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Orbital and Periorbital Cellulitis

Periorbital cellulitis is a bacterial infection of the skin and structures superficial to the orbit; orbital cellulitis is a bacterial infection of the orbit. The most common causes of eyelid redness and swelling are allergy, trauma, and insect stings.

Cellulitis  usually occurs after the skin near the eye has been broken by trauma, an insect bite, or infection with herpes simplex or varicella zoster viruses; a secondary infection occurs at the site of injury which then spreads to the tissues. The organisms that most frequently cause following trauma are Staphylococcus aureus and Streptococcus pyogenes (group A beta-hemolytic streptococci).

Infection also occurs when the tissues are seeded with bacteria during bacteremia, most frequently with Haemophilus influenzae type b (Hib) and S pneumoniae. A bacterial pathogen is identified in only 30% of cases of cellulitis, and the pathogen is isolated from the blood in about two thirds of these cases.

Since the introduction of H influenzae type b conjugate vaccines (HbCV), Hib disease accounts for fewer than 15%. A child who has received a second dose of HbCV more than 1 week before the onset of eyelid swelling is very unlikely to have HIB disease. The infection may progress to subperiosteal abscess, orbital abscess, and cavernous sinus thrombosis.

About one fourth of eye infection isolates are S aureus; one fifth, S pyogenes; one fifth, HiB; one tenth, S pneumoniae; one tenth, anaerobic bacteria; and the remaining 15%, other bacteria. A pathogen is identified in only 25% of cases.

Periorbital usually occurs in children younger than 2 years of age. Clinical findings include a temperature of 39C or more and a peripheral white blood cell count of greater than 15,000/mm.

Cause eyelid swelling, with the swelling being unilateral in 95-98% of cases. Virtually all involved eyelids will be erythematous or violaceous (purple).

Signs of trauma or local infection are observed in one third of patients. Herpes simplex and varicella zoster virus infections of the eyelid can serve as a nidus for a secondary bacterial infection.

Treatment