>Periorbital Inflammation – Red Eye – Red Flags


Medical Student Clinical Pearl

Alysha Roberts

MD Candidate, Class of 2021

Dalhousie University


Reviewed & Edited by Dr David Lewis (@e_med_doc)

All case histories are illustrative and not based on any individual.


A 40 year old male presents to the emergency department with a red, swollen eye. Without a known trigger, he had a one day history of progressive pain, erythema, and edema surrounding his left eye. He denied any fever or chills or visual changes, or headache. A thorough review of systems was negative, except for a complaint of worsening pain with extraocular movement.

On exam, he was afebrile and his vital signs were within normal limits. His visual acuity was normal, and pupils were equal and reactive to light. Extraocular movements were intact but associated with worsening pain. The periorbital tissue was erythematous, edematous, and hot to touch. Examination is limited by the severity of the patient’s swelling. Figure 1 illustrates an example of a patient with severe, unilateral eyelid swelling and erythema.

You suspect periorbital cellulitis.

Figure 1. Unilateral eyelid edema. Retrieved from https://www.merckmanuals.com/professional/eye-disorders/orbital-diseases/preseptal-and-orbital-cellulitis


Periorbital Versus Orbital Cellulitis

Periorbital cellulitis, commonly referred to as pre-septal cellulitis, is an infection of the skin and soft tissue surrounding the orbit. Most commonly, it is the result of an infection spreading from the sinuses or from local trauma.1,2 It presents as a unilateral swelling of the eye-lid. Both periorbital and orbital cellulitis are most commonly caused by Staphylococcus Aureus and Streptococcus Pneumoniae. It is important to distinguish periorbital from orbital cellulitis, which is an infection of the orbit itself extending beyond the orbital septum. Orbital cellulitis is a sight-threatening emergency, and urgent imaging should be acquired in addition to consultation with ophthalmology or otolaryngology.3 Other complications of orbital cellulitis include orbital or subperiosteal abscess, and cavernous sinus thrombosis. Figure 2 illustrates the difference between periorbital (preseptal) and orbital cellulitis, as well as its complications.

Figure 2. Orbital anatomy and potential complications from orbital cellulitis. Retrieved from https://www.merckmanuals.com/professional/eye-disorders/orbital-diseases/preseptal-and-orbital-cellulitis

Any patient with unilateral eyelid edema should be evaluated for red flags of orbital cellulitis, given its potential seriousness. Red flag signs and symptoms include:3,4

  • Painful or restricted extraocular movements
  • Reduced visual acuity
  • Relevant afferent pupillary defect
  • Diplopia
  • Proptosis
  • Chemosis
  • Severe headache


Differential Diagnosis

Other considerations for the differential diagnosis in a unilateral, swollen red eye include:5

  • Periorbital ecchymosis due to blunt trauma
  • Contact dermatitis secondary to local irritant
  • Atopic dermatitis due to allergic sensitivity
  • Orbital tumors


Risk Factors

Risk factors for periorbital and orbital cellulitis include:6

  • Sinusitis
  • Dental infection
  • Insect bite
  • Trauma


Periorbital cellulitis is most commonly caused by an insect bite in children, and trauma in adults. Comparatively, orbital cellulitis is most often the result of trauma in children, and sinusitis in adults.


Diagnostic Investigations

Patients who are febrile or appear unwell should have early initiation of IV antibiotics following blood cultures. Though periorbital cellulitis is a clinical diagnosis, if there is suspicion for orbital cellulitis a CT scan of the orbits and sinuses is the gold standard. Positive findings include inflammation of extraocular muscles, anterior globe displacement, and fat stranding. Inflammation of the sinuses should not be used to differentiate periorbital from orbital cellulitis, as up to 41% of cases of periorbital cellulitis may have CT evidence of sinusitis. Figure 3 displays a labelled CT image with common findings in orbital cellulitis.7


Figure 3. Orbital CT image with labels. Retrieved from https://ctscanmachines.blogspot.com/2018/07/ct-scan-of-periorbital-cellulitis.html

In addition to CT imaging, there may be a role for point of care ultrasound (PoCUS) in the diagnosis and management of periorbital and orbital cellulitis. However, research is currently lacking on whether its use may avoid the need for further diagnostic imaging.8 Findings from pediatric emergency medicine suggest that orbital ultrasound may be preferred in evaluating young patients who are unable to cooperate with a thorough physical examination.9 One important application of orbital PoCUS is in the assessment of orbital abscesses. Subperiosteal abscesses may complicate more than 50% of cases of orbital cellulitis, and are not reliably detected by CT.10 Additionally, orbital ultrasound may be an appropriate alternative in settings where advanced imaging is not available, in order to guide early initiation of antibiotics.

Orbital Abscess from – The PoCUS Atlas



Treatment Best Practices  

Antibiotic choice should be guided by local susceptibility guidelines. An appropriate choice would cover S. aureus, S. pyogenes, and anaerobes.11,12 In this case, we initiated intravenous ceftriaxone and metronidazole while awaiting CT results.

The following therapeutic guidelines are from Bugs and Drugs – It is recommended that that guidelines for therapy are accessed directly from their website or from other reputable sources.

Periorbital Cellulitis


Orbital Cellulitis

From Bug and Drugs


Case Conclusion

Given this patient’s complaint of increased pain with extraocular movement, a CT orbit was performed. Fortunately, there were no signs of orbital cellulitis. The patient was treated with IV ceftriaxone and metronidazole and scheduled to return to the emergency department the next day for re-evaluation and consideration of step-down to oral antibiotics.


Orbital cellulitis is a serious condition that should be carefully distinguished from periorbital cellulitis. On history, clinicians should ensure they inquire about recent sinus or dental infections, trauma to the orbit, or possible insect bites. Physical exam should carefully assess for signs of orbital cellulitis, including proptosis, chemosis, and limited extraocular movements. Any positive red flag or clinical suspicion warrants a CT scan of the orbits and sinuses to exclude orbital cellulitis.

Further Reading

Great photo article in Canadian Family Physician

Management algorithm

Patient Information Leaflet





  1. Preseptal and Orbital Cellulitis – Eye Disorders – Merck Manuals Professional Edition. (n.d.).Retrieved January 12, 2021, from https://www.merckmanuals.com/professional/eye-disorders/orbital-diseases/preseptal-and-orbital-cellulitis
  2. Lightning Learning: Orbital Cellulitis — #EM3: East Midlands Emergency Medicine Educational Media. (n.d.). Retrieved January 12, 2021, from https://em3.org.uk/foamed/7/5/2019/lightning-learning-orbital-cellulitis
  3. Periorbital cellulitis — entsho.com. (n.d.). Retrieved January 12, 2021, from https://entsho.com/periorbital-cellulitis
  4. Distinguishing Periorbital from Orbital Cellulitis. (2003). American Family Physician, 67(6), 1349.
  5. Differential Diagnosis of the Swollen Red Eyelid – American Family Physician. (n.d.). Retrieved January 12, 2021, from https://www.aafp.org/afp/2015/0715/p106.html
  6. Risk factors of preseptal and orbital cellulitis – PubMed. (n.d.). Retrieved January 12, 2021, from https://pubmed.ncbi.nlm.nih.gov/19149979/
  7. Ct Scan Of Periorbital Cellulitis – ct scan machine. (n.d.). Retrieved January 12, 2021, from https://ctscanmachines.blogspot.com/2018/07/ct-scan-of-periorbital-cellulitis.html
  8. Kang, T. L., Seif, D., Chilstrom, M., & Mailhot, T. (2014). Ocular ultrasound identifies early orbital cellulitis. Western Journal of Emergency Medicine, 15(4), 394. https://doi.org/10.5811/westjem.2014.4.22007
  9. Seguin, J., Le, C.-K., Fischer, J. W., Tessaro, M. O., & Berant, R. (2019). Ocular Point-of-Care Ultrasound in the Pediatric Emergency Department. Pediatric Emergency Care, 35(3), E53–E58. https://doi.org/10.1097/PEC.0000000000001762
  10. Derr, C., & Shah, A. (2012). Bedside ultrasound in the diagnosis of orbital cellulitis and orbital abscess. Emergency Radiology, 19(3), 265–267. https://doi.org/10.1007/s10140-011-0993-0
  11. Orbital Cellulitis – StatPearls – NCBI Bookshelf. (n.d.). Retrieved January 12, 2021, from https://www.ncbi.nlm.nih.gov/books/NBK507901/
  12. Periorbital Cellulitis – StatPearls – NCBI Bookshelf. (n.d.). Retrieved January 12, 2021, from https://www.ncbi.nlm.nih.gov/books/NBK470408/
Print Friendly, PDF & Email