Subscleral trabeculectomy (SST) is the gold standard technique for the management of nearly most glaucoma cases. Many complications, either intraoperative or postoperative, have been reported to be associated with SST. No publication has reported orbital abscess following SST; to best of our knowledge, only ten cases of orbital cellulitis have been reported following the use of glaucoma drainage devices [1],[2],[3],[4],[5],[6],[7],[8],[9],[10].

A 53-year-old female patient was referred for the management of uncontrolled primary open angle glaucoma. She had a surgical history of bilateral phacoemulsification approximately two years prior. She had a medical history of controlled hypertension and, right bundle branch block; otherwise, the patient was systemically free. On presentation, her visual acuity (VA) was 1/60 in the right eye and 6/24 in the left eye. Her intraocular pressure (IOP) was 30 mmHg in the right eye on full topical antiglaucoma medication and 14 mmHg in the left eye on combined beta blockers and carbonic anhydrase inhibitors. Anterior segment examination revealed clear cornea, posterior chamber intraocular lens (IOL) and opened anterior chamber angle gonioscopy. Posterior segment examination revealed advanced disc cupping in the right eye with (a cup-to-disc ratio) C/D of 0.95, whereas the C/D ratio of the left eye was 0.60. The patient was advised to undergo SST in the right eye, and the patient agreed. Routine preoperative labs including complete blood count (CBC), erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), liver function test, kidney function test, and conjunctival swab test (which is performed routinely at our institute before ocular surgeries) were used. All the labs were within the normal limits apart from positive conjunctival swabs for Escherichia coli, for which the patient received topical eyedrops and the test turned negative before surgery.

Uneventful SST under peribulbar anaesthesia was performed on the patient with mitomycin C (MMC) application. The first-day post-operative follow-up revealed that the VA was the same (1/60), a clear cornea, no evidence of bleb leakage, an IOP of 10 mmHg and no obvious fundus abnormalities. After one week, the patient presented the same picture. Ten days later, the patient developed right hypertropia with limited right ocular motility in the inferior gaze associated with conjunctival chemosis.

Her body temperature was 37.0 degrees; in addition, we asked for CBC, ERS, and CRP. We also performed MRI brain and orbit to exclude both central and local causes, especially because the patient showed subtle local signs. The CBC and CRP returned to within normal limits, and the ERS was slightly elevated; therefore, we started empirical oral broad-spectrum antibiotics (in the form of ciprofar 750 mg tab twice daily) and low doses of systemic steroids (solupred 20 mg once daily) while waiting for the results of neuroimaging.

While pending the investigation results, there was a progressive worsening of the patient’s condition, with limited ocular motility in the lateral gazes with marked conjunctival chemosis. Visual acuity (VA), IOP, and fundus examination results were unchanged, body temperature was 37.1 degrees, so the patient was hospitalized and we started intravenous (IV) antibiotics in the form of empiric intravenous antibiotics third-generation cephalosporins (ceftazidem 500 mg twice daily), diflucan 150 mg every 72 hour and flagyl 500 mg every 12 hours while the body temperature was assessed twice daily, routine labs in the form of ESR CBC and renal functions were performed on a daily base.

One day later, the patient’s clinical status worsened with the development of a frozen globe while the body temperature was unchanged (Figure 1). At that time, the MRI orbit returned with orbital collection, so lateral canthotomy, inferior cantholysis, and evacuation for orbital collection were performed for the patient with culture and sensitivity for the resultant discharge, which subsequently became negative (Figure 2).

Four days later, the patient developed marked proptosis with progressive conjunctival chemosis, so CT was ordered for the patient which revealed right orbital wall heterogeneous lesion showing hypodense areas inside with involvement of the lateral rectus muscle and medial displacement of the inferior rectus muscle with no effect on the optic nerve or cavernous sinus and evidence of right proptosis. Orbital evacuation was performed again with an orbital drain, and systemic antibiotics with the same pervious regimen were continued while the renal function test was observed (Figure 3).

After one week, the patient showed regression of proptosis and conjunctival chemosis so, the drain was removed, and the patient was switched to oral antibiotics in the form of ciprofar 750 mg twice daily. Three weeks later, the patient started to regain ocular motility. Complete recovery of ocular motility was noticed after additional two weeks (Figure 4).

Orbital abscess is a rare but potentially life-and sight-threatening condition that requires prompt recognition and management due to its proximity to critical structures such as the optic nerve and the risk of rapid intracranial spread [11]. It typically arises from trauma, sinusitis, dental infections, or postoperative complications, and presents with acute pain, decreased vision, lid edema, proptosis, and restricted ocular motility. Systemic symptoms such as fever, lethargy, and headache may be observed in larger abscesses [11]. Early diagnosis through imaging and timely intervention is essential to prevent irreversible ocular or systemic complications.

Postoperative orbital abscess following glaucoma or ocular surgeries is exceedingly rare. Orbital cellulitis has been reported in only a few cases after glaucoma drainage implantation, strabismus surgery, orbital fractures, and orbital implants, often associated with predisposing factors such as tube exposure, scleral perforation, or sinus communication [10],[12],[13],[14],[15]. In our case, the patient developed orbital abscess following an otherwise uncomplicated SST without any evident ocular source of infection, such as a leaking bleb or exposed sutures. The delayed onset of systemic symptoms and gradual progression of ocular signs complicated early diagnosis. To our knowledge, there are no publications concerning early postoperative orbital cellulitis following SST surgery. Given the absence of identifiable predisposing factors and the fact that SST does not violate the orbital septum, we hypothesize that local anesthesia may have contributed to the infection, particularly considering prior conjunctival colonization with E. coli, although cultures at discharge showed no growth.

Publications have reported orbital cellulitis following cataract surgery under both peribulbar and subtenon anesthesia, which occurs nearly within the first week after surgery [16],[17]. To our knowledge only one case of orbital abscess has been reported after phacoemulsification [18]. Orbital abscess has also been reported after posterior subtenon steroid injection [19].

Escherichia coli is a rare cause of orbital abscess compared with Gram-positive cocci like Staphylococcus aureus and Streptococcus species [20],[21],[22]. In a series of 56 cases, E. coli was isolated in a minority of infections and associated with higher ocular morbidity. While empirical therapy targets Gram-positive cocci, culture-directed treatment is essential, particularly in immunocompromised patients, as E. coli can cause aggressive endogenous panophthalmitis [23].

Postoperative orbital inflammation can mimic infectious abscess, notably in hypersensitivity to peribulbar anesthesia with hyaluronidase. Such reactions may present with edema, proptosis, chemosis, and motility restriction, often without systemic symptoms, and typically resolve quickly with steroids. Positive intradermal testing can confirm the allergy [24],[25].

Early suspicion and timing of the intervention are important, particularly given that our patient already had a compromised optic disc, which may be affected very easily by compression.

Orbital abscess is an extremely rare condition following ocular surgery, especially in those without damage to the orbital septum. Orbital cellulitis with subsequent development of orbital abscess has been reported following cataract surgeries in which local anaesthesia was used as the cause. Accurate and rapid interventions are very important for saving these patients.