Orbital cellulitis is an inflammation of the soft tissues of the eye socket behind the orbital septum, a thin tissue which divides the eyelid from the eye socket. Orbital cellulitis most commonly refers to an acute spread of infection into the eye socket from either the adjacent sinuses, skin or from spread through the blood.
Orbital Cellulitis (ICD-9 #376.01)
Orbital cellulitis most commonly occurs when bacterial infection spreads from the paranasal sinuses. It can also occur when an eyelid skin infection or an infection in an adjacent area spreads to the orbit or from an infection in the blood system.
Risk factors include recent upper respiratory illness, acute or chronic bacterial sinusitis, recent trauma, recent ocular or periocular infection, or systemic infection.
The orbital tissues are infiltrated by acute and chronic inflammatory cells and the infectious organisms may be identified on the tissue sections. The organisms are best identified by microbiologic culture. The most common infectious pathogens include gram positive streptococcal and staphylococcal species. In children younger than 9, the infections are typically from one organism; in children older than 9 and in adults, the infections may be polymicrobial with both aerobic and anaerobic bacteria.
The most common pathogens in orbital cellulitis, strep and staph are both gram positive. Streptococcal infections are identified on culture by their formation of pairs or chains. Streptococcal pyogenes (Group A Strep) requires blood agar to grow and exhibits clear (beta) hemolysis on blood agar. Streptococcus such as streptococcus pneumonia produce Green (alpha) hemolysis, or partial reduction of red blood cell hemoglobin. Staphyloccal species show a cluster arrangement on gram stain. Staphylococcus aureus forms a large yellow colony on rich medium in distinction to Staphylococcus epidermidis which forms white colonies. Gram negative rods can be seen in both orbital cellulitis related to trauma and in some older children or adults. Anaerobic bacteria such as peptococcus, peptostreptococcus, bacteroides can be involved in infections extending from sinusitis in adults or older children. Fungal infections with either mucor or aspergillus need to be considered in immunocompromised or diabetic patients; immunocompetent patients may also have fungal infections in rare cases.
Orbital cellulitis most commonly occurs in the setting of an upper respiratory or sinus infection. The human upper respiratory tract is normally colonized with Strep pneumoniae and infection can occur through several mechanisms. Strep pyogenes infections also occur primarily in the respiratory tract. The complex cell surface of this gram positive organism determines its virulence and ability to invade the surrounding tissue and incite inflammation. Staph aureus infections occur commonly in the skin and spread to the orbit from the skin. Staphylococcal organisms also produce toxins which help to promote their virulence and leads to the inflammatory response seen in these infections. Staph epi can produce a biofilm accounting for involvement in implant related infections. The inflammatory response elicited by all these pathogens plays a major role in tissue destruction in the orbit.
Identifying patients and effectively treating upper respiratory or sinus infections before they evolve into orbital cellulitis is an important aspect of preventing preseptal cellulitis from progressing to orbital cellulitis. Equally important in preventing orbital cellulitis is prompt and appropriate treatment of preseptal skin infections or even odentogenic infections before they spread into the orbit.
A critical determinant in evaluation a patient with periorbital complaints is to determine if the infection involves only the most superficial tissues of the eyelids or has progressed to involve the orbit. The comprehensive evaluation (history and physical examination) includes those components of the comprehensive medical eye evaluation specifically relevant to the diagnosis and treatment of an orbital process as listed below.
Patient history, including the patient’s assessment of visual status, headache, orbital pain, double vision, progression of symptoms, recent upper respiratory symptoms including nasal discharge or stuffiness, pain over sinuses, fever, lethargy, recent periocular trauma or injury, family or health care contacts with MRSA, history of sinus, ear, or facial infections or surgery, recent ocular surgery, pertinent medical conditions, medications currently used, and other risk factors that can affect the surgical plan or outcome of surgery (e.g., immunosuppressive conditions, diabetes). Specific questions regarding any change in mental status, pain with neck movement, or nausea or vomiting should be asked.
- Visual acuity with current correction (the power of the present correction recorded) at distance and when appropriate at near or pinhole vision in some emergency room settings.
- Color vision assessment
- Visual field assessment with confronation fields
- Assessment of pupillary function with particular attention paid to any relative afferent pupillary defect.
- External examination (lids, lashes, lacrimal apparatus, orbit). o Position and function of lids, erythema, swelling of lids, discharge on lashes,
- Orbit exam should include documentation of direction of displacement of globe (a superior subperiosteal abscess will displace the globe inferiorly), resistance to retropulsion on palpation, unilateral or bilateral involvement
- Evaluation of lacrimal gland should discern whether any injection or purulence is present.
- Examination of ocular alignment and motility.
- Measurement of intraocular pressure (IOP).
- Slit-lamp biomicroscopy of the anterior segment if possible.
- Dilated examination of the lens, macula, peripheral retina, optic nerve, and vitreous.
- Assessment of relevant aspects of the patient’s mental and physical status.
As a preseptal infection progresses into the orbit, the inflammatory signs typically increase with increasing redness and swelling of the eyelid with a secondary ptosis. As the infection worsens, proptosis develops and extraocular motility becomes compromised. When the optic nerve is involved, loss of visual acuity is noted and an afferent pupillary defect can be appreciated. The intraocular pressure often increases and the orbit becomes resistant to retropulsion. The skin can feel warm to the touch and pain can be elicited with either touch or eye movements.
Systemic symptoms including fever and lethargy may or may not be present. Change in the appearance of the eyelids with redness and swelling is frequently a presenting symptom. Pain, particularly with eye movement, is commonly noted. Double vision may occur once orbital cellulitis has developed. Decreased vision or change in vision is a symptom suggestive of optic nerve compromise.
The clinical diagnosis is established by both the history and the examination. The history supports the diagnosis particularly when a recent upper respiratory infection or eyelid infection has been reported. Signs which suggest the orbit is involved include warmth, redness and swelling of the eyelids, proptosis or bulging of the eye, limitation of eye movement, decrease in vision, afferent pupillary defect, and increased pressure in the orbit. Examination may include the nose and mouth to look for any black eschar which would suggest a fungal infection. Imaging studies are critical in determining the extent of orbital involvement and the risk to vision and the intracranial structures. It is often not possible to differentiate early orbital cellulitis from preseptal cellulitis and a low threshold for imaging should exist.
Computed tomography of the orbit, with axial and coronal cuts, to look for adjacent sinusitis with subperiosteal abscess, stranding of orbital fat, or an orbital abscess needs to be performed. The location and extend of any abscess needs to be carefully assessed and documented. Abscesses along the roof, or extending into the posterior orbit can be indications for emergent surgical drainage. In some patients magnetic resonance imaging may give further information regarding intracranial involvement.
A complete blood count and differential along with a complete metabolic profile should be completed. If systemic symptoms or a febrile illness are associated with the orbital changes, blood cultures should be sent. If meningeal signs are present or an intracranial infection suspected, a lumbar puncture should be performed. If any purulent drainage is present from a wound or the conjunctiva or nasal passages it should be swabbed and sent for culture. If an abscess is drained then the fluid should be sent for both anaerobic and aerobic culture; if fungal infection is suspected then these too should be sent. In certain presentations, cultures for acid fast bacilli should also be sent. Any tissue biopsied should be sent separately for both histopathological evaluation as well as microbiology evaluation.
• Orbital Pseudotumor • Acute Thyroid Eye Disease • Orbital Tumor • Allergic Reaction • Dacryocystitis • Dacryoadenitis
The management of any abscess is surgical drainage with intravenous antibiotics. There are select cases of orbital cellulitis in children younger than the age of 9 who meet strict criteria who may be considered for medical management. These criteria are discussed below. Once treated with medical management, prompt improvement observed on serial frequent examinations must be documented. Imaging changes may lay the clinical improvement and the decision for surgical intervention should be based on clinical assessment rather than on imaging features. Antibiotic choice is very much dependent on the organisms suspected to be involved in the infection.
General treatment involves intravenous antibiotics and frequent evaluations for improvement or progression. This is typically best accomplished as a hospital in patient. Examination by an ophthalmologist establishes the vision function and threat. Orbital cellulitis can progress to blindness, cavernous sinus thrombosis, intracranial abscess and death. It is aggressively treated as an ophthalmic emergency. Computed tomography helps to establish the location and extent of the disease and the status of periorbital structures, such as the brain and sinuses. Laboratory evaluation with complete blood count, differential, wound cultures, blood cultures if septic and lumbar puncture if neurologic compromise should be performed. A low threshold for surgical intervention should exist. Conservative management with intravenous antibiotics, nasal toilet with decongestants in patients with nasal or sinus disease, and frequent re-evaluation may considered for patients with no orbital abscess, or in children with small, anterior, medial subperiosteal abscesses without posterior extent or visual compromise. When pansinusistis, intracranial involvement, a large abscess, threat to the posterior orbit or orbital roof, intraorbital gas, or visual compromise exist surgical intervention needs to be promptly performed.
Emperic coverage with antibiotics needs to consider the possible bacterial pathogens involved. Respiratory infections are commonly caused by gram positive Strep and Staph along with anaerobic bacteria. Penicillins are still effective in the treatment of group A strep infections such as Strep pyogenes. Options for coverage include both penicillins and cephalosporins for these infections. Drug resistance has developed in staphylococci and this is seen most prominently in the recent rise in Methicillin resistent Staph aureus orbital cellulitis. Coverage for suspected MRSA may be warranted particularly if any recent contacts with MRSA positive individuals, health care workers or if orbital cellulitis has progressed from a skin infection. In most communities, intravenous Vancomycin shows effective coverage for MRSA. Alternatives MRSA coverage may include Clindamycin, Doxycycline, or Trimethoprim/Sulfamethoxizole. Once improvement has been documented with 48 hours of intravenous antibiotics, consideration for switching to oral antibiotics may be appropriate. Often 2-3 weeks of oral antibiotics are necessary. In complex or posterior infection, prolonged treatment with intravenous antibiotics or oral antibiotics may be required. Consultation with an infectious disease specialist may be required.
Medical follow up
In hospital patients on medical management are often seen every 4-6 hours to determine if their status is worsening. Once the threat to vision or neurologic status has cleared, they are then seen daily to confirm improvement. Once vision and the orbit is stable hospital discharge is arranged with follow up within 7-10 days of discharge with clear instructions that if symptoms or signs return or vision changes, the patient must immediately return to the emergency room or clinic.
Surgery is performed for any abscess that threatens vision or neurologic status. Typically sinus drainage is performed concurrently for any significant sinus disease. If a small or modest subperiosteal abscess is present in the medial orbit, the drainage can be performed endoscopically during the sinus drainage. Orbital approaches include transcaruncular to the medial orbit, a Lynch incision to the medial orbit, a swinging eyelid flap to the floor, or an upper lid crease incision to the superior orbit. All of these surgical approaches can provide excellent post-operative cosmesis.
Surgical follow up
While in hospital, initial surgical follow up includes post-operative day 1 check and then as dictated by the clinical situation. Patients are often seen back in the office in 1-2 weeks or earlier should there be any recurrence of symptoms or signs.
The complications of orbital cellulitis are ominous and include blindness, cavernous sinus thrombosis, intracranial brain abscess, and death.
With prompt recognition and aggressive medical and surgical treatment the prognosis can be excellent.
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