Four cases of traumatic optic nerve blindness in the horse

Abstract

Summary Traumatic optic nerve atrophy is characterised clinically by a unilateral or bilateral sudden onset of blindness. Dilated, fixed pupils and a lack of a menace reflex are the only abnormalities noted soon after the trauma. Within three to four weeks the optic disc becomes paler and the retinal vasculature is markedly decreased. The pathological lesion is a rupture of the nerve axons from stretching forces produced by the posterior movement of the brain against the fixed canalicular portion of the optic nerves. Medical therapy has not been successful.

Differential Diagnosis and Management of Cranial Nerve Abnormalities

“…Head trauma is a common injury in the horse, and blindness can result even after recovery from other neurologic deficits, or from even apparently mild trauma that does not lead to unconsciousness. 47 Traumatic optic nerve atrophy presumably results from stretching and/or avulsion of the nerve following a deceleration injury. Typically, the ocular fundus is normal initially, but 3-4 weeks after the incident fundic examination finds a pale optic nerve with decreased retinal vessels.…”

“…Typically, the ocular fundus is normal initially, but 3-4 weeks after the incident fundic examination finds a pale optic nerve with decreased retinal vessels. 47 Treatment of such cases appears unrewarding and blindness is permanent. Meningitis arising from bacterial, viral, parasitic, and mycotic organisms has been reported to be associated with blindness in the horse.…”

Central Nervous System Trauma

“…Moreover, optic nerves and other attachments may be torn from the cerebral hemispheres. 10 Impact to the dorsal surface of the head may result in damage to the frontal or parietal bones with subsequent cerebral cortical injury or, more commonly, damage to the cervical vertebrae with subsequent SCI. 4 Also, cranial nerve XII may be injured as it exits the hypoglossal foramen.…”

Blindness associated with nasal/paranasal lymphoma in a stallion

“…The striking feature of the damage is degeneration and/or atrophy, and there are a variety of possible causes, including trauma, inflammation and glaucoma [2,3,4, 13]. Tumors involving the optic pathway can also be a cause of blindness.…”

“…The various causes of equine blindness associating with degeneration of optic pathway have been reported [2,3,4, 13]. It is relatively uncommon, but the nasal and paranasal sinus tumors have a potential to provoke the visual impairment caused by damage of the optic pathway in relation to their growth and/or invasion.…”