DISEASES OF THE EYE. 125 



pencil or some such instrument, and turning the margin of the eyelid 

 upward and inward at the same time. Foreign bodies seldom lodge on 

 the cornea, because the action of the haw, aided by the flow of tears which 

 i are at once effused, speedily carries them away. 



Although blows over the eye, or upon it, are not usually productive of 

 dangerous symptoms, yet we occasionally find disastrous results. Concus- 

 sion of the retina may take place from the effect of a violent blow on the 

 eye, and may be followed by temporary or permanent blindness. Again, the 

 humors of the eye may be lost; or the rupture may be internal, and 

 we may then have an escape of blood into the anterior chamber of the eye; 

 or the ciliary margin of the iris may lose its connection, and may after- 

 ward, by process of adhesive inflammation, become attached to some ad- 

 jacent structure; or there may be displacement of the crystalline lens, 

 which may be driven into the vitreous humor; or it may fall forward into 

 the anterior chamber. When the blow is so violent that the cornea is 

 lacerated and penetrated, there is no chance of a cure, because the re- 

 tractor-oculi muscle acts so strongly that the lens is usually forced out. 



Simple ophthalmia often accompanies catarrh and influenza and also 

 dentition. In these cases, however, the affection is only sympathetic, 

 and subsides with the cause. The inflammation of the membrane is only 

 an extension of the inflammation previously existing in the neighboring 

 mucous membrane of the nose or gums. 



Inflammation of the conjunctiva seldom appears as a separate disease. 

 When it cannot be traced either to some external injury or to sympathy 

 with a previously existing affection, such as catarrh or influenza, it should 

 be looked upon with great suspicion, lest it should be the prelude of 

 specific ophthalmia 



In simple ophthalmia, the cornea, from the effect of the inflammation, 

 often has a bluish tint which is peculiar to this form of ophthalmia, and 

 which distinguishes it from periodic ophthalmia; but in other cases it 

 remains clear and bright. The size of the pupil, it is to be particularly 

 remarked, is seldom diminished, whilst in the specific disease this symp- 

 tom is always present. Again, in simple ophthalmia there is a state of 

 general suffusion and redness about the cornea, whilst in the specific disease 

 the vessels which traverse the palpebral portion of the conjunctival mem- 

 brane investing the cornea take a circular direction round it, with rami- 

 fications proceeding toward its centre. 



Treatment. — The treatment of simple ophthalmia, when it arises 



