Prominent Eyes - Part 2 April 2013

(Please let us know if you did not receive part 1)

Further Diagnostic tests for a prominent eye

Ultrasound: can be used to differentiate between solid masses eg a tumour and fluid filled structures such as a retrobulbar abscess or a zygomatic sialocele. The US may also be used to a guide a trucut biopsy or a fine needle aspirate.

X ray: bony changes are suggestive of a tumour. Nasal or sinus adenocarcinomas growing into the orbit or an orbital tumour growing out through the orbital walls into the nasal cavity can be visualized on plain radiographs.

CT scans and NMRI scans: These are the best way to image the orbit, the eye and retrobulbar structures. They usually yield valuable diagnostic information.

Differential Diagnosis of a Prominent Eye

Glaucoma: think breed, red eye, blue eye, with dilated AND non-responsive pupil. For the globe to become enlarged the glaucoma is likely to be chronic. You will then usually also see signs of corneal exposure eg vascular or pigmentary changes. For an enlarged, blind, and potentially painful eye either an ISP—intraocular silicone prosthesis or enucleation is recommended.
Retrobulbar abscess: sudden onset with pain on opening the mouth. Usually young dogs. May need a temporary tarsorrhaphy to protect the cornea from exposure. Most dogs respond well to systemic antibiotics and NSAIDs. Rare that you need to drain these, most discharge spontaneously.
Older cats may have underlying dental disease or a necrotic tumour. Young dogs with recurrent retrobulbar abscesses start looking for a foreign body.
Retrobulbar tumour: slow, progressive onset,in an older dog or cat. Use X ray to define any bone involvement. NMRI or CT Scans are very useful to determine the extent of involvement. Orbital surgery may be indicated., usually requires eye removal.
Mucocele, Sialocele: rare. Present with non-painful fluid like swelling usually of the ventral conjunctiva. Aspiration yields salivary secretions. Surgical removal of the zygomatic salivary gland is indicated.
Globe prolapse: eg in a Peke that has been scruffed tightly, or has had trauma. Prompt globe replacement is indicated. Close eyelids with tarsorrhaphy sutures. Leave these in for 10 to 14 days, systemic antibiotics and prednisolone.
Dilated pupil: eg after atropine administration, or a efferent pathway lesion. A widely dilated can give the impression of a prominent globe. Normal retropulsion, normal IOP, view from above the head, and the eye is not exophthalmic.
Chemosis: this may follow allergic reactions, or Chlamydial conjunctivitis in a cat. The swollen hyperaemic conjunctiva may give the impression of a prominent globe.