Orbital cellulitis is an infection of the eye that may be caused by a bacteria or a fungus. It typically presents with a redden, painful and swollen eye. In most cases, the infection is acquired from the adjacent facial sinuses. The infection may even be acquired hematogenously from other parts of the face and can threaten vision. In some cases, the infection may extend to the CNS. Cavernous sinus thrombosis is the most severe form of orbital cellulitis.
The history should focus on when the symptoms started and the physical exam should be accompanied by selective imaging tests. In children the typical signs of a CNS abscess are not always present and hence clinical suspicion must be high.
When orbital cellulitis is suspected, ultrasound is often the first test of choice. Even though Ultrasound can detect abscess of the anterior orbit or medial wall, it is not very sensitive and very operator dependent. Thus, most healthcare providers order a CT scan. CT scan should be performed on any patient whose vision or range of motion of the globe cannot be properly assessed. In addition, CT should be performed when there are visual deficits. Ct scan can identify abscesses, inflammatory changes and even provide the location with great accuracy. CT scan can also influence the course of treatment. MRI has been used to assess patients with orbital cellulitis but it is more expensive and does not offer any more diagnostic information compared to a CT scan.
Once the diagnosis of orbital cellulitis is made, the treatment depends on the severity of the condition, patient’s comorbid disorders, age, ability to take oral medications, compliance and presence of complications. Orbital cellulitis is managed as an inpatient initially with parenteral antibiotics. Both the otolaryngologist and ophthalmologist should be consulted for all cases of orbital cellulitis .
All patients who present with diplopia, eyelid edema, decreased visual acuity, abnormal light reflex, proptosis and ophthalmoplegia need admission. In addition, if the patient appears toxic and an incomplete eye exam is not possible admission is required. Patients with lethargy, nausea, vomiting, headache, seizures or cranial nerve deficits also need more extensive in hospital work up .
Admitted patients usually require IV antibiotics for 5-10 days. Initially broad spectrum antibiotics are started to cover both gram positive and negative organisms. Once culture results are available, the therapy can be tailored to the organism. It is recommended that the selected antibiotic cover Staphylococcus, Streptococci and Haemophilus species. Initially the broad spectrum of antibiotics should cover methicillin resistant staphylococcus. Other measures of treatment include control of fever and warm compresses. If there is no improvement in 24-48 hours after initiating antibiotics, one should panculture the patient and consult with an ID expert.
In general, cultures from the nose, throat and conjunctiva do not represent the pathogen cultures from the abscess. Blood cultures are often negative and not helpful. The antibiotics recommended are third generation cephalosporins and the quinolones. Once the patient has stabilized and has no fever or signs of an infection, he/she can be discharge home on oral antibiotics. If the patient fails to improve within 24-36 hours after initiating IV antibiotics, a CT scan of the brain should be obtained and consideration should be given to an orbital or subperiosteal abscess. The duration of antibiotics in outpatients may vary from 3 -30 days, depending on symptoms and improvement.
The decision to undertake surgery in patients with orbital abscess depends on response to therapy, the sinus involved, type of microorganism, visual status, location of orbital abscess and any potential intracranial complications. In general surgery to drain an abscess is usually done when the optic nerve or retinal function is compromised.
When an abscess is present and compressing on a vital structure, emergency drainage may be necessary, especially in patients with compromised vision. Surgery should also be considered when fever does not abate within 24-48 hours after starting IV antibiotics. Surgery should also be considered when there is progressive deterioration of vision despite continuing antibiotics. Urgent drainage is often recommended for large superior or inferior orbital abscess and for patients with CNS complications. In addition, any dental abscess also needs surgical drainage. Patients who are not improving should always be suspected of having an abscess and a CT scan is recommended to follow the course of treatment. Anytime a sinus infection has extended into the orbit, urgent drainage is required. In some cases, even the CT scan may not be accurate in assessing the clinical course in some patients and hence surgical judgment is required.
Overall, orbital cellulitis can be treated with minimal morbidity and mortality.
With improve diagnosis and prompt medical diagnosis, intracranial complications following orbital cellulitis are now rare. Most intracranial complications occurrin the frontal lobe, subdural or epidural compartment. Sinus infections are generally the most common causes of intracranial abscess. The most common is the frontal sinus followed by ethmoid and maxillary sinuses. Complications of orbital cellulitis include subperiosteal or orbital abscess, vision loss, cavernous sinus thrombosis, and intracranial infection.
Death is very rare with orbital cellulitis today. When the diagnosis is made promptly and antibiotics are taken, the cure rates are high. However, if the diagnosis is missed or there is a delay in treatment, orbital abscess can result which carries a high morbidity. In spite of systemic antibiotics and surgical intervention, orbital abscess is a serious disorder with devastating outcome. Statistical evidence reports visual loss in 7-24 percent of patients. Visual loss may be due to central retinal artery occlusion, optic nerve atrophy, or exposure keratopathy which has led to development of corneal ulcers. Other complications of orbital cellulitis include cavernous sinus thrombosis, meningitis and cranial nerve palsies. Any delay in treatment is also associated with a negative outcome. Other reported complications include endophthalmitis, which usually requires evisceration or enucleation.
In children the most common predisposing factor for orbital cellulitis is sinus infection. Others may develop orbital cellulitis as a result of trauma to the eyelids or presence of dental abscess.
Other rare causes of orbital cellulitis include :
A wide range of organisms can cause orbital cellulitis. The most common include Staphylococcus aureus, Staphylococcus epidermidis, Streptococci, Haemophilus influenzae, E.coli, diphtheroids and anaerobes. However, the most common organism in most cases is Staphylococcus aureus. From published reports, children tend to have a simple infection caused by a single aerobe organism. Older children and adults tend to develop more complex infections caused by multiple bacteria that often tend to be resistant to antibiotics.
In children orbital cellulitis is thought to result because of incomplete development of immunity, resulting in sinus disease. The majority of children with orbital cellulitis are known to have sinusitis of the ethmoidal and maxillary sinuses.
In adults, frontal sinus disease is more common. Other sources of infection include retained foreign body. Dacryocystitis, infected malignancy, panophthalmitis, fungal infection (mucormycosis) and herpes zoster.
In diabetic patients with orbital cellulitis, a fungal cause must be ruled out. The two most common fungus associated with orbital cellulitis in diabetics include Aspergillosis and Mucormycosis. The latter seems to be more common in diabetic ketoacidosis. The onset of Mucromycosis is very rapid whereas Aspergillosis may be a gradual infection. Histology of tissues in cases of Mucromycosis will reveal thrombosed vessels with ischemic necrosis.
Orbital cellulitis is not a common disorder. The incidence is reported to range from 0.5 to 4% in tertiary care centers. Most new series do not report a high number of orbital abscesses cases and only a few reports of intracranial complications. The complication rates of orbital cellulitis do vary in the literature because of various inclusion and exclusion criteria. In the present era, the incidence of CNS complications in patients with orbital cellulitis has been reported to be less than 2%. The main reason why complications of orbital cellulitis have decreased is because of awareness, earlier diagnosis and more effective antibiotics. Orbital cellulitis can occur at all ages and in both genders. The infection appears to be slightly more common in diabetics and immunocompromised individuals.
Orbital cellulitis can occur in several ways. If there is trauma to the eye, then foreign bodies and microorganism can be introduced into the ocular tissues and initiate an infection. In some cases, there may be hematogenous transfer of bacteria from a distant site that can induce the infection.  However, in the majority of cases, the infection is from the adjacent sinuses. When a sinus infection occurs, it can easily extend across the thin orbital wall into the eye tissues and initiate an infection. Once orbital cellulitis occurs, the infection can even be transmitted to the CNS via the valveless veins that interconnect the orbit with the sinuses, eyelid and cavernous sinus.
The mechanical pressure of the edema and inflammatory process (abscess) on the optic nerve and retinal vessels is also responsible for the optic nerve atrophy. When the retinal vessels are compressed as well as the presence of inflammation, it can result in infarction of the sclera, optic nerve, retina and choroid. A rare complication of orbital cellulitis is glaucoma that can present with diminished vision, reduce visual field and an enlarged blind spot.
Orbital cellulitis can not be completely prevented but one can reduce the morbidity of the disorder by seeking immediate attention. Any individual with redness, visual loss and fever should be asked to seek immediate attention from a healthcare professional. Diabetics should ensure that their blood sugars are well controlled and avoid ketoacidosis as this makes them prone to mucormycosis. When the diagnosis of orbital cellulitis is made close followup and compliance with antibiotics is essential. Any patient who presents with visual difficulty, pain or redness around the eye should have the visual acuity measured and have a thorough eye exam.
Orbital cellulitis is a rare infectious disorder of the eye which typically presents with pain, decreased visual acuity, diminished motility of the ocular muscles and prominent proptosis. In the present era of healthcare, complete loss of vision following orbital cellulitis is rare because of improved diagnosis tests and effective antibiotics. In the majority of cases in children there is a prior history of an upper respiratory tract infection before the onset of orbital cellulitis. While most cases of orbital cellulitis can be readily treated, however, whenthe diagnosis is missed, it can lead to a fatal outcome because of extension of the infection to the cavernous sinus and CNS. Further loss of vision can be permanent in some people. Since the widespread use of antibiotics, complications of orbital cellulitis are rarely seen today .
Orbital cellulitis is a serious infection of the eye. It typically occurs after a sinus infection and can present with redness, pain, drainage and poor vision. One should seek immediate medical attention if these symptoms occur. If the treatment is delayed, the eye infection can easily reach the brain tissues and induce seizures, nausea, vomiting and even death. The diagnosis of orbital cellulitis is based on the clinical presentation and imaging studies like the CT scan. The infection is readily treated with antibiotics, but in some cases, surgery may be required to drain the pus. The prgnosis for most patients with orbital cellulitis is good.