It is important to correlate physical findings with patient history and reported symptoms.CT scan and MRI of the orbits are two imaging modalities that are commonly used to aid in the diagnosis and monitoring of orbital cellulitis, as they can provide detailed images that can show the extent of inflammation along with possible abscess location, size, and involvement of surrounding structures. Ultrasound has also been used as an imaging modality in the past, but it cannot provide the same level of detail as CT or MRI.Blood cultures, electrolytes, and a complete blood count (CBC) with differential showing elevated white blood cell count is a useful laboratory test that may aid in diagnosis. Differential Diagnosis
A variety of pathologies and diseases can present similarly to orbital cellulitis, including:
Inflammatory causes (thyroid eye disease, idiopathic orbital inflammatory syndrome, sarcoidosis, granulomatosis with polyangiitis)
Infectious causes (subperiosteal abscess)
Neoplastic, benign and malignant (dermoid cyst, capillary hemangioma, rhabdomyosarcoma, optic nerve glioma, lymphangioma, neurofibroma, leukemia)
Trauma (orbital fracture, retrobulbar hemorrhage, orbital foreign body, carotid cavernous fistula)
Malformation (congenital, vascular)

Treatment
Immediate treatment is very important, and it typically involves intravenous (IV) antibiotics in the hospital and frequent observation (every 4–6 hours). Several lab tests should be ordered, 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.
Epidemiology
Orbital cellulitis is an uncommon medical condition, with the reported rates being much higher among the pediatric population compared to the adult population. One study reported that children are approximately 16 times more likely to suffer from orbital cellulitis compared to adults. It is twice as common among male children compared to female children. Some studies reported that orbital cellulitis follows a seasonal pattern, with the highest rates occurring during the fall and winter, which coincides with the higher rates of sinus infection during the colder months. References
Noel LP, Clarke WN, MacDonald N (1990). "Clinical management of orbital cellulitis in children". Canadian Journal of Ophthalmology. 25 (1): 11–16. PMID 2328431. Shapiro E, Wald E, Brozanski B (1982). "Periorbital cellulitis and paranasal sinusitis: a reappraisal". Pediatric Infectious Disease. 1 (2): 91–94. doi:10.1097/00006454-198203000-00005. PMID 7177909. S2CID 24237202. External links

MedlinePlus. Death Rates for Orbital Cellulitis
Pub Med Health - Orbital Cellulitis