Retrobulbar Abscess in a Cat ~ introvetsurgeon

An abscess or pocket of infection/pus can develop behind the eye, often referred to as a retrobulbar abscess. This is usually associated with inflammation and infection of the tissues behind the eye. Unlike most abscesses where the route of infection is through the skin, retrobulbar abscesses are said to occur when infection or foreign material migrates from either the teeth, gums, eyes or the sinus cavities.

Signs often include bulging of the eye, Facial asymmetry, Swelling of tissues surrounding the eye, prolapse of the third eyelid partially over the cornea, pain upon oral manipulation and examination, quidding, crying when chewing, lethargy and fever.

Clinical examination is the single most important diagnostic technique. Direct orbital palpation and globe retropulsion clearly reveals resistance on the affected side. can also be performed for diagnostic purposes. Signs of pain on orbital and/or oral examination are clinically relevant and hint towards a retrobulbar abscess. Although radiography is occasionally helpful, the image will have a lot of noise making interpretation challenging and a confirmatory diagnosis difficult. Advanced orbital imaging techniques like ultrasound, computed tomography (CT), and Magnetic Resonance Imaging (MRI) are more diagnostic but at the same time expensive and often impractical.

Treatment is aimed at eliminating the infection and creating drainage for evacuation of any pus. Oral antibiotics might be useful in case of orbital cellulitis and early in the course of the abscess. The abscess warrants drainage if it is already mature. The abscess can be lanced through the skin in most cases if palpable topically but will need an intraoral approach (behind the molar teeth) if the abscess is seated caudo-medial to the globe. The location of the abscess has to be elucidated through physical examination and diagnostics prior to establishing a drainage.

Laddu was a 4 year old neutered male. The owners presented with the complaint of unilateral epiphora from the right eye and inappetence. General physical examination revealed no significant insights. The cat was uncooperative for a complete ocular and oral examination. IOP of the right eye was 32 mm H2O and that of the left eye was 17 mm H2O. Topical dorzolamide and timolol was prescribed assuming a Glaucoma. The IOP remained the same on the visit 3 days later and the cat was presented with fever and generalized malaise. Facial asymmetry was also clearly evident owing to the soft and hot to touch swelling caudal to the right eye. It seemed like a retrobulbar abscess at this point in the course of the disease and not glaucoma as considered before. The same was confirmed with ultrasonography as well. The abscess was visible as a hyperechoic patch caudal to the anechoic globe. Hematology and biochemistry revealed no significant findings apart from high band cells count and hyperglobulinemia.

Laddu was sedated using the routine protocol and the abscess lanced carefully taking note of the superficial and deep structures. A complete oral examination revealed no abnormalities. The etiology of this abscess could likely have been an external wound. The abscess healed uneventfully after a 2-week course of antibiotics.

Cat presenting with facial asymmetry and the swollen right retrobulbar region

Ultrasonography of the retrobulbar region showing the anechoic globe and the hyperechoic irregular patch caudal to it representing the abscess. Color doppler showing minimal blood flow, thus ruling out a mass.

Intraoperative video showing the lancing of the retrobulbar abscess