DEFINITION Orbital cellulitis is an infection of eye tissues posterior to the orbital septum. It most commonly refers to an acute spread of infection into the eye socket from either the adjacent sinuses or through the blood. When it affects the rear of the eye, it is known as retro-orbital cellulitis.Orbital cellulitis is an acute infection of the tissues immediately surrounding the eye, including the eyelids, eyebrow, and cheek.It should not be confused with periorbital cellulitis, which refers to cellulitis anterior to the septum.
SYMPTOMS
Symptoms of orbital cellulitis may include:
-Painful swelling of upper and lower eyelid, and possibly the eyebrow and cheek
-Bulging eyes
-Decreased vision
-Eye pain, especially when moving the eye
-Fever, generally 102 degrees F or higher
-General feeling of discomfort
-Painful or difficult eye movements
-Shiny, red or purple eyelid
CAUSES
Orbital cellulitis occurs commonly from bacterial infection spread by the paranasal sinuses. Other ways in which orbital cellulitis may occur is from infection in the blood stream and from an eyelid skin infection. Upper respiratory infection, sinusitis, trauma to the eye, ocular or periocular infection and systemic infection all increase one’s risk of orbital cellulitis.Staphylococcus aureus, Streptococcus pneumoniae and beta-hemolytic streptococci are three bacteria that can be responsible for orbital cellulitis.
Staphylococcus aureus, is a gram-positive bacterium which is the most common of staph infections. Staphylococcus aureus infection can spread to the orbit from the skin. Staph organisms are able to produce toxins which promote their virulence which leads to the inflammatory response seen in orbital cellulitis. Staphylococcus infections are identified by a cluster arrangement on gram stain. Staphylococcus aureus forms large yellow colonies (which is distinct from other Staph infections such as Staphylococcus epidermis which forms white colonies).
Streptococcus pneumoniae, is also a gram-positive bacterium responsible for orbital cellulitis due to its ability to infect the sinuses (sinusitis). Strep organisms are able to determine their own virulence and can invade surrounding tissues causing an inflammatory response seen in orbital cellulitis (similar to Staphyloccoccus aureus). Streptococcal infections are identified on culture by their formation of pairs or chains. Streptococcus pneumoniae produce green (alpha) hemolysis, or partial reduction of red blood cell hemoglobin.
TREATMENT
Prompt treatment is vital for a patient when fighting orbital cellulitis. Treatment typically involves IV antibiotics in the hospital and frequent observation (every 4-6 hours). Along with this several laboratory tests are run including a complete blood count, differential, and blood culture.
Antibiotic Therapy - Since orbital cellulitis is commonly caused by Staphylococcus and Streptococcus species both penicillins and cephalosporins are typically the best choices for IV antibiotics. However, due to the increasing rise of MRSA (methicillin-resistant Staphylococcus aureus) orbital cellulitis can also be treated with Vancomycin, Clindamycin, or Doxycycline. If improvement is noted after 48 hours of IV antibiotics, healthcare professions can then consider switching a patient to oral antibiotics (which must be used for 2-3 weeks).
Surgical Intervention - An abscess can threaten the vision or neurological status of a patient with orbital cellulitis, therefore sometimes surgical intervention is necessary. Surgery typically requires drainage of the sinuses and if a subperiosteal abscess is present in the medial orbit, drainage can be performed endoscopically. Post-operatively, patients must follow up regularly with their surgeon and remain under close observation
INVESTIGATIONS AND TESTS
Tests commonly include:
-CBC (complete blood count)
-Blood culture
-Spinal tap in extremely sick children
Other tests may include:
-X-ray of the sinuses and surrounding area
-CT scan or MRI of the sinuses and orbit
-Culture of eye and nose drainage
-Throat culture
PROGNOSIS
Although orbital cellulitis is considered an ophthalmic emergency the prognosis is good if prompt medical treatment is received.
Bacterial infections of the orbit have long been associated with a risk of catastrophic local sequelae and intracranial spread.
The natural course of the disease, as documented by Gamble (1933), in the pre-antibiotic era, resulted in death in 17% of patients and permanent blindness in 20%.
COMPLICATIONS
PREVENTION
-Receiving the HiB vaccine according to recommended schedules generally will prevent most haemophilus infections in children. Young children in the same household who have been exposed to this bacteria may receive antibiotics to prevent getting sick.
-Proper detection and early treatment of sinus, dental, or other infections may prevent the spread of infection to the eyes.
