Orbital infection is a bacterial, viral or parasitic infection of tissues around the eyes. It can lead to a dramatic outcome and fast management of this infection is critical for the preservation of eyesight and prevention of possible meningitis.
When orbital infection (OI) is suspected, patient history should be taken into account as some non-infectious etiologies can mimic the presentation of this disease. Hence, inquiries about recent insect stings, battles, trauma, allergies should be made. Furthermore, a survey about traveling, and any factors contributing to infection, like immunosuppressive medication use, chronic diseases is also significant. Patients with orbital infection may have had previous occasions of infections in structures anatomically close to the orbit e.g. a dental abscess or sinusitis. Likewise, respiratory system infections are known to be associated with OI [1].
Orbital infection is divided into five groups [2]:
Each group manifests in individual ways. For instance, preseptal cellulitis affects eyelids, thus clinical presentation is inflammation of the eyelid with edema, warmth, pain, and erythema [3].
Orbital cellulitis (OC) exhibits as inflammation of fat tissue surrounding the globe. In this case, the edematous lid will not show signs of inflammation, as edema arises from disrupted venous outflow. Additionally, eyelids can show signs of palsy due to compression of the oculomotor nerve. Other signs of orbital cellulitis are chemosis, displacement of the orbit (proptosis), as well as disturbed vision [1].
Subperiosteal abscess clinically presents as proptosis, restricted mobility of the eye, and sensations of pain during motion [2].
Orbital abscess presents with more serious proptosis, in addition to ophthalmoplegia, and disturbed visual acuity. Palsy of abducens nerve is possible resulting in diplopia or double vision [2].
Cavernous sinus thrombosis is characterized by bilateral photophobia, proptosis, ophthalmoplegia, hypoesthesia of the cornea. Paresis or palsy of cranial nerves IV and VI are seen as well [4].
Severe cases of orbital infection can cause complications like meningitis, infarction of orbital structures such as the optic nerve, sclera, choroid and retina. Infarction may arise due to compression of surrounding arteries with mass lesions or inflammation [5]. Glaucoma, although a rare manifestation, can present in OI by interfering with visual acuity [6].
For workup of orbital infection, radiologic investigations are essential to visualize the lesions, their localization, severity and spread to nearby tissues. Computed tomography (CT) scan of the orbit, sinuses, and frontal lobe is one of the primary modalities for diagnosis. Contrast is commonly used to exclude the presence of artifacts. In pediatric patients, it is important to lower the dose of radiation [7] by choosing magnetic resonance imaging (MRI) over CT scan.
MRI scan is less cost-effective but more specific in investigating the soft tissues, specifically those that are infected. Also, MRI creates the possibility to visualize the spread of the orbital lesion and is better in distinguishing the cavernous sinus [8]. To further increase accuracy rate of the MRI, a contrast enhanced scan (gadolinium-based intravenous contrast) is used, particularly if there is high suspicion of infectious advancement deeper into anatomical structures [9]. T1-weighted imaging typically exposes infiltrations into periorbital fat if they exist. On the other hand, T2-weighted imaging distinguishes infectious lesions that are identified by hyperintense properties [10] [11]. MRI findings also include abscess masses, a presence of inflammation marked by enhanced eyelids and soft tissues of the orbit [11].
Laboratory studies comprise blood glucose level, complete blood count, as well as cerebrospinal fluid (CSF) analysis if meningitis is suspected. In presence of fever, a blood sample for possible leukocytosis must be obtained [10] [6].