Definition. Neurites descendens and ascendens. Extension to bulb,
other eye, or brain. Causes: traumas, meningitis, infectious diseases,
toxins, lead, tobacco, etc. Symptoms: partial blindness: congestion of
papilla, exudates in adjacent retina. Treatment: eliminate poisons,
lead, toxins, correct precedent disease, saline laxatives, diuretics,
potassium iodide, cupping, local bleeding, counter-irritants. Hygiene.
This is inflammation of the optic nerve commencing behind the eyeball
and only involving the papilla secondarily. Extension to the papilla has
been called _neuritis descendens_ in contradistinction to _neuritis
ascendens_ in which the inflammation extends along the nerve toward the
brain. There is always a tendency to extension, it may be to the papilla
and retina, it may be to the chiasma and opposite eye, and it may be
inward toward the ganglia and choroid plexus.
_Causes._ Apart from traumatic causes, retro-bulbar neuritis in the
domestic animals has been mainly seen in connection with constitutional
or infectious diseases; in the horse with petechial fever (Peters),
contagious pneumonia (Schindelka), meningitis (Peters, Straub) and
parotitis (Möller). It has also followed meningitis in cattle (Nebelen).
In man it has been traced to lead, tobacco, alcohol and other poisons.
_Symptoms._ At first the patient may seem partially blind without
apparent cause. Later ophthalmoscopic examination reveals congestion and
swelling of the papilla, and congestion (especially venous and
capillary) of the retinal vessels. The discolorations in streaks and
spots, from exudates and degenerations follow as noticed under
papillitis. It is difficult to distinguish between this and papillitis
during life.
_Treatment_ should be first directed toward the elimination of any
poisons, such as lead or tobacco, which may act as a causative factor.
Saline laxatives and in chronic cases potassium iodide would be
indicated. Every attention should be given to the maintenance of good
general health, and in acute attacks, local bleeding and
counter-irritation may be resorted to.