Definition

Orbital cellulitis is a severe infection affecting the fatty tissue and eye muscles situated behind the orbital septum, a thin membrane that separates the eyelid from the eye socket. This condition, often referred to as post-septal cellulitis based on the infected organ, poses significant risks and can lead to lasting complications. 

Orbital cellulitis may impact one or both eyes, with symptoms arising suddenly or following another eye infection spreading to surrounding tissues. While individuals of all ages can develop orbital cellulitis, it is more frequently observed in children. If not properly treated, it can result in blindness.

Causes

Approximately 98% of orbital cellulitis cases originate from untreated sinus infections (sinusitis) that spread to the area behind the orbital septum. The causative pathogens may be commensal skin bacteria or other bacterial species. Historically, sinusitis due to Haemophilus influenzae was the most common cause, especially in children under seven years old. However, the prevalence has declined due to the HiB vaccine. 

Common bacteria currently implicated include Staphylococcus aureus, Streptococcus pneumoniae, and beta-hemolytic Streptococcus. In children under nine years old, a single bacterial species is typically responsible for the infection, while older children and adults often have polymicrobial infections, complicating treatments. Rare cases may involve aerobic, anaerobic bacteria, or fungi, particularly in immunocompromised individuals such as those with HIV/AIDS, diabetes, or on immunosuppressive medications. In newborns, consider Gonorrhoea and Chlamydia as potential bacterial causes.

This condition can also arise from infections spreading from the teeth or other body areas via the bloodstream. Additionally, wounds or insect bites around the eyes can precipitate orbital cellulitis.

In children, orbital cellulitis infections can rapidly progress, potentially causing blindness, necessitating urgent medical intervention.

Risk Factors

Several conditions can increase the risk of developing orbital cellulitis, including:

• Upper respiratory tract infections, such as sinusitis
• Dental, middle ear, or facial infections
• Dacryocystitis, an infection of the lacrimal glands
• Eye injuries involving fractures or foreign bodies
• Eye surgeries
• Periorbital anesthesia
• Immunodeficiency conditions, such as HIV/AIDS or diabetes

Symptoms

Symptoms of orbital cellulitis include:

• Painful swelling of the eyelids, eyebrows, or cheeks
• Eye redness
• Difficulty opening the eyes
• Pain with eye movement
• Protruding eyes
• Double vision
• Impaired eye movements
• Decreased or loss of vision
• Fever, typically >38.8°C
• General weakness
• Headache

Diagnosis

Diagnosis of orbital cellulitis involves patient interviews, physical examinations, and diagnostic tests if needed. Initially, the doctor will inquire about recent surgeries, dental procedures, facial injuries, skin conditions, or sinusitis.

The following examinations are typically conducted:

• Eye movements: Assessing pain during eye movements.
• Visual acuity and color vision: Decreased acuity or color vision may indicate optic nerve issues.
• Proptosis: Evaluating the protrusion of the eye.
• Visual field: Using the confrontation test to assess the visual field.
• Pupillary reflex: Problems in this reflex may suggest optic nerve disorders.
• Intraocular pressure: Increased pressure might indicate venous blockage in the eye.
• Slit-lamp biomicroscopy: Examining the front segment of the eyeball.
• Ophthalmoscopy: Checking the retina and optic nerve condition.

Diagnostic tests are considered for pediatric patients or cases unresponsive to antibiotic therapy with worsening symptoms, as they help detect complications early. These may include:

• Complete peripheral blood check: To identify elevated white blood cells, indicating bacterial infection.
• Blood culture: To identify the causative germ.
• Fluid cultures: The samples are taken from the eye, ear, or throat.
• Lumbar puncture: In children with specific conditions.
• X-rays: Scans of the sinuses and surrounding areas.
• CT scan: Scans of the sinuses, eyes, or head to distinguish orbital cellulitis from preseptal cellulitis and detect early complications.
• MRI: Scans of the sinuses, eyes, or head to examine soft tissues.

Management

In many cases, hospitalization is often required, especially in mild to moderate cases without optic nerve complications. Initial treatment involves intravenous antibiotics and supportive medications. Surgery may be necessary to drain pus or relieve pressure around the eye. Due to the rapid progression of orbital cellulitis, frequent monitoring is essential. With prompt treatment, full recovery is possible.

Ophthalmologists and otolaryngologists collaborate to determine the appropriate therapy. Surgery is considered for patients with brain infections, those unresponsive to antibiotics, optic nerve involvement indicated by worsening vision or pupil changes, large abscesses (>10 mm), clinical deterioration, or recurrent abscesses. Surgical intervention helps stop the infection by draining infectious fluid from affected organs like sinuses or teeth. Without proper diagnosis and treatment, the infection can spread and cause severe complications.

During hospitalization, patients are monitored for worsening brain infection complications, which can be life-threatening. If improvement is observed within 48 hours of intravenous antibiotics, therapy is transitioned to oral antibiotics. Comorbidities such as sinusitis are also treated. With timely and appropriate treatment, orbital cellulitis can be cured.

Complications

Complications of orbital cellulitis include:

• Corneal damage
• Glaucoma
• Uveitis or retinitis
• Retinal detachment
• Panophthalmitis (widespread infection of the eyeball and its tissues)
• Retinal blood vessel blockage
• Abscesses in the bone covering, eyeball, or brain
• Hearing loss
• Septicemia (widespread blood infection)
• Meningitis (inflammation of the brain's covering)
• Decreased visual acuity
• Cavernous sinus thrombosis (blood clots in the brain's cavity)
• Optic nerve damage and vision loss (11% of cases)
• Brain infection
• Brain nerve damage

Prevention

The HiB vaccine can effectively prevent most cases of orbital cellulitis in children. Children with family members who have experienced this infection may require prophylactic antibiotics, which should always be administered under medical supervision. Timely treatment of sinus or dental infections can also prevent their progression to orbital cellulitis.

Experiencing orbital cellulitis once does not guarantee a recurrence. However, individuals prone to recurrent sinusitis should be vigilant about their health and seek immediate treatment if sinusitis symptoms appear to prevent infection spread and future recurrence. This is particularly crucial for those with weakened immune systems.

When to See a Doctor?

Orbital cellulitis constitutes a medical emergency requiring immediate treatment due to the rapid spread of infection. Promptly consult a doctor if you experience sinusitis or any of the aforementioned symptoms of orbital cellulitis.

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