg, herpes simplex virus infection, tuberculosis, mumps, syphilis, and varicella).
Episcleritis occurs in association with certain systemic diseases, including herpes zoster, erythema multiforme, and syphilis, and severe drug allergies (eg, penicillin allergy). Episcleritis is an inflammation of the episclera, without the severe pain that is common with scleritis, and is characterized by an area of conjunctival injection with dilated vessels. Topical phenylephrine, which constricts the vessels of the conjunctiva but not of the episclera or sclera, may be helpful in differentiating between conjunctivitis and episcleritis/scleritis.
Treatment. For both scleritis and episcleritis, treatment involves managing the underlying condition and use of NSAIDs, cycloplegics, and topical corticosteroids.
INFECTIONS OF THE UVEAL TRACT
Uveitis is defined as an inflammation of any part of the uveal tract (iris, choroids, ciliary body, retina). Because all of these structures share a common blood supply, inflammation of multiple structures is possible. Concurrent involvement of the adjacent ocular structures, such as the optic nerve, also may occur. Specific designations are given depending on the area or areas involved (eg, iritis for iris inflammation, cyclitis for ciliary body inflammation, or iridocyclitis when both are involved).
Inflammation of the anterior choroids, iris, and ciliary body is called anterior uveitis. Posterior uveitis is inflammation of the posterior choroids (choroiditis), retina (retinitis), or both (chorioretinitis). Intermediate uveitis refers to the involvement of the middle portion of the eye (retinal vessels and peripheral retina).
Uveitis is the third leading cause of blindness in the United States and 5% to 10% of cases occur in children.1 In general, the most common type of uveitis in children is posterior uveitis, which is associated with a high risk of vision loss. Thus, blindness associated with posterior uveitis appears to affect more children than adults, particularly because the diagnosis is often delayed in nonverbal children.
Anterior uveitis is associated with multiple systemic disorders and may be caused by tuberculosis, syphilis, sarcoidosis, toxocariasis, and toxoplasmosis. Juvenile arthritis, particularly pauciarticular arthritis in girls, and a positive antinuclear antibody result are also associated with uveitis. Hence, frequent monitoring for juvenile arthritis and associated systemic diseases is important when treating a case of anterior uveitis.
Anterior uveitis presents with sudden onset of redness, pain, photophobia, and tearing. Visual acuity may be mildly decreased. On examination, the conjunctiva and sclera appear congested (ciliary flush), or perilimbic redness may occur. The pupil may be small and irregular with a clear cornea.
Diagnosis is made with a slit lamp examination, which shows cells and protein within the aqueous chamber (aqueous flare). Keratic precipitates and adhesions between the iris and the anterior surface of the lens (posterior synechiae) may occur. Formation of anterior synechiae between the iris and the cornea may increase intraocular pressures and result in corneal edema.
The diagnosis of uveitis may be confused with conjunctivitis. Findings that distinguish uveitis from conjunctivitis include watery discharge from the eye, absence of foreign-body sensation, and a constricted and an irregular pupil (a characteristic of uveitis).
Treatment. Early diagnosis and treatment of uveitis improves prognosis. The mainstay of treatment is topical corticosteroids, such as 1% prednisolone acetate. Resistant cases may require periocular corticosteroids or rarely oral corticosteroids. NSAIDs may also be added to the regimen. Cycloplegic-mydriatic agents, such as 1% atropine, help reduce the development of synechiae. In addition to synechiae, other complications of uveitis are band keratopathy, glaucoma, and cataracts.
Rosenberg and colleagues2 in their study of 148 children with uveitis found that 31% had 1 or more complications at the time of the diagnosis, which increased to 83% by 3 years after diagnosis. Anterior and intermediate uveitis had a higher risk of band keratopathy. Intermediate uveitis also had a higher risk of cystoid macular edema compared with anterior or posterior uveitis. The authors concluded that uveitis is associated with numerous vision-threatening complications that increase with duration of disease.2
INFECTIONS OF THE ORBIT
Knowledge of the orbit anatomy is important for understanding its susceptibility to the spread of infection from surrounding structures. The orbit is a bony pyramid with 4 walls: the roof, lateral wall, medial wall, and floor. The roof, which is very strong, is comprised almost entirely of the frontal bone with a small contribution from the sphenoid. The thick lateral wall is formed by the zygoma anteriorly and the greater wing of the sphenoid posteriorly. The medial wall, formed largely by the thin lamina papyracea overlying the ethmoid sinus, extends from the frontal maxillary process (containing the lacrimal fossa) anteriorly to part of the sphenoid bone posteriorly.
The lamina papyracea can facilitate spread of any infection from the ethmoid sinus into the orbit. The floor is formed by the orbital plate of the maxilla with contributions from the zygoma and palatine bone.
Because of the unique anatomy of the orbit, infections that originate in the paranasal sinuses can spread to the bone (osteitis with or without subperiosteal abscess) and the intraorbital contents. Further, ophthalmic veins that drain the orbit, the ethmoid and maxillary sinuses, and the skin of the eyelids and periorbital tissues are an anastomosing and a valveless network. This facilitates the spread of infection from one anatomic site to another and predisposes to involvement of the cavernous sinus.
Thus, it is critical that eye infections be identified and treated early to prevent spread to contiguous structures.
Preseptal and orbital cellulitis may result from hematogenous seeding, including bacterial endocarditis, or by secondary spread from adjacent structures. In preseptal, or periorbital, cellulitis, the infection and inflammation are restricted to the tissues anterior to the orbital septum, which arises from and is continuous with the periosteum at the orbital rim and separates the soft tissues of the eyelid from those of the orbit (Figure 1). In contrast, extension of the infection and inflammation into the postseptal or orbital tissues constitutes orbital cellulitis (Figure 2). Other orbital infections with increasing severity include subperiosteal abscess (Figure 3, see case on page 435) and orbital abscess (Figure 4).
Preseptal cellulitis usually results from direct inoculation near the eyelids caused by trauma, insect bites, or any local infection (dacrocystitis, impetigo, chalazion, or hordeolum). In a recent study by Moubayed and colleagues,3 the most common predisposing conditions to periorbital cellulitis were sinusitis (24.8%), trauma (23.1%), and ocular conditions (13.7%). Orbital cellulitis is most often caused by paranasal sinusitis, specifically ethmoid sinusitis, because of the anatomic proximity of the orbit to the sinuses, which allows easy extension of a sinus infection into the orbit.4
Other causes of preseptal and orbital cellulitis include:
•Blunt or penetrating trauma to the orbits, chronic cocaine use, foreign bodies, and local surgery. (It is important to rule out the presence of orbital foreign bodies in penetrating trauma.)
•Maxillary odontogenic abscess as the primary site of infection.
The infectious agents vary with the primary cause and age of the child. In a study of children treated for subperiosteal abscess of the orbit, Harris5 found that infections in children younger than 9 years were less likely to be associated with anaerobes and tended to be caused by single organisms. On the contrary, children older than 15 years had polymicrobial infections with mixed aerobes and anaerobes.
The principle organisms causing orbital cellulitis are S pneumoniae, nontypeable H influenzae, Staphylococcus, other streptococcal species, and nonspore-forming anaerobes.
H influenzae is no longer a significant pathogen causing orbital cellulitis or sinusitis. In a study of children with orbital cellulitis, McKinley and colleagues6 found S aureus to be the most common organism followed by Streptococcal species. They also found methicillin-resistant S aureus (MRSA) to represent nearly 73% of staphylococcal isolates. Only 2 of 27 blood cultures yielded a positive result, while surgical aspirates yielded the highest positive cultures.6
A recent study by Seltz and colleagues7 found that among those children with orbital cellulitis in whom an infectious agent was identified, the most common was Streptococcus anginosus (15%) followed by S aureus (9%). Neonatal postseptal infections, which tend to form abscesses, are mostly caused by staphylococcal species. Fungal infections caused by Mucor and Aspergillus may occur. Mucormycosis occurs mostly in diabetic ketoacidosis.
Clinical features. Preseptal cellulitis is more common than orbital cellulitis. While preseptal cellulitis affects mainly preschool-aged children, the median age for children admitted with orbital cellulitis is 7 years. Common complaints include sudden onset of fever, malaise, eye pain, and periorbital swelling and, in the case of sinusitis, associated upper respiratory tract symptoms. With preseptal cellulitis, the erythema and swelling may extend over the superior orbital rim into the brow (see Figure 1); however, this extension of erythema and swelling into the brow is not seen with orbital cellulitis.
Proptosis, impaired eye movement, and impaired visual acuity are highly suggestive of postseptal involvement (see Figure 2). Other nonspecific findings of orbital cellulitis include pain, chemosis, conjunctival redness, and afferent pupillary defect. Most orbital cellulitis involves the formation of a subperiosteal abscess.
Posterior orbital cellulitis is an extremely rare disease and occurs as a complication of sphenoethmoiditis. In this condition, vision loss precedes accompanying inflammatory orbital signs.8 The vision loss is due to involvement of the orbital apical segment of the optic nerve.
Investigations. A complete blood cell count should be obtained in all suspected cases of orbital cellulitis; white blood cell counts are often elevated in affected patients. Although blood cultures are more frequently positive in children than in adults, they still carry a low sensitivity. If the child appears toxic, a lumbar puncture should be performed. Cultures of the conjunctival sac, sinus, and abscess aspirates may help in identification of the causative organism.
CT is the most widely used modality for evaluating orbital cellulitis and can help differentiate preseptal from orbital cellulitis. A contrast-enhanced CT with axial and coronal thin cuts of the sinuses and orbits is the study of choice. MRI is the preferred modality for diagnosing cavernous sinus thrombosis and provides further details of the soft tissues of the orbit, globe, visual pathways, and brain. Ultrasound imaging poorly visualizes the posterior aspects of the globe and thus is of limited value.
Treatment. If the child with preseptal cellulitis is afebrile and appears nontoxic and the reliability of follow-up is assured, then outpatient management with oral antibiotics may be appropriate. However, if the child looks toxic or the diagnosis is unclear or orbital cellulitis or abscess is suspected, then hospitalization, imaging, and parenteral antibiotics are warranted.
Neonates with preseptal cellulitis from dacrocystitis require hospitalization and treatment with parenteral antibiotics. Oral antibiotics, such as amoxicillin/clavulanate or cefuroxime axetil, should be used for outpatient management to cover ß-lactamase–producing organisms. Parenteral agents include cefuroxime and ampicillin/sulbactam. Addition of clindamycin or vancomycin in sick children should be considered in the face of recent studies showing an increase in MRSA. Intranasal decongestants, such as oxy-metazoline, may be useful. Early consultation with both an ophthalmologist and otorhinolaryngologist is important.
For orbital cellulites, parenteral antibiotic therapy should be empirically chosen to be effective against S aureus, S pyogenes, anerobic bacteria, and any pathogens (such as S pneumoniae and H influenzae) that cause sinusitis. This includes cefur-oxime and ampicillin/sulbactam. Clindamycin or metronidazole may be added for suspected anaerobic organisms. For patients with orbital cellulitis, once the condition improves, parenteral antibiotics can be replaced with oral antibiotics for a total treatment period of 3 weeks.
Huang and colleagues9 found that the most important factor in predicting failure of antibiotic treatment of sinusitis-associated periorbital infections was the presence of an abscess. Indications for surgery include the presence of a large abscess, ophthalmoplegia, visual acuity of 20/60 or worse on initial examination, blindness, progression of orbital signs, and lack of improvement despite 48 hours of aggressive medical management.
Some studies have reported success with drainage of the abscess using an endoscope, thus avoiding an external incision. An orbital abscess would necessitate drainage, whereas a cavernous sinus thrombus requires treatment with high-dose antibiotics. Starkey and colleagues10 in their study of 9 patients with orbital cellulitis and subperiosteal abscesses concluded that an initial medical management approach for such patients is justified in this era of CT and vaccination.
Complications. Meningitis, cavernous sinus thrombosis, and blindness are known complications of orbital cellulitis. Intracranial extensions, including subdural empyema, intracerebral abscess, and extradural abscess, may occur and are more common with a superior orbital abscess.
Acknowledgments: The authors would like to thank Dr Baker and Dr Tigchelaar at Children’s Hospital of Michigan for their help with the photographs of the different eye conditions.