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Basics ⬇

Outline

BASICS

Overview!!navigator!!

  • A slowly enlarging, well-defined white or gray mass protruding from the edge of the optic disk into the vitreal chamber. The lesion is generally “fixed” (i.e. it does not move when the eye moves). Can be associated with superficial vascularization and small hemorrhages
  • Systems affected—ophthalmic

Signalment!!navigator!!

Primarily horses >15 years of age.

Signs!!navigator!!

  • None, or minimal effect on vision
  • Pupillary light reflex is normal
  • Generally unilateral
  • No signs of pain
  • Usually incidental finding

Causes and Risk Factors!!navigator!!

Unknown

Diagnosis ⬆ ⬇

Outline

DIAGNOSIS

Differential Diagnosis!!navigator!!

  • Ischemic optic neuropathy
  • Exudative optic neuropathy
    • Traumatic optic neuropathy
  • Optic nerve neoplasia—glioma, astrocytoma, medulloepithelioma, and neuroepithelioma
  • Granuloma
  • Abscesses

CBC/Biochemistry/Urinalysis!!navigator!!

N/A

Other Laboratory Tests!!navigator!!

N/A

Imaging!!navigator!!

N/A

Other Diagnostic Procedures!!navigator!!

N/A

Pathologic Findings!!navigator!!

  • Histologically it resembles a schwannoma in many cases but may also be similar to an astrocytoma or xanthoma
  • Schwannomas are well-circumscribed masses attached to peripheral nerves, cranial nerves, or spinal nerve roots. They contain areas of densely packed spindle cells intermixed with looser, myxoid regions

Treatment ⬆ ⬇

TREATMENT

There is no therapy for this condition.

Medications ⬆ ⬇

MEDICATIONS

N/A

Follow-up ⬆ ⬇

Outline

FOLLOW-UP

Patient Monitoring!!navigator!!

Observe for vision changes.

Prevention/Avoidance!!navigator!!

N/A

Possible Complications!!navigator!!

None

Expected Course and Prognosis!!navigator!!

  • Excellent prognosis for vision and life
  • Slowly progressive in size

Miscellaneous ⬆ ⬇

Outline

MISCELLANEOUS

Associated Conditions!!navigator!!

N/A

Age-Related Factors!!navigator!!

Primarily horses >15 years of age.

Suggested Reading ⬆ ⬇

Brooks DE. Retinopathies and ocular manifestations of systemic diseases in the horse. In: Brooks DE, ed. Ophthalmology for the Equine Practitioner, 2e. Jackson, WY: Teton NewMedia, 2008:207–225.

Dubielzig RR, Ketring K, McLellan GJ, Albert DM. Veterinary Ocular Pathology. Philadelphia, PA: WB Saunders, 2010.

Gilger BC. Equine ophthalmology. In: Gelatt KN, Gilger BC, Kern TJ, eds. Veterinary Ophthalmology, 5e. Ames, IA: Wiley Blackwell, 2013:1560–1609.

Nell B, Walde I. Posterior segment diseases. Equine Vet J Suppl 2010;37:69–79.

Wilkie DA. Diseases of the ocular posterior segment. In: Gilger BC, ed. Equine Ophthalmology, 2e. Maryland Heights, MO: Elsevier Saunders, 2011:367–396.

Author(s) ⬆

Author: Bianca C. Martins

Consulting Editor: Caryn E. Plummer

Acknowledgment: The author and editor acknowledge the prior contribution of Maria Kȁllberg and Dennis E. Brooks.