74 Eyelids and Conjunctiva 



enlarged, constituting the disease known as ' granular lids' So 

 loosely is the conjunctiva attached over the sclerotic, however, that 

 large extravasations of blood may occur beneath it. When this is 

 observed after a fall upon the head the question arises as to the 

 existence of a fracture extending across the anterior fossa of the base 

 of the skull, with laceration of the ethmoidal arteries. 



At the inner commissure the conjunctiva forms a mucous fold, the 

 plica semilunaris, the homologue of the horizontal eye-lid of birds, 

 the membrana nictitans. On the inner side of this is the caruncula 

 lachrymalis a collection of sebaceous glands beneath the conjunctiva. 



Chronic conjunctivitis is sometimes spoken of as ' weakness of the 

 eyes ' ; certainly it is often found when vision is imperfect, as the con- 

 stant effort at accommodation is associated with increased flow of blood 

 to the orbit, and with lachrymation. 



In the case of unhealthy children, the chronic condition may some- 

 times be successfully dealt with by counter-irritation at the temple or 

 behind the ear. Such beneficial effect has sometimes been inadver- 

 tently produced by piercing the lobe of the ear and inserting a ring, with 

 the inartistic idea of personal adornment, and thus it has come about that 

 * ear-rings are good for weak eyes.' The late Mr. Critchett told the writer 

 that some of his first success in practice was due to his having treated 

 chronic conjunctivitis by a slender seton behind the ear, * so that,' said he, 

 ' friends remarked that my reputation hung on a thread ! ' 



Sometimes a thick triangular growth of the conjunctiva extends 

 from near one of the commissures towards the pupils ; it is- called a 

 pterygium (rrrepvyiov, a little wing), and, passing over the pupil, it ulti- 

 mately obscures the vision. It may have to be removed by the opera- 

 tion of transplantation. 



The Meibomi an glands are arranged in pearly rows beneath the con- 

 junctiva, imbedded in the tarsal cartilages ; they can be seen on everting 

 the lids, and their minute orifices detected near the eye-lashes. Their 

 sebaceous secretion oozes upon the edges of the lids to lubricate the 

 cornea and to render it waterproof. 



Should secretion be retained in one of the Meibomian follicles, a 

 small hard tumour is felt in the substance of the lid. It is called a 

 chalazion (^aXa^a, hail) or tarsal tumour. It is treated by everting 

 the lid and scooping out the contents of the cyst. 



Supplementary sebaceous glands also open at the roots of the eye- 

 lashes, and, should one of them become inflamed, the condition is 

 known as hordeolum (hordeum, a barley-corn) or stye. 



Supply. The conjunct! val arteries are derived from the palpebral, 

 lachrymal, and other branches of the ophthalmic ; the nerves come from 

 the ophthalmic and infra-orbital parts of the fifth. 



Haemorrhages beneath the conjunctiva which occur in an oldish sub- 

 ject after an attack of coughing or vomiting are suggestive of atheroma, 

 and sometimes come as warnings of an apoplectic storm. 



