eMedicine Specialties > Ophthalmology > Orbit

Cellulitis, Orbital

Author: John N Harrington, MD, FACS, Director of Ophthalmic Plastic and Reconstructive Surgery, Department of Ophthalmology, Baylor University Medical Center; Clinical Professor, Department of Ophthalmology, University of Texas Southwestern
Contributor Information and Disclosures

Updated: Dec 31, 2008

Introduction

Background

The orbital septum is a layer of fascia extending vertically from the periosteum of the orbital rim to the levator aponeurosis in the upper eyelid and to the inferior border of the tarsal plate in the lower eyelid. Orbital cellulitis and preseptal cellulitis are the major infections of the ocular adnexal and orbital tissues. Orbital cellulitis is an infection of the soft tissues of the orbit posterior to the orbital septum, differentiating it from preseptal cellulitis, which is an infection of the soft tissue of the eyelids and periocular region anterior to the orbital septum. Orbital cellulitis has various causes and may be associated with serious complications. Up to 11% of cases of orbital cellulitis result in visual loss. Prompt diagnosis and proper management are essential for curing the patient with orbital cellulitis.

Pathophysiology

Orbital cellulitis occurs in the following 3 situations: (1) extension of an infection from the periorbital structures, most commonly from the paranasal sinuses, but also from the face, the globe, and the lacrimal sac; (2) direct inoculation of the orbit from trauma or surgery; and (3) hematogenous spread from bacteremia.

The medial orbital wall is thin and perforated not only by numerous blood valveless vessels and nerves but also by numerous other defects (Zuckerkandl dehiscences). This combination of thin bone, foramina for neurovascular passage, and naturally occurring defects in the bone allows for easy communication of infectious material between the ethmoidal air cells and the subperiorbital space in the medial aspect of the orbit. The most common location of a subperiorbital abscess is along the medial orbital wall. The periorbita is adherent relatively loosely to the bone of the medial orbital wall, which allows abscess material to easily move laterally, superiorly, and inferiorly within the subperiorbital space.

In addition, the lateral extensions of the sheaths of the extraocular muscles, the intermuscular septa, extend from one rectus muscle to the next and from the insertions of the muscles to their origins at the annulus of Zinn posteriorly. Posteriorly in the orbit, the fascia between the rectus muscles is thin and often incomplete allowing easy extension between the extraconal and intraconal orbital spaces.

Venous drainage from the middle third of the face, including the paranasal sinuses, is mainly via the orbital veins, which are without valves, allowing the passage of infection both anterograde and retrograde.

Infectious material may be introduced into the orbit directly from accidental or surgical trauma.

Ethmoid sinusitis is the most common cause of orbital cellulitis in all age groups and aerobic non-spore–forming bacteria are the organisms most frequently responsible.

Frequency

An increased incidence of orbital cellulitis occurs in the winter, both nationally and internationally, because of the increased incidence of sinusitis in cold weather.

United States

There is a noted increase in the frequency of orbital cellulitis due to community-acquired methicillin-resistant Staphylococcus aureus infections involved in orbital cellulitis.  

Mortality/Morbidity

Prior to the availability of antibiotics, patients with orbital cellulitis had a mortality rate of 17%, and 20% of survivors were blind in the affected eye. However, with prompt diagnosis and appropriate use of antibiotics, this rate has been reduced significantly; blindness occurs in up to 11% of cases. Orbital cellulitis due to methicillin-resistant S aureus can lead to blindness despite antibiotic treatment.

Race

No racial predilection exists for orbital cellulitis.

Sex

No frequency difference exists between the sexes in adults, except for cases of methicillin-resistant S aureus, which are more common in females than in males by a ratio of 4:1. However, in children, orbital cellulitis has been reported as twice as common in males than in females.

Age

Orbital cellulitis, in general, is more common in children than in adults. Median age of children hospitalized with orbital cellulitis is 7-12 years.

Clinical

History

A thorough history and physical examination are critical in establishing a diagnosis of orbital cellulitis. Patients with orbital cellulitis frequently complain of fever, malaise, and a history of recent sinusitis or upper respiratory tract infection. Questioning the patient about any recent facial trauma or surgery, dental work, or infection elsewhere in the body is important.

• Other common but variable accompanying signs include the following:
  • Conjunctival chemosis
  • Decreased vision
  • Elevated intraocular pressure
  • Pain on eye movement
• The above signs may be accompanied by the following:
  • Fever
  • Headache
  • Lid edema
  • Rhinorrhea
  • Increasing malaise

Physical

Proptosis and ophthalmoplegia are the cardinal signs and symptoms of orbital cellulitis. The symptoms advance rapidly at an alarming rate and eventually lead to prostration.

• Proptosis and ophthalmoplegia may be accompanied by the following:
  • Conjunctival chemosis
  • Decreased vision
  • Elevated intraocular pressure
  • Pain on eye movement
  • Orbital pain and tenderness are present early.
  • Vision may be normal early, but it may become difficult to evaluate in very ill children with marked edema.
  • Dark red discoloration of the eyelids, chemosis, hyperemia of the conjunctiva, and resistance to retropulsion of the globe may be present.
  • Purulent nasal discharge may be present.

Causes

Orbital cellulitis is caused by infection of the orbital soft tissues by extension of infection from periorbital structures, direct inoculation from accidental trauma or surgery, or hematogenous spread of infection.

• Orbital cellulitis is caused most commonly by ethmoid sinusitis, accounting for more than 90% of all cases. The process involves edema of the sinus mucosa, which leads to narrowing of the ostia and subsequent reduction or cessation of normal sinus drainage. Microflora indigenous to the sinuses and upper respiratory tract proliferate and invade the edematous mucosa, resulting in suppuration. It is enhanced by the reduced oxygen tension within the obstructed sinus cavity. The organisms gain access to the orbit through thin bones of the orbital walls, venous channels, foramina, and dehiscences. Then, subperiorbital and intraorbital abscesses may occur. The resulting elevation of intraorbital pressure results in the typical signs of proptosis, ophthalmoplegia, and chemosis.
• Orbital cellulitis can be caused by direct extension of infection from the globe, eyelids, ocular adnexum, and other periocular tissues, as well as the sinuses. Orbital cellulitis may follow dacryocystitis, osteomyelitis of the orbital bones, phlebitis of the facial veins, and dental infections.
• Orbital cellulitis may be caused by any injury perforating the orbital septum. Orbital inflammation may be noted within 48-72 hours after injury, or, in the case of a retained orbital foreign body, it may be delayed for several months. Orbital fractures may result in orbital cellulitis.
• Surgical procedures, including orbital decompression, dacryocystorhinostomy, eyelid surgery, strabismus surgery, retinal surgery, and intraocular surgery, have been reported as the precipitating cause of orbital cellulitis. Postoperative endophthalmitis can extend to the orbital soft tissues.
• Bacterial causes of orbital cellulitis are most commonly Streptococcus species, S aureus, and Haemophilus influenzae type B. Pseudomonas, Klebsiella, Eikenella, and Enterococcus are less common culprits. Polymicrobial infections with aerobic and anaerobic bacteria are more common in patients aged 16 years or older.
• Fungal causes of orbital cellulitis are most commonly Mucor and Aspergillus species. Orbital cellulitis due to fungal infections carries a high mortality rate in patients who are immunosuppressed. Fungi can enter the orbit, most commonly Mucor and Aspergillus species. Mucormycosis is widespread in distribution, while aspergillosis more commonly is seen in warm humid climates. Mucormycosis has a rapid onset (1-7 days), while aspergillosis is much slower (months to years). Aspergillosis initially gives chronic proptosis and decreased visions, while mucormycosis gives the orbital apex syndrome (involving cranial nerves II, III, IV, V-1, and VI, and orbital sympathetics), and, more commonly, it presents with pain, lid edema, proptosis, and visual loss. While both may result in nasal and palatal necrosis, mucormycosis also may give thrombosing arteritis and ischemic necrosis, while aspergillosis gives chronic fibrosis and a nonnecrotizing granulomatous process.

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