DEPARTMENT OF SURGERY 
543 
(a) Ruptures. —Concussions or compressions may cause a 
rupture of the eyeball, choroid coat, zonula of Zinn, intraocular 
blood vessels or capsule of the lens ; each of these may occur 
singly, but in some instances, two or more of these ruptures are 
caused by the same injury. (£) Detachments. —The retina, 
choroid or iris are occasionally detached by concussions and 
sometimes lacerated. Detachments of the retina more com¬ 
monly result from morbid conditions that are not caused by 
traumatic injuries, although such injuries followed by a loss of 
vitreous humor is sometimes followed by such a condition. 
Concussion of the retina (< commotio retince ) is probably the most 
common condition following such injuries, and may terminate 
in oedema of the retina, which is a very serious sequel ; or, it may 
produce a condition known as traumatic anaesthesia of retina 
marked by only a temporary impairment of vision. Detach¬ 
ment of the choroid is a rare condition and seldom occurs without 
a displacement of the retina ; although it is an exceedingly 
rare condition, it is known to be caused by concussion of the 
eyeball (. Amer. Jour. Opthal ., Mar., pj). Detachment of the 
iris is a common condition resulting from contusions, concus¬ 
sions or compressions of the eyeball. In some instances the iris 
is detached from the entire peripheral attachment ( traumatic 
aniridia ), while in others, only part of it is detached from its 
periphery ( iridodialysis ). Beside these detachments, we may 
detect radial and meridional lacerations, (c) Lacerations of the 
iris and ciliary bodies. The iris may be lacerated in various 
ways ; the radial fibres alone are sometimes torn, while in other 
instances both meridional and radial fibres are involved ( trau¬ 
matic colobomd). Lacerations of the ciliary bodies are not easily 
detected and seldom, if ever, occur without complications. 
(d) Paralysis of the iris and ciliary muscle are two condi¬ 
tions that occasionally are caused by trauma. Paralysis of the 
iris ( iridoplegia ) due to injuries to the eye may be of short du¬ 
ration, lasting but a few days, but in some cases, especially 
when associated with other injuries, the dilatation of the pupil 
(mydriasis ) becomes permanent; this is caused generally by 
adhesions of the iris to surrounding structures. Paralysis of 
ciliary muscles (, cycioplegia ) sometimes follows concussions, or 
contusions, of the eye. This, however, is not so serious as 
iridoplegia. 
(e) Spasms of iris and ciliary muscle are conditions that are 
not very common, at least they are not detected in domestic 
animals. 
