CHAPTER XIV. 



THE OPTIC NERVE. 



The Optic Nerve. — Of this we will have but little to 

 say. The anatomy of the nerve is so well laid clown 

 in Chauveau and the various works on anatomy thab 

 I will proceed at once to an affection called Amaurosis 

 (Ambhjopia). Palsy of the nerve. The term amblyopia 

 is used when there is some impairment of vision for 

 which we can ascribe no cause. Vision is often thus 

 defective where the eye has long been disused — ambly- 

 opia from disuse or ex anopsia. In anaemia subsequent 

 to severe illness or hemorrhages, amemic amblyopia. 

 In lead poisoning. From exposure to prolonged glare, 

 as in snow-blindness. From irritation of the fifth pair, 

 as in neuralgia ; overdosing with quinine. Also tumors 

 and other diseases of the brain implicating the roots of 

 the optic nerve. Injury to the nerve between the 

 brain and eye. Iletinitis. Undue pressure upon the 

 retina from dropsical or inflammatory effusion. Also 

 occurs from overloaded stomach, even from pressure of 

 the gravid uterus. 



Sywjytoms. — The pupils are dilated widely and do 



not react to light. A feint to strike does not cause the 

 117 



