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DEFINITIONS AND EPIDEMIOLOGY
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Whereas the terms periorbital (preseptal) and orbital (postseptal) cellulitis sound similar, their pathogenesis, management, and complications are quite different. Periorbital infections refer to infections located anterior to the orbital septum, while orbital infections are infections located posteriorly.1,2
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Periorbital infections typically occur in children 10 years of age and younger and occur more frequently than orbital infections.3 Both are most commonly bacterial in origin and represent inflammation of the eyelid and the soft tissue surrounding the orbit. In general, periorbital and orbital cellulitis derive from contiguous spread from adjacent infected structures, local trauma, or bacteremia. Noninfectious etiologies of periorbital and orbital cellulitis include inflammatory, allergic, endocrinologic, and neoplastic diseases.
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The occurrence of both types of infections tends to peak in the winter months when sinusitis and upper respiratory infections are more prevalent (Table 25-1).4
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PERIORBITAL CELLULITIS
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Prior to licensure and widespread use of the Haemophilus influenzae type b polysaccharide vaccine in 1985 and the H. influenzae type b conjugate vaccine several years later, most (80%) cases of periorbital cellulitis in children were secondary to bacteremia from H. influenzae type b.2 The introduction of the H. influenzae type b polysaccharide vaccine reduced pediatric cases of periorbital and orbital cellulitis by 59%.5,6 The most common cause of periorbital cellulitis is now adjacent spread from infected neighboring structures, including skin, conjunctiva, eyelids, sinuses, respiratory tract, and teeth. Other causes of periorbital cellulitis include blunt or penetrating trauma and viral infections such as adenovirus, enteroviruses, or Epstein–Barr virus. In immunocompromised hosts, fungal etiologies, such as aspergillosis and zygoomycosis, should be considered.7,8
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Orbital cellulitis refers to inflammation of ...