Overview

• Sympathetic denervation to the eye.
• Anatomic pathway very important.
• Affects the ophthalmic and nervous systems.

Signalment

• Idiopathic-one study suggests male golden retrievers 4–13 years of age at increased risk. Most of these localize to a postganglionic lesion.
• Idiopathic-dogs, 50–93%; cats, 45%.
• Other causes-N/A.

Signs

• Miosis.
• Protruding third eyelid.
• Ptosis (drooping) of upper eyelid.
• Enophthalmia.
• Other neurologic and non-neurologic signs dependent on the underlying cause.

Causes & Risk Factors

See Table 1.

Differential Diagnosis

Anterior uveitis-IOP usually low; aqueous flare.

CBC/Biochemistry/Urinalysis

N/A

Other Laboratory Tests

N/A

Imaging

• See Table 1.
• Thoracic radiographs-may reveal cause of injury to the sympathetic trunk (e.g., trauma and mediastinal tumor).
• Skull radiographs-may reveal middle ear problem.
• MRI-may help identify brainstem lesion, retrobulbar mass, cervical spinal cord problem.
• CT may help identify middle ear problem.
• Ultrasonography-orbit; may reveal retrobulbar mass.

Diagnostic Procedures

See Table 1.

• CSF tap-investigate brain and spinal cord disease.
• Electromyography-look for brachial plexus avulsion.
• Pharmacologic testing-see Anisocoria.

Treatment

Treat underlying disease.

Drug(s)

• Depends on underlying disease
• Idiopathic-none

Contraindications/Possible Interactions

Do not use drugs which alter the autonomic nervous system prior to referral for lesion localization.

Miscellaneous

Abbreviations

• CN = cranial nerve
• CSF = cerebrospinal fluid
• CT = computed tomography
• FCE = fibrocartilagenous embolism
• IVDH = intervertebral disc herniation
• MRI = magnetic resonance imaging